a study on organic tomatoes: effect of a biostimulator on

Research ArticleA Study on Organic Tomatoes Effect of a Biostimulator onPhytochemical and Antioxidant Activities

Varinder Sidhu Dilip Nandwani Li Wang and Ying Wu

Tennessee State University 3500 John A Merritt Blvd Nashville TN 37209 USA

Correspondence should be addressed to Ying Wu ywutnstateedu

Received 12 July 2017 Revised 28 October 2017 Accepted 7 November 2017 Published 10 December 2017

Academic Editor Senem Kamiloglu

Copyright copy 2017 Varinder Sidhu et alThis is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

The objective of the present study is to investigate nutritional and antioxidant activity of four types of organic tomato cultivarsThe differences in tomato quality are also tested between groups with or without treatment using an organic biostimulatorStimplex Total phenolic compounds (TPC) lycopene 120573-carotene DPPH free radical scavenging activity reducing power andcolor parameters were investigated in the current study The results showed that there was no significant difference in TPC amongcultivars regardless of Stimplex treatment Higher lycopene and 120573-carotene were obtained in Stimplex treated tomatoes Lycopeneand 120573-carotene contents were significantly different among cultivars (119875 lt 005) DPPH scavenging activity in controlled group wassignificantly higher than that in the Stimplex treated tomatoes (119875 lt 005) No significant difference in reducing power was detectedamong cultivars treatment groups The study showed that the darker the tomato color the higher the lycopene and 120573-carotenecontents and the stronger the reducing power

1 Introduction

Tomato (Lycopersicum esculentum) is a widely grown andversatile vegetable throughout the world for taste color highnutritive value and diversified use Tomato fruit mainlycontains fiber phytonutrients vitamin A C B complex andcarotenoids Carotenoids include 120573-carotene and lycopenewhere120573-carotene is a pro vitamin and lycopene is a bright redcarotene which has antioxidant properties two times higherthan 120573-carotene in destruction of free radicals [1]

Color is the most important quality indicator of tomatofruit Pigmentation of red ripe tomato fruit is a resultof synthesis of carotenoids lycopene and 120573-carotene [2]Lycopene in tomato is responsible for the redness and 120573-carotene can cause orange coloration Intense red colortomato indicates predominant amounts of lycopene andhigh levels of antioxidants which prevents cancerous andcardiovascular diseases [3]

Due to the restrictions on organic foods not manyfertilizers or growth promoters are available for organictomatoes Products of natural origin such as seaweed extractare already used in plant production Many species of sea-weed (Ecklonia maxima Kappaphycus alvarezii Ascophyllum

nodosum Laminaria digitata Laminaria hyperborea Fucusvesiculosus Durvillaea potatorum and Fucus serratus) areused in agricultural and horticultural crops as a stimulatorof the growth and development of plants Application ofthese stimulators may contribute to enhanced growth yieldand resistance against agricultural and horticultural plantpathogens as well as the positive impact of content andactivity of certain bioactive compounds [4] Zarzecka et al[5] also concluded that application of biostimulators forexample seaweed extract Kelpak SL and Asahi in the studycan increase the total phenolic level in potato tubers butthe degree of the increase varied depending on the potatocultivars

Stimplex is a seaweed extract (Ascophyllum nodosum)containing 001 cytokinin as an active ingredient whichstimulates plant growth and development promotes yieldsand earlier maturity improves resistance to environmentalstress improves fruit quality and increases fruit set Astudy showed that Stimplex treated drought stressed treesperformed better than the untreated trees [6] There is littleavailable literature on the effect of biostimulants on the phy-tochemical contents and antioxidant activities in tomatoes

HindawiJournal of Food QualityVolume 2017 Article ID 5020742 8 pageshttpsdoiorg10115520175020742

2 Journal of Food Quality

Hence the objectives of this study were to compare thetomato qualities grown organically and to observe the effectof biostimulant (Stimplex) on fruit quality attributes includ-ing fruit color phytochemical level and antioxidant activitiesin four tomato cultivars namely Black Cherry BrandywineGerman Johnson and Roma Correlation between fruit colorphytochemical level and antioxidant activity was studied

2 Materials and Methods

21 Materials In the current study organic tomato cultivarexperiment was conducted during spring and summer in2015 at Tennessee State University certified organic farmin Nashville (latitude 12730m 36∘101015840 N 86∘491015840 W) Theexperiments were run using randomized block design (RBD)with three replications Four tomato cultivars Black CherryBrandywine German Johnson and Roma were investi-gated under organic farming system Organic seeds wereobtained from an organic seed company (Johnnyrsquos SelectedSeeds and High Mowing Organic Seeds company WinslowMaine United States) Stimplex was procured from AcadianAgriTech (Alberta Canada) Each cultivar was treated withStimplex on a weekly basis at 25mlgallon via foliar spray

All the chemicals and reagents for analysis were pur-chased from Sigma-Aldrich (St Louis MO United States)

22 Methods

221 Sample Preparation After physical analysis of tomatofruit fruits from each cultivar were selected randomly in eachreplication Freshly harvested tomatoeswere rinsed and driedfor color measurement and then chopped and blended inwaring blender to produce a homogenous mass for furtheranalysis [7] The homogenized samples were tightly sealed insample vials and stored in aminus20∘C freezer Before analysis thesamples were thawed to room temperature and homogenizedusing a polytron (PT 2100 Kinematica AG Schweiz) for3min before determination of total phenolic content totallycopene content total carotenoid content and antioxidantactivities

222 Moisture Content Determination The fresh tomatosamples were cut into small pieces (1 cm3) weighed (100 plusmn5 g) and kept at 103∘C to reach the consistent weightsMoisture content was calculated as follows

Moisture content () = wet weight minus dry weightwet weight

times 100(1)

