maize grain stored in hermetic bags: effect of moisture and ...maize (zea mays l.) is an important...

Research ArticleMaize Grain Stored in Hermetic Bags Effect of Moisture andPest Infestation on Grain Quality

Paddy Likhayo 12 Anani Y Bruce3 Tadele Tefera4 and Jones Mueke2

1Kenya Agricultural and Livestock Research Organisation (KALRO) Food Crops Research Institute PO Box 14733-00800Nairobi Kenya2Kenyatta University (KU) Department of Zoological Sciences PO Box 43844-00100 Nairobi Kenya3International Maize and Wheat Improvement Centre (CIMMYT) PO Box 1041-00621 Nairobi Kenya4International Centre of Insect Physiology and Ecology (ICIPE) ILRI Campus PO Box 5689 Addis Ababa Ethiopia

Correspondence should be addressed to Paddy Likhayo paddylikhayokalroorg

Received 16 May 2018 Accepted 17 September 2018 Published 4 November 2018

Academic Editor Daniel Cozzolino

Copyright copy 2018 Paddy Likhayo et al is is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work isproperly cited

Maize (Zea mays) is an important staple food crop produced by the majority of smallholder farmers that provides household foodsecurity through direct consumption and income generation However postharvest grain losses caused by insect pests duringstorage pose a major constraint to household food security Hermetic storage technology is an alternative method that minimisespostharvest losses by depleting oxygen and increasing carbon dioxide levels within the storage container through metabolicrespiration of the grains insects and microorganism Maize grain was stored for 180 days in hermetic bags or open-weavepolypropylene bags to compare quality preservation when subject to initial grain moisture contents of 12 14 16 and 18 percentand infestation by Sitophilus zeamaisemoisture content of grain in hermetic bags remained unchanged while in polypropylenebags decreased Dry grains (12moisture content) stored well in hermetic bags and suered 12 weight loss while for equivalentgrains in polypropylene bags the weight loss was 358 Moist grains (18moisture content) recorded the lowest insect density (7adultskg grain) in hermetic bags while polypropylene bags had the highest (1273 adultskg grain) Hermetic and polypropylenebags recorded the lowest (0ndash4 adultskg grain) and highest (16ndash41 adultskg grain) Prostephanus truncatus population re-spectively Discoloured grains were 4 6 and 12 times more in grains at 14 16 and 18 than 12 percent moisture content inhermetic bags Grains at 18 moisture content recorded signicantly lower oxygen (102) and higher carbon dioxide (189)levels Holes made by P truncatus in the hermetic bags were observed In conclusion storage of moist grains (14ndash18 moisturecontent) in hermetic bags may pose health risk due to grain discolouration caused by fungal growth that produces mycotoxins ifthe grains enter the food chain e study was on only one site which was hot and dry and further investigation under cool hotand humid conditions is required

1 Introduction

Maize (Zea mays L) is an important staple food in sub-Saharan Africa but is also used for industrial purposes andanimal feed worldwide [1] In the tropics in locations wherethere are two annual maize harvests it is not uncommon forone harvest to coincide with the start of the rainy season Asnearly all smallholder farmers rely on sun-drying prior tograin storage this poses a serious threat of grain qualitydeterioration [2] If the crop is stored while still moist and

warm there may be rapid spoilage due to mould growth andinsect pests [3] Due to the demand for high quality and safefood by the consumers there is a need tomaintain and protectmaize grain from insect damage and fungal infection [4]

Important physical factors that may aect the quality ofstored grain are moisture content temperature the type ofstorage structure used and the gaseous environment par-ticularly levels of carbon dioxide and oxygen [5] All thesefactors may have interactive eects on mould growth andinsect pests [6 7] evolution of carbon dioxide [8] and grain

HindawiJournal of Food QualityVolume 2018 Article ID 2515698 9 pageshttpsdoiorg10115520182515698

colour and weight [9] e optimum temperature for thedevelopment of storage moulds and insects is generallyaround 30degC Requirements for moisture are more wideranging with most moulds failing to germinate below 80relative humidity but insect needing a grain moisturecontent of at least 10 to 12 [10] which is typically inequilibrium with around 50 to 70 relative humidityWhen grain with higher moistures (gt14) is stored underwarm conditions mould growth may result in seriousquality changes [3] and insect attack may reduce quality andcause weight losses Simple and low cost storage facilitiesthat isolate grains from unfavourable environmental con-ditions are therefore required by farmers

e main insect pests of stored maize include the largergrain borer Prostephanus truncatus (horn) (ColeopteraBostrichidae) and maize weevil Sitophilus zeamais (Mot-schulsky) (Coleoptera Curculionidae) [11] For the past 35years sub-Saharan Africa has witnessed the outbreak andspread of larger grain borer (LGB) in 20 countries [12] eimpact of insect infestation of stored grain is usuallyexpressed as percentage weight loss [13] Losses as high as36 have been documented on stored maize in Benin [14]and 35 in Kenya [15] e losses are attributed to the use ofineffective storage structures such as cribs jute and poly-propylene bags for storing grains [16] ese losses affect thefood security and income of the 90 of the Kenyan pop-ulation that relies on the crop as staple food [17] besidescontributing to increased food prices due to removal of partof the supply from the market [18]

A promising technology to store grains safely is airtight(hermetic) storage (self-regulated modified atmosphere)e technology was developed in response to concern aboutthe adverse effects of pesticide residues in grains and en-vironment [19] e respiration of the grains insects andmoulds within hermetic stores result in depletion of oxygenand increase of carbon dioxide [20 21] Under such con-ditions fungal growth may be inhibited [22] and when theoxygen level falls to 10 insect activity is reduced and insectwill die if subjected to less than 2 oxygen for periods inexcess of 14 days Consequently hermetic storage can beused to maintain grain quality without the need for pesticideapplication [23] e rate at which oxygen is reduced andcarbon dioxide generated is a function of both grainmoisture content and the ambient temperature the rate islow at temperatures below 20degC [24]

Storage systems based on the hermetic principle includeairtight bags bunkers and silos While hermetic metal silos[25] and polythene (plastic) bags [26] have been developedtheir use for storage of grains by smallholder farmers is stilllimited ere is also scant information on the storability ofmaize grain at the range of moisture contents that are typicalin tropical storage systems e key to successful hermeticstorage is air-tightness and control of moisture content epresent study was undertaken to investigate quality changeof maize stored in hermetic bags subject to infestation bySitophilus zeamais and a variety of initial grain moisturecontent level e parameters monitored were moisturecontent grain discolouration insect density weight lossand oxygen and carbon dioxide levels

