Effect of gum arabic as an edible coating on antioxidant capacity of tomato (Solanum lycopersicum L.) fruit during storage

Postharvest Biology and Technology 76 (2013) 119–124

Contents lists available at SciV SciVerse erse ScienceDirect

Postharvest Postharvest Biology and Technology  j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / p o s t h a r v b i o

Effect of gum arabic as an edible coating on antioxidant capacity of tomato (Solanum lycopersicum L.) fruit during storage Asgar Ali ∗ , Mehdi Maqbool, Peter G. Alderson, Noosheen Zahid School of Biosciences, Faculty of Science, The University of Nottingham Malaysia Campus, Semenyih, 43500 Selangor, D.E., Malaysia

a r t i c l e

i n f o

 Article history: Received 21 June 2012 Accepted 23 September 2012 Keywords: Antioxidant capacity Gaseous exchange Gum arabic Solanum lycopersicum

a b s t r a c t

Coating of tomato fruit with gum arabic has been found to delay the ripening process and maintain the antioxidant capacity. Gum arabic in aqueous solutions of 5, 10, 15 and 20% was applied as an edible coating to green-mature tomatoes which were stored at 20 ◦ C and 80–90% 80–90% RH for 20 days. Fruit coated with 10% gum arabic delayed the ripening process by slowing down the rate of respiration and ethylene production and also maintained total antioxidant capacity, lycopene content, total phenolics and total carotenoids during storage as compared to the uncoated control and fruit treated with 5% gum arabic concen concentrat tration ion.. Theresults Theresults sugges suggestt thatby using using 10%gum arabic arabic as an ediblecoatin ediblecoating, g, theripeningproces theripeningprocesss oftomato oftomatoescan escan bedelaye bedelayed d and and theantio theantioxid xidantcan antcan bepreser bepreserve ved d for for upto 20daysduringstor 20daysduringstorag age e at 20 ◦ C without any negative effects on postharvest quality. © 2012 Elsevier B.V. All rights reserved.

1. Introducti Introduction on

Tomato (Solanum lycopersicum L.) fruit consumption is highly correlate correlated d with reduced reduced risk of cancer cancer and also low incidence incidence of  some cardiac cardiac diseases, diseases, due to some importan importantt constitu constituents ents present present inthefruit(Franc inthefruit(Francesch eschii et al.,1994 al.,1994). ). Themostimportan Themostimportantt of theseare theseare carotenoids, particularly lycopene and ␤-carotene which are accumulate mulated d in plasma plasma and and tissue tissuess in relati relation on to the intake intake of tomato tomatoes es (Oshima et al., 1996). 1996 ). In addition to the carotenoids, tomato fruit are also a rich source of natural antioxidants, which can delay or restra restrain in the the oxidat oxidation ion of lipids lipids or other other molecu molecules les by inhibi inhibitin ting g the the initiation of oxidative chain reactions ( Yahia et al., 2007). 2007 ). However, tomato being a climacteric fruit, has a short postharvest life due to several factors such as high rate of respiration, weight weight loss and enhancedripenin enhancedripening, g, which which resultin the earlydeterioratio oration n of fruit fruit qualit quality y ( Javanmardi and Kubota, 2006; Zapata et al., 2008). 2008 ). Moreover, during ripening the chemical composition of the fruit also changes dramatically, affecting texture, flavour, antioxidantcontents dantcontents mainly mainly phenoliccompoun phenoliccompounds, ds, flavonoid flavonoidss and ascorbic ascorbic acid (Bailén (Bailén et al., 2006). 2006). Generally, low temperature storage is used to reduce the rate of respiration and thermal decomposition for extending storage life of tomatoes. However, the prolonged storage at low temperature causes chilling injury and also contraction of the skin occurs as waterfromthe waterfromthe skin skin of thefruitmoves thefruitmoves into into thepulpwhich thepulpwhich lowers lowers down down the the taste taste and and also also damage damagess thefruit physio physiolog logy y (Zap Zapataet ataet al. al.,,

∗

Corresponding author. Tel.: +60 3 8924 8219; fax: +60 3 8924 8018. E-mail address: [email protected] (A. Ali).

