evaluation of early maturing, medium maturing and...
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CHAPTER–III
EVALUATION OF EARLY MATURING, MEDIUMMATURING AND PROCESSING GENOTYPES/ HYBRIDSFOR STORAGE BEHAVIOUR AND PROCESSINGCHARACTERS OF THE PROCESSING HYBRIDS/GENOTYPES
3.1. INTRODUCTIONIn India about, 67 per cent of total potato produced being consumed as vegetable.
Around 10 per cent as seed, less than 10 per cent as for processing purpose, another less than
1 per cent is exported and around 12 per cent goes as waste. The status of potato processing
varies in different countries of the World. Among various countries, USA stands 1st and
process about 60 per cent, the Netherlands 47 per cent and China 22 per cent, whereas, India
process about 10 per cent of the total production. In recent years the demand for processed
products has been increased in India and in the whole World. The rise noticed to be due to
increased urbanization, rise in per capita income, increase in number of working women and
expanding tourism.
In India potato processing is an emerging industry due to the increased demand for the
processed products. Besides the traditional potato products like dehydrated chips, Papads,
Varies and Lacchas, products like fried chips, French fries and other western processed
products are gaining popularity in India. However, the quality of the processed products in
India is not upto the mark due to the poor quality of potatoes used. This is mainly due to non
availability of Indian potato varieties for processing. Potato varieties with specific quality
attributes are required for processing purposes. Potato processing quality refers to specific
traits or characters, which need to be present in potato for making processed products of
established standards.
The storage behaviour of a particular potato variety is a varietal character and it
depends on its dormancy period and weight loss. The storage pest (PTM damage) and rotting
are also reported to be dependent on periderm thickness and physico chemical composition
(Naidu and Nandekar, 2005).
Varieties with longer dormancy period, lower number of eye sprouts per tuber and
slower rate of sprout growth are expected to have better keeping quality and hence, there
would be limited weight loss during storage (Pandey, et al., 2007).
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Though the yield of different genotypes may be good, but their storage ability may
not be same. Hence it is necessary to know the storage behaviour along with yield
superiority of individual genotypes under different maturity/ processing groups and it will be
helpful in the identification of potential genotypes for the region.
Majority of the processing industries concentrated in northern part of India due to
higher potato production from more than 95 per cent of total area under potato cultivation. In
northern part of India, potato being cultivated during rabiseason and produced fresh
potatoes. Usually prices for processing genotypes will fetch premium prices and price
differences always will be higher than the ware potato. The processing genotypes of potato
produced only in areas which are suitable for processing because favourable environmental
conditions during crop growth, variety, tuber characteristics and biochemical constituents are
most important that affect the quality of finished products (Ezekiel, et al., (1999). In the
southern transition zone of Karnataka, include Hassan and Chikmagalore the crop being
cultivated during kharif season as the rainfed crop in the remaining five per cent of the total
potato area.
Normally, varieties should posses high dry matter, less reducing sugars and less tuber
defects for producing quality processed potato products. Patel, et al., (2002) reported that
early crop of potato is mostly used for table purpose, hence quickly disposed off following
the harvest to get maximum remunerative returns. Considering the total and marketable yield
at 75 days of harvest, the variety, Kufri Pukhraj appears to be suitable only for introduction as
early cultivar.
Since the fresh potatoes are very much required to feed to the chipping industries for
continuous run of the industries, they have to depend upon the kharif season potatoes which
produced from southern transition zone of Karnataka. Since the industries are not getting
sufficient quantity of processing quality potato tubers from southern transitional zone, the
industries are not running with full capacity. At present, the genotype Kufri Jyoti a table
potato is being cultivated in more than 95 per cent of total potato area. To get more income
to farming community and provide sufficient raw materials to the industry emphasis required
to be given to cultivate more processing genotypes.
In this context, suitable processing genotype for the zone which have processing
qualities viz., higher dry matter, less reducing sugars, good chip colour score with early
bulking, short duration and heat tolerant genotypes are required.
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3.2. REVIEW OF LITERATURE3.2.1. STORAGE BEHAVIOUR OF EARLY MATURING, MEDIUM MATURING
AND PROCESSING POTATO HYBRIDS
Hariom Katiyar et. al., (2000) observed minimum storage rot of tubers in JX-216,
MS/86-89 and Kufri Bahar and maximum in MS/89-60 after 8 weeks of storage. The higher
rotting percentage of different strains was particularly due to varietal differences in response to
unfavourable storage conditions. Storage behaviour of 7 advanced potato hybrids stored for
four months at ambient temperature at Modipuram in western UP, revealed minimum
sprouting and least physiological and total weight loss in hybrids JW-160 ( Kufri Pushkar)
followed by MS/89-60. The hybrids appear promising, considering their yield above 35 t ha-1
and resistance to late blight, for on farm storage to avoid distress sale at harvest (Singh et.al.,
2001). Sharma et. al., (2001) studied the storage behaviour of two advanced potato hybrids,
viz., HB/83-39 and HB/82-372 and two commercial varieties, viz., Kufri Jyoti & Kufri Giriraj,
from December – June at room temperatures in country store at Kufri (Fagu). The advanced
hybrids were found superior in respect of weight loss and sprouting behaviour than commercial
cultivars. From storage point of view they stored well until February for ware potatoes and
until April as seed tubers. Eleven advanced hybrids along with three control varieties were
evaluated for their storability at room temperature during March to July, 1999 and 2000.
Minimum total weight loss at 90 and 120 days of storage was observed in Hybrid JW-160
followed by JW-96, JX-216 and MS/89-60, respectively. These four hybrids had significantly
lower total weight loss than the best control variety Kufri Badshah (Kang et.al., 2001). Jitender
Kumar et. al., (2001) reported that the physiological loss in weight increased with increasing
period of storage in all cultivars. On 15th day of storage, these losses varied from 0.3% to 1.1%
in different cultivars. Cultivars MS/89-1095, 85-P-670, JX-108, OP-1, JX-118 and MS/86-89
crossed 10% PLW. More than 10% PLW was observed for all cvs., on 75th day of storage.
Maximum PLW was observed in MS/89-1095 on 75th day (16.6%) followed by 85-P/670
(16.5%). Minimum PLW was observed in cv. JX-23 (10.0) after the storage for the same
period. Decay loss also increased with increasing period of storage in all cultivars. Minimum
decay loss was observed in cv. JX-118(4.3%) after 75th days of storage followed by K.Badshah
(8.3%) and 85-P-670(8.7%). Maximum decay loss was observed in cv. JX-23(32%) followed
by cv. JX-214 (26.7%) after the storage for same period. (Jitender Kumar et.al.,2001).
Two traditional methods of potato storage – heaps and pits – were evaluated in
northern Indo-Gangetic plains for three years. Of the two cultivars, viz., Kufri Bahar and Kufri
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Jyoti tested in the experiment, the cv. Kufri Jyoti was found to be a better keeper under all the
storage methods, i.e., heap, Katccha pit and pucca pit. The results showed that the overall
storage losses and weight losses were least in the pits as compared to the heap method of
storage. Regardless of storage methods used, the major storage loss was due to weight loss
followed by losses on account of rottage and sprout weight. The better performance of pit
storage may be due to a decrease in temperature by 10 C and an increase in relative humidity by
9 per cent. The results indicated the suitability of on-farm storage methods in the Indo-
Gangetic plain for a period of 90 days for storing potatoes (Vijay Paul et. al., 2002).
Kaul et. al., (2002) evaluated healthy and well-cured tubers of Kufri Chandramukhi
and Kufri Jyoti under two different storage conditions viz., Kutcha and pucca pits (10’ deep
and 5’ dia) and in heaps covered with thick layer of sugarcane trash under a thatched roof from
March to June. The pits were provided with a platform made of bamboo strips placed 1” apart
and 2’ above the base. The maximum temperature in the pucca pit remained 8 to 13 0C less and
relative humidity 8 to 27% more than the ambient (28.5 – 41.50 C, RH 45.0 – 78.6 % ) with
lower relative humidity ( 40.8 – 88.0%). Total losses (weight loss, sprout loss and rottage)
were minimum in potatoes stored in pucca pit (11.4 -12.4%) as compared to heaped potatoes
(13.2 – 16.4%) after 105 days. Visible rating for firmness showed shrivelled condition of
heaped tuber after 90 days which fetched significantly lower auction rates than the cold stored
material. The studies showed that potatoes could be safely stored in low cost storage structures
for 3-4 months so as to get remunerative prices. Patel et. al., (2002) studied the storage
behaviour of the eight potato cultivars and two TPS populations for 4 months at ambient
temperature and observed minimum sprouting, less physiological and total weight loss in cv.
Kufri Chandrmukhi followed by cvs., Kufri Jawahar and Kufri Badsha. Patel et. al., (2002)
reported that cultivation of hybrid JW-160 will be desirable and advantageous along with
potato cv. Kufri Badshah. The produce of these cultures can be kept for three to four months in
the ordinary stores without much deterioration and released at the appropriate time in the
market.
Heat tolerant genotype (K.Surya) had lower rottage, sprouting and weight loss after
75 DAS and had better keeping quality at room temperature than control cultivars - K.Bahar
and K.Jyothi. (Devendra Kumar and Minhas, 2003). Pande and Luthra (2003) studied the
storage behaviour under ambient temperatures up to 90 days and observed that hybrids –
MS/95-117 and MS/95-1309 had longer dormancy and less sprout weight than Kufri Pukhraj
and Kufri Sutlej. The per cent rottage and physiological weight loss of these hybrids were
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similar to control varieties and had firm tuber appearance up to 90 days of storage. Jitender
Kumar et. al., (2003) observed on 60th and 75th day of storage, the lowest PLW in JW-160
(11.10%) and Kufri Pukhraj (13.20%). Rotting of tubers did not occur up to 60 days of storage
in most of the genotypes. Rotting incidence on the 75th day of storage ranged from 3.4 (Kufri
Pukhraj) to 13.7 per cent (MS/92-209). Rotting was less than 5 per cent in Kufri Pukhraj,
MS/92-3146 and MS/92-3128 and more than 10 per cent in Kufri Sutlej, JX-371 and MS/92-
209 on the 75th day. The genotypes MS/92-2105, Kufri Pukhraj and JW-160 are more suitable
when stored for 60 days
Hybrids JW-160, MS/92-1326 showed low sprouting after 120 days of storage and
had long dormancy duration, which was indicated by low sprout weight. Minimum rotting
was observed in hybrid JW-160 and maximum was observed in Kufri Bahar., It is concluded
that hybrid JW-160 possess better keeping quality than controls - Kufri Bahar, Kufri Pukhraj
and Kufri Sutlej ( Jaiswal et.al., 2003). Among the genotypes used in the study by Devender
Kumar and Minhas (2003), all the heat tolerant genotypes were free from tuber rot at 30 days
after storage, while, the heat tolerant genotypes showed less than 0.3 per cent rotting at 60
days after storage as compared to 1.9 per cent in Kufri Jyoti.