2 Materials and Methods

21 Preparation of Maize Grain Hybrid maize (H614) wascleaned to remove mouldy and broken grains and foreignmaterials and sun-dried to 12 moisture content Samplesof grain at three further moisture contents 14 16 and 18were prepared by adding predetermined amount of distilledwater then mixing thoroughly in plastic bags [3 27] eamount of water added was calculated as follows Q A((bminusa)(100minusa)) where A weight of grain b desiredmoisture content and a initial grain moisture contentebags were then kept in a cold room for two weeks Everyother day the bags were retrieved grains mixed andreturned to the cold room Prior to the conditioning of thegrains four grain samples were taken and tested formoisturecontent using a Foss Infratectrade 1241 grain analyzer (Sweden)and weight as the baseline e moisture content of themaize grain in the 12 14 16 and 18 categories was close tothe desired ones 124 plusmn 00 143 plusmn 01 162 plusmn 02 and 182 plusmn02 (wet basis) respectively while the quality of the grainswas 12 plusmn 02 discoloured at the start of the storage period

22 Test Storage Bags e storage bags tested were Super-Grain IV-Rtrade bag (74 cm wide and 64 cm length) of 25 kgholding capacity (supplied by GrainPro Inc) and open-weave polypropylene bags of the same capacity eSuperGrain IV-Rtrade bag is tougher than the earlier version ofthe SuperGrain bag and has an extremely low oxygenpermeability (lt4 ccm2day) in which oxygen is reducedfrom 20 to 8 in 14 days for P truncatus under controlledconditions of 27 plusmn 1degC and 75 plusmn 1 relative humidity [28]As recommended by the manufacturer each SuperGrain IV-Rtrade bag was placed inside a woven polypropylene bag toprovide support and handling convenience e open endsof SuperGrain IV-Rtrade bags were cut to fit the height di-mension of these polypropylene outer bags

23 Experimental Procedure e bags were each filled with20 kg maize grains and then ldquoseededrdquo with 20 live adultmaize weevil (1 beetlekg grain) e barn had an LGBpopulation and were interested to see whether this pestwould penetrate from the outside into the bags (entry holes)while S zeamais on the inside potentially made emergenceholes on the grains e bags were closed according tomanufacturerrsquos instructions the entrapped air was squeezedout and then secured tightly with rubber straps e grainswere not inoculated with fungi since maize usually harbourssufficient fungal spores that fungal growth will occur nat-urally if environmental conditions are conducive e ex-periment consisted of eight treatments with fourreplications (1) SuperGrain IV-Rtrade bag + grains at 12moisture content (2) SuperGrain IV-Rtrade bag + grains at 14moisture content (3) SuperGrain IV-Rtrade bag + grains at 16moisture content (4) SuperGrain IV-Rtrade bag + grains at 18moisture content (5) Polypropylene bag + grains at 12moisture content (6) Polypropylene bag + grains at 14moisture content (7) Polypropylene bag + grains at 16moisture content and (8) Polypropylene bag + grains at 18

2 Journal of Food Quality

moisture content To monitor hermetic conditions carbondioxide levels were measured using a MOCONreg portableoxygencarbon dioxide analyzer (Pac Checkreg 325 MoconInc USA) Measurement of carbon dioxide in polypropylenebags was not considered worthwhile as their open weavewould allow free exchange of gas and so it was not expectedto accumulate carbon dioxide ese measurements weretaken every seven days and their means at the end of eachstorage period calculated

e bags were stored in a completely randomised fac-torial design in an open side barn at ambient conditionseambient mean monthly temperatures and relative humidityin the barn during the trial were 26degC (range 23ndash30degC) and54 (range 46ndash58) respectively e highest and lowestmean temperatures were recorded in MarchApril andJuneJuly respectively For relative humidity the highestrecords were in April and lowest records in SeptemberGrain bags were sampled destructively after 60 120 and 180days storage

At each sampling interval bags were unsealed and about350 g grains were drawn using a 6-slot probe from the centreand four cardinal points e samples were put in labelledplastic bags and taken to the laboratory for grain damageanalysis A set of 475mm and 10mm aperture size sieves(Endecott Ltd UK) were used to separate grains and flourfrom the insects Record of adult insects was taken accordingto species After sieving the grains were tested for moisturecontent using the Foss Infratectrade 1241 grain analyzer Half ofthe grain samples obtained using riffle divider were analysedfor damage e grains were sorted into undamaged dam-aged and discoloured fractionse number of grains and theweight of each fraction were recorded e grains wereweighed on a precision electronic scale (to two decimalpoints) Discoloured grains were expressed as a percentage ofthe total number of grains A grain was regarded discolouredwhen its surface was darkened Grain weight loss was de-termined by count and weight method [29]

discoloured grain() number of discoloured grain

total number of graintimes 100

weight loss() Wu times Nd( 1113857minus Wd times Nu( 11138571113858 1113859

Wu times Nu + Nd( 1113857times 100

(1)

where Wu weight of undamaged grain Nu number ofundamaged grain Wd weight of damaged grain and Nd

number of damaged graine full contents of each bag were also sieved and all

insects present counted according to the species e insectcounts were added to those obtained from the 350 g samplesto give a total number of insects presente total number ofadult insects per bag were divided by the initial grain weight(20 kg) and recorded as number of insects per kilogram

3 Statistical Analysis

e number of insects was transformed to log10 (count + 1)while percent discoloured grain weight loss and oxygen and

carbon dioxide data were square root (radicx) transformed inorder to stabilize the variances e transformed data werefirst analysed using one-way repeated measures ANOVA(SPSS version 20 IBM Corporation 2011) to compare grainmoisture content insect numbers percent discoloured grainweight loss and oxygen and carbon dioxide at each storagetime among the treatment as the response variable andtreatment as the main effect Storage time represented therepeated factor Afterwards and separately each responsevariable was analyzed using general linear model procedureof GenStat Release 121 (VSN International Ltd 2009) withtreatment as main effect Significant differences between themeans were separated by the StudentndashNewmanndashKeuls(SNK) test at Plt 005 However for ease of understandingthe untransformed means are presented

4 Results

41 Grain Moisture Content and Grain Discolouratione grain moisture content differed significantly withtreatments (F724 264348 Plt 00001 coefficient of var-iation 099) and storage period (F248 161192 Plt 00001coefficient of variation 087) Significant interaction(Plt 00001 coefficient of variation 088) was also detectede treatment effects explained the significant differencesobserved SuperGrain IV-Rtrade bag maintained moisturecontent of the grains constantly throughout the storageperiod (Table 1) e equivalent grains stored in poly-propylene bags showed a decrease in grain moisture contentover the same storage period with the final contents rangingfrom 112 to 116 after 180 days storage (Table 1) epresence of fermented smell in moist grains at 18 initialmoisture content stored in the hermetic bag was observed

ere were differences in the percentage grain dis-colouration with treatments (F724 19123 Plt 00001coefficient of variation 098) and storage period (F248