0925-5214/$ – see front matter © 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.postharvbio.2012.09.011

2008). 2008 ). Controlled atmosphere and hypobaric storage techniques are also also useful useful in extend extendin ing g the shelfshelf-lif life e of tomato tomatoes es but these these are very expensive to run on a commercial scale ( Artés et al., 2006). 2006 ). Thus, edible coatings based on natural products can provide an additi addition onal al protec protectio tion n for fresh fresh fruit fruit and vegeta vegetable bless and and be comple comple-mentary mentary to low temperatu temperature, re, controll controlled ed atmosphe atmosphere re and hypobari hypobaricc storage techniques (Baldwin (Baldwin et al., 1995). 1995 ). Appropriate formulations of an edible coating may provide an excellent barrier against gaseous gaseous exchangeand exchangeand water water loss which which are detriment detrimental al to postharpostharvest quality. Gum arabic, obtained from stems or branches of  Acacia species, is the most common polysaccharide used in the industrial sector because because of its unique unique emulsifica emulsification tion,, andfilm forming forming andencapsulation properties which has received the highest toxicology safety status by the joint FAO/WHO Expert Committee on Food Additives (Anderson and Eastwood, 1989; Motlagh et al., 2006 ). When used as an edible coating, gum arabic also showed some positive results and significantly delayed ripening of cold-stored apples ( El-Anany et al., 2009). 2009 ). Moreover, in a recent study by our group it was found that gum arabic not only enhanced shelf-life but also maintained postharvest quality of mature-green tomatoes for up to 20 days during storage at 20 ◦ C (Ali et al., 2010). 2010 ). In another study by Zapata et al. (2008), (2008) , it was found that polysacc polysaccharid haride-bas e-based ed edible edible coatings coatings such as alginate alginate or zein showed some beneficial effects in retarding the ripening process and maintaining quality of stored tomatoes. Similarly, Oms-Oliu et al. (2008) also studied the effect of alginate, pectin and gellanbased edible coatings on the shelf-life and antioxidant properties of fresh-cut ‘Piel de Sapo’ melon. They found that polysaccharidebased edible coatings not only prevented the dehydration but also

120

A. Ali et al. / Postharvest Biology and Technology 76 (2013) 119–124

inhibited the ethylene production and triggered the accumulation of total phenolic compounds and other compounds with antioxidant properties. However, there has been limited information available on the use of edible coatings in delaying ripening processes and preserving antioxidants during storage, particularly in fresh fruit and vegetables. Therefore, the aim of this study was to determine whether gum arabichas the potential to be used as an edible coating for delaying ripening whilst maintaining the antioxidant properties of tomatoes during storage. 2. Materials and methods  2.1. Plant material

Tomato (S. lycopersicum L. var. Money Maker) fruit of colour index 2 (greenwithtrace of yellow) according tothe USDA standard tomato colour classification chart (USDA, 1991) were obtained from a local supplier in Semenyih, Selangor, Malaysia. Fruit of uniform size, shape, free from any mechanical damage and insect or pathogenic infection were selected for the experiment.  2.2. Preparation of gum arabic solutions and application of  coating treatments

Gum arabic powder (KB-120, Food Grade) was imported from  Jumbo Trading Co., Ltd. Bangkok, Thailand. Gum arabic concentrations were selected on the basis of previous experiments (Ali et al., 2010). Briefly, gum arabic solutions (5, 10, 15 and 20%, w/v), were prepared bydissolving5, 10, 15and 20g of powder in 100 mL  purified water. The solutions were stirred with low heat (40 ◦ C) for 60min on a magnetic stirrer/hot plate (Model: HTS-1003), then filtered to remove any undissolved impurities using a vacuum flask. After cooling to 20 ◦ C, glycerol monostearate (1.0%) (Sigma) was added as a plasticizer to improve the strength and flexibility of the coating solutions. The pH of the solutions was adjusted to 5.6 with 1 N NaOH. Tomato fruit were washed with sodium hypochlorite (0.05%) for 3 min and air-dried at ambient temperature (25 ± 3 ◦ C). Afterdrying, tomato fruitwere randomly divided intofive different treatments andeach treatmentwas conducted withfour replicates. Fruitwere dipped in eachconcentration of gum arabic coating solution (5, 10, 15 and 20%) for 2–3min and it was assured that the coating solution was applied uniformly on the whole surface while control fruit were dipped in purified water only. The fruit were then air-dried, packed in cardboard boxes and stored at 20 ± 1 ◦ C and 80–90% RH. The data were collected before treatment (day 0) and at 4 day intervals for 20 days.  2.3. Determination of respiration rate and ethylene production