223 Total Phenolic Content (TPC) TPC was determined byFolin-Ciocalteu method with some modifications [8] Briefly1 g of tomato sample was added to 5ml of 50 methanoland kept in a tightly capped bottle in the dark for 24 hoursat 60∘C with constant stirring After being cooled to roomtemperature the samples were centrifuged at 10000 g for5min Supernatant was used for the determination of totalphenolic content The supernatant (05ml) was thoroughlymixed with 05ml of distilled water and 125120583l of Folin-Ciocalteu reagent for 6min before the addition of 125ml

of 7 sodium carbonate Final volume of solution was 3mLusing distilled water and was left in the darkness for 90minAbsorbance was measured at 760 nm Each test was repeated3 times in triplicate each time

TPC was calibrated by using a standard curve of gallicacid TPC for each cultivar extract was expressed as gallic acidequivalent (GAE) in 120583g of GAEg fresh tomatoes

224 Total Lycopene and Total 120573-Carotene Estimation Mea-surement of total lycopene and total carotenoids has followedthe method described by Barros et al [9] which is based onthemethod byNagata andYamashita [10] withmodificationsThe extraction of freshly harvested tomatoes was conductedusing a mixture of solvents hexane acetone ethanol (2 1 1vvv) with 25 butylated hydroxytoluene (BHT) addedto each cultivar bottle [11] Aliquots of 025 g homogenizedsamples were added to 25ml extraction solvent The bot-tles were tightly closed and agitated for 10 minutes on ashaker at 300 rpm followed by leaving the bottles at roomtemperature to stand for 15min for phase separation toform a distinct aqueous polar layer and a nonpolar layerAliquots of 4ml extracts from the top layer of the nonpolarphase were withdrawn and filtered through Whitmanrsquos filterpaper Absorbance was measured spectrophotometrically at453 505 645 and 663 nm [12] Contents were calculatedaccording to the following equations120573-carotene (mg100mL)= 0216 times A663 minus 1220 times A645 minus 0304 times A505+ 0452 times A453

Lycopene (mg100mL)= minus00458 times A663 + 0204 times A645 minus 0304 times A505+ 0452 times A453

(2)

The concentration of total lycopene and total 120573-carotenewas further expressed in g kgminus1 of fresh weight (fw)

225 Antioxidant Activity

DPPH Free Radical Scavenging Property DPPH free rad-ical scavenging property was evaluated using the methoddescribed by Shahzad and others [13] with modificationsAbout 300 g of freshly harvested tomato was cut into piecesand homogenized using a polytron at medium speed for5min Methanol (10ml 100) was mixed with sample (10 g)and the mixture was centrifuged at 8000 g for 10min Super-natant (2ml) was filtered through a 045 um Nylon Syringefilter for absorbance measurement at 517 nm

DPPH free scavenging effect was calculated using thefollowing equation

DPPH scavenging effect ()

= [1198600 minus (119860 minus 1198601)1198600 times 100] (3)

Journal of Food Quality 3

Where 1198600 is the absorbance of the DPPH solution withoutsample 119860 is the absorbance of the test sample mixed withDPPH solution and 1198601 is the absorbance of sample withoutDPPH solution

Reducing Power The reducing power assay was determinedaccording to Oyaizu [14] with slight modification Freshtomato samples were homogenized using the polytron atmedium speed for 5min Methanol (10ml 100) was addedto sample (10 g) mixed well and followed by centrifugationat 8000 g for 10min Tomato supernatant (05ml) was mixedwith 05ml of 01M sodium phosphate buffer (pH 70) and05ml of 1 (wv) potassium ferricyanideThemixtures wereincubated at 50∘C for 20min followed by adding 1ml of10 (wv) trichloroacetic acid 1ml of deionized water and01ml of 01 ferric chloride sequentiallyThe absorbancewasmeasured at 700 nm against a blank A higher absorbanceindicates a higher reducing power Ascorbic acid was used forcomparison

Color Measurement Color measurement was performed fol-lowing the method described by Khairi and others [15] usinga Minolta CR 300 Chroma Portable Colorimeter purchasedfrom Hunterlab Reston Virginia United States with Cilluminant expressed as 119871lowast 119886lowast and 119887lowast The instrumentwas calibrated using the black and white tiles providedThree measurements were performed with three replicatesin each measurement In addition hue angle and total colordifference (Δ119864) were calculated using the following equation

Δ119864 = radic(Δ119871lowast2 + Δ119886lowast2 + Δ119887lowast2) (4)

where the control values are from a reference tomato BingCherry tomato

23 Statistical Analysis Statistical analysis was performedusing Microsoft Excel and SAS Software For each cultivarsample three extracts were obtained and all the attributeswere carried out in triplicate Results were expressed asmeans plusmn standard error Analysis of Variance (ANOVA) test(5 Confidence Interval) was used to determine significantdifferences between the results Correlation analysis wasexamined by using the CORR and TTEST protocol for paired119905-test In 119905-test 119875 lt 005 was considered to be statisticallysignificant

3 Results and Discussion

31 Effect of Stimplex onMoisture Content Moisture contentsare presented in Figure 1 Control plants of Black CherryGerman Johnson and Roma tomatoes had higher levels ofmoisture content than that of Stimplex-treated tomatoesHowever the control plant of Brandywine tomato showed alower level of moisture content than that of Stimplex treatedtomatoes These differences were not significant (119875 lt 005)for the Stimplex treated tomatoes and control in each cultivarThese results agreed with the study by Pinela et al [16]who reported that the moisture content of different tomatocultivars ranged from 9063 to 9370 g100 g fresh weights

Black Cherry Brandywine German Johnson RomaCultivar

ControlTreated

aa a

a a a

a

a

8500

9000

9500

10000

Moi

sture

cont

ent (

)

Figure 1 Moisture content of Stimplex treated and control tomatocultivars Note Values with different superscript letters were signifi-cantly different at 119875 lt 005