Manish Das et. al., (2004) observed that no marked variations in sprouting and
keeping quality in varieties and hybrids under test, while, cv. Kufri Ashoka was found to be a
poor keeper. All the varieties and hybrids showed dormancy ranging 8 to 9 weeks. The
study indicated that more emphasis needed to be placed on these characters along with yield
to have better keeping varieties for export and domestic consumption. Kang et. al., (2005)
recorded variation in the degree of rotting per cent among the cultivars used for storage
studies in North Western plains of India. After 90 days of storage the highest per cent rotting
by weight was recorded in Kufri Pukhraj (12.3%) and the lowest was recorded in J/96-149
(6.7%). Autumn and spring crop harvests of 6 potato cultivars were evaluated for storability
at room temperature during March to June 2002 and 2003, and April to July 2002 and 2003,
respectively. Minimum total weight loss at 90 days of storage was observed in processing
cultivar Kufri Chipsona-1 in both autumn and spring crop harvests. The cv. Kufri Jyoti from
spring harvest also showed good keeping quality up to 90 days of storage. Exotic processing
cultivars Atlantic and Frito Lay-1533 showed poor keeping quality. ( Raj Kumar et.al., 2005).
New potato hybrid JW-160 showed superiority in terms of total as well as marketable yield,
compromised dry matter content and minimum physiological loss in weight up to 60 days of
storage at room temperature under tropical conditions of Haryana. (Bhutani et. al.,
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2005).Bhutani and Khurana (2005) stored the tubers of seven potato genotypes at room
temperature from March to May, to compare their shelf life. Cv. Kufri Bahar recorded the
lowest weight loss due to rotting and it was closely followed by JW-160. However,
physiological loss in weight was lowest in JW-160 followed by cv. Kufri Bahar. Cv. Kufri
Sutlej recorded maximum weight loss due to rotting and physiological loss in weight
followed by cv. Kufri Anand for weight loss due to rotting and JX-576 for physiological loss
in weight. Different genotypes behaved differently over the years.
Patel et. al., (2005) studied the storage behaviour of five processing hybrids in
Gujarat. Among the hybrids, highest per cent rottage after 120 days of storage was recorded
in Kufri Sutlej (40.76%) and lowest per cent weight loss was recorded in HT/.92-621(2.97%).
Naidu and Nandekar (2005) evaluated three heat tolerant potato hybrids, viz., HT/93-707,
HT/93-727 and HT/92-621 along with two control varieties Kufri Pukhraj and Kufri Lauvkar
for storage at room temperature (30.90C) for 75 days at Chhindwara in Chhotanagpur Plateau.
Tuber weight loss in heat tolerant hybrids was at par with control cultivars up to 60 days
after storage (DAS), while, it was significantly lower (11.5%) than control (13.8 to 14.5) at
75 DAS. Substantial increase in weight loss after 60 DAS could be attributed to higher
sprouting intensity in cv. Kufri Lauvkar and higher rottage in cv. Kufri Pukhraj. Heat
tolerant hybrids had lower rottage, sprouting and weight loss at 75 DAS, hence, had a better
keeping quality at room temperature than controls.
Ashiv Mehta et. al., (2006) reported that cultivars Kufri Pushkar, Kufri Surya and
Kufri Chipsona-1 could be safely stored for 3-4 months under RT (room temperature) ECS
(evaporative cooled store) without much reduction in tuber weight and deterioration in
physical appearance. These cultivars could be of much benefit to the farmers who can store
considerable quantity of potatoes on-farm during March to June to avoid glut situation at
harvest and get remunerative prices.
Pande et.al., (2007) recorded the longest dormancy period in Kufri Sindhuri and
shortest in Kufri Lauvkar varieties. The number of sprouts per tuber was maximum in Kufri
Anand and minimum in Kufri Safed after 60 days of sprouting. The highest length of the
longest sprout (5.3 cm) was recorded in Kufri Alankar and Kufri Chipsona-1 and lowest
(2.1cm) in Kufri Surya after 60 days. The per cent weight loss after 60 days of sprouting was
higher in varieties Kufri Jeevan (12.6%) and Kufri Swarna (11.7%) and was lowest in
varieties Kufri Safed and Kufri Chandramukhi (4.6 and 5.2 %, respectively). A significant
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correlation existed between weight loss and number and length of sprouts, whereas, with
dormancy period, weight loss showed negative correlation. The study indicated that the
varieties with longer dormancy period, lower number of sprouts per tuber and slower rate of
sprout growth are expected to have better keeping quality and hence there would be limited
weight loss during storage. Therefore the study suggests potato breeders to consider keeping
quality as one of the important characteristic during the screening of hybrids. Potatoes stored
at 40 C were not acceptable for processing due to excessive accumulation of reducing sugars.
However, even at the storage temperature of 10 or 120 C, generally the chip colour was not
acceptable in seven varieties tried, when grown at Jalandhar. Of the seven varieties grown at
Modipuram, only Kufri Chipsona-1 produced chips of acceptable colour up to 115 days
storage (Eziekiel et. al., 2007).
Kufri Khyati (J/93-86) has good keeping quality than the early maturing varieties used
as control. It exhibited comparatively lower sprout weight, physiological weight loss and
total weight loss than the control varieties Kufri Ashok and Kufri Pukhraj at 90 days after
storage at ambient temperatures (Raj Kumar et.al., 2009).
Roy and Mukhopadhyay,(2010), reported that KCH-1 and MP/98-172 showed
minimum physiological loss in weight (13.88% and 15.25%) and rotting of tubers (11.1% and
12.1%) after 90 days of storage in alluvial zone of West Bengal.
Gautam, et al.,(2012) reported that the genotype PRP 28861.1 with the highest dry
matter content was suitable for only 45-60 days storage in ambient room temperature (25.8
±1.2 oC and 86.1% RH). This genotype had significantly early sprouting and reaching >50%
sprouting within 45 days after storage. Genotype BSU-PO3, HPS-II/67, KCH-1 ( North
Indian Plains processing variety) and HPS-7/67 were suitable for 75 days of storage in
ambient room temperature. The genotype Yagna and L-235 could be successfully stored in
ambient room temperature for maximum period of 120 days with minimum total weight loss
of 7.88 and 8.30(%) and rotting weight loss of 0.33 and 1.03%, respectively.
3.2.2. PROCESSING CHARACTERS OF PROCESSING HYBRIDS OF POTATO
All potato varieties are not suitable for diverse forms of processing. The suitability of
varieties for processing form depends on the chemical composition of the variety such as dry
matter, reducing sugar and total starch content besides the shape, size and colour of tubers.
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These characters greatly depend on the genotype and may be influenced considerably by the
soil and climatic conditions also.
Dry matter content determines the yield and texture of processed product and it is one
of the major factors that decide the suitability of a variety for processing into different forms
besides, other factors. It is of direct importance in chips and French fries as the weight of
processed products depends directly on the amount of the dry matter present per quantitative
unit of fresh potatoes.
Sugar content of potato tubers is of considerable importance in relation to processing,
especially for fried products. Potatoes containing more than 0.4 per cent reducing sugars on
fresh weight basis are not suitable for chips and French fries, as the resultant product will be
dark in colour owing to the reaction between the aldehyde groups of reducing sugars and
amino acids. Similarly, potatoes containing sucrose above 1.5 per cent are also considered
unsuitable for processing.
The processing quality of French fries and chips is largely determined by the colour
after frying which is closely related to reducing sugars as these combine with free amino
acids leading to non-enzymatic browning through Maillard reaction (Fuller and Hughes, 1984
and Roe et. al., 1990). Excessive darkening and development of off-flavours due to high
reducing sugar content is un acceptable for processed products. Phenolic compounds are
also important in processing as they are responsible for enzymatic discolouration and after
cooking darkening in potatoes.
An average dry matter content of 20 per cent and above was observed at Deesa,
Dholi, Jorhat, Kota, Chindwara and Faizabad. The reducing sugar content was less than 100
mg/100g fresh tuber weight at Deesa, Dholi, Jorhat and Kota and the low level of reducing
sugars resulted in an average chip colour score of 4 and below at these four places. The
sucrose content was below 200 mg/100g of fresh tuber at Jorhat, Kota and Chindwara. These
results provide experimental evidence to show that potatoes grown in warmer area contain
higher dry matter content and lower level of reducing sugars resulting to higher yield of good
quality chips, and these parameters vary considerably from season (year) to season in the
same location. Amongst cultivars, Kufri Jyoti gave higher dry matter content at several
locations (Dinesh Kumar et. al., 2003).
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3.2.2.1. Quality characters of tuberSingh et. al., (1997) reported the highest tuber dry matter content in FL-1533 (22.4%)
which was at par with the selected genotypes MP/91-9(22.3%). Kufri Chipsona-2 had
consistently maintained higher tuber dry matter (22.4 – 23%) at different locations. The tuber
dry matter is known to influence the oil uptake during frying as with increase of tuber dry
matter the oil uptake decreases. The use of Kufri Chipsona-2 variety will thus, economizes
the oil consumption and improves the quality of the product which will be less greasy and
low in calories (Gaur et. al., 1999). Marawaha (2000) reported that among the five exotic
and three Indian potato cultivars, evaluated for their fried chips quality, the dry matter content
of exotic cultivars (Atlantic, Frito-Lay, FL-1533, FL-1584 and FL-1625 ) was higher (20.2-
23%) than Indian cultivars (Kufri Chandramukhi, Kufri Jyoti and Kufri Laukar) with 18-
20.5% of dry matter.
The study conducted by Shika et. al., (2003) the results revealed that the dry matter
content varied between 14.86 per cent to 24.39 per cent. Kufri Chipsona-2 had highest dry
matter content succeeded by Kufri Chipsona -1 (23.2%), SM/92-168(23.07%) and SM/91-
1515 (21.98%). Kufri Ashoka, Kufri Giriraj, SM/87-151, SM/91-1515 and SM/92-168 were
also considered good for processing as they had high dry matter content, specific gravity,
total soluble solid (TSS) ascorbic acid and less percentage wastage and percentage oil
absorption. (Shika et. al., 2003). Pandey et. al., (2005) studied ten indigenous and exotic
potato cultivars, amongst which the cultivars Kufri Chipsona-1 and Atlantic (American) had
recorded higher dry matter (> 21.8%).