The rates of respiration andethyleneproduction weremeasured according to the method describedby Maqbool et al. (2011). Respirationrateas indicatedby CO2 production was measured by placing two tomatofruitin 1 L plastic container for 1 h,and1 mLof gas sample waswithdrawn fromthe headspace witha gastight hypodermic syringe and analysed with a gas chromatograph (GC) (Claru-500, Perkin Elmer, USA) equipped with a stainless steel column (Porapak R 80/100). Helium served as the carrier gas at a flow rate of  20mL −1 min. Temperatures were 60, 100 and 200 ◦ C for the oven, injector and thermal conductivitydetector (TCD), respectively. One mL of CO2 gas (1.0%) (Scotty gases, Beltifonte, PA, USA) was used as theexternalstandard for calibration.The amount of CO2 production was expressed in mg−1 kg−1 h. The ethylene production was measured by taking 1 mL sample from each jar using hypodermic syringe and injecting it into a GC. The GC was equipped with a stainless steel column (PorapakT,

100/120) and a flame ionization detector (FID). Nitrogen, hydrogen and air flow rates were 20 mL −1 min. Nitrogen served as a carrier gas. Temperatures were 150, 200 and 200 ◦ C for the oven, injector and FID, respectively. One mL ethylene gas (10 ␮L −1 mL) (Scotty gases, Beltifonte, PA USA) was used as the external gas standard wasinjectedfor calibration.The amount of ethylene wasexpressed in ␮g−1 kg−1 h.  2.4. Total phenolic content 

Theamountof total phenolic contents intomato fruit wasdetermined according to the Folin-Ciocalteau (FC) procedure ( Singleton and Rossi, 1965) with slight modifications. Briefly, 0.1 mL of fruit samplefroma mixture of 15fruitin each treatmentwas mixed with 0.5 mL of FC along with 1.5 mL of 7% sodium carbonate solution. Purified water was added to the solution to make the volume up to 10 mL. The mixture was incubated at 40 ◦ C for 2 h. The absorbance was recorded at 750 nm using a UV-VIS Spectrophotometer (Varioskan Flash Multimode Reader, Thermo Fisher Scientific, USA) and the results were expressed in mg of gallic acid equivalent to 100 g of fresh weight of fruit sample.  2.5. Lycopene extraction

Lycopene extraction was based on the method of  Fish et al. (2002) with minor modifications. Briefly, 0.6 mL of fruit juice from a mixture of 15 fruit in each treatment was mixed with 5 mL of  0.05% butylated hydroxytoluene in acetone along with 5 mL of 95% ethanol and 10mL of hexane. The mixture was agitated at 180 rpm for 15 min on ice. Three mL of ice cold water was added and again shaked for 5 min. The absorbance was recorded at 503nm using a UV-VIS Spectrophotometer (Varioskan Flash Multimode Reader, Thermo Fisher Scientific, USA). The amount of lycopene in tissues was then calculated by the following formula: Lycopene(␮g−1 g)

=

( x/y) × A503 × 3.12

(1)

where x is the amount of hexanes (mL), y the weight of fruit tissue (g), A503 the absorbance at 503 nm and 3.12 is the extinction coefficient.  2.6. Total carotenoids

Total carotenoids were estimated following the method of Lalel et al. (2003). Briefly, 2 g of fruit pulp from a mixture of 15 fruit in each treatment was ground with 0.05g of magnesium carbonate and extracted two times with a 20mL of acetone: n-hexane [75:60, v/v]. The pool extract was washed with a 40mL of 10% NaCl and 2 × 40 mL of distilled water to remove acetone. The n-hexane extract was measured for its absorbance at 436 nm using UV-VIS Spectrophotometer (Varioskan Flash Multimode Reader, Thermo Fisher Scientific, USA). Total carotenoids were expressed as mg−1 g of  ␤-carotene equivalent to a standard curve of  ␤-carotene.  2.7. Antioxidant capacity