Idah and others [17] treated Roma cultivar using chemicalsand revealed that moisture was lower in control plants thanthat in chemically treated groups Togun and Akanbi [18]used different types and doses of fertilizers on tomato plantsand found that the dry matter accumulation increased intomato fruits However the difference between control andtreatment groups was not significantThey explained that theincreased dry matter accumulation was due to the increasednutritional level for the plant growth In the current studyno significant increase of dry matter was detected althoughthree out of the four Stimplex treated cultivars Black CherryGerman Johnson and Roma showed increase in dry matter(Figure 1)

32 Total Phenolic Content (TPC) The results of TPC arepresented in Table 1 Stimplex treated Black Cherry andBrandywine tomatoes have shown slightly higher TPC andTPC in controlled cultivar German Johnson and Roma washigher than that in Stimplex treated tomatoes No signifi-cance was detected among treatment groups and varieties(119875 gt 005) The TPC obtained from the current study werecomparable with the TPC values obtained from otherresearch groups for example TPC was 068 g kgminus1 freshweight (FW) in Indian tomato varieties [19] Figas and others[20] analyzed TPC in 8 local tomato cultivars in Spain usinga similar method and found that the TPC ranged from035 to 137 g kgminus1 Aldrich and others [21] reported a TPCrange of 060ndash090 g kgminus1 FW in 10 tomato cultivars A lowerrange in TPC was found from various research groups forexample 025ndash031 g kgminus1 FW [14] 015ndash017 g kgminus1 FW [22]007ndash022 g kgminus1 FW [7] and 014 g kgminus1 FW [23]

In the current study TPC ranged from 082 to 095 g kgminus1FW TPC in Brandywine cultivar treated with Stimplex con-tained the highest TPC but the difference was not significant(119875 gt 005) Therefore the results indicated that Stimplexhad no effect on TPC in tomato cultivars Similarly Riahiand Hdider [22] have used different organic fertilizers on


Table 1 Total phenolic content in different tomato cultivars

Treatment Varieties Total phenolic content (g kgminus1 FW)

Control

Black Cherry 8800 plusmn 202119864 minus 02aBrandywine 8771 plusmn 466119864 minus 02a

German Johnson 8685 plusmn 517119864 minus 02aRoma 8606 plusmn 304119864 minus 02a

Stimplex treatment



Note Values with the same superscript letters were not significantly different at 119875 lt 005

Table 2 Estimated lycopene and 120573-carotene concentrations in tomato cultivars

Treatment Varieties Lycopene (g kgminus1 FW) 120573-Carotene (g kgminus1 FW)

Control

Black Cherry 697 plusmn 035119864 minus 02b 199 plusmn 011119864 minus 02aBrandywine 521 plusmn 024119864 minus 02c 169 plusmn 003119864 minus 02c

German Johnson 582 plusmn 007119864 minus 02c 182 plusmn 002119864 minus 02bRoma 678 plusmn 004119864 minus 02b 188 plusmn 004119864 minus 02ab

Stimplex treatment

Black Cherry 732 plusmn 022119864 minus 02ab 196 plusmn 014119864 minus 02aBrandywine 534 plusmn 014119864 minus 02c 171 plusmn 009119864 minus 02bc

German Johnson 683 plusmn 016119864 minus 02b 190 plusmn 009119864 minus 02aRoma 783 plusmn 024119864 minus 02a 193 plusmn 011119864 minus 02a

Note Values with different superscript letters were significantly different at 119875 lt 005

two tomato cultivars and found that organic fertilizers hadno significant effect on TPC in tomatoes There was no sig-nificant difference among the tomato varieties which agreeswith Riahi and others [24] However Aldrich and others [21]reported that variety affects TPC in organic tomatoes

Kocira and others [4] carried out a study investigatingeffect of a seaweed extract Lelpak SL on two common beancultivars Their results have shown that the biostimulatorresulted in an increase in phenolic contents and the degreeof increase varied based on the cultivar Similarly Fan andothers [25] in their research have found that the commercialextracts of brown seaweed (A nodosum) have enhanced thetotal phenolic and flavonoid content and antioxidant activityin spinach leaves Also Keitt mango trees treated with algaeextracts reacted to the increased production of vitamin C infruits [26]

33 Total Lycopene and 120573-Carotene Content Absorbance oftomato extracts was obtained at different wavelengthsfor calculating total lycopene and total carotenoidconcentrations Results are presented in Table 2 Guinanand others [27] reported that biostimulants improve stresstolerance due to a greater production of antioxidants Theresults from this current study concurred with Guinan andothers [27] and showed that Stimplex treated tomatoescontained higher lycopene (antioxidant) content than thatin the controlled group Significant difference was detectedin two cultivars German Johnson and Roma respectively(119875 lt 005) Higher 120573-carotene contents were found inStimplex treated tomatoes however only one cultivarGerman Johnson was detected with significant difference

(119875 lt 005) The results from the current study showed thatStimplex application has affected lycopene and 120573-carotenecontents Among the cultivars treated with Stimplex Romacultivars exhibited the highest lycopene content (0078 g kgminus1FW) followed by Black Cherry (0073 g kgminus1 FW) GermanJohnson (0068 g kgminus1 FW) and Brandywine (0053 g kgminus1FW) respectively Moreover Black Cherry containedhigher carotenoids (0020 g kgminus1 FW) followed by Roma(0019 g kgminus1 FW) German Johnson (0019 g kgminus1 FW) andBrandywine (0017 g kgminus1 FW) respectively (Table 2) BlackCherry recorded approximately the same amount of carotenefor Stimplex treated and control fruits The results showedagreement to the earlier studies conducted by Shahzad andothers [13] that lycopene content in tomatoes ranged from0055 to 0181 g kgminus1 FW Pinela and others [16] analyzedtomato and 120573-carotene content using the same methods onfour tomato cultivars and reported that the lycopene contentranged within 0051ndash0095 g kgminus1 FW and 120573-carotene contentranged within 0003ndash0004 g kgminus1 FW Figas and others [20]studied eight tomato cultivars and found that the rangesfor total lycopene and 120573-carotene were 0011ndash0098 g kgminus1FW and 0004ndash0022 g kgminus1 FW respectively The differencesin lycopene and 120573-carotene were significant (119875 lt 005)among some tomato varieties as shown in Table 2 which hasagreed with the results from other groups [16 20] Pise andSabale [28] studied the effect of three seaweed extracts (Ulvafasciata Sargassum ilicifolium and Gracilaria corticata) onthe yield and quality of T foenum-graecum L and foundsignificantly higher chlorophyll carotenoid and phenoliccontents in plant sprayed with the tested extracts