The commonly cultivated potato variety, Kufri Jyoti, showed low tuber dry matter
content (13.3-19.6%). Conversely, processing hybrids, Kufri Chipsona-1, Kufri Chipsona-3,
Atlantic, and Lady Rosetta, contained higher dry matter content (19.3-23.3%) (Singh et.al.,
2009).
Roy and Mukhopadhyay,(2010), reported that the cultivars MP/98-172, MP/99-322,
MP/99-406, KCH-1 and KCH-2 were recorded higher dry matter content (>20%) and highest
specific gravity in the genotype KCH-2(1.080).
3.2.2.2.. Biochemical analysisSingh et. al., (1997) evaluated advanced stage potato hybrids for processing and
recorded the reducing sugar content ranging between 150 and 216 mg/100g fresh weight. In
most of the varieties the content of non reducing sugars was lower than reducing sugars.
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Kufri Dewa (0.05%) and Kufri Alankar (10.05%) accumulated minimum amounts of non
reducing sugars. Total sugars ranged from 0.59 per cent to 1.12 per cent on fresh weight
basis among the different varieties evaluated (Marawaha, 1998). The analysis of tuber for
reducing sugars, total phenols and free amino acids revealed that Kufri Chipsona-2 will have
lower values of these components than Kufri Jyoti (Gaur et. al., 1999). Singh et. al., (1999)
Kufri Chipsona-1 and KCH-2 has low reducing sugar (below 150mg/100g fresh weight).
While, Kufri Lalima had maximum non reducing sugars (0.66%). Marawaha (2001) studied
seven Indian and five exotic cultivars for desirable processing traits. The exotic cultivars
possessed higher tuber dry matter, lower enzymatic and non enzymatic discolouration, lower
reducing and non reducing sugars and phenolic compounds compared to Indian varieties.
Uppal et. al., (2001) evaluated heat tolerant genotypes for processing quality and recorded
highest starch content of 15.8 per cent in cultivar D-9 and lowest was found in Kufri
Badhshah (13.5%). The average starch content recorded for all the eleven genotypes was
14.7%. Singh et. al., (2003) evaluated advanced stage potato hybrids for processing and
recorded reducing sugar content ranging between 150 and 216 mg/100g of fresh weight.
All the cultivars produced chips of acceptable colour and had a high dry matter ( 18.5
– 27.2%) and low concentration (69-250 mg/100g fresh weight) of reducing sugars. The
chips made from Kufri Chipsona –1 and Kufri Chipsona –2 were superior in colour and taste.
The amount of sucrose was much more than hexoses. The colour of chips, dry matter and
level of free sugars varied among cultivars and between growing seasons (Uppal and Paul
Khurana, 2003).
Pandey et. al., (2005) reported that among the several Indian and exotic cultivars
studied for their processing characteristics, the highest total sugars was found in PSP-310
(1898 mg) and the lowest total sugars was in PSP-901 (491 mg).
The reducing sugar content of tubers of Kufri Surya was less than 100 mg/100g fresh
weight and the tuber dry matter content was 20-21 per cent at harvest (Minhas et. al., 2006)
The cultivated potato variety, Kufri Jyoti showed high levels of reducing sugars (75.7-
240.7 mg/100g fresh wt.). Conversely, processing hybrids, Kufri Chipsona-1, Kufri
Chipsona-3, Atlantic, and Lady Rosetta, contained lower contents of reducing sugars (21.0-
57.7 g/100g fresh wt). In general, processing varieties contained lower levels of free amino
acids and total phenols which are desirable from processing point of view (Singh et. al.,
2009).
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Roy and Mukhopadhyay,(2010), reported that the processing genotypes KCH-1 ,
KCH- 2, MP/98-172, MP/99-322, MP/99-406 and Atlantic have recorded low reducing sugar
content (<100mg/100g fw basis)
Vineeth and Singh,(2011) reported that pest infestation significantly lowered the level
of both reducing sugar and sucrose content in early crop season. Since leaf hoper, mites and
white flies were found to be associated with early crop season, it is concluded that if these
pest are allowed to infest the crop could lead to decrease in the sugar content which could
result in better quality of chips.
Rivera, et al.,(2011) reported that the cultivar Criolla Columbia and Clone 98-71.26
showed the best behaviour for pre cooking processing. The best characteristic for individual
quick freezing (IQF) and pickling corresponded to tubers with yellow coloured peel, round
shape, shallow eyes , 16 to 20.5 per cent dry weight, 2.5 to 3.5 cm diameter and less than 0.1
per cent reducing sugar at Columbia.
3.2.2.3. Chipping qualityChip colour is the most important criterion for marketing of the finished product. The
chipping industry accepts chip colour in the range of 1 to 3 on a scale of 1-8 (1 being the
lightest and 8 the darkest). Kufri Chipsona-2 had given the lightest colour chips in the range
of 1 to 3. In contrast, popular processing variety Kufri Jyoti produced chips in the colour
range of 4.5 to 6 (Gaur et.al., 1999). Uppal et. al., (2001) evaluated the heat tolerant
genotypes for chip colour and processing characters. The highest dry matter was in D-9 (6.13
t ha-1) and significantly lowest was in Kufri Badhshah and Kufri Chandramukhi while, the
dry matter content ranging between 18.4 and 21.8%. Uppal and Khurana (2001) revealed
that the chip quality and contents of dry matter and free sugars varied among varieties and
locations. Potatoes grown at Bhubaneswar, Chhindwara, Deesa, Kota and Patna produced
acceptable chips of golden yellow colour and had low concentration, 0.13 to 0.24 per cent of
reducing sugars(fresh weight basis). The amount of reducing sugars was much more, 0.29 to
0.40%, than the permissible limits for processing at Faizabad, Muzaffarpur, Hissar, Jalandhar
and Udham, Singh Nagar that made the tubers unfit for making chips.
Patel et. al., (2002) reported that chip colour decreased with maturity. Chip colour
improved with the increase in tuber dry matter. Tawfik et.al., (2002) reported that varieties
Bolesta, Diamant, Exauisa, and Silvester consistently exhibited the highest yield of chips
during spring. While, Diamant, Exquisa, Silvester and Spey exhibited the greatest net
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weight of chip during fall. The same varieties plus Bolesta recorded the highest yield of
French fry during spring and fall.
Singh et. al., (2003) evaluated four processing potato cultivars for their chipping
qualities. The chip colour of all the four cultivars was within the acceptable range except for
Kufri Jyoti which produced dark chips. Late planting resulted in the highest average values
of white coloured chips, with Kufri Chipsona-1 producing the highest average percentage of
white coloured chips.
The genotypes Kufri Chipsona – 1, Kufri Chipsona –2 were found most suitable for
processing into chips and French fries (Shika et. al., 2003). Nine Indian and exotic cultivars
grown at Kota (Rajasthan) were evaluated for chip colour and processing characters after
harvest for 2 years. All the cultivars produced chips of acceptable colour and had a high dry
matter ( 18.5 – 27.2%) and low concentration (69-250 mg/100g fresh weight) of reducing
sugars. The chips made from Kufri Chipsona –1 and Kufri Chipsona – 2 were superior in
colour and taste. The amount of sucrose was much more than hexoses. The colour of chips,
dry matter and level of free sugars varied among cultivars and between growing seasons
(Uppal and Khurana, 2003).
Ezekiel et. al., (2003) reported that lighter chip colour could be related to lower level
of reducing sugars. Cultivar Kufri Bahar accumulated excessive reducing sugars resulting in
dark colour chips. Tubers of cultivars Kufri Jyoti and Kufri Lauvkar, produced and stored at
Indore and Ujjain, respectively were found to be suitable for processing.
High quality French fries can be prepared from heat tolerant hybrid HT/92-621(Kufri
Surya), which produced highest French fries grade tuber yield with > 21% tuber dry matter.
Due to excellent shelf life it can be stored in heap after harvest and appeared suitable to
supply raw material to French fries processing industries continuously up to four months
without any appreciable storage losses (Patel et. al., 2005).
Kufri Surya yields excellent defect free tubers with high proportion of large (>85mm)
tubers suitable for processing into high quality French fries and chips (Minhas et.al., 2006).
Singh et. al., (2009) reported that Kufri Chipsona-1, Kufri Chipsona-3, Atlantic and
Lady Rosetta had produced fresh fried chips of acceptable colour Score (Score 1.75 to 2.75)
compared to commonly cultivated Kufri Jyoti with unacceptable chips of dark colour (Score
4.5-7.0). Based on tuber shape, yield and sensory characteristics of fries, such as colour,
59
texture and taste, three varieties viz., Kufri Chipsona-1, Kufri Chipsona-3 and Kufri Surya
were found to be most suitable for French fries. The recovery of flakes was maximum in
Lady Rosetta (21.7%), followed by Kufri Chipsona-3(20.8%), Kufri Chipsona-1 (19.2%) and
Atlantic (19%), while, the recovery from other table varieties varied between 10.1 to 16.6%.
Dehydrated chips and flour also followed a similar trend as that of flakes.
Simango, et al.,(2011), reported that the genotype PHIL 2.21.6.2 and the check
variety Igorta have good fry quality based on high dry matter content and high fry yield.
Both the genotypes produced fries which were liked much by panelists at Philphines.
Pentangelo et al., (2011), reported that the genotype, Aurea, Rumba, Taurus and VR were
proved to be good cultivars for frying chips. Ashiv Mehta, et al., (2011), reported that four
potato cultivars viz., KCH-1, KCH-3, Kufri Surya and Kufri Frysona can be successfully
grown for producing potatoes for making good quality French fries even in cooler Northern
Plains, an area previously presumed to be unsuitable for producing potatoes for processing.
Vineeth and Singh,(2011) reported that infestation of leaf hopper, white fly and mite in early
crop season had an undesirable effect on chipping quality of potatoes. Due to pest infestation
the dry matter, specific gravity, reducing sugar, sucrose and free amino acids contents were
decreased whereas phenol was increased.
3.3. MATERIAL AND METHODS3.3.1. Materials
Harvested potato tubers of early, medium maturing and processing genotypes/hybrids
which were mentioned in the chapter II – material and methods (2.3.1.1., 2.3.2.1. and
2.3.3.1.) were utilised for the study of storage behaviour and evaluation of processing
characters and chipping quality attributes
3.3.2. Methodology3.3.2.1. STORAGE BEHAVIOUR
The harvested tubers were cured for 10 days and were sorted into undamaged and
apparently healthy tubers with average weight of 50-60g in each genotype. In each genotype
the tubers were replicated thrice. In each replication five kg tubers were filled in small gunny
bags and the bags were stored at room temperature from September to December for 90 days.