Ferric Reducing Antioxidant Power (FRAP) assay was used to measure the total antioxidant capacity in tomato fruit. Briefly, the FRAPreagentcontained2.5 mL of 10 mM 2,4,6-Tripyridyl-s-triazine (TPTZ) solution in 40 mM hydrochloric acid along with 2.5 mL of  20mM FeCl3 and 25 mL of 0.03 mM acetate buffer having pH 3.6 (Benzie andStrain, 1996). The reaction mixture consists of 40 ␮L of  fruit extract from a mixture of 12 fruit in each treatment mixed with 3mL of FRAP reagent followed by incubation at 37 ◦ C for 4 min. Absorbance was recorded at 593nm using UV-VIS Spectrophotometer (Varioskan Flash Multimode Reader, Thermo Fisher

121

 A. Ali et al. / Postharvest Biology and Technology 76 (2013) 119–124

Scientific, USA) and the results were expressed as the concentration of antioxidant having a ferric reducing activity equivalent to 1 mg−1 g ferrous sulphate (FeSO4 ) of fresh weight of fruit sample. Total antioxidant capacity was also measured through determining the free radical scavenging effect on 1,1-diphenyl-2picrylhydrazyl (DPPH) radical, according to the method described by Elez-Martínez and Martín-Belloso (2007) with slight modification. Prior to analysis, 25 mg−1 L of DPPH solution was freshly prepared by dissolving in 100% (v/v) methanol. Cuvette was filled with 3 mL of DPPH solution. Then 5 ␮L ofsample froma mixture of  12 fruit in each treatment was added into the cuvette and mixed well by using the same pipette tip. The mixture was left to react for 15min. Theabsorbance was measured at 515 nmwavelength using UV-VIS Spectrophotometer (Varioskan Flash Multimode Reader, Thermo Fisher Scientific, USA) against a blank of methanol without DPPH. Results were expressed as a percentage decrease with respect to the absorption value of reference DPPH solution.

a

Control 5% gum arabic 10% gum arabic 15% gum arabic 20% gum arabic

20 18 16

14    )    h    1   -  g 12    k    1   -  g 10   m    (    2    O 8    C 6 4 2 0

 b 30

 2.8. Statistical analysis 25

The experiment was arranged in a completely randomized design (CRD) with four replications. The data were subjected to analysis of variance (ANOVA) using MSTAT-C software (Version 1.3, Department of Crop and Soil Sciences, Michigan State University, EastLansing, Michigan, USA), while LeastSignificantDifference (LSD) test was used to compare differences between treatments at 95% confidence level of each variable.

   )    h 20    1   -  g    k    1   -  g   u 15    (   e   n   e    l   y    h    t 10    E

3. Results and discussion

5

 3.1. Rate of respiration and ethylene production

0 0

Rate of respiration and ethylene production in fresh fruit and vegetables are considered good indexes for the determination of  storage life. A decrease in respiration rate was observed initially in fruit treated with higher concentrations of gum arabic while a sharp increase in untreated control and5% gumarabic treated fruit was observed which reached to a peak value after 8 days and after that therewas a continuous decrease until theend of storage period (Fig. 1a). However, fruit treated with 10% gum arabic significantly delayed respiration rate and showed the similar peak height after 12days of storage. In the case of 15 and 20% gumarabic coatedfruit, a slight increase in respiration rate was observed during complete storage period. Ethylene production in untreated control and 5% gum arabic coated fruit increased rapidly and reached a peak after 8 days then decreased sharply during the complete storage period (Fig. 1b). However, 10% gum arabic treated tomatoes showed a maximum value of ethylene production after 12 days of storage and thereafter, a slow decrease until the end of storage period. While the fruit treated with 15 and 20% gum arabic showed a slight but continuous increase in ethylene production during complete storage period. The delayed increase in respiration rate and ethylene production of 10% gum arabic coated fruit as compared to the untreated control and 5% gum arabic coated fruit suggests that edible coating exerted a barrier to the gaseous exchange. The reduced rate of  respiration and ethylene production in tomato fruit might be correlated with delayed senescence (Ali et al., 2010) and a reduced susceptibility to decay (Maqbool et al., 2010). Similarly, in a previous study on tomato using gum arabic, it was found that fruit coated with 10 and 15% gum arabic had less weight loss during storage as compared to the control which could be attributed to the coatings providing a semi-permeable barrier against gas movement and therefore, reduced the rate of respiration and ethylene