Black Cherry Brandywine German Johnson RomaTomato cultivars

ControlStimplex treated

aa a a

a

a

a

a

82

84

86

88

90

92

94

96

98

100

DPP

H sc

aven

ging

activ

ity (

)

Figure 2 DPPH scavenging activity of different tomato cultivarsNote Values with different superscript letters were significantlydifferent at 119875 lt 005

Black Cherry Brandywine German Johnson Roma

ControlTreated

a

aa a aa a

a

00

05

10

15

20

25

30

35

Redu

cing

pow

er

Figure 3 Reducing power of different tomato cultivarsNote Valueswith different superscript letters were significantly different at 119875 lt005

34 Antioxidant Activities Comparison of DPPH scavengingactivities of tomatoes between Stimplex treated and controlcultivars is presented in Figure 2 Stimplex treated tomatocultivars exhibited significantly lower DPPH scavengingactivity than that of control (119875 lt 005)TheDPPH free radicalscavenging ability of tomatoes also varied depending on thecultivars Of the four tomato cultivars Roma presented thehighest DPPH free radical scavenging activity followed byBlack Cherry German Johnson and Brandywine Liu andothers [29] found a negative correlation between lycopeneand DPPH scavenging activity The results from the currentstudy concurred with Liu and othersrsquo [29] statement by show-ing an increased lycopene level but a decreased DPPH scav-enging activity in treated cultivars compared to the control

The results of reducing power are presented in Figure 3Three tomato cultivars in control group namely BlackCherry Brandywine and German Johnson exhibited higherreducing power than that of the Stimplex treated tomatoesbut the difference was not significant (119875 gt 005) while

Stimplex treated Roma had a slightly higher reducing powerthan that of the control group but the difference was also notsignificant (119875 gt 005)This result also indicated that therewasno significant difference among tomato cultivars in reducingpower (Figure 3)

Kocira and others [4] also investigated the effect ofseaweed extract Kelpak KL on the antioxidant activities oftwo common bean cultivars The methods they have used forantioxidant activity determination were antiradical activity(ABTS) and reducing power (RP) They have found thatthe antioxidant capacity of one cultivar was significantlyimproved by all the studied treatments while for another cul-tivar the antioxidant activity varied based on the applicationtreatments

Many compounds contribute to the antioxidant activitiesfor example Pinela and others [16] and Ochoa-Velasco andothers [30] concluded that higherDPPH scavenging activitiesand reducing power are related to the higher antioxidantcontents such as phenolic flavones anthocyanins carotenelycopene vitamin C and tocopherol Kubola and Siriamorn-pun [31] reported that DPPH FRAP and hydroxyl radicalscavenging ability had significant correlation with TPC Shanand others [32] reported that with the concentration increaseof flavonoids the antioxidant activity and free radical scav-enging power were enhanced as well However Islam andothers [33] reported that there was no significant differencein the antioxidant activities among species and preparingmethods even though the TPC was significantly influencedTherefore TPC was not influencing the antioxidant activitiesThe result discrepancy between DPPH and RP methods maybe due to the difference in principles of the methods ForDPPH method the antioxidants transfer either electron orhydrogen atom to DPPH [31] On the other hand ferri-cyanide method was a ferric iron-based total antioxidantcapacity assay This assay was used to convert the potassiumferricyanide complex to potassium ferrocyanide complexwhich would constitute ferrous complex by reducing ferricchloride [34] The reducing potential was related to theratio of compounds which donate hydrogen atoms to breakthe free radical chain [31] Thus it was the hydrogen oncarboxyl groups of phenolic acid that helped reduce DPPHfree radicals and potassium ferricyanide complex

For the reducing power method the hydrogen groupionized from carboxyl and hydroxy donated by the phyto-chemical compounds were oxidized by Fe3+ processed byferricyanide complex Reducing power also varied accordingto different fractions based on molecular weight cutoff(MWCO) Fractions with smaller MWCO exhibited superiorantioxidant activities compared to the other fractions [35]

In the current study three phytochemical compoundswere measured The trend of antioxidant activities mayinvolve other phytochemicals that are not investigated here

35 Color Colormeasurements of tomatoes were performedin triplicate with the 119871lowast 119886lowast and 119887lowast values received directlyusing aMinolta CR 300 Chroma Portable ColorimeterThesevalues were used to calculateΔ119864 (color variation) and rednessto yellowness (119886lowast119887lowast) values (Table 3) Δ119864 represents actualdifference in color and larger Δ119864 values show higher redness


Table 3 Color change and redness to yellowness of tomatoes

Treatment Varieties Δ119864 Redness to yellowness (119886lowast119887lowast)

Control

Black Cherry 5400 plusmn 002dx 125 plusmn 032Brandywine 7053 plusmn 023ax 092 plusmn 013

German Johnson 6561 plusmn 003bx 109 plusmn 016Roma 6193 plusmn 006cy 102 plusmn 023