8856 Plt 00001 coefficient of variation 079) e in-teraction (Plt 00001 coefficient of variation 088) was alsosignificant e significant differences observed in graindiscolouration were explained by the treatment effects ediscoloured grains were 4 6 and 12 times more in the grainsstored in hermetic bags at 14 16 and 18 than grains with12 initial moisture content at the end of the experimentrespectively (Table 2) For the grains stored in polypropylenebags the percentage discolouration reduced with storageperiod e grain darkening and its associated off-odourwere indicative of spoilage and changes in the quality of thegrains

42 Infestation by Sitophilus zeamais and Prostephanustruncatus Although the grain was deliberately seeded withS zeamais infestation by P truncatus occurred naturallyfrom a residual population in the barn thus both insectspecies were followed during the study e number of adultS zeamais differed significantly with treatment (F724

19746 Plt 00001 coefficient of variation 098) andstorage period (F248 8315 Plt 00001 coefficient of var-iation 078) e interaction was significant (Plt 0002

Journal of Food Quality 3

coefficient of variation 065) e significant differencesobserved were explained by the treatment effects epopulation increasedmarginally 180 days after storage (7ndash60adultskg grain) in SuperGrain IV-Rtrade bags compared toequivalent grains (894ndash1273 adultskg grain) stored inpolypropylene bags (Table 3) SuperGrain IV-Rtrade bag withmoist grains (18 moisture content) recorded the lowestinsect density (7 adultskg grain) while equivalent grains inpolypropylene bags had the highest insects (1273 adultskggrain) (Table 3) Very few S zeamais survived in moist grainsstored in SuperGrain IV-Rtrade bags and the population wasalmost the same throughout the storage duration

e mean difference of the number of adult P truncatusdiffered significantly with treatment (F724 6526Plt 00001 coefficient of variation 095) and storage period(F248 5578 Plt 00001 coefficient of variation 070) einteraction was also significant (P 0002 coefficient ofvariation 048) e significant differences observed wereexplained by the treatment effects Grains stored inSuperGrain IV-Rtrade bags were infested with P truncatus 120days after storage e population increased marginally 180days after storage (ranged from 0ndash10 adultskg grain)compared to equivalent grains stored in polypropylene bags(Table 4) Overall SuperGrain IV-Rtrade bags and poly-propylene bags had the lowest (0ndash4 adultskg grain) andhighest (16ndash41 adultskg grain) insects (Table 4)

43 Grain Weight Loss At the onset of the storage theweight loss of the grains was 12 plusmn 02 ere were sig-nificant mean differences in percentage weight loss withtreatment (F724 480414 Plt 00001 coefficient of var-iation099) and storage period (F248 552198 Plt 00001coefficient of variation 099) e interaction was alsosignificant (Plt 00001 coefficient of variation 099) esignificant differences observed were explained by the in-teraction effects e results showed significantly increasingtrend in grain weight loss over the storage period andtreatment e mean percentage weight loss increased from19 to 209 (Table 5) after 180 days of storage Grain at 12moisture content stored in the SuperGrain IV-Rtrade bagsrecorded the lowest (12) while grains at 16 moisturecontent stored in polypropylene bags incurred highest(426) weight loss (Table 5) Overall irrespective of initialgrain moisture content SuperGrain IV-Rtrade bags preventedand maintained almost similar grain weight loss (le1)compared to equivalent grains in polypropylene bags over120 days after storage As grains in the polypropylene bagslost moisture during the storage period significantly higherlosses were observed (Table 5) By the end of storage periodgrains at 12 initial moisture content stored in SuperGrainIV-Rtrade bags suffered least weight loss (12) translating to966 weight loss reduction compared to the equivalentgrains in polypropylene bags

Table 1 Mean (plusmnSE) percent grain moisture content after 60 120 and 180 days of storage

TreatmentStorage period (days)

60 120 180Polypropylene bag + 12 MC grain 121 plusmn 01a 117 plusmn 01a 112 plusmn 00aPolypropylene bag + 14 MC grain 134 plusmn 01b 124 plusmn 01c 116 plusmn 00bPolypropylene bag + 16 MC grain 136 plusmn 01b 124 plusmn 01c 116 plusmn 02bPolypropylene bag + 18 MC grain 139 plusmn 01c 126 plusmn 01c 115 plusmn 00bSuperGrain IV-Rtrade bag + 12 MC grain 120 plusmn 01a 120 plusmn 01b 120 plusmn 01cSuperGrain IV-Rtrade bag + 14 MC grain 142 plusmn 00c 141 plusmn 01d 141 plusmn 00dSuperGrain IV-Rtrade bag + 16 MC grain 160 plusmn 01d 159 plusmn 01e 160 plusmn 01eSuperGrain IV-Rtrade bag + 18 MC grain 180 plusmn 01e 181 plusmn 01f 179 plusmn 01fF value 49590 60306 56120P value lt0001 lt0001 lt0001Means within a column followed by the same letter are not significantly different (SNK test Pgt 005)

Table 2 Mean (plusmnSE) percent grain discolouration after 60 120 and 180 days of storage


60 120 180Polypropylene bag + 12 MC grain 27 plusmn 02b 24 plusmn 02ab 02 plusmn 02aPolypropylene bag + 14 MC grain 55 plusmn 02c 41 plusmn 08b 00 plusmn 00aPolypropylene bag + 16 MC grain 45 plusmn 02c 25 plusmn 02ab 01 plusmn 01aPolypropylene bag + 18 MC grain 76 plusmn 07d 62 plusmn 05c 08 plusmn 02bSuperGrain IV-Rtrade bag + 12 MC grain 16 plusmn 01a 19 plusmn 01a 23 plusmn 08cSuperGrain IV-Rtrade bag + 14 MC grain 95 plusmn 04e 100 plusmn 09d 92 plusmn 06dSuperGrain IV-Rtrade bag + 16 MC grain 141 plusmn 09f 100 plusmn 09d 130 plusmn 06eSuperGrain IV-Rtrade bag + 18 MC grain 203 plusmn 10g 192 plusmn 25e 282 plusmn 19fF value 9997 4513 17595P value lt0001 lt0001 lt0001Means within a column followed by the same letter are not significantly different (SNK test Pgt 005)