Five tubers from each treatment were marked as 1,2,3,4 and 5 their initial and final weights
were recorded (Pandey et al., 2007). The following parameters were recorded at 90th day
from the date of storage of tubers.
60
3.3.2.1.1. Tuber rot (%)The tuber rot was calculated using following formula.
Weight loss due to rot (%) =
3.3.2.1.2. Tuber sprouting (%)The tuber having at least one sprout longer than 0.5 mm was counted as sprouted
tubers and the sprouting percentage was calculated by the following formula.
Sprouting (%) =
3.3.2.1.3. Potato Tuber Moth infection (%)The number of tubers attacked by tuber moth during storage was recorded and the per
cent incidence was calculated using the following formula.
Potato tuber moth infection (%) =
3.3.2.1.4. Physiological Loss of Weight (%)Weight loss in storage is a common phenomenon due to several physiological
reasons. The physiological weight loss of the tubers was calculated by using the following
formula.
PLW (%) =
3.3.2.1.5. Total weight loss in storage (%)Physiological loss in weight and weight loss due to rot were added to estimate total
weight loss in storage
Total weight loss = Physiological weight loss (%) + Weight loss due to rots (%)
3.3.2.1.6. Days for sprout initiationNumber of days taken for the first sprout initiation in stored tubers was recorded.
Weight of tubers rotten ----------------------------X100Initial weight of tubers
Number of tubers sprouted------------------------------------X100Total number of tubers
Number of infected tubers----------------------------- X 100Total number of tubers
IW of marked tubers - Final weight of marked tubers---------------------------------------------------------------- X100Initial weight (IW) of marked tubers
61
3.3.2.2. BIOCHEMICAL ANALYSIS3.3.2.2.1. Reducing sugars (mg/100g fresh weight)
The reducing sugar content of the tubers was estimated by following Nelson-
Somogy’s micro method on fresh weight basis (Somogyi, 1952 and Sadasivan and
Manickam, 1992).
3.3.2.2.2. Non-reducing sugars (mg/100g fresh weight)The non-reducing sugar content of the fresh tubers was analysed by following Nelson
- Somogy’s micro method (Malhotra and Sarkar, 1979).
3.3.2.2.3. Total sugar (mg/100g fresh weight)The total sugar content of the fresh tubers was obtained by adding the contents of
reducing sugars and non-reducing sugars.
3.3.2.2.4. PhenolsThe total phenols in the tubers was estimated by following the standard procedure
outlined by Swain & Hills, (1959).
3.3.2.2.5. Starch content (%)For the estimation of starch 0.1 to 0.5 g of the tuber sample was homogenised in 80%
hot ethanol for removing the sugars. The residue was retained by centrifuging. The residue
was washed repeatedly with hot 80% ethanol till the washings did not give colour with
anthrone reagent. The residue was dried well over a water bath. To the residue add 5.0 ml of
water and 6.5 ml of 52% perchloric acid were added. Further extraction was done at 00C for
20 min. To save the supernatant the residue was again centrifuged. The extraction was
repeated using fresh perchloric acid. Centrifuging was done again and the supernatants were
pooled and the volume was made up to 100 ml. About 0.1 or 0.2 ml of the supernatant was
pipetted out and made up to the volume to 1 ml with water. Standards were prepared by
taking 0.2, 0.4, 0.6 0.8 and 1 ml of the working standard and the volume was made up to 1 ml
for each tube with water. 4 ml of anthrone reagent was added to each tube. Heating was
done for 8 min. in a boiling water bath. The tubers were cooled rapidly and the intensity of
green to dark green colour was read at 630 nm.
The glucose content in the sample was calibrated using the standard graph. The value
was multiplied by a factor 0.9 to arrive at the starch content (Hodge, 1962; Thayumanavan
and Sadasivam, 1984 and Sadasivam and Maickam, 1992)
62
3.3.2.3. CHIPPING QUALITY
Preparation of potato chips and their characteristics
Potato tubers were washed in clean water and were hand peeled and cut into slices of
1.75mm thickness. The slices were washed thoroughly in water, air dried and fried in refined
groundnut oil at 180o C till the bubbling on the chip surface stopped. The colour of chips and
other parameters were estimated with standard quality chart developed by M/S Pepsi Food
Ltd. The following observations were made on quality of the chips.
3.3.2.3.1. Chipping quality grade
The chip colour was determined visually on 1-10 scale (Appendix -I). Chips were
scored based on the scale, where 1 was white and 10 was dark brown. Fried chips were
observed under fluorescent tube light using the chip colour cards. The chip colour grade up
to 4 was acceptable. (Ezekiel, et al., 1999)
3.3.2.3.2. Undesirable colour (%) (UC)The chips of different hybrids were evaluated for undesirable colour visually.
3.3.2.3.3. Internal defects (%)The chips of different hybrids were evaluated for internal defects.
3.3.2.3.4. External defects (%)The chips of different hybrids were evaluated for external defects.
3.3.2.3.5. Total defects (TPOD)After the evaluation of chips of different hybrids for undesirable colour, the internal
defects and external defects, the individual figures were added up to get the total number of
defective chips and the percentage was worked out.
3.4. EXPERIMENTAL RESULTS3.4.1. STORAGE BEHAVIOUR
The keeping quality of potatoes has been one of the considerations before the release
of any variety, so that the farmers are able to store their produce for desired period of time in
their farm or in refrigerated storages. For estimating the keeping quality of a particular potato
variety, its dormancy period and weight loss had been the major criteria in the past. The
CPRI has been developing different genotypes which suit to different agro-climatic
situations. Likewise, different maturing genotypes were evaluated for 90 days under ambient
condition to know the storage behaviour of early, medium maturing and processing
63
genotypes in southern transition zone of Karnataka. The results of the studies on storage
behaviour of different genotypes of different groups are as follows:
3.4.1.1. Early maturing genotypes:
Percentage of tuber rot (Table-7) was significantly least and was at par in the
genotypes Kufri Ashoka (0.63%), Kufri Surya (0.83%), J/95-227(0.98%), J/93-86(1.09%),
J/97-243(1.10%), J/95-378(1.11%), J/95-144(1.14%), J/95-229(1.19%), J/96-84(1.47%),
J/96-238(1.45%) and Kufri Pukhraj(1.73%) .
The percentage tuber (Table-7) sprouting at 90th day of storage was significantly least
in genotype Kufri Surya (29.85%) followed by the genotypes J/95-229(47.67%) and J/95-
227(52.63%).
The percentage PTM infestation (Table-7) to stored tubers was significantly least in
the genotypes J/95-378(6.05%), J/95-227(6.33%), J/96-149(6.58%), J/95-221(7.38%), J/95-
229(7.67%) and Kufri Surya (8.0%).
The percentage physiological loss of weight (PLW) (Table-8) was significantly least
in the genotypes Kufri Surya (4.18%), J/95-221(4.32%), J/95-229(4.83%), Kufri Jyoti
(5.02%), J/92-159(5.07%), J/95-227(5.33%) and J/95-242(5.53%).
The percentage total weight loss (TWL) percentage of tuber (Table-8) was
significantly least in the genotypes Kufri Surya (5.02%), J/95-229(6.02%), J/95-227(6.32%)
and J/95-221(7.03%).
Number of days taken for tuber sprouting (Table-8) was significantly higher in
genotypes J/97-243(81.33), J/93-86(78.5), Kufri Surya (77), and J/96-149 (76.67) and
followed by J/96-238(75).
3.4.1.2. Medium maturing genotypes
The percentage of tuber rot (Table-9) was at par in the genotypes MS/99-
1871(0.16%), MS/0-3808(0.24%), Kufri Pushkar (0.39%), and DSP-7(0.49%).
The sprouting percentage of tubers (Table-9) was significantly least in the genotype
Kufri Jyoti (47.95%) followed by the genotype Kufri Pushkar (59.10%) and DSP-
19(64.54%).
64
Table -7. Storage behaviour of different early maturing potato genotypesSl.No.
Genotypes Tuber rot (%) Tuber sprouting (%) PTM infection (%)2007 2008 Pooled 2007 2008 Pooled 2007 2008 Pooled
1 J/92-159 2.83 5.57 4.20 60.79 68.00 64.40 20.73 20.33 20.53
2 J/93-86 0.00 2.18 1.09 95.33 97.00 96.17 85.00 91.67 88.33
3 J/95-221 0.00 5.43 2.72 81.33 88.67 85.00 6.60 8.17 7.38
4 J/95-227 0.00 1.96 0.98 52.93 52.33 52.63 5.60 7.07 6.33
5 J/95-229 0.00 2.38 1.19 48.00 47.33 47.67 7.10 8.23 7.67
6 J/95-242 3.83 27.38 15.61 85.00 87.98 86.49 9.33 10.33 9.83
7 J/95-144 0.00 2.29 1.14 66.09 65.67 65.88 34.00 36.33 35.17
8 J/95-378 0.00 2.21 1.11 86.15 72.69 79.42 5.80 6.30 6.05
9 J/96-80 8.00 9.63 8.82 88.63 96.21 92.42 16.67 18.33 17.50
10 J/96-84 0.00 2.94 1.47 72.63 83.00 77.82 22.33 25.00 23.67
11 J/96-149 3.67 4.89 4.28 46.53 77.29 61.91 6.00 7.17 6.58
12 J/96-171 7.00 8.06 7.53 100.00 94.77 97.39 21.83 23.00 22.42
13 J/96-238 0.00 2.91 1.45 73.33 75.00 74.17 7.67 9.40 8.53
14 J/97-243 0.00 2.20 1.10 100.00 95.40 97.70 8.00 11.00 9.50
15 K.Ashoka 0.00 1.27 0.63 75.33 98.14 86.74 26.67 28.33 27.50
16 K.Pukhraj 0.00 3.47 1.73 99.00 96.71 97.85 15.00 19.33 17.17
17 K.Surya 0.00 1.67 0.83 30.37 29.33 29.85 8.00 8.00 8.00
18 K.Jyoti 4.77 5.67 5.22 61.83 70.67 66.25 19.33 22.00 20.67
F -Test * * * * * * * * *
SEm± 0.28 0.40 0.51 3.48 2.73 2.18 1.08 0.74 0.78
CD (p=0.05) 0.81 1.16 1.11 10.04 7.87 6.29 3.13 2.15 2.24
CV (%) 9.43 12.89 10.76 7.76 5.75 4.72 9.79 6.09 6.67
* = Significant at 5 per cent K=Kufri PTM= Potato Tuber Moth
65
Table -8. Storage behaviour of different early maturing potato genotypesSl.No.