5

10

15

20

25

Storage Time (Days)

Fig.1. Effect of differentconcentrations of gum arabicon (a)respiration rateand (b) ethylene production of tomato fruit during storage (20 ◦ C, 80–90% RH). The vertical bars represent the standard error of means for four replicates.

production (Ali et al., 2010). The pattern of respiration rate and ethylene production in this study was in agreement with the findings of Banks (1984), who reported that coating bananas with TAL  Pro-long suppressed the rates of respiration and ethylene production by modifying the internal atmosphere of the fruit. Similar results were also observed by Ali et al. (2011), where they found that control fruit showedearlyrise in respiration and ethylene production as compared to 1.5% chitosan coated papayas during five weeks of storage. A reduction in respiration rate and ethylene production as a result of coating with films has also been reported by many researchers in various fruit, such as papaya, grapes, mango and strawberries (El-Ghaouth et al., 1992; Kittur et al., 2001; Ali et al., 2011).  3.2. Total phenolic content 

The maximum amount of total phenolic content was observed in 10% gum arabic coated fruit and reached to a peak after 12 days thendecreased sharply during thecomplete storageperiod (Fig.2a). However, untreated control and 5% gum arabic coated tomatoes showed a maximum value of total phenolic content after 8 days of storage and thereafter, a slow decrease until the end of storage period. While the fruit treated with 15 and20% gumarabic showed a slight but continuous increase in total phenolic content during complete storage period. The increase in total phenolic content is related with the enhancement of antioxidant capacity( Reyes and Cisneros-Zevallos,

122

a

A. Ali et al. / Postharvest Biology and Technology 76 (2013) 119–124

The early increase in lycopene content in untreated control and fruit treated with 5% gum arabicconcentration might be due to the faster ripening of fruit than in the fruit treated with higher concentrations of gum arabic. The production of lycopene content is directly correlated with ripening ( Javanmardi and Kubota, 2006 ). Similar results were also reported when tomato fruit were stored at 4 ◦ C (Giovanelli et al., 1999). It has also been reported that the formation of lycopene depends on the temperature range and rate of respiration during storage ( Javanmardi and Kubota, 2006). In a recent study on tomato using gum arabic as an edible coating, a slight change in colour in fruit coated with 15 and 20% gum arabic concentrations was observed even after 20 days of storage which suggest that at higher concentrations the ripening process was blocked and therefore, fruit were still green but off-flavoured after 20 days of storage (Ali et al., 2010).

20

18    )    W    F   g 16    0    0    1 14    1      d    i   c   a 12   c    i    l   a   g 10   g   m    (   s   c 8    i    l   o   n   e    h   p 6    l   a    t   o    T 4

Control 5% gum arabic 10% gum arabic 15% gum arabic 20% gum arabic

2

 b

 3.4. Total antioxidant capacity

100

The maximum amount of total antioxidant contents in terms of  both FRAP and DPPH was observed in 10% gum arabic coated fruit and reached to a peak after 16 days and then decreased sharply until the end of storage period (Fig. 3a and b). However, untreated control and 5% gum arabic coated tomatoes showed a maximum value of total antioxidant after 8 and 12 days, respectively, and thereafter, a slow decrease until the end of storage. It has been shown that the main antioxidants in tomatoes are carotenoids, ascorbic acid and phenolic compounds (Giovanelli

90 80    )    1   -  g 70   g   µ    (   e   n   e   p 60   o   c   y    L 50 40

a

Control 5% gum arabic 10% gum arabic 15% gum arabic 20% gum arabic

1.8

30

1.6 0

4

8

12

16

20

24

Storage Time (Days) Fig. 2. Effectof differentconcentrationsof gumarabicon (a)totalphenoliccontent and (b) lycopene content of tomato fruit during storage (20 ◦ C, 80–90% RH). The vertical bars represent the standard error of means for four replicates.