44 Carbon Dioxide Levels e carbon dioxide levelsrecorded in the grains at different initial grain moisturecontents stored in the SuperGrain IV-Rtrade bag affected theinsect population observed in the bags e buildup ofcarbon dioxide varied significantly with the treatment(F312 6411 Plt 00001 coefficient of variation 094) andthe storage period (F336 19943 Plt 00001 coefficient ofvariation 094) e interaction between these two factorswas also significant (F936 10403 Plt 00001 coefficient of

variation 096) e significant differences observed wereexplained by the interaction effects During the first 60 daysof storage carbon dioxide levels increased reaching a valueof 157 for grains stored at 12 moisture content andthereafter declined marginally when SuperGrain IV-Rtradebags became perforated by P truncatus (Table 6) Overallgrains stored at 16 and 18 moisture contents recordedlowest (88) and highest (156) carbon dioxide levels(Table 6)

Table 4 Mean (plusmnSE) number of adult Prostephanus truncatus per kilogram of grain after 60 120 and 180 days of storage


60 120 180SuperGrain IV-Rtrade bag + 12 MC grain 0 plusmn 0a 1 plusmn 1a 4 plusmn 2bSuperGrain IV-Rtrade bag + 14 MC grain 0 plusmn 0a 0 plusmn 0a 10 plusmn 9bSuperGrain IV-Rtrade bag + 16 MC grain 0 plusmn 0a 1 plusmn 0a 3 plusmn 2bSuperGrain IV-Rtrade bag + 18 MC grain 0 plusmn 0a 1 plusmn 1a 0 plusmn 0aPolypropylene bag + 12 MC grain 8 plusmn 1b 74 plusmn 6c 41 plusmn 3cPolypropylene bag + 14 MC grain 6 plusmn 2b 18 plusmn 3b 41 plusmn 5cPolypropylene bag + 16 MC grain 10 plusmn 6b 17 plusmn 5b 40 plusmn 5cPolypropylene bag + 18 MC grain 3 plusmn 1b 16 plusmn 3b 30 plusmn 3cF value 1609 6190 2084P value lt0001 lt0001 lt0001Means within a column followed by the same letter are not significantly different (SNK test Pgt 005)

Table 5 Mean (plusmnSE) percentage weight loss after 60 120 and 180 days of storage


60 120 180Polypropylene bag + 12 MC grain 16 plusmn 01d 152 plusmn 05d 358 plusmn 01dPolypropylene bag + 14 MC grain 43 plusmn 05e 197 plusmn 03e 407 plusmn 03cPolypropylene bag + 16 MC grain 56 plusmn 01f 218 plusmn 02f 426 plusmn 07fPolypropylene bag + 18 MC grain 13 plusmn 01cd 209 plusmn 06f 401 plusmn 01eSuperGrain IV-Rtrade bag + 12 MC grain 02 plusmn 00a 03 plusmn 01a 12 plusmn 01aSuperGrain IV-Rtrade bag + 14 MC grain 10 plusmn 00bc 09 plusmn 01c 30 plusmn 02cSuperGrain IV-Rtrade bag + 16 MC grain 08 plusmn 00b 08 plusmn 00c 20 plusmn 01bSuperGrain IV-Rtrade bag + 18 MC grain 04 plusmn 01a 05 plusmn 01b 18 plusmn 01bF value 14360 194775 530788P value lt0001 lt0001 lt0001Means within a column followed by the same letter are not significantly different (SNK test Pgt 005)

Table 3 Mean (plusmnSE) number of adult Sitophilus zeamais per kilogram of grain after 60 120 and 180 days of storage


60 120 180SuperGrain IV-Rtrade bag + 12 MC grain 4 plusmn 1a 33 plusmn 8b 60 plusmn 9bSuperGrain IV-Rtrade bag + 14 MC grain 8 plusmn 4a 9 plusmn 4a 8 plusmn 1aSuperGrain IV-Rtrade bag + 16 MC grain 6 plusmn 1a 11 plusmn 3a 8 plusmn 2aSuperGrain IV-Rtrade bag + 18 MC grain 2 plusmn 1a 9 plusmn 5a 7 plusmn 1aPolypropylene bag + 12 MC grain 163 plusmn 123b 685 plusmn 55c 961 plusmn 20cPolypropylene bag + 14 MC grain 331 plusmn 37c 1092 plusmn 18c 1043 plusmn 99cPolypropylene bag + 16 MC grain 439 plusmn 113c 1230 plusmn 134c 894 plusmn 94cPolypropylene bag + 18 MC grain 54 plusmn 15b 1227 plusmn 165c 1273 plusmn 57cF value 2879 7897 40842P value lt0001 lt0001 lt0001Means within a column followed by the same letter are not significantly different (SNK test Pgt 005)


5 Discussion

51 Moisture Content and Grain Discolouration Moisturecontent and temperature are among the most critical factorsthat affect the quality of grains during storage e normalharvesting moisture content for most maize farmers in thetropics particularly in Africa is 18ndash20e ears are usuallyput into drying cribs to reduce the moisture content toaround 14 shelled and bagged Maize is therefore storedwhile still relatively with high moisture content e com-bined effect of warm temperatures and high moisturecontent results in accelerated grain deterioration and pro-motes growth of insects and fungi [30] To maintain goodquality maize during storage grains must be protected fromchanges in moisture content and growth of insects andmicroorganisms such as fungi is study demonstrated thatmoisture of maize grains stored in SuperGrain IV-Rtrade bagdid not change over the whole storage period indicating lackof exchanges between the SuperGrain IV-Rtrade bag and theoutside environmentis suggests that the grains would notdry in the bag if not dried to safe moisture content levelbefore storing e finding confirms earlier study thatshowed themoisture content of grains stored in the hermeticbags remains unchanged during storage [31] In contrastbecause of permeability of polypropylene bags grains lostmoisture in response to ambient relative humidity Amongfactors that influence insect infestation in grain storageecosystem are water temperature and air [32 33] and thusinsect damage increases during storage

e most common mould damage shows grain dark-ening symptoms Safe grain storage is assessed by amongother factors fungal growth moisture content and storageperiod Infection of maize by storage fungi results in graindiscolouration Grain discolouration is a key factor forassessing the visual quality and market value Kenyarsquos maizestandards and specifications KS01-143 ensure acceptablegrain quality classification for producers processors andconsumers e standards which are harmonised with re-gional and international standards compare well with theSouth African and US corn specifications [34] To facilitatemarketing maize grain is classified into four differentgrades based on several factors For the discoloured grainsthe amount varies from 2 for grade 1 (K1) to 6 for grade 4(K4) ese grades attract different market prices NationalCereals and Produce Board (NCPB) whose core businessconstitutes commercial grain trading sells 90 kg bag ofpremier maize grain (grade 2) for human consumption at