Stimplex treatment

Black Cherry 5274 plusmn 003cy 086 plusmn 014Brandywine 6782 plusmn 030by 093 plusmn 021

German Johnson 6478 plusmn 009by 089 plusmn 022Roma 7184 plusmn 006ax 086 plusmn 014

Notes a b c d as superscript letters show significant differences in the treatment (119875 lt 005) x y as superscript letters show significant differences betweentreatment groups (119875 lt 005)

Table 4 Correlation coefficients of different nutritional parameters

Lyc TPC Caro DPPH RP 119871lowast 119886lowast 119887lowast Δ119864 119886lowast119887lowast1000minus0405lowast 1000+0845lowastlowast minus0399 1000+0154 minus0359 +0257 1000+0340 +0125 +0518lowastlowast +0276 1000+0379 minus0076 +0305 +0316 minus0039 1000minus0239 minus0165 minus0455lowast +0039 minus0820lowastlowast +0093 1000minus0147 minus0156 minus0413lowast minus0176 minus0836lowastlowast minus0014 +0953lowastlowast 1000minus0361 minus0106 minus0530lowastlowast minus0200 minus0662lowastlowast minus0510lowastlowast +0800lowastlowast +0853lowastlowast 1000minus0085 minus0017 +0152 +0633lowastlowast +0576lowastlowast +0149 minus0318 minus0560lowastlowast minus0428lowast 1000Symbol ldquo+rdquo indicates positive correlation Symbol ldquominusrdquo indicates negative correlation lowastlowastSignificantly correlated at 119875 lt 001 lowastSignificantly correlated at 119875 lt005 Lyc lycopene concentration TPC total phenolic content Caro 120573-carotene content DPPH DPPH free radical scavenging ability RP reducing powerΔ119864 actual color change 119871lowast lightness 119886lowast119887lowast redness to yellowness

values [36]Thepattern of color change (Δ119864) was significantlydifferent for BlackCherry comparedwith the other 3 cultivarsfor both treated and control groups (Table 3) Lower Δ119864for Black Cherry was obtained as a result of the typicalblackish red (purple) color tomato The Stimplex treatmenthad significant effect on two tomato cultivars in Δ119864 (119875 lt005) Black Cherry and Roma respectivelyThe difference inΔ119864 is also significant among cultivars (119875 lt 005)36 Correlation Analysis Correlation coefficients amongTPC lycopene content 120573-carotene antioxidant activity andcolor indexes are presented in Table 4 The study showedthat lycopene content was positively correlated with DPPHand RP but the result is not significant However Liu andothers [29] reported a negative correlation between lycopeneand DPPH No significant correlation was detected between120573-carotene content and DPPH in the present study whichagrees with Liu and others [29] and Duan and others [37]However 120573-carotene content was significantly correlatedwith RP (119875 lt 001) TPC and lycopene were not correlatedwith any of the color indices Carotenoids were correlatedwith 119886lowast (119875 lt 005) 119887lowast (119875 lt 005) and Δ119864 (119875 lt 001) Theindex 119886lowast119887lowast was used to present linear relation in maturitystages of the tomatoes [38] therefore no correlation with119886lowast119887lowast was detected because all samples were collectedwhen they were ripened In the present study Δ119864 was

not significantly correlated with lycopene and 120573-carotenecontent The fruit lightness (119871lowast) redness to yellowness(119886lowast119887lowast) and actual color change (Δ119864) are not correlated tolycopene and total phenolic content in this study This mightbe due to the complex nature of the tomato color whichranged from yellow and red to purple [39]

4 Conclusions

The results showed that there was no significant difference(119875 gt 005) in TPC among cultivars regardless of Stimplextreatment Higher lycopene and 120573-carotene were obtainedin Stimplex treated tomatoes however only one cultivarGerman Johnson showed significant difference (119875 lt 005)Lycopene and120573-carotene contentswere significantly differentamong cultivars (119875 lt 005) DPPH scavenging activityin controlled group was significantly higher than that inthe Stimplex treated tomatoes (119875 lt 005) No significantdifference in reducing power was detected among cultivarsin control and treatment groups The Black Cherry tomato apurple colored cultivar exhibited a much lower Δ119864 value anda higher 119886lowast119887lowast value compared to the other red colored culti-vars Correlation study has revealed that Δ119864was significantlycorrelated to lycopene content 120573-carotene and reducingpower (119875 lt 001) Lycopene contentwas negatively correlatedto DPPH (119875 lt 005) The result indicated that the darker


(from red to purple) the tomato color the higher the lycopeneand120573-carotene contents and the stronger the reducing powerConflicts of Interest

The authors declare that there are no conflicts of interestregarding the publication of this paper

Acknowledgments

This work was supported by USDA Evans-Allen Program toDr Dilip Nandwani (Grant no 222305) The authors wouldalso like to acknowledge the research team members MsDarlene Gunther Ravneet Sandhu Sochinwechi NwosisiEddie Williams and Mr Shahidullah Chowdhury for theirassistance in the field experiment

References

[1] Y Liu S Roof Z Ye et al ldquoManipulation of light signal trans-duction as a means of modifying fruit nutritional quality intomatordquo Proceedings of the National Acadamy of Sciences of theUnited States of America vol 101 no 26 pp 9897ndash9902 2004

[2] Z Pek L Helyes and A Lugasi ldquoColor changes and antiox-idant content of vine and postharvest ripened tomato fruitsrdquoHortScience vol 45 no 3 pp 466ndash468 2010

[3] G R Takeoka L Dao S Flessa et al ldquoProcessing effects onlycopene content and antioxidant activity of tomatoesrdquo Journalof Agricultural and Food Chemistry vol 49 no 8 pp 3713ndash37172001

[4] A Kocira M Swieca S Kocira U Złotek and A JakubczykldquoEnhancement of yield nutritional and nutraceutical propertiesof two common bean cultivars following the application ofseaweed extract (Ecklonia maxima)rdquo Saudi Journal of BiologicalSciences 2016