Genotypes PLW (%) Total weight loss (%) Days for sprout initiation
2007 2008 Pooled 2007 2008 Pooled 2007 2008 Pooled
1 J/92-159 4.73 5.40 5.07 7.57 10.97 9.27 52.00 56.33 54.17
2 J/93-86 10.60 11.17 10.88 10.60 13.35 11.98 76.00 81.00 78.50
3 J/95-221 4.33 4.30 4.32 4.33 9.73 7.03 67.00 72.00 69.50
4 J/95-227 5.23 5.43 5.33 5.23 7.40 6.32 42.67 45.00 43.83
5 J/95-229 4.90 4.77 4.83 4.90 7.15 6.02 44.67 50.00 47.33
6 J/95-242 5.33 5.73 5.53 9.17 33.11 21.14 67.33 70.67 69.00
7 J/95-144 6.80 8.47 7.63 6.80 10.75 8.78 65.00 70.33 67.67
8 J/95-378 6.07 10.12 8.09 6.07 12.33 9.20 66.00 65.33 65.67
9 J/96-80 8.86 8.37 8.62 16.86 18.00 17.43 60.00 62.00 61.00
10 J/96-84 5.67 10.53 8.10 5.67 13.47 9.57 63.67 67.67 65.67
11 J/96-149 6.13 10.02 8.08 9.80 14.91 12.36 75.00 78.33 76.67
12 J/96-171 6.23 10.46 8.35 13.23 18.52 15.88 74.00 60.67 67.33
13 J/96-238 4.83 11.63 8.23 4.83 14.54 9.69 67.00 83.00 75.00
14 J/97-243 5.00 9.18 7.09 5.00 11.38 8.19 80.67 82.00 81.33
15 K.Ashoka 6.80 12.15 9.47 6.80 13.41 10.11 70.33 73.33 71.83
16 K.Pukhraj 4.57 11.91 8.24 4.57 15.38 9.97 62.33 62.67 62.50
17 K.Surya 4.37 4.00 4.18 4.37 5.67 5.02 73.00 81.00 77.00
18 K.Jyoti 4.97 5.07 5.02 9.73 10.73 10.23 66.67 67.33 67.00
F -Test * * * * * * * * *
SEm± 0.52 0.67 0.46 0.59 0.76 0.68 2.58 1.83 1.58
CD (p=0.05) 1.49 1.95 1.36 1.71 2.20 2.02 7.68 5.27 4.67
CV (%) 14.45 13.36 10.42 12.89 9.31 7.29 5.38 4.38 3.77
* = Significant at 5 per cent PLW = Physiological Loss of Weight
66
Table -9. Storage behaviour of different medium maturing potato genotypes
Sl.
No.Genotypes
Tuber rot (%) Tuber sprouting (%) PTM infection (%)
2007 2008 Pooled 2007 2008 Pooled 2007 2008 Pooled
1 DSP-7 0.00 0.99 0.49 75.67 82.67 79.17 14.00 12.33 13.17
2 DSP-19 3.00 3.51 3.25 62.74 66.33 64.54 12.00 11.67 11.83
3 MS/99-1871 0.00 0.31 0.16 98.25 96.87 97.56 23.67 21.67 22.67
4 MS/0-3808 0.00 0.48 0.24 99.67 99.00 99.33 32.33 31.00 31.67
5 MS/0-3740 0.00 3.10 1.55 90.33 93.67 92.00 4.00 2.33 3.17
6 K.Pushkar 0.00 0.77 0.39 45.57 72.63 59.10 22.33 16.00 19.17
7 K.Pukhraj 0.00 3.48 1.74 99.00 96.37 97.69 15.33 13.33 14.33
8 K.Jyoti 4.33 7.67 6.00 46.23 49.67 47.95 17.67 15.00 16.33
F -Test * * * * * * * * *
SEm± 0.22 0.39 0.16 2.94 2.48 2.05 1.19 1.05 0.93
CD (p=0.05) 0.68 1.18 0.49 8.91 7.51 6.23 3.51 3.13 2.72
CV (%) 12.08 16.60 16.06 6.59 5.22 4.47 8.11 15.29 8.37
* = Significant at 5 per cent PTM= Potato Tuber Moth
67
The percentage of potato tuber moth infestation (Table-9) was significantly least in
the genotype MS/0-3740(3.17%) followed by the genotypes DSP-19(11.83%), DSP-
7(13.17%) and Kufri Pukhraj (14.33%).
The percentage physiological loss of weight (PLW) of stored tubers (Table-10) was
significantly least and was at par in genotypes DSP-19(5.05%), Kufri Pukhraj (5.62%) and
Kufri Pushkar (5.68%) at 90th day of storage at ambient condition.
The percentage total tuber weight loss (Table-10) was significantly least in the
genotypes Kufri Pushkar (6.07%), MS/0-3808(6.14%), DSP-7(6.53%) and MS/99-
1871(7.39%).
The day taken for sprout initiation in tubers (Table-10) noticed was significantly more
in the genotypes Kufri Jyoti (67) and Kufri Pukhraj (63.67).
3.4.1.3. Processing genotypes
The tuber rot was not (Table-11) observed in the promising genotype Kufri Surya and
it was observed in other promising genotypes Atlantic (7.01) and MP/99-322(1.0%).
The percentage tuber sprouting (Table-11) was significantly least and was at par in
the genotypes KCH-1(27.15%), MP/98-172(36.05%) and MP/98-71(36.27%).
The percentage PTM infestation in stored tubers (Table-11) was significantly least
and was at par in the genotype MP/98-71(4.05%) followed by the genotypes KCH-
2(14.78%) and MP/98-172(25.48%) at 90th day of storage.
The percentage physiological loss of weight (PLW) (Table-12) was significantly least
in Kufri Surya (2.73%) followed by Atlantic (6.02%), Kufri Jyoti (7.55%) and KCH-3
(7.82%).
The percentage total weight loss (TWL) (Table-12) was significantly least in the
genotype Kufri Surya (2.73%) followed by the genotypes KCH-3(7.82%) and Kufri Jyoti
(8.35%).
The day taken for tuber sprout initiation (Table-12) was significantly more in the
genotypes Kufri Surya (73.67 days), MP/98-172(75.33 days), KCH-3(75.67 days) and
MP/99-322(76.33 days).
68
Table -10. Storage behaviour of different medium maturing potato genotypes
Sl.
No.Genotypes
PLW (%) Total weight loss (%) Days for sproutinitiation
2007 2008 Pooled 2007 2008 Pooled 2007 2008 Pooled
1 DSP-7 5.00 7.07 6.03 5.00 8.05 6.53 23.00 25.33 24.17
2 DSP-19 4.03 6.07 5.05 7.03 9.57 8.30 39.00 38.33 38.67
3 MS/99-1871 6.23 8.23 7.23 6.23 8.54 7.39 35.33 37.00 36.17
4 MS/0-3808 4.87 6.93 5.90 4.87 7.41 6.14 34.00 35.67 34.83
5 MS/0-3740 6.23 8.23 7.23 6.23 11.33 8.78 26.67 27.33 27.00
6 K.Pushkar 4.67 6.70 5.68 4.67 7.47 6.07 28.67 30.00 29.33
7 K.Pukhraj 4.57 6.67 5.62 4.57 10.14 7.36 64.00 63.33 63.67
8 K.Jyoti 4.97 6.83 5.90 9.30 14.50 11.90 66.67 67.33 67.00
F-Test * * * * * * * * *
SEm± 0.24 0.23 0.22 0.38 0.47 0.21 1.60 1.37 1.24
CD (p=0.05) 0.72 0.64 0.64 1.15 1.43 0.64 4.84 4.06 3.75
CV (%) 8.08 4.68 4.98 10.93 8.50 4.66 6.97 4.31 5.35
* = Significant at 5 per cent PLW= Physiological Loss of Weight
69
Table - 11 Storage behaviour of different processing potato genotypes
Sl.
No.Genotype
Tuber rot (%) Tuber sprouting (%) PTM infestation (%)
2007 2008 Pooled 2007 2008 Pooled 2007 2008 Pooled
1 MP/98-71 4.54 3.83 4.18 38.27 35.27 36.77 3.96 4.13 4.05
2MP/98-
1726.82 5.66 6.24 30.69 41.40 36.05 22.14 20.81 21.48
3MP/99-
3220.00 2.00 1.00 55.83 29.00 42.41 46.05 40.24 43.15
4MP/99-
4068.23 4.83 6.53 51.05 42.23 46.64 58.33 47.67 53.00
5 KCH-1 0.00 0.00 0.00 41.96 12.33 27.15 38.33 32.33 35.33
6 KCH-2 0.00 0.00 0.00 63.02 12.33 37.68 16.41 13.15 14.78
7 KCH-3 0.00 0.00 0.00 71.31 12.33 41.82 87.27 82.27 84.77
8 Atlantic 8.71 5.30 7.01 63.26 40.67 51.96 61.38 48.33 54.86
9 K.Surya 0.00 0.00 0.00 63.64 11.53 37.58 38.12 30.00 34.06
10 K.Jyoti 0.00 1.60 0.80 53.28 60.17 56.72 49.48 51.82 50.65
F -Test * * * * * * * * *
SEm± 0.23 0.18 0.12 5.32 1.26 3.49 3.10 2.68 2.43
CD (p=0.05) 0.68 0.53 0.35 15.82 3.76 7.35 10.35 7.94 7.25
CV (%) 9.10 9.41 7.96 11.32 7.37 10.33 11.74 9.20 7.73
* = Significant at 5 per cent PTM= Potato Tuber Moth
70
Table -12. Storage behaviour of different processing potato genotypes
Sl.No. Genotype
PLW (%) Total weight loss (%) Days for sproutinitiation
2007 2008 Pooled 2007 2008 Pooled 2007 2008 Pooled
1 MP/98-71 17.85 17.33 17.59 22.38 21.17 21.78 63.67 60.33 62.00
2 MP/98-172 4.74 12.00 8.37 11.56 17.66 14.61 76.67 74.00 75.33
3 MP/99-322 13.39 11.00 12.20 13.39 13.00 13.20 78.00 74.67 76.33
4 MP/99-406 8.36 8.67 8.51 16.60 13.50 15.05 71.33 68.33 69.83
5 KCH-1 12.25 12.33 12.29 12.25 12.33 12.29 70.00 68.00 69.00
6 KCH-2 18.07 16.33 17.20 18.07 16.33 17.20 50.67 52.00 51.33
7 KCH-3 8.96 6.67 7.82 8.96 6.67 7.82 76.33 75.00 75.67
8 Atlantic 7.01 5.04 6.02 15.72 10.34 13.03 67.33 64.67 66.00
9 K.Surya 3.35 2.12 2.73 3.35 2.12 2.73 74.33 73.00 73.67
10 K.Jyoti 5.10 10.00 7.55 5.10 11.60 8.35 66.33 65.33 65.83
F -Test * * * * * * * * *
SEm± 1.18 1.02 0.76 1.15 1.07 0.77 1.43 1.20 1.11
CD (p=0.05) 3.50 3.04 2.26 3.41 3.18 2.30 4.26 3.57 3.31
CV (%) 10.61 10.46 10.15 11.61 11.85 10.62 3.57 3.08 2.81
* = Significant at 5 per cent PLW= Physiological Loss of Weight
71
3.4.2. Processing and chipping quality
Potatoes for processing require certain attributes which can be broadly characterized
as morphological and biochemical. Morphological attributes are mainly size, shape of tubers,
eye depth, etc., whereas, biochemical attributes includes dry matter, reducing sugars, phenol
and starch content. These attributes determine the quality and quantity of the finished
products and contribute to the production efficiency of processing plant.