Ksh2300 (USD 23) and Ksh1400 (USD 14) for grade 4 foranimal feed processing is study showed that insignificantdiscolouration (2 up from 12 at the onset of the study)was only found with grains at 12 moisture content storedin SuperGrain IV-Rtrade bags 180 days after storagee resultsare in agreement with [35] findings on storage studies onpinto beans under different moisture contents and tem-perature regimes In contrast grain discolouration inpolypropylene bags reduced with storage period becausediscoloured grains that showed signs of insect damage (holesandor tunnelling) were classified as damaged From healthview consumption of grains with higher percentage ofdiscolouration is a potential risk due to mycotoxin con-tamination such as aflatoxin produced by the moulds Casesof aflatoxin poisoning are high in Kenya which is exacer-bated by untested maize flour from local posho mills in therural areas It would be risky to store moist grains (14ndash18moisture content) in hermetic bags due to higher graindiscolouration that may result in loss of market price pre-mium and because of associated health hazard due to fungalgrowth that produce mycotoxins if the grains enter the foodchain However grain quality before storage will determinewhether the grain will maintain quality during longerstorage period As grain moisture level greatly influences thetype of moulds that infect and grow on grains moisturecontent must therefore be reduced by drying to levels belowthat at which moulds grow (13) within the storage envi-ronment under tropical conditions

52 Sitophilus zeamais and Prostephanus truncatusPopulation A significant reduction of S zeamais and Ptruncatus population when maize grains were stored inSuperGrain IV-Rtrade bags was demonstrated in this studyeprevailing mean ambient temperature (26degC) and relativehumidity (54) during the study were within the range forthe development of both insect species However thepopulation growth in the SuperGrain IV-Rtrade bags was lowe reduction could be attributed to carbon dioxide levelsachieved within SuperGrain IV-Rtrade bags when properly tiedFor effective control of storage pests [36] showed thatcarbon dioxide level above 40 is required In [37] it isreported that mortality of immature and adult insectsrapidly increased when exposed to carbon dioxide levels of7ndash19 and defined the level that would kill 95 Triboliumcastaneum adult population as 20 in five days Overallcarbon dioxide levels in the present study were maintained

Table 6 Mean (plusmnSE) carbon dioxide levels within SuperGrain IV-Rtrade bags after 60 120 and 180 days of storage


0 60 120 180SGB IV-Rtrade + 12 MC grain 22 plusmn 01a 157 plusmn 04c 121 plusmn 07b 125 plusmn 09cSGB IV-Rtrade + 14 MC grain 104 plusmn 03c 110 plusmn 04a 96 plusmn 08a 105 plusmn 03bSGB IV-Rtrade + 16 MC grain 79 plusmn 01b 109 plusmn 03a 89 plusmn 04a 76 plusmn 04aSGB IV-Rtrade + 18 MC grain 123 plusmn 03d 143 plusmn 04b 189 plusmn 01c 170 plusmn 09dF value 52102 4117 4946 4831P value lt0001 lt0001 lt0001 lt0001Means within a column followed by the same letter are not significantly different (SNK test Pgt 005) SGB IV-Rtrade SuperGrain IV-Rtrade bag


within 8ndash16 range and the observed reduction in insectpopulation probably could be attributed to high temperature(23ndash30degC) and lower relative humidity (46ndash58) that en-hanced insect metabolism and accelerated carbon dioxidetoxicity In the hermetic storage system insect developmentis delayed and fecundity altered [31] e reduction in insectpopulation observed is consistent with the findings reportedin [31] when maize was stored in PICS bags PICS andSuperGrain IV-Rtrade bags are type of multilayer coextrudedtougher plastics with low permeability of gas and good waterbarrier properties e population growth of S zeamais washigher than P truncatus during the entire storage durationin polypropylene bags Since P truncatus was not artificiallyintroduced into the grains interspecific competition with Szeamais probably affected its population increase [38]

53 Grain Weight Loss e effectiveness of grain storage isgreatly influenced by storage period and weight loss duringstorage duration e weight loss levels observed in the bagsare attributed to insect population in the bags Maize grainsstored in SuperGrain bags IV-Rtrade maintained very lowweight loss (1ndash3) compared to the equivalent grains inpolypropylene bags (35ndash43) at 180 days after storage eweight loss levels were much lower than 13 which has beenreported by DeGroote et al [39] e observed differenceprobably could be ascribed to differences in the evaluatedSuperGrain bag types In the present study the usedSuperGrain IV-Rtrade bag is an improved version of the onereported by [39] e new SuperGrain IV-Rtrade bag is char-acterised by ultra-low oxygen permeability greater tough-ness and perforation resistance while retaining the original0078mm thickness [28] Higher losses were recorded in thegrains stored in polypropylene bags SuperGrain IV-Rtrade bagskept grains at 12 moisture content within the acceptablelow weight loss level (12) Similar observations have beenreported under high levels of artificial infestation in themaize grain at similar moisture content stored in theSuperGrain bag [39] and PICS bag [31] When the marketsupply cannot satisfy the demand grains at 12 moisturecontent stored in SuperGrain IV-Rtrade bags would be sold atthe highest price because of very low percentage of dis-coloured grains and weight loss thus contributing to im-proved livelihood income of the smallholder farmers

54 Carbon Dioxide Levels SuperGrain bag IV-Rtrade isa hermetic bag and its mode of action in protecting the grainagainst insect pests is through composition of atmosphericgases rich in carbon dioxide and low in oxygen within thestorage enclosure that suppress the ability of pests to developand reproduce [40] Insects die when the oxygen level in theair is reduced below 3 [20] and feeding activity stops whenthe level falls below 4 [41] Although the carbon dioxidelevel in moist grains was higher it did not exceed 20 eresults obtained from this study confirm the study in [3]which showed that the generation of carbon dioxide ingrains at 14 and 16 moisture content under hermeticstorage conditions did not exceed 20 e apparent lack ofhermetic conditions could have been caused by P truncatus

perforation of the bags which probably facilitated gaseousexchange during storage between the outside environmentand the inside of the bags e holes were made by this pestfrom the outside source in the barn as it was not infestedwith the grains at the onset of the experiment Perforation ofthe hermetic bags has been reported by Gracıa-Lara et al[28] when evaluating the effectiveness of SuperGrain IV-Rtradebags and Kukom et al [31] PICS bags for protection againstinsect pests in stored maize In other studies in NigerCallosobruchus maculatus Fabricius (Coleoptera Bruchidae)was found to perforate PICS bags which are used for cowpeastorage [42] e other factor could be that the respiration ofthe grains insects and microorganism did not greatlycontribute to the evolution of carbon dioxide