[5] K Zarzecka M Gugała A Sikorska et al ldquoThe effect of herbi-cides and biostimulants on polyphenol content of potato (Sola-num tuberosum L) tubers and leavesrdquo Journal of the SaudiSociety of Agricultural Sciences 2017

[6] T Spann Effect of Stimplex crop bio-stimulant on drought tol-erance of hamlin sweet orangeFla State Hortic Soc123 sweetorangeFla State Hortic Soc123 100-104 2010

[7] B George C Kaur D S Khurdiya and H C Kapoor ldquoAntiox-idants in tomato (Lycopersium esculentum) as a function ofgenotyperdquo Food Chemistry vol 84 no 1 pp 45ndash51 2004

[8] NK Marsic L Gasperlin V Abram M Budic and R VidrihldquoQuality parameters and total phenolic content in tomatofruits regarding cultivar and microclimatic conditionsrdquo Turk JAgric35 pp 185ndash194 2011

[9] L Barros A M Carvalho and I C F R Ferreira ldquoLeavesflowers immature fruits and leafy flowered stems of Malvasylvestris A comparative study of the nutraceutical potentialand compositionrdquo Food and Chemical Toxicology vol 48 no6 pp 1466ndash1472 2010

[10] M Nagata and I Yamashita ldquoSimple method for simultaneousdetermination of chlorophyll and carotenoids in tomato fruitrdquoNippon Shokuhin Kogyo Gakkaishi vol 39 no 10 pp 925ndash9281992

[11] G Sadler J Davis and D Dezman ldquoRapid Extraction of Lyco-pene and 120573-Carotene from Reconstituted Tomato Paste andPink Grapefruit Homogenatesrdquo Journal of Food Science vol 55no 5 pp 1460-1461 1990

[12] R Choudhary Rapid estimation of lycopene concentration inwatermelon and tomato samples by fiber optic visible spectroscopy[PhD thesis] Oklahoma State University Doctor of philoso-phy 2004

[13] T Shahzad I Ahmad S Choudhry M K Saeed and M NKhan ldquoDpph free radical scavenging activity of tomato cherrytomato and watermelon Lycopene extraction purification andquantificationrdquo International Journal of Pharmacy and Pharma-ceutical Sciences vol 6 no 2 pp 223ndash228 2014

[14] M Oyaizu ldquoStudies on products of browning reaction antiox-idative activity of products of browning reaction prepared fromglucosaminerdquo The Japanese Journal of Nutrition and Dieteticsvol 44 pp 307ndash315 1986

[15] A Khairi M Falah A Suyantohadi N Takahashi and HNishina ldquoEffect of Storage Temperatures on Color of TomatoFruit (Solanum Lycopersicum Mill) Cultivated under Moder-ateWater Stress TreatmentrdquoAgriculture andAgricultural ScienceProcedia vol 3 pp 178ndash183 2015

[16] J Pinela L Barros A M Carvalho and I C F R Fer-reira ldquoNutritional composition and antioxidant activity offour tomato (Lycopersicon esculentum L) farmerrsquo varietiesin Northeastern Portugal homegardensrdquo Food and ChemicalToxicology vol 50 no 3-4 pp 829ndash834 2012

[17] PA Idah OI Obajemihi OA Adeboye and AM OlaniyanldquoAssessment of osmotic pre-drying treatment on drying ratesof fresh tomato fruitsrdquo Nigerian Journal of Technological Devel-opment vol 11 no 1 pp 22ndash26 2014

[18] A O Togun and W B Akanbi ldquoComparative effectiveness oforganic-based fertilizer to mineral fertilizer on tomato growthand fruit yieldrdquo Compost Science and Utilization vol 11 no 4pp 337ndash342 2003

[19] CKaur andHCKapoor ldquoAnti-oxidant activity and total phen-olic content of some asian vegetablesrdquo Journal of Food Scienceand Technology vol 37 no 2 pp 153ndash161 2002

[20] M R Figas J Prohens M D Raigon et al ldquoCharacterizationof composition traits related to organoleptic and functionalquality for the differentiation selection and enhancement oflocal varieties of tomato from different cultivar groupsrdquo FoodChemistry vol 187 pp 517ndash524 2015

[21] H T Aldrich K Salandanan P Kendall et al ldquoCultivar choiceprovides options for local production of organic and conven-tionally produced tomatoes with higher quality and antioxidantcontentrdquo Journal of the Science of Food and Agriculture vol 90no 15 pp 2548ndash2555 2010

[22] A Riahi and C Hdider ldquoBioactive compounds and antioxidantactivity of organically grown tomato (Solanum lycopersicumL)cultivars as affected by fertilizationrdquo Scientia Horticulturae vol151 pp 90ndash96 2013

[23] P Brat L Mennen S George et al ldquoDetermination of thePolyphenolContent of Fruits andVegetables Establishment of aDatabase and Estimation of the Polyphenol Intake in the FrenchDietrdquo Acta Horticulturae no 744 pp 61ndash70 2007

[24] A Riahi C Hdider M Sanaa N Tarchoun M B Kheder andI Guezal ldquoThe influence of different organic fertilizers on yieldand physico-chemical properties of organically grown tomatordquoJournal of Sustainable Agriculture vol 33 no 6 pp 658ndash6732009

[25] D FanDMHodges J Zhang et al ldquoCommercial extract of thebrown seaweed Ascophyllum nodosum enhances phenolicantioxidant content of spinach (Spinacia oleracea L) whichprotects Caenorhabditis elegans against oxidative and thermalstressrdquo Food Chemistry vol 124 no 1 pp 195ndash202 2011