Evaluation of processing genotypes for chipping quality is vital in addition to their
tuber yield and processing qualities. Without the evaluation of the processing genotype for
chipping quality identification of superior processing genotypes would not be complete.
Thus, all the processing genotypes were evaluated for chipping quality; through chip colour,
undesirable colour, internal and external defects and total percentage of defects. Processing
and chipping qualities of processing genotypes are presented in tables -
PROCESSING QUALITY ATTRIBUTES
3.4.2.1. MORPHOLOGICAL:Tuber size:
Based on size of the tubers, MP/98-71, MP/98-172, MP/99-322, KCH-2, KCH-3 and
Kufri Jyoti were categorised under medium size tuber group, whereas, MP/99-406, KCH-1,
Atlantic and Kufri Surya (Table-13) were categorised under medium-large size tuber group.
Tuber shape:
Based on shape of the tubers, (Table-13) the genotypes MP/99-406 and Atlantic were
categorised under round shape group. The genotypes MP/98-172, MP/99-322 and KCH-2
were categorised under round-oval shape group. Whereas, the genotypes MP/98-71 and
KCH-3 were categorised under oval-long shape group. The remaining genotypes KCH-1 and
Kufri Surya were categorised as oblong and Kufri Jyoti as oval shape group.
Tuber eye depth:
Based on eye depth of the tubers, (Table-13) the processing genotypes MP/98-172,
KCH-1, KCH-2, KCH-3, Atlantic and Kufri Surya were categorised under shallow group.
The genotype Kufri Jyoti was categorised under fleet group. Whereas, the genotypes MP/98-
71, MP/99-322 and MP/99-406 were categorised under medium – deep group. All the
processing genotypes evaluated have white skin.
72
Table -13. Morphological characters of tubers in different processing potato genotypes
Sl.No. Genotypes Tuber size Tuber shape Tuber eye
depthTuber skincolour
1 MP/98-71 Medium Oval-long Medium deep White
2 MP/98-172 Medium Round-oval Shallow White
3 MP/99-322 Medium Round-oval Medium deep White
4 MP/99-406 Medium-large Round Medium deep White
5 KCH-1 Medium-large Oblong Shallow White
6 KCH-2 Medium Round-oval Shallow White
7 KCH-3 Medium Oval-long Shallow White
8 Atlantic Medium-large Round Shallow White
9 K.Surya Medium-large Oblong Shallow White
10 K.Jyoti Medium Oval Fleet White
73
3.4.2.2. Bio-chemical contents:
Dry Matter of tuber:
The percentage tuber dry matter (Table-14) was significantly higher in the genotypes
MP/99-406 (23.24%) and KCH-2(22.49%) followed by the genotypes MP/98-71(22.29%)
and MP/98-172(21.8%).
Reducing Sugars:
The reducing sugar content in the tubers at harvest (Table-14) was significantly least
and was at par in the genotypes Kufri Surya (45.66 mg/100g fresh wt.) and KCH-3(46.8
mg/100 g fresh wt.).
Total Sugars:
The total sugar content in the harvested tuber (Table-14) was significantly least in the
genotypes MP/99-322(79.13 mg/100 g fresh wt.) followed by the genotypes Kufri Jyoti
(82.15 mg/100 g fresh wt.) and KCH-3(82.79 mg/100 g fresh wt.
Phenols:
The phenol content (Table-15) was significantly least in the genotype MP/99-
406(8.29 mg/100 g fresh wt.) followed by the genotype MP/98-172(8.82 mg/100 g fresh wt.).
Starch:
The percentage starch content in the harvested tuber (Table-15) was significantly
more and it was at par in the genotypes MP/98-172(21.2.) and MP/99-322(21.08%)
3.4.2.3. Chipping quality
The tuber chip colour (Table-16) observed was less than 3 in all the genotypes except
Kufri Jyoti where the chip colour was 3.
The percentage of undesirable colour (UC) of 0.9 per cent (Table-16) was least in the
majority of the genotypes and it ranged from 0.9 to 1.5 per cent and the maximum was
noticed in MP/98-71(4.7%) and Kufri Jyoti (5.0%).
The internal defect of chips (Table-16) was less than 5 per cent in majority of the
genotypes, except in the genotypes KCH-3(7.5%) and MP/98-172(7.5%).
74
Table -14. Variations in bio chemical attributes in different processing potato genotypes
Sl.No. Genotypes
Tuber dry matter (%) Reducing sugar1 Total sugar1
2007 2008 Pooled 2007 2008 Pooled 2007 2008 Pooled
1 MP/98-71 22.39 22.20 22.29 59.79 59.03 59.41 88.68 87.56 88.12
2 MP/98-172 22.20 21.41 21.81 60.38 59.62 60.00 90.95 89.80 90.37
3 MP/99-322 20.71 20.58 20.65 55.86 55.15 55.50 79.64 78.63 79.13
4 MP/99-406 24.26 22.23 23.24 62.69 61.90 62.29 92.96 91.78 92.37
5 KCH-1 21.97 20.85 21.41 58.43 57.70 58.06 90.63 89.49 90.06
6 KCH-2 22.50 22.49 22.49 59.03 58.29 58.66 92.23 91.06 91.65
7 KCH-3 21.32 21.30 21.31 47.10 46.50 46.80 83.31 82.26 82.79
8 Atlantic 20.65 20.72 20.69 51.79 51.13 51.46 87.69 86.58 87.14
9 K.Surya 20.27 20.04 20.16 45.95 45.37 45.66 86.71 85.62 86.17
10 K.Jyoti 19.41 17.88 18.65 50.56 49.93 50.24 82.67 81.63 82.15
F -Test * * * * * * * * *
SEm± 0.47 0.36 0.27 0.61 0.61 0.61 0.52 0.51 0.51
CD (p=0.05) 1.41 1.06 0.81 1.82 1.81 1.81 1.54 1.51 1.52
CV (%) 3.80 2.94 2.22 1.92 1.94 1.93 1.02 1.02 1.02
1 (mg/100 g fresh tuber weight) * = Significant at 5 per cent
75
Table -15. Variations in bio chemical attributes in different processing potato genotypes
Sl.No. Genotypes
Phenols (mg/100g freshtuber weight) Starch (%)
2007 2008 Pooled 2007 2008 Pooled
1 MP/98-71 12.63 12.33 12.48 19.97 19.93 19.95
2 MP/98-172 8.52 9.12 8.82 21.27 21.13 21.20
3 MP/99-322 11.34 11.41 11.38 21.06 21.09 21.08
4 MP/99-406 7.48 9.10 8.29 19.18 19.16 19.17
5 KCH-1 15.42 15.29 15.36 20.35 20.15 20.25
6 KCH-2 14.65 15.53 15.09 18.88 18.84 18.86
7 KCH-3 11.06 12.55 11.81 18.66 19.00 18.83
8 Atlantic 15.78 16.51 16.14 18.75 18.85 18.80
9 K.Surya 12.42 13.47 12.95 19.78 19.99 19.88
10 K.Jyoti 21.62 22.05 21.83 19.47 19.83 19.65
F -Test * * * * * *
SEm± 0.12 0.18 0.12 0.15 0.15 0.14
CD (p=0.05) 0.34 0.53 0.36 0.43 0.46 0.40
CV (%) 1.53 2.24 1.57 1.28 1.35 1.19
* = Significant at 5 per cent
76
Table -16. Chipping qualities of different processing genotypes of potato
Sl.No. Genotypes Chip colour score Undesirable colour (%)
(UC) Internal defects (%) External Defects (%) Total potato defects (%)
2007 2008 Pooled 2007 2008 Pooled 2007 2008 Pooled 2007 2008 Pooled 2007 2008 Pooled
1 MP/98-71 3.0 2.0 2.5 8.3 1.0 4.7 5.0 2.0 3.5 0.0 2.0 1.0 13.3 5.0 9.2
2 MP/98-172 1.8 2.5 2.2 0.0 2.5 1.3 10.0 5.0 7.5 0.0 3.0 1.5 10.0 10.5 10.3
3 MP/99-322 2.0 2.5 2.3 0.0 1.8 0.9 0.0 4.0 2.0 0.0 1.0 0.5 0.0 6.8 3.4
4 MP/99-406 2.0 2.6 2.3 0.0 2.0 1.0 0.0 3.0 1.5 0.0 0.0 0.0 0.0 5.0 2.5
5 KCH-1 2.0 2.4 2.2 0.0 1.7 0.9 0.0 5.0 2.5 0.0 0.0 0.0 0.0 6.7 3.4
6 KCH-2 2.2 2.2 2.2 0.0 2.0 1.0 0.0 7.0 3.5 0.0 0.0 0.0 0.0 9.0 4.5
7 KCH-3 2.4 2.3 2.4 0.0 3.0 1.5 10.0 5.0 7.5 0.0 0.0 0.0 10.0 8.0 9.0
8 Atlantic 2.8 2.1 2.5 0.0 2.3 1.2 0.0 4.0 2.0 0.0 0.0 0.0 0.0 6.3 3.2
9 K.Surya 2.4 2.2 2.3 0.0 3.0 1.5 0.0 3.0 1.5 0.0 0.0 0.0 0.0 6.0 3.0
10 K.Jyoti 2.4 3.5 3.0 0.0 10.0 5.0 0.0 3.0 1.5 5.0 6.0 5.5 5.0 19.0 12.0
77
The external defects in chips (Table-16) were nil in majority of the genotypes except
in the genotypes MP/99-322(0.5%), MP/98-71(1%), MP/98-172(1.5%) and Kufri Jyoti
(5.5%).
The total percentage defect (Table-16) was less than 15 per cent in all the genotypes.