6 Conclusion

e study confirms the effectiveness of SuperGrain IV-Rtradebag as a storage method Grains should be sorted and sievedto remove debris and broken grains to limit sources anddevelopment of insect pests and moulds e initial grainmoisture content remained unchanged while in poly-propylene bags it reduced Moist grains must be dried tolower level before storage for a longer period to avoidspoilage due to moulds and grain discolouration e res-piration of grains and insects in the bags did not contributegreatly to the evolution of carbon dioxide due to holes madein the bags by P truncatus is study was only carried out atone site therefore further study under cool hot and humidconditions is needed to confirm the findings

Data Availability

e data used to support the findings of this study areavailable from the corresponding author upon request

Disclosure

e mention of trade names in this paper is only for thepurpose of providing specific information and does notimply endorsement by KALRO CIMMYT ICIPE andKenyatta University e views expressed in the study aresolely the opinion of the authors

Conflicts of Interest

e authors declare no conflicts of interest

Acknowledgments

e authors are grateful to the Kenya Agricultural andLivestock Research Organisation (KALRO) for providingspace at Kiboko to conduct the study is study wassupported by Swiss Agency for Development Cooperation(SDC) through CIMMYT Effective Grain Project IIGrainPro-Kenya provided the materials small equipmentsand transport funds


References

[1] L C Nwosu O Amana and O Onyeje ldquoEfficacy of bonecharcoal dust of six mammalian species as eco-friendly al-ternatives to conventionl synthetic insecticides in the controlof Sitophilus zeamais Motschulsky (Coleoptera Curculioni-dae) infesting stored resistant and susceptible maize culti-varsrdquo Jordan Journal of Agricultural Sciences vol 12 no 1pp 311ndash320 2016

[2] E Mendoza A C Rigor C C Mordido Jr and A A MarajasldquoGrain quality deterioration in on-farm level of operationrdquo inProgress in Grain Protection N C Tefer and A S Frio Edspp 107ndash117 Proceedings of the 5th Annual Grains Post-harvest Workshop 19ndash21 January 1982 Chiang Maiailand 1982

[3] Z G Weinberg Y Yan Y Chen S Finkelman G Ashbelland S Navarro ldquoe effect of moisture level on high-moisturemaize (Zea mays L) under hermetic storage conditions-invitro studiesrdquo Journal of Stored Products Research vol 44pp 136ndash144 2008

[4] R N Sinha ldquoe stored-grain ecosystemrdquo in Stored GrainEcosystems D S Jayas N D White and W E Muir Edspp 1ndash32 Marcel Dekker New York NY USA 1995

[5] D S Jayas ldquoMathematical modelling of heat moisture andgas transfer in stored-grain ecosystemrdquo in Stored GrainEcosystems D S Jayas N D White and W E Muir Edspp 527ndash567 Marcel Dekker New York NY USA 1995

[6] D Abramson R Hulasare N D G White D S Jayas andR R Marquardt ldquoMycotoxin formation in hulless barleyduring granary storage at 15 and 19 moisture contentrdquoJournal of Stored Products Research vol 35 no 3 pp 297ndash305 1999

[7] U Nithya V Chelladarai D S Jayas and N D G WhiteldquoSafe storage guidelines for durum wheatrdquo Journal of StoredProducts Research vol 47 no 4 pp 328ndash333 2011

[8] C Reed S Doyungan B Loerger and A Getchell ldquoResponseof storage moulds to different initial moisture content ofmaize (corn) stored at 25degC and effect on respiration rate andnutrient compositionrdquo Journal of Stored Products Researchvol 43 no 4 pp 443ndash458 2007

[9] S M Nasar-Abbas K H M Siddique J A Plummer et alldquoFaba bean (Vicia faba L) seeds darken rapidly and phenoliccontent falls when stored at higher temperature moisture andlight intensityrdquo Food Science and Technology vol 42 no 10pp 1703ndash1711 2009

[10] D S Jayas and N D GWhite ldquoStorage and drying of grain inCanada low cost approachesrdquo Food Control vol 14 no 4pp 255ndash261 2003

[11] G I Odour S M Smith E A Chandi L W KaranjaJ O Agano and D Moore ldquoOccurrence of Beauveriabassiana on insect pests of stored maize in Kenyardquo Journal ofStored Products Research vol 36 pp 177ndash185 2000

[12] B L Muatinte J Van Den Berg and L A Santos ldquoProste-phanus truncatus in Africa a review of biological trends andperspectives on future pest management strategiesrdquo AfricanCrop Science Journal vol 22 no 3 pp 237ndash256 2014

[13] R A Boxall ldquoDamage and loss caused by the larger grainborer Prostephanus truncatusrdquo Integrated Pest ManagementReviews vol 7 no 2 pp 105ndash121 2002

[14] Y Lamboni and K Hell ldquoPropagation of mycotoxigenic fungiin maize stores by postharvest insectsrdquo International Journalof Tropical Insect Science vol 29 no 1 pp 31ndash39 2009

[15] S K Muhihu and G N Kibata ldquoDeveloping a control pro-gramme to combat an outbreak of Prostephanus truncatus

(Horn) (Coleoptera Bostrichidae) in Kenyardquo Tropical Sciencevol 25 pp 239ndash248 1985

[16] K Hell K F Cardwell M Setamou et al ldquoe influence ofstorage practices on aflatoxins contamination in maize in fouragro-ecological zones in Benin West Africardquo Journal ofStored Products Research vol 36 no 4 pp 365ndash382 2000

[17] Z M Kinyua J J Smith G N Kibata S A Simons andB C Langat ldquoStatus of grey leaf spot disease in Kenyan maizeproduction ecosystemsrdquo African Crop Science Journal vol 18no 4 pp 183ndash194 2010

[18] F Abebe T Tefera S Mugo Y Beyene and S Vidal ldquoRe-sistance of maize varieties to the maize weevil Sitophiluszeamais (Motsch) (Coleoptera Curculionidae)rdquo AfricanJournal of Biotechnology vol 8 no 21 pp 5937ndash5943 2009

[19] S Navarro ldquoModified atmospheres for the control of storedproduct insects and mites Chapter 11rdquo in Insect Managementfor Food Storage and Processing J W Heaps Ed AAOCCInternational St Paul MN USA 2nd edition 2006

