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Improving Storability of Le Conte Pear Fruit Using Aminoethoxyvinylglycine (AVG) and Oxalic Acid (OA) under Cold Storage Conditions



M.E. Tarabih
 
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ABSTRACT

Le Conte pear fruits were dipped in 200 ppm aminoethoxyvinylglycine (AVG) and 5 mM oxalic acid (OA) solution either alone or in combination for 5 min to investigate their effects on delay ripening and prolong storability during cold storage and marketing conditions in 2012 and 2013 seasons. Pear fruits were kept at 0±1°C with 90-95% R.H for 90 days and 5 days after each storage period as marketing at room temperature. The results showed that the physiological effects of AVG and/or OA treatments in decreasing ethylene production were an important contributor to delaying the ripening process and reduced fruit decay incidence compared to the control. Besides, AVG+OA treatment was more effective in reduced respiration rate, showed slight browning and produced a lower fruit sugar. Weight loss percentage was significantly decreased with aminoethoxyvinylglycine (AVG) treatment alone, since, it was more effective to maintain fruit firmness at the end of the storage and preserve a higher green color. Furthermore, dipping fruits with oxalic acid (OA) alone decreased decay and total loss percentage after cold storage and 5 days during marketing. Since, hue angle values decreased in all treatments during cold storage.

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  How to cite this article:

M.E. Tarabih , 2014. Improving Storability of Le Conte Pear Fruit Using Aminoethoxyvinylglycine (AVG) and Oxalic Acid (OA) under Cold Storage Conditions. Asian Journal of Crop Science, 6: 320-333.

DOI: 10.3923/ajcs.2014.320.333

URL: https://scialert.net/abstract/?doi=ajcs.2014.320.333
 
Received: May 18, 2014; Accepted: July 01, 2014; Published: August 27, 2014



INTRODUCTION

Pear fruits (Pyrus communis L., CV. Le Conte) grown successfully under Egypt conditions and still need for further studies to improve the quality of the fruit. Fruit softening and other ethylene mediated processes are correlated with an increase in 1-Amino-Cyclopropane-Carboxylate (ACC) synthase (Tonutti et al., 1997). To extend the postharvest shelf life of climacteric fruit such as pears, ethylene synthesis or action must be inhibited to slow down the ripening processes. Inhibitors such as AVG and oxalic acid were used with success on produce such as apples, pears and bananas.

Aminoethoxyvinylglycine (AVG) is a vinylglycine analog with a chemical formula of [NH2-CH2-CH2-O-C=CH-CH-(NH2)-COOH]. Vinylglycine analogs are irreversible inhibitors of pyridoxal phosphate linked enzymes. It is the active ingredient of a commercial product known as ReTain® which containing 150 mg (AVG/g; Valent Bio Science Corp). Aminoethoxyvinylglycine (AVG) is an ethylene-biosynthesis inhibitor approved for field applications in pome fruit orchards. AVG delay fruit softening and prolong the postharvest life of apricots. This delay could allow additional time for transport and marketing and may reduce physical damage to the fruit. It is a human and environmentally friendly organic product registered for use for apple, pear, peach, plum and nectarine in several countries (Greene and Schupp, 2004; Rath and Prentice, 2004).

The mode of action of aminoethoxyvinylglycine (AVG) is the inhibition of ACC-synthase activity, when applied as a pre harvest spray, it inhibited ethylene production during fruit ripening by blocking the conversion of S-adenosylmethionine (SAM) to 1-aminocyclopropane-1-carboxylic acid (ACC). When applied as a postharvest dip treatment on peaches and nectarines, it reduced the rate of fruit softening (Garner et al., 2001).

Oxalic acid (OA) is an organic acid naturally occurring in plants and fungi and seems to play different roles in different living organisms. Recently, oxalic acid application for food preservation has received much attention, as it has been shown not only to be an anti-browning agent for harvested vegetables, banana slices (Yoruk et al., 2002), but also to be available as a natural antioxidant in the natural and artificial preservation of oxidized materials (Kayashima and Katayama, 2002). Tian et al. (2006) have reported that oxalic acid inhibited the progress of Alternaria rot in harvested pear fruit associated with an increase in defense related enzymes. The effect of oxalic acid could contribute to maintaining the membrane integrity and delaying the fruit ripening process.

The objective of this study was to examine the effect of aminoethoxyvinylglycine (AVG) and oxalic acid (OA) treatment each alone or in combination on delay ripening, keep firmness and reduce internal browning to improve Le Conte pear fruits life during cold storage and marketing as long as possible.

MATERIALS AND METHODS

Le Conte pear fruits picked from private orchard at EL-Khatatba city, Monifia, Governorate during 2012 and 2013 seasons, respectively from trees about seven years old grown in sandy soil and spaced at 5 m apart. The fruits were harvested at physiologically matured when the average of fruit firmness reached about 13-14 Ib inch-2 and soluble solids in fruits juice reached about 13-14% according to Swindeman (2002).

Fruits were harvested from trees expected common horticultural practices, undamaged and free from any obvious pathogen infection, then transported to the laboratory and washed thoroughly with tap water to remove undesirable particles from the surface. At the beginning of the experiment, samples of 15 fruits were taken to determine the initial fruits properties and then received the following treatments:

Treatments:

Dipping fruits in AVG 200 ppm for 5 min
Dipping fruits in oxalic acid 5 mM for 5 min
Dipping fruits in AVG 200 ppm+oxalic acid 5 mM for 5 min
Control (Dipping fruits in tap water) for 5 min

For storage study, fruits of all treatments were sorted to remove any infected and damaged ones and then stored in perforated plastic bags (each contains 5 fruits). All bags with fruits were weighted and every three bags were put in ventilated carton box. The boxes were stored 90 days at 0±1°C with 90-95% R.H, fruits for each treatment were taken 30 days intervals to determine fruits characteristics.

For shelf life study, after every cold storage period fruits for each treatment were held 5 days at room temperature conditions as shelf life at 28±2°C with 65-70% relative humidity to determine the following parameters:

Loss in fruit weight: It was determined according to the following equation:

Image for - Improving Storability of Le Conte Pear Fruit Using Aminoethoxyvinylglycine (AVG) and Oxalic Acid (OA) under Cold Storage Conditions

Decay: It was determined according to the following equation:

Image for - Improving Storability of Le Conte Pear Fruit Using Aminoethoxyvinylglycine (AVG) and Oxalic Acid (OA) under Cold Storage Conditions

 

Total loss in fruit (%): It was determined according to the following equation:

Total loss in fruit (%) = Loss weight (%)+Decayed fruits weight (%)

Respiration rate (mg CO2/kg/h): Carbon dioxide produced by pear fruits was