[26] E Abd El-Motty M Shahin M El-Shiekh and M Abd-El-Migeed ldquoEffect of algae extract and yeast application on growthnutritional status yield and fruit quality of Keitte mango treesrdquoAgriculture and Biology Journal of North America (ABJNA) pp421ndash429 2010

[27] K J Guinan N Sujeeth R B Copeland et al ldquoDiscrete roles forExtracts of Ascophyllum nodosum in enhancing plant growthand tolerance to abiotic and biotic stressesrdquo Acta Horticulturaevol 1009 pp 127ndash136 2012

[28] NM Pise and AB Sabale ldquoEffect of seaweed concentrates onthe growth and biochemical constituents of Trigonella foenum-graecumLrdquo Journal of Phytology vol 2 no 4 pp 50ndash56 2010

[29] D Liu J Shi A Colina Ibarra Y Kakuda and S Jun XueldquoThe scavenging capacity and synergistic effects of lycopenevitamin E vitamin C and 120573-carotene mixtures on the DPPHfree radicalrdquo LWT- Food Science and Technology vol 41 no 7pp 1344ndash1349 2008

[30] C E Ochoa-Velasco R Valadez-Blanco R Salas-Coronadoet al ldquoEffect of nitrogen fertilization and Bacillus licheni-formis biofertilizer addition on the antioxidants compoundsand antioxidant activity of greenhouse cultivated tomato fruits(Solanum lycopersicum L var Sheva)rdquo Scientia Horticulturaevol 201 pp 338ndash345 2016

[31] J Kubola and S Siriamornpun ldquoPhenolic contents and antiox-idant activities of bitter gourd (Momordica charantia L) leafstem and fruit fraction extracts in vitrordquo Food Chemistry vol110 no 4 pp 881ndash890 2008

[32] B Shan J-H Xie J-H Zhu and Y Peng ldquoEthanol modifiedsupercritical carbon dioxide extraction of flavonoids fromMomordica charantia L and its antioxidant activityrdquo Food andBioproducts Processing vol 90 no 3 pp 579ndash587 2012

[33] S Islam M Jalaluddin and NS Hettiarachchy ldquoBio-activecompounds of bitter melon genotypes (Momordica charantiaL) in relation to their physiological functionsrdquo Foods in Healthand Dis vol 2 pp 61ndash74 2011

[34] S-M Hue A N Boyce and C Somasundram ldquoAntioxidantactivity phenolic and flavonoid contents in the leaves ofdifferent varieties of sweet potato (Ipomoea batatas)rdquoAustralianJournal of Crop Science vol 6 no 3 pp 375ndash380 2012

[35] O Kenny T J Smyth C M Hewage and N P BruntonldquoAntioxidant properties and quantitative UPLC-MS analysis ofphenolic compounds from extracts of fenugreek (Trigonellafoenum-graecum) seeds and bitter melon (Momordica charan-tia) fruitrdquo Food Chemistry vol 141 no 4 pp 4295ndash4302 2013

[36] K G L R Jayathunge I R Grant M Linton M F Pattersonand A Koidis ldquoImpact of long-term storage at ambient tem-peratures on the total quality and stability of high-pressureprocessed tomato juicerdquo Innovative Food Science and EmergingTechnologies vol 32 pp 1ndash8 2015

[37] X-J Duan W-W Zhang X-M Li and B-G Wang ldquoEvalua-tion of antioxidant property of extract and fractions obtainedfrom a red alga Polysiphonia urceolatardquo Food Chemistry vol95 no 1 pp 37ndash43 2006

[38] R Arias T-C Lee L Logendra and H Janes ldquoCorrelation oflycopene measured by HPLC with the Llowast alowast blowast color readingsof a hydroponic tomato and the relationship of maturity withcolor and lycopene contentrdquo Journal of Agricultural and FoodChemistry vol 48 no 5 pp 1697ndash1702 2000

[39] A F Lopez Camelo and P A Gomez ldquoComparison of colorindexes for tomato ripeningrdquoHorticultura Brasileira vol 22 no3 pp 534ndash537 2004

Submit your manuscripts athttpswwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Anatomy Research International

PeptidesInternational Journal of


Hindawi Publishing Corporation httpwwwhindawicom

International Journal of

Volume 201


Molecular Biology International

GenomicsInternational Journal of


The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014


BioinformaticsAdvances in

Marine BiologyJournal of



Signal TransductionJournal of


BioMed Research International

Evolutionary BiologyInternational Journal of



Biochemistry Research International

ArchaeaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014


Genetics Research International


Advances in

Virolog y

Hindawi Publishing Corporationhttpwwwhindawicom

Nucleic AcidsJournal of

Volume 2014

Stem CellsInternational



Enzyme Research



Microbiology


Hence the objectives of this study were to compare thetomato qualities grown organically and to observe the effectof biostimulant (Stimplex) on fruit quality attributes includ-ing fruit color phytochemical level and antioxidant activitiesin four tomato cultivars namely Black Cherry BrandywineGerman Johnson and Roma Correlation between fruit colorphytochemical level and antioxidant activity was studied

2 Materials and Methods

21 Materials In the current study organic tomato cultivarexperiment was conducted during spring and summer in2015 at Tennessee State University certified organic farmin Nashville (latitude 12730m 36∘101015840 N 86∘491015840 W) Theexperiments were run using randomized block design (RBD)with three replications Four tomato cultivars Black CherryBrandywine German Johnson and Roma were investi-gated under organic farming system Organic seeds wereobtained from an organic seed company (Johnnyrsquos SelectedSeeds and High Mowing Organic Seeds company WinslowMaine United States) Stimplex was procured from AcadianAgriTech (Alberta Canada) Each cultivar was treated withStimplex on a weekly basis at 25mlgallon via foliar spray

All the chemicals and reagents for analysis were pur-chased from Sigma-Aldrich (St Louis MO United States)