[20] M E Moreno A S Jimenez and M E Vazquez ldquoEffect ofSitophilus zeamais and Aspergillus chevalieri on the oxygenlevel in maize stored hermeticallyrdquo Journal of Stored ProductsResearch vol 36 no 1 pp 25ndash36 2000

[21] N D G White and D S Jayas ldquoControlled atmospherestorage of grain Chapter 10rdquo in Handbook of postharvesttechnology Cereals Fruits Vegetables Tea and SpicesA Chakraverty A S Majumdar G S W Raghavan andH S Ramaswamy Eds pp 235ndash251 Marcel DekkerNewYork NY USA 2003

[22] Z G Weinberg G Ashbell Y Hen and A Azrielli ldquoeeffect of applying lactic acid bacteria at ensiling on the aerobicstability of silagesrdquo Journal of Applied Bacteriology vol 75no 6 pp 512ndash518 1993

[23] I B Baoua L Amadou and L L Murdock ldquoTriple baggingfor cowpea storage in rural Niger questions farmers askrdquoJournal of Stored Products Research vol 52 pp 86ndash92 2013

[24] T DeBruin P Villers A Wagh and S Navarros ldquoWorldwideuse of hermetic storage for preservation of agriculturalproductsrdquo in Proceedings of 9th International ControlledAtmosphere and Fumigation Conference (CAF) AntalyaTurkey October 2012

[25] T Tefera F Kanampiu H DeGroote et al ldquoemetal silo aneffective grain storage technology for reducing postharvestinsect and pathogen losses in maize while improving small-holder farmersrsquo food security in developing countriesrdquo CropProtection vol 30 no 3 pp 240ndash245 2011

[26] K O K Popoola ldquoHermetic control treatment of Proste-phanus truncatus (Horn) (Coleoptera Bostrichidae) in-festation on stored dried cassava chips in polythene bagsrdquoAdvance Journal of Food Science and Technology vol 4 no 3pp 118ndash120 2012

[27] M Y Quezada J Moreno M E Vazquez M MendozaA Mendez-Albores and E Moreno-Martinez ldquoHermeticstorage system preventing the proliferation of Prostephanustruncatus Horn and storage fungi in maize with differentmoisture contentsrdquo Postharvest Biology and Technologyvol 39 no 3 pp 321ndash326 2006

[28] S Garcıa-Lara S Ortız-Islas and P Villers ldquoPortable her-metic storage bag resistant to Prostephanus truncatus Rhy-zopertha Dominica and Callosobruchus maculatusrdquo Journalof Stored Products Research vol 54 pp 23ndash25 2013

[29] R A BoxallACritical Review of theMethodology for AssessingFarm-Level Grain Losses after Harvest p 139 TDRI SloughUK 1986


[30] O V Ekechukwua and B Norton ldquoReview of solar-energydrying systems II an overview of solar drying technologyrdquoEnergy Conversion and Management vol 40 no 6 pp 615ndash655 1999

[31] E O Kukom A K Tounou Y Lamboni and K Hell ldquoPost-harvest insect infestation in maize grain stored in wovenpolypropylene and in hermetic bagsrdquo International Journal ofTropical Insect Science vol 33 no 1 pp 71ndash81 2013

[32] S Marin N E Companys V Sanchis A J Ramos andN Magan ldquoEffect of water activity and temperature oncompeting abilities of common maize fungirdquo MycologicalResearch vol 120 no 8 pp 959ndash964 1998

[33] D Rees Insects of Stored Products CSIRO Publishing Mel-bourne Victoria Australia 2004

[34] ACDIVOCA-Kenya Kenya Maize Handbook TrainingManual No 27 ACDIVOCA Kenya 2007

[35] P R Rani V Chelladurai D S Jayas N D G White andC V Kavitha-Abirami ldquoStorage studies on pinto beans underdifferent moisture contents and temperature regimesrdquoJournal of Stored Products Research vol 52 pp 78ndash85 2013

[36] S W Bailey ldquoAir-tight storage of grains its effect on insectpests-IV Rhyzopertha Dominica (F) and some other Co-leoptera that infest stored grainrdquo Journal of Stored ProductsResearch vol 1 no 1 pp 25ndash33 1965

[37] N D G White D S Jayas and W E Muir ldquoToxicity ofcarbon dioxide at biologically producible levels to stored-product beetlesrdquo Environmental Entomology vol 24 no 3pp 640ndash647 1995

[38] D P Giga and S J Canhao ldquoCompetition between Proste-phanus truncatus (Horn) and Sitophilus zeamais (Motsch) inmaize at two temperaturesrdquo Journal of Stored Products Re-search vol 29 no 1 pp 63ndash70 1993

[39] H DeGroote S C Kimenju P Likhayo F KanampiuT Tefera and J Hellin ldquoEffectiveness of hermetic systems incontrolling maize storage pests in Kenyardquo Journal of StoredProducts Research vol 53 pp 27ndash36 2013

[40] S Navarro and E J Donahaye ldquoInnovative environmentallyfriendly technologies to maintain quality of durable agri-cultural productsrdquo in Environmentally Friendly Technologiesfor Agricultural Produce Quality Y S Ben Ed pp 204ndash260CRS Press Boca Raton FL USA 2005

[41] L L Murdock D Seck G Ntoukam L Kitch andR E Shade ldquoDearth by desiccation effect of hermetic storageon cowpea bruchidsrdquo Journal of Stored Products Researchvol 49 pp 166ndash170 2012

[42] I B Baoua V Margam L Amadou and L L MurdockldquoPerformance of triple bagging hermetic technology forpostharvest storage of cowpea grain in Nigerrdquo Journal ofStored Products Research vol 51 pp 81ndash85 2012


Hindawiwwwhindawicom

International Journal of

Volume 2018

Zoology

Hindawiwwwhindawicom Volume 2018

Anatomy Research International

PeptidesInternational Journal of



Journal of Parasitology Research

GenomicsInternational Journal of


Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom

The Scientific World Journal

Volume 2018


BioinformaticsAdvances in

Marine BiologyJournal of



Neuroscience Journal


BioMed Research International

Cell BiologyInternational Journal of



Biochemistry Research International

ArchaeaHindawiwwwhindawicom Volume 2018


Genetics Research International


Advances in

Virolog y Stem Cells International



Enzyme Research



MicrobiologyHindawiwwwhindawicom

Nucleic AcidsJournal of

Volume 2018

Submit your manuscripts atwwwhindawicom

colour and weight [9] e optimum temperature for thedevelopment of storage moulds and insects is generallyaround 30degC Requirements for moisture are more wideranging with most moulds failing to germinate below 80relative humidity but insect needing a grain moisturecontent of at least 10 to 12 [10] which is typically inequilibrium with around 50 to 70 relative humidityWhen grain with higher moistures (gt14) is stored underwarm conditions mould growth may result in seriousquality changes [3] and insect attack may reduce quality andcause weight losses Simple and low cost storage facilitiesthat isolate grains from unfavourable environmental con-ditions are therefore required by farmers