2003). Therefore, in our study, the maximum amount of total phenolic content in 10% gum arabic coated tomatoes means that those fruit maintained higher amounts of antioxidants than uncoated and fruit coated with higher concentrations of gum arabic. A low amount of total phenolic content or a sharp decline after 8 days in untreated control and 5% gum arabic coated fruit might be due to the higherrate of respiration whichresulted in the loss of total phenolic contentdue to thedegradationof certain phenoliccompounds (Day, 2001). It might also be due to senescence and breakdown of cell structure during storage, as was observed in a previous study on tomato using gum arabic ( Ali et al., 2010). The results of the present study are comparable with the previous findings of  Ghasemnezhad et al. (2010), in which they reported the decrease in phenolic content of apricot at higher concentrations of chitosan due to senescence.  3.3. Lycopene content 

The lycopene content increased with the storage time in all the treated and untreatedcontrol fruit(Fig.2b). However, the lycopene content in untreated control and 5% gum arabic coated tomatoes increased sharply and reached to a maximum peak after 12 days of storage while the similar peak in 10% gum arabic coated fruit was observed after 16 days of storage. On the other hand, there wereminimumlevels of lycopene contentin tomatoes treated with higher concentrations of gumarabic(15 and20%) evenafter 20 days of storage.

   )    W    F   g    1     g   m    4    O    S   e    F    (    P    A    R    F

1.4 1.2 1.0 0.8 0.6 0.4 0.2 0.0

 b

220 200 180

   ) 160    %    (    H    P    P 140    D 120 100 80 0

4

8

12

16

20

24

Storage Time (Days) Fig. 3. Effect of differentconcentrations of gum arabic on totalantioxidant capacity (a) FRAP and (b) DPPH value of tomato fruit during storage (20 ◦ C, 80–90% RH). The vertical bars represent the standard error of means for four replicates.

 A. Ali et al. / Postharvest Biology and Technology 76 (2013) 119–124

et al., 1999). However, the antioxidant capacity of tomatoes also depends on several other factors including genetics, environmental conditions, production techniques used, date of harvest and postharvest storage conditions (Dumas et al., 2003). In general, a positive correlation has been reported between total phenolic content and total antioxidant capacity ( Reyes and CisnerosZevallos, 2003). The delayed increase in antioxidant activity in fruit treated with 10% gum arabic concentration could be related to the delayed ripening of those fruit as compared to the control and 5% gum arabic coated fruit, and it was quite obvious in a previous study as well where the tomato fruit coated with higher concentrations of gum arabic slowed down the ripening process by delaying the biochemical and physiological changes occurring during storage (Ali et al., 2010). The total antioxidant activity is highly dependent on ripening processes of fruit. During ripening, the total antioxidant activity increases and this increase is mainly due to the changes into the lipophilic antioxidant activity (Cano et al., 2003). In addition, some other possible factors such as the amount of  ␤-carotene, vitamin C and vitamin E also affect the antioxidant activity ( Dumas et al., 2003).  3.5. Total carotenoids

The amount of total carotenoids increased initially and reached to a maximum in control fruit after 8 days of storage andthe similar peak in fruit treated with 5% and 10% gum arabic concentrations was achievedafter 12and 16days,respectively (Fig.4). However,in fruittreatedwith higher concentrations of gumarabic (15 and20%), there was a slight increase in total carotenoids during complete storage period. The early increase in total carotenoids in control and 5% gum arabic treated fruit suggests that those fruit were ripened earlier as compared to the fruit treated with higher concentrations of gum arabic as it was observed in a previous study as well, where gum arabic coated fruit at higher concentrations gave better results in terms of quality andshelf-life(Aliet al., 2010). Thegum arabiccoating concentration of 10% delayed the ripening process by slowing down the respiration and therefore, maintained higher amount of  total carotenoids until day 16 of storage. Yahia et al. (2007) also reported similar results when they exposed tomatoes to 34 ◦ C and then stored at 20 ◦ C for up to 4 weeks.