22 Methods

221 Sample Preparation After physical analysis of tomatofruit fruits from each cultivar were selected randomly in eachreplication Freshly harvested tomatoeswere rinsed and driedfor color measurement and then chopped and blended inwaring blender to produce a homogenous mass for furtheranalysis [7] The homogenized samples were tightly sealed insample vials and stored in aminus20∘C freezer Before analysis thesamples were thawed to room temperature and homogenizedusing a polytron (PT 2100 Kinematica AG Schweiz) for3min before determination of total phenolic content totallycopene content total carotenoid content and antioxidantactivities

222 Moisture Content Determination The fresh tomatosamples were cut into small pieces (1 cm3) weighed (100 plusmn5 g) and kept at 103∘C to reach the consistent weightsMoisture content was calculated as follows

Moisture content () = wet weight minus dry weightwet weight

times 100(1)

223 Total Phenolic Content (TPC) TPC was determined byFolin-Ciocalteu method with some modifications [8] Briefly1 g of tomato sample was added to 5ml of 50 methanoland kept in a tightly capped bottle in the dark for 24 hoursat 60∘C with constant stirring After being cooled to roomtemperature the samples were centrifuged at 10000 g for5min Supernatant was used for the determination of totalphenolic content The supernatant (05ml) was thoroughlymixed with 05ml of distilled water and 125120583l of Folin-Ciocalteu reagent for 6min before the addition of 125ml

of 7 sodium carbonate Final volume of solution was 3mLusing distilled water and was left in the darkness for 90minAbsorbance was measured at 760 nm Each test was repeated3 times in triplicate each time

TPC was calibrated by using a standard curve of gallicacid TPC for each cultivar extract was expressed as gallic acidequivalent (GAE) in 120583g of GAEg fresh tomatoes

224 Total Lycopene and Total 120573-Carotene Estimation Mea-surement of total lycopene and total carotenoids has followedthe method described by Barros et al [9] which is based onthemethod byNagata andYamashita [10] withmodificationsThe extraction of freshly harvested tomatoes was conductedusing a mixture of solvents hexane acetone ethanol (2 1 1vvv) with 25 butylated hydroxytoluene (BHT) addedto each cultivar bottle [11] Aliquots of 025 g homogenizedsamples were added to 25ml extraction solvent The bot-tles were tightly closed and agitated for 10 minutes on ashaker at 300 rpm followed by leaving the bottles at roomtemperature to stand for 15min for phase separation toform a distinct aqueous polar layer and a nonpolar layerAliquots of 4ml extracts from the top layer of the nonpolarphase were withdrawn and filtered through Whitmanrsquos filterpaper Absorbance was measured spectrophotometrically at453 505 645 and 663 nm [12] Contents were calculatedaccording to the following equations120573-carotene (mg100mL)= 0216 times A663 minus 1220 times A645 minus 0304 times A505+ 0452 times A453

Lycopene (mg100mL)= minus00458 times A663 + 0204 times A645 minus 0304 times A505+ 0452 times A453

(2)

The concentration of total lycopene and total 120573-carotenewas further expressed in g kgminus1 of fresh weight (fw)

225 Antioxidant Activity

DPPH Free Radical Scavenging Property DPPH free rad-ical scavenging property was evaluated using the methoddescribed by Shahzad and others [13] with modificationsAbout 300 g of freshly harvested tomato was cut into piecesand homogenized using a polytron at medium speed for5min Methanol (10ml 100) was mixed with sample (10 g)and the mixture was centrifuged at 8000 g for 10min Super-natant (2ml) was filtered through a 045 um Nylon Syringefilter for absorbance measurement at 517 nm

DPPH free scavenging effect was calculated using thefollowing equation

DPPH scavenging effect ()

= [1198600 minus (119860 minus 1198601)1198600 times 100] (3)











ControlTreated

aa a

a a a

a

a

8500

9000

9500

10000

Moi

sture

cont

ent (

)








Control



Stimplex treatment






Control



Stimplex treatment











aa a a

a

a

a

a

82

84

86

88

90

92

94

96

98

100

DPP

H sc

aven

ging

activ

ity (

)



ControlTreated

a

aa a aa a

a

00

05

10

15

20

25

30

35

Redu

cing

pow

er













Control



Stimplex treatment








4 Conclusions





Acknowledgments


References
















































Volume 201






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology











ControlTreated

aa a

a a a

a

a

8500

9000

9500

10000

Moi

sture

cont

ent (

)








Control



Stimplex treatment






Control



Stimplex treatment











aa a a

a

a

a

a

82

84

86

88

90

92

94

96

98

100

DPP

H sc

aven

ging

activ

ity (

)



ControlTreated

a

aa a aa a

a

00

05

10

15

20

25

30

35

Redu

cing

pow

er













Control



Stimplex treatment








4 Conclusions





Acknowledgments


References
















































Volume 201






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology




Control



Stimplex treatment






Control



Stimplex treatment











aa a a

a

a

a

a

82

84

86

88

90

92

94

96

98

100

DPP

H sc

aven

ging

activ

ity (

)



ControlTreated

a

aa a aa a

a

00

05

10

15

20

25

30

35

Redu

cing

pow

er













Control



Stimplex treatment








4 Conclusions





Acknowledgments


References
















































Volume 201






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology




aa a a

a

a

a

a

82

84

86

88

90

92

94

96

98

100

DPP

H sc

aven

ging

activ

ity (

)



ControlTreated

a

aa a aa a

a

00

05

10

15

20

25

30

35

Redu

cing

pow

er













Control



Stimplex treatment








4 Conclusions





Acknowledgments


References
















































Volume 201






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology




Control



Stimplex treatment








4 Conclusions





Acknowledgments


References
















































Volume 201






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology




Acknowledgments


References
















































Volume 201






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology























Volume 201






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology

a study on organic tomatoes: effect of a biostimulator on

Documents