3.5. DISCUSSION
3.5.1. STORAGE BEHAVIOUR
3.5.1.1. Early maturing genotypes:
Tuber rotting was least in the promising genotypes Kufri Surya (0.83%), J/97-
243(1.10%) and Kufri Pukhraj (1.73%) but it was comparatively more in the genotype J/96-
171(7.53%). Among the promising genotypes, Kufri Surya, J/97-243 and Kufri Pukhraj have
less than 2 per cent rotting at 90th day of storage
The tuber sprouting (Fig.1) was least in the promising genotype Kufri Surya
(29.85%). Whereas, in other promising genotypes like; Kufri Pukhraj, J/97-243 and J/96-
171, it was highest and it ranged from 94.77 to 100 per cent. It was comparatively least and
i.e., around 30 per cent in the genotype Kufri Surya and whereas, in other promising
genotypes like Kufri Pukhraj J/97-243 and J/96-171 the sprouting was more than 90 per cent
at 90th day of storage. Thus, Kufri Surya may be stored more than 90 days in the storage,
whereas the other promising genotypes may not be suitable for storage for more than 60 days.
The PTM infestation of tubers was least in Kufri Surya (8.0%), whereas, in other
promising genotypes; J/97-243(9.5%) Kufri Pukhraj (17.17%), and J/96-171(22.42%), it was
comparatively more. The potato tuber moth infestation in the promising genotypes Kufri
Surya (8.0%) and J/97-243(9.5%) was least followed by the promising genotypes Kufri
Pukhraj (17.2%) and J/96-171(22.4%). The PTM infestation varies with periderm thickness
and cortex resistance in the tuber (Horgan, et al., 2010). Similarly, in the present study also
variations were observed among the genotypes.
The Physiological loss of weight (PLW) (Fig.1) was least in the genotype Kufri Surya
(4.18%) but, it was comparatively more in other promising genotypes J/95-171(8.35%), Kufri
Pukhraj (8.24%), and J/97-243(7.09%).
78
Fig. 1: Storage behaviour of different early maturing genotypes / hybrids of potato
0
10
20
30
40
50
60
70
80
90
0
5
10
15
20
25
Physiologica loss of weight ( %) Total weight loss (%) Days for sprout initiationPe
rcen
tage
(%)
Num
ber of days for sprout initiation
79
The total percentage weight loss (TWL) of tubers (Fig.1) was least in the promising
genotype Kufri Surya and it ranged from 4.37 to 5.67 per cent. It was comparatively more in
the genotypes J/97-243(8.19%) and Kufri Pukhraj (9.97%) respectively. But, in other
promising genotype; J/96-171, it was comparatively more than the other three promising
genotypes and it ranged from 13.23 to 18.52 per cent. The total weight loss of tubers in the
genotype Kufri Surya was less than 6 per cent and it was comparatively more and less than
10 per cent in the genotypes Kufri Pukhraj and J/97-243. Whereas, the genotype J/96-171
has the total weight loss of 15.88 per cent. Thus, the genotypes which have the weight loss of
less than 10 per cent, may be stored up to 90 days, whereas, in the other genotypes where the
total weight loss was more than 10 per cent, may not be ideal to store up to 90 days and early
disposal is ideal.
The number of days taken for sprout initiation (Fig.1.) was around 80 days in the
promising genotypes J/97-243 and Kufri Surya. Whereas, the genotype J/96-171 has taken
67.3 days and Kufri Pukhraj has taken 66.5 days. It indicates that the J/97-243 and Kufri
Surya genotypes have a dormancy period of 80 days and the later genotypes have 65-70 days,
of dormancy.
The promising genotype, Kufri Surya recorded less than 2 per cent rotting, sprouting
of around 30 per cent, tuber moth infestation of 8.0 per cent, PLW of 4.2 per cent, TWL of
less than 6 per cent and dormancy of 80 days. This genotype is a heat tolerant and it realised
least storage losses, this may be mainly due to its longer dormancy and unique physico-
chemical properties. Similar observations were recorded in the earlier studies (Devender and
Minhas, 2003; Naidu & Nandekar, 2005; Coria et al., 1988). During the glut, the genotype
may be stored up to 90 days with minimum loss and can be sold after realising higher prices
in between.
Though the genotype J/97-243 has longer dormancy of 80 days, but within 10 days
period, its sprouting intensity has reached to more than 94 per cent. Usually after sprouting
the physiological weight loss will be increased substantially (Pandey et al., 2007) and it adds
for total weight loss. Thus, the genotypes may be stored up to maximum of 80 days and
should be disposed within that period to get maximum returns.
The genotype Kufri Pukhraj has a dormancy period of 66 days, rotting of less than 2
per cent and attained more than 94 per cent sprouting within 24 days. After initiation of
sprouting weight loss usually will be faster due to more permeability of actively growing
80
cells of sprouts. The PTM prefers soft tissue of actively growing cells of sprouts to lay its
eggs. Thus, the damage will be more pronounced in the genotype after sprout initiation.
Hence, Kufri Pukhraj is a good keeper up to 67 days only and the produce should be disposed
within that period. Similar observations were made by Naidu and Nandekar (2005), Patel et
al., (2006); Jitender et al., (2003); Jaiswal et al., (2003).
Though the genotype J/96-171 was found to have the dormancy period of 60 days, but
the rotting, PTM infestation of tubers, PLW and TWL loss were higher. Thus, the keeping
quality of this genotype is poor and it should be disposed within 67 days for more returns
from the produce. The genotype may not have required periderm thickness, least number of
lenticels and phytochemical contents for resistance (Eziekiel, et al., 2004)
3.5.1.2. Medium maturing genotypes
The tuber rot was less than 0.5 per cent in the promising genotypes Kufri Pushkar,
MS/99-1871 and DSP-7 at 90th day of storage. The tuber rot in other promising genotype
MS/0-3740 and Kufri Pukhraj was 1.5 and 1.7 per cent, respectively.
The tuber sprouting was comparatively least in the promising genotype Kufri Pushkar
(59.1%), but, it was more in other promising genotypes, DSP-7(79.17%), MS/0-3740 (92%),
MS/99-1871(97.56%) and Kufri Pukhraj (97.69%). All the promising genotypes have more
than 50 per cent tuber sprouting and it ranged from 59.1 to 97.7 per cent in Kufri Pushkar,
DSP-7, MS/0-3740, MS/99-1871 and Kufri Pukhraj.
The potato tuber moth infestation was least in the promising genotype MS/0-
3740(3.17%) followed by the genotypes DSP-7(13.17%), Kufri Pukhraj (14.33%), Kufri
Pushkar (19.17%) and MS/99-1871(22.67%) at 90 days after storage. The potato tuber moth
infestation in storage at 90th day was least in the promising genotype MS/0-3740 (3.2%),
whereas, the other promising genotypes have the infestation of more than 10 per cent in DSP-
7(13.2%), Kufri Pukhraj (14.3%), Kufri Pushkar (19.2%), and MS/99-1871 (22.7%). The
genotype MS/0-3740 manifested resistance to PTM and it was recorded only 3.2 per cent
PTM infestation.
The physiological loss of weight (PLW) (Fig.2.) was least in the promising genotypes
Kufri Pukhraj (5.62%) and Kufri Pushkar (5.68%), but it was comparatively higher in other
promising genotypes DSP-7(6.03%), MS/99-1871(7.23%) and MS/0-3740(7.23%). The
81
mean PLW was more than 5 per cent in all the promising genotypes Kufri Pukhraj (5.6%),
Kufri Pushkar (5.7%), DSP-7(6.0%), MS/99-1871(7.2%) and MS/0-3740(7.2%).
The total weight loss (TWL) was least (Fig.2.) in the promising genotype Kufri
Pushkar (6.07%), whereas, it was comparatively more in other promising genotypes DSP-
7(6.53%), Kufri Pukhraj (7.36%), MS/99-1871(7.39%) and MS/0-3740 (8.78%). The mean
TWL was less than 10 per cent in all the promising genotypes Kufri Pushkar (6.1%), DSP-
7(6.5%), Kufri Pukhraj (7.4%), MS/99-1871(7.4%) and MS/99-3740(8.8%). Thus, all
promising genotypes should not be stored up to 90 days.
The days for sprout initiation (Fig.2.) was more in the Kufri Pukhraj (63.7 days),
followed by the other promising genotypes MS/0-1871(36.2 days), Kufri Pushkar (29.3
days), MS/0-3740(27 days) and DSP-7(24.2 days).
Among the genotypes evaluated, the promising genotypes Kufri Pushkar had the
dormancy period of 29 days , 0.4 per cent tuber rotting, 59.1 per cent sprouting, PLW of 5.7
and TWL of 6.1 per cent. Though, its dormancy was 29 days, the losses through other means
were found to be least up to 90th day of storage. However, the genotypes may be stored up to
30 days to get more benefits. Because, after commencement of sprouting, the tubers would
loose its firmness and weight loss would be faster. In earlier studies, the genotype Kufri
Pushkar has been reported to have longer dormancy (Mehtha, 2006). Eziekiel & Singh,
(2003) reported that, dormancy is considered to be a varietal character during crop growth
and the storage environment. With the commencement of sprouting, it is better to dispose the
tubers as ware potato to get maximum returns.
The genotype Kufri Pukhraj was found to have longer dormancy i.e., more than 8
weeks, and TWL was less than 10 per cent. Though PTM infestation (14.3%) and rotting
(0.7%) were noticed in tubers, may be due to field infestation/infection. It can be managed
with proper plant protection measures and plot maintenance. Thus, the genotype may be
stored at ambient condition up to 8 weeks period.
All other promising genotypes were found to have short dormancy period (Eziekiel &
Singh, 2003), thus, the disposal of tubers within 30 days was found to be most appropriate.
82
Fig. 2: Storage behaviour of different medium maturing genotypes / hybrids of potato
0
10
20
30
40
50
60
70
80
0
2
4
6
8
10
12
14
Physiological loss of weight ( %)Total weight loss (%)Days for sprout initiation
Num
ber of days for sprout initiation
Perc
enta
ge(%
)
Medium maturing genotypes
83
3.5.1.3. Processing genotypes
Tuber rot was not noticed in the promising genotype Kufri Surya followed by one per
cent in other promising genotype MP/99-322. Whereas, in the genotype Atlantic, it was 7.0
per cent at 90th day of storage.
The tuber sprouting percentage was more in the promising genotypes; Kufri Surya
(37.6%), MP/99-322(42.4%) and Atlantic (52%), respectively.
The potato tuber moth infestation of tuber was 34, 43.1 and 54.9 per cent in Kufri
Surya, MP/99-322 and Atlantic, respectively.