e main insect pests of stored maize include the largergrain borer Prostephanus truncatus (horn) (ColeopteraBostrichidae) and maize weevil Sitophilus zeamais (Mot-schulsky) (Coleoptera Curculionidae) [11] For the past 35years sub-Saharan Africa has witnessed the outbreak andspread of larger grain borer (LGB) in 20 countries [12] eimpact of insect infestation of stored grain is usuallyexpressed as percentage weight loss [13] Losses as high as36 have been documented on stored maize in Benin [14]and 35 in Kenya [15] e losses are attributed to the use ofineffective storage structures such as cribs jute and poly-propylene bags for storing grains [16] ese losses affect thefood security and income of the 90 of the Kenyan pop-ulation that relies on the crop as staple food [17] besidescontributing to increased food prices due to removal of partof the supply from the market [18]

A promising technology to store grains safely is airtight(hermetic) storage (self-regulated modified atmosphere)e technology was developed in response to concern aboutthe adverse effects of pesticide residues in grains and en-vironment [19] e respiration of the grains insects andmoulds within hermetic stores result in depletion of oxygenand increase of carbon dioxide [20 21] Under such con-ditions fungal growth may be inhibited [22] and when theoxygen level falls to 10 insect activity is reduced and insectwill die if subjected to less than 2 oxygen for periods inexcess of 14 days Consequently hermetic storage can beused to maintain grain quality without the need for pesticideapplication [23] e rate at which oxygen is reduced andcarbon dioxide generated is a function of both grainmoisture content and the ambient temperature the rate islow at temperatures below 20degC [24]

Storage systems based on the hermetic principle includeairtight bags bunkers and silos While hermetic metal silos[25] and polythene (plastic) bags [26] have been developedtheir use for storage of grains by smallholder farmers is stilllimited ere is also scant information on the storability ofmaize grain at the range of moisture contents that are typicalin tropical storage systems e key to successful hermeticstorage is air-tightness and control of moisture content epresent study was undertaken to investigate quality changeof maize stored in hermetic bags subject to infestation bySitophilus zeamais and a variety of initial grain moisturecontent level e parameters monitored were moisturecontent grain discolouration insect density weight lossand oxygen and carbon dioxide levels

2 Materials and Methods

21 Preparation of Maize Grain Hybrid maize (H614) wascleaned to remove mouldy and broken grains and foreignmaterials and sun-dried to 12 moisture content Samplesof grain at three further moisture contents 14 16 and 18were prepared by adding predetermined amount of distilledwater then mixing thoroughly in plastic bags [3 27] eamount of water added was calculated as follows Q A((bminusa)(100minusa)) where A weight of grain b desiredmoisture content and a initial grain moisture contentebags were then kept in a cold room for two weeks Everyother day the bags were retrieved grains mixed andreturned to the cold room Prior to the conditioning of thegrains four grain samples were taken and tested formoisturecontent using a Foss Infratectrade 1241 grain analyzer (Sweden)and weight as the baseline e moisture content of themaize grain in the 12 14 16 and 18 categories was close tothe desired ones 124 plusmn 00 143 plusmn 01 162 plusmn 02 and 182 plusmn02 (wet basis) respectively while the quality of the grainswas 12 plusmn 02 discoloured at the start of the storage period

22 Test Storage Bags e storage bags tested were Super-Grain IV-Rtrade bag (74 cm wide and 64 cm length) of 25 kgholding capacity (supplied by GrainPro Inc) and open-weave polypropylene bags of the same capacity eSuperGrain IV-Rtrade bag is tougher than the earlier version ofthe SuperGrain bag and has an extremely low oxygenpermeability (lt4 ccm2day) in which oxygen is reducedfrom 20 to 8 in 14 days for P truncatus under controlledconditions of 27 plusmn 1degC and 75 plusmn 1 relative humidity [28]As recommended by the manufacturer each SuperGrain IV-Rtrade bag was placed inside a woven polypropylene bag toprovide support and handling convenience e open endsof SuperGrain IV-Rtrade bags were cut to fit the height di-mension of these polypropylene outer bags

23 Experimental Procedure e bags were each filled with20 kg maize grains and then ldquoseededrdquo with 20 live adultmaize weevil (1 beetlekg grain) e barn had an LGBpopulation and were interested to see whether this pestwould penetrate from the outside into the bags (entry holes)while S zeamais on the inside potentially made emergenceholes on the grains e bags were closed according tomanufacturerrsquos instructions the entrapped air was squeezedout and then secured tightly with rubber straps e grainswere not inoculated with fungi since maize usually harbourssufficient fungal spores that fungal growth will occur nat-urally if environmental conditions are conducive e ex-periment consisted of eight treatments with fourreplications (1) SuperGrain IV-Rtrade bag + grains at 12moisture content (2) SuperGrain IV-Rtrade bag + grains at 14moisture content (3) SuperGrain IV-Rtrade bag + grains at 16moisture content (4) SuperGrain IV-Rtrade bag + grains at 18moisture content (5) Polypropylene bag + grains at 12moisture content (6) Polypropylene bag + grains at 14moisture content (7) Polypropylene bag + grains at 16moisture content and (8) Polypropylene bag + grains at 18









(1)







4 Results





























5 Discussion













6 Conclusion


Data Availability


Disclosure




Acknowledgments



References
















































Volume 2018

Zoology











Volume 2018

















Advances in




Enzyme Research





Volume 2018









(1)







4 Results





























5 Discussion













6 Conclusion


Data Availability


Disclosure




Acknowledgments



References
















































Volume 2018

Zoology











Volume 2018

















Advances in




Enzyme Research





Volume 2018
























5 Discussion













6 Conclusion


Data Availability


Disclosure




Acknowledgments



References
















































Volume 2018

Zoology











Volume 2018

















Advances in




Enzyme Research





Volume 2018






6 Conclusion


Data Availability


Disclosure




Acknowledgments



References
















































Volume 2018

Zoology











Volume 2018

















Advances in




Enzyme Research





Volume 2018


References
















































Volume 2018

Zoology











Volume 2018

















Advances in




Enzyme Research





Volume 2018


















Volume 2018

Zoology











Volume 2018

















Advances in




Enzyme Research





Volume 2018


maize grain stored in hermetic bags: effect of moisture and ...maize (zea mays l.) is an important...

Documents