Control 5% gum arabic 10% gum arabic 15% gum arabic 20% gum arabic

100 90

   )    1     g   g   µ    (   s    d    i   o   n   e    t   o   r   a   c    l   a    t   o    T

80 70 60 50 40 30 20 0

4

8

12

16

20

24

Storage Time (Days) Fig.4. Effect ofdifferent concentrationsof gumarabic ontotal carotenoidsof tomato fruit during storage (20 ◦ C, 80–90% RH). The vertical bars represent the standard error of means for four replicates.

123

4. Conclusions

In conclusion, the present study shows that gum arabic, as a preservative material, could delay the ripening process by inhibiting the respiration rate and ethylene production in tomato fruit. This suggests that gum arabic not only extends the storage life but also preservesthe antioxidant capacityduringstorage andalso suggests that gum arabic is promising as an edible coating to be used in commercial postharvest applications for prolonging the storage life and preserving antioxidant levels of tomato fruit.  Acknowledgements

The authors would like to thank the Ministry of Agriculture (MOA), Malaysia for providing financial support under the project grant (05-02-12-SF0031) and Jumbo Trading Co., Ltd. Bangkok, Thailand for providing gum arabic. References Ali, A., Maqbool, M., Ramachandran, S., Alderson, P.G., 2010. Gum arabic as a novel edible coating for enhancing shelf-life and improving postharvest quality of  tomato (Solanum lycopersicum L.) fruit. Postharvest Biology and Technology 58, 42–47. Ali, A., Mahmud, T.M.M., Kamaruzaman, S., Siddiqui, Y., 2011. Effect of chitosan coatings on the physico-chemical characteristics of Eksotika II papaya ( Carica  papaya L.) fruit during cold storage. Food Chemistry 124, 620–626. Anderson,D.M.W.,Eastwood, M.A., 1989. Thesafety ofgum arabicas a food additive andits energyvalueas an ingredient:a briefreview. Journal ofHumanNutrition and Dietetics 2, 137–144. Artés, F., Gómez, P.A.,Artés-Hernández, F., 2006. Modified atmosphere packaging of  fruits and vegetables. Stewart Postharvest Review 2, 1–13. Bailén, G., Guillén, F., Castillo, S., Serrano, M., Valero, D., Martínez-Remero, D., 2006. Use of activated carbon inside modified atmosphere packages to maintain tomato fruit quality during cold storage. Journal of Agricultural and Food Chemistry 54, 2229–2235. Baldwin, E.A., Nisperos-Carriedo, M., Shaw, P.E., Burns, J.K., 1995. Effect of coatings and prolonged storage conditions on fresh orange flavour volatiles, degrees brix and ascorbic acid levels. Journal of Agricultural and Food Chemistry 43, 1321–1331. Banks, N.H.,1984. Someeffectsof TAL-Prolong coating on ripening bananas. Journal of Experimental Botany 35, 127. Benzie, I.F.F., Strain, J.J., 1996. The ferric reducing ability of plasma (FRAP) as a measure of antioxidant power: the FRAP assay. Analytical Biochemistry 239, 70–76. Cano,A., Acosta, M., Arnao, M.B., 2003. Hydrophilic and lipophilic antioxidantactivitychanges duringon-vineripeningof tomatoes ( Lycopersicon esculentum Mill). Postharvest Biology and Technology 28, 59–65. Day, B., 2001. Modified atmosphere packaging of fresh fruits and vegetables – an overview. Acta Horticulturae 553, 585–590. Dumas, Y., Dadomo, M., Di Lucca, G., Grolier, P., 2003. Review: effects of environmental factors and agricultural techniques on antioxidant content of tomatoes.  Journal of the Science of Food and Agriculture 83, 369–382. El-Anany,A.M., Hassan, G.F.A., Rehab Ali, F.M.,2009.Effectsof ediblecoatingson the shelf-life andqualityof Anna apple( Malus domestica Borkh) during coldstorage.  Journal of Food Technology 7, 5–11. El-Ghaouth, A., Arul, J., Ponnampalam, R., Boulet, M., 1992. Chitosan coating to extend the storage life of tomatoes. HortScience 27, 1016–1018. Elez-Martínez, P., Martín-Belloso, O., 2007. Effect of high intensity pulsed electric fieldprocessing conditions on vitamin C andantioxidant capacity oforange juice and gazpacho a cold vegetable soup. Food Chemistry 102, 201–209. Fish, W.W., Perkins-Veazie, P., Collins, J.K., 2002. A quantitative assay for lycopene that utilizes reduced volumes of organic solvents. Journal of Food Composition and Analysis 15, 309–317. Franceschi, S., Bidoli, E., La Vecchia, C., Talamini, R., D’Avanzo, B., Negri, E., 1994. Tomatoes and risk of digestive-tractcancers. InternationalJournal of Cancer 59, 181–184. Ghasemnezhad, M.,Shiri, M.A., Sanavi,M., 2010. Effectof chitosan coatings onsome quality indices of apricot ( Prunus armeniaca L.) during cold storage. Caspian  Journal of Environmental Science 9, 25–33. Giovanelli, G., Lavelli, V., Peri, C., Nobili, S., 1999. Variation in antioxidant components of tomatoduring vine andpost-harvest ripening.Journal of theScienceof  Food and Agriculture 79, 1583–1588.  Javanmardi, J., Kubota, C., 2006. Variation of lycopene, antioxidant activity, total soluble solids andweight lossof tomato during postharvest storage.Postharvest Biology and Technology 41, 151–155. Kittur, F.S., Saroja, N., Habibunnisa Tharanathan, R.N., 2001. Polysaccharide-based compositecoating formulations for shelf-extensionof fresh banana and mango. European Food Research and Technology 213, 306–311.