The physiological loss of weight (PLW) (Fig.3.)of tuber was 2.7, 6.02 and 12.2 per
cent in the promising genotypes Kufri Surya, Atlantic and MP/99-322, respectively. It was
less than 10 per cent in the genotypes Kufri Surya and Atlantic.
The total weight loss (TWL) (Fig.3.) was least in the promising genotype Kufri Surya
(2.73%) at 90th day after storage. Whereas, in the other promising genotypes; Atlantic
(13.03%) and MP/99-322 (13.2%) it was comparatively higher. The TWL was 2.7, 13.0 and
13.2 per cent in the genotypes Kufri Surya, Atlantic and MP/99-322, respectively. The TWL
in excess of 10 per cent reduces the marketability of potato because of their shrivelled
appearance (Booth and Shaw, 1981). Thus, Kufri Surya has good keeping quality, since its
TWL is least.
The number of days taken for sprout initiation (Fig.3) was 73.7, 76.3 and 66 days in
the genotypes Kufri Surya, MP/99-322 and Atlantic. Thus, their dormancy is considered to
be longer and hence the genotypes MP/99-322, Kufri Surya and Atlantic can be stored up to
76, 74 and 76 days, respectively.
The promising genotype Kufri Surya has a dormancy period of 74 days, PLW of 2.7
and TWL of 2.7, PTM infestation of 34.1, sprouting of 38 per cent and no tuber rotting. The
TWL was less than 3 per cent in addition no rotting was observed. Besides, Kufri Surya is a
heat tolerant hybrid, it has different physico-chemical properties; periderm thickness, number
of cell layers and less number lenticels which are desirable for the least TWL. The prolonged
dormancy of the tubers also add to prolonged storage and keeping quality of the genotype.
The results are in agreement with the studies conducted by Pande et al., (2007), Ashiv et al.,
(2006) and Naidu and Nandekar (2005).
84
Fig. 3: Storage behaviour of different processing genotypes/ hybrids
0
10
20
30
40
50
60
70
80
90
0
5
10
15
20
25
Physiological loss of weight ( %) Total weight loss (%) Days for sprout initiation
Perc
enta
ge(%
)
Num
ber of days sprout initiation
Processing genotypes
85
PROCESSING AND CHIPPING QUALITY
An ideal processing genotype must meet the specifications of acceptable chip colour
and low reducing sugars, high dry matter, proper shape and size, free from mechanical injury
and physiological disorders. Specifications of important characters are discussed here under:
The tubers of 6-8 cm diameter are preferred for making chips. Round shape is
preferred to obtain uniformly round chips. For French fries, oblong or long (more than 90
mm length) tubers are desired, eye depth is an inherited trait of a cultivar and should be
shallow/fleet, so that peeling losses would be least before slicing. Potato tubers on an
average contain 80 per cent moisture. Potatoes having high dry matter content are preferred
for fried and dehydrated products. Dry matter content of 18-20 per cent is considered
acceptable for canning but for chips, French fries and dehydrated products it should be more
than 20 per cent. Sugar content of potato plays a very important role in determining the
acceptability of fried products like chips and French fries. Reducing sugars content below
250mg/100 g fresh wt., is acceptable for producing chips. However, for French fries and
dehydrated products reducing sugar content up to 500 mg/100 g fresh weight is acceptable.
In addition to the discolouration of fried products, tubers show enzymatic
discoloration and after cooking discolorations. Enzymatic discolouration occurs when the
potatoes are peeled, cut or injured. The enzymic browning occurs because of oxidation of
tyrosine and other ortho dihydric phenols by poly phenoloxydase (PPO). Tyrosine oxidation
initiates the subsequent formation of a dark or black melanin pigment. About 3 per cent of
the World Crop of potato is used for the production of starch and the world consumption of
potato starch is approximately 2 million tonnes. Starch is the major carbohydrate source in
potato tubers, yet small but varying amount of sugars namely sucrose, glucose and fructose
are also present.
3.5.2. PROCESSING QUALITY ATTRIBUTES3.5.2.1. Morphological characters:Tuber size:The promising genotypes; Kufri Surya and Atlantic are categorised under medium-large size
tuber group and the other promising genotype MP/99-322 is categorised under medium size
tuber group.
86
Tuber shape:The promising genotype Atlantic has round shaped tubers, whereas, the genotype
MP/99-322 has round to oval shaped tubers. The genotype Kufri Surya has oval shaped
tubers.
Tuber eye depth:The tubers of the promising genotypes Kufri Surya and Atlantic have shallow eye
depth, whereas, the tubers of other promising genotype MP/99-322 as medium deep eye
depth and all three promising genotypes have white periderm.
The genotype Kufri Surya has medium – large size tubers of oval shape with shallow
eye depth. Thus, peeling losses will be least before slicing. Since, it has oval shaped tubers,
the tubers are ideal to make finger chips in addition to chips. This is in agreement with
earlier studies by Minhas et al., (2006) and Patel et al., (2006).
The advanced promising genotype MP/99-322 has medium sized tubers of round to
oval shape with medium eye depth. Hence, the tuber of this genotype can be utilised for
making chips as well as finger chips with minimum peeling losses. The morphological
features of tubers fulfil the requirement for making chips and Finger chips.
The exotic genotype Atlantic has medium to large sized tubers of round shape with
shallow eye depth. By virtue of its morphological features the peeling losses will be least and
the chips yield also would be more (Ezekiel, et al., 1999; Manivel, et al., 2007).
3.5.2.2. Bio-chemical content:Tuber Dry Matter:
The promising genotypes Kufri Surya, Atlantic and MP/99-322 have more than 20 per
cent tuber dry matter (Fig.4.) content except in the genotype Kufri Jyoti.
Reducing Sugars:
The reducing sugar (Fig.4.) content in the freshly harvested tubers was comparatively
least in the promising genotype Kufri Surya (45.66 mg/100 g fresh wt.) followed by the other
promising genotypes Atlantic (51.46 mg/100 g fresh wt.) and MP/99-322(55.50 mg /100 g
fresh wt.).
87
Total Sugars:
The total sugar content in the fresh tubers (Fig.4.) was least in the promising
genotypes MP/99-322(79.13 mg/100 g fresh wt) followed by the genotype Kufri Surya (86.17
mg/100 g. fresh wt.) and Atlantic (87.14 mg /100 g fresh wt.).
The reducing and total sugar content (Fig.4.) of evaluated processing genotypes was
less than 250 mg/ 100 g fresh wt. of tubers. This may be due to cultivation of the crop under
warmer situation i.e., southern transition of Karnataka during kharif season. Similar findings
were reported by Singh et al., (2008).
Phenols:
The phenol (Fig.4.) content in the freshly harvested tubers was less than 20 mg/100 g
fresh weight in the promising genotypes MP/99-322(11.38 mg/100 g fresh wt.), Kufri Surya
(12.95 mg / 100 g fresh wt.) and Atlantic (16.14 mg/100 g fresh wt.). The phenol content in
tubers was less than 20 per cent in all genotypes except Kufri Jyoti. The phenol content
varies with the genotype and it is a varietal character. Phenol content of the tubers will be
resulted in less browning of dehydrated and chips (Singh et al., 2008). Hence, all promising
genotypes can be used to produce quality chips.
Starch:
The starch content was maximum in the promising genotypes MP/99-322(21.08%)
followed by Kufri Surya (19.88%) and Atlantic (18.80%). The estimated starch content
ranged from 18.8 to 21.2 per cent which is quite high. Thus, all the genotypes can be used
for the production of starch.
The promising genotypes Kufri Surya and MP/99-322 have more than 20 per cent
tuber dry matter, less than acceptable quantity of reducing and total sugars, phenol and
acceptable limit of starch content. This is in agreement with the studies conducted by Minhas
et al., (2006).
Other promising genotype Atlantic also has the tuber dry matter of more than 20 per
cent and the acceptable limit of sugar and phenol content is more than in Kufri Surya and
starch content in MP/99-322 and that is 16.1 per cent. This is in agreement with studies of
Singh et al., (2008).
88
Fig. 4: Bio-chemical content of different processing genotypes of potato
0
10
20
30
40
50
60
70
80
90
100
0
10
20
30
40
50
60
70
Tuber dry matter (%) Reducing sugar (mg/100g fw.)
Total sugar (mg/100g fw.) Phenols (mg/100g fresh tuber weight
Total sugar and Phenols (mg/100 fw
)
Tube
r dry
mat
ter(
%)
and
redu
cing
suga
r (m
g/10
0g fw
)
Processing genotypes
89
3.5.3. Chipping quality
The chip colour index (Fig.5) of all the genotypes was less than 3, except Kufri Jyoti
(3.0) in the scale of 1-10. The chip colour index was less than acceptable limits i.e., less than
3 in all promising genotypes; MP/99-322(2.3), Kufri Surya (2.3) and Atlantic (2.5).
The undesirable colour percentage was less than 5 per cent in the promising
genotypes MP/99-322(0.9%), Atlantic (1.2%) and Kufri Surya (2.5%).
The internal defects of chips of different genotypes evaluated were less than 5 per
cent. Whereas, in all promising genotypes; Kufri Surya (1.5%), Atlantic (2.0%) and MP/99-
322(2.0%) have recorded zero to maximum of 4 per cent.
The external defects of chips was not observed in the promising genotype Kufri Surya
and Atlantic, but in other promising genotype; MP/99-322 it was least (0.5%).
The total potato defect (Fig.5) was less than 15 per cent in all genotypes. It was less
than 5 per cent in the promising genotypes MP/99-322(3.4%), Atlantic (3.2%) and Kufri
Surya (4.0%).
The promising genotypes Kufri Surya, MP/99-322 and Atlantic have the chip colour
index of less than 3 and that is the acceptable standard (Singh et al., 2008). The mean
undesirable chip colour, internal defects and external defects were less than 2 per cent in all
the promising genotypes. According to Pandey et al., (2001), the acceptable limit of less than
2 per cent of external defects and total potato defects should not be more than 15 per cent is
desired in the production of quality chips. In the present study also revealed chipping quality
parameters within the acceptable limit in the promising genotypes, hence, all promising
genotypes are ideal for processing. Based on the results of the present study the exotic
genotype Atlantic can be used for making chips, MP/99-322 can be used both for making
chips and finger chips, whereas, Kufri Surya is ideal for making finger chips.
90
Fig. 5: Response of different processing genotypes of potato on chipping qualities
0
2
4
6
8
10
12
14
Chip colour score Total potato defects (%)
Chi
p co
lour
scor
e an
d T
otal
pot
ato
defe
cts
(%)
Processing genotypes