124

A. Ali et al. / Postharvest Biology and Technology 76 (2013) 119–124

Lalel, H.J.D., Singh, Z., Tan, S.C., 2003. Distribution of aroma volatile compounds in different parts of mango fruit. Journal of Horticultural Science & Biotechnology 78, 131–138. Maqbool,M., Ali,A., Alderson,P.G.,Zahid,N., Siddiqui,Y., 2011.Effectof a novel edible composite coating based on gum arabic and chitosan on biochemical and physiological responses of banana fruits during cold storage. Journal of Agricultural and Food Chemistry 59, 5474–5482. Maqbool, M., Ali, A., Ramachandran, S., Smith, D.R., Alderson, P.G., 2010. Control of  postharvest anthracnose of banana using a new edible composite coating. Crop Protection 29, 1136–1141. Motlagh, S., Ravines, P., Karamallah, K.A., Ma, Q., 2006. The analysis of  Acacia gums using electrophoresis. Food Hydrocolloid 20, 848–854. Oms-Oliu, G., Soliva-Fortuny, R., Martin-Belloso, O., 2008. Using polysaccharidebasededible coatings to enhance quality and antioxidantproperties of fresh-cut melon. LWT – Food Science and Technology 41, 1862–1870. Oshima, S., Ojima, F., Sakamoto, H., Ishiguro, Y., Terao, J., 1996. Supplementation with carotenoids inhibits singlet oxygen mediated oxidation of human

plasma low-density lipoprotein. Journal of Agricultural and Food Chemistry 44, 2306–2309. Reyes, L.F.,Cisneros-Zevallos,L., 2003. Wounding stress increasesthe phenolic content and antioxidant capacity of purple-flesh potatoes. Journal of Agricultural and Food Chemistry 51, 5296–5300. Singleton, V.L., Rossi Jr., J.A., 1965. Colorimetry of total phenolics with phosphomolybdic-phosphotungstic acid reagents.American Journal of Enology and Viticulture 16, 144–158. USDA, 1991. United States Standard for Grades of Fresh Tomatoes. US Department of Agriculture, Agricultural Marketing Service, Washington, DC. Yahia, E.M., Soto-Zamora, G., Brecht, J.K., Gardea, A., 2007. Postharvest hot air treatment effects on the antioxidant system in stored mature-green tomatoes. Postharvest Biology and Technology 44, 107–115. Zapata, P.J.,Guillén, F.,Martínez-Romero, D., Castillo,S., Valero, D., Serrano,M., 2008. Use of alginate or zein as edible coatings to delay postharvest ripening process and to maintain tomato ( Solanum lycopersicon Mill) quality. Journal of the Science of Food and Agriculture 88, 1287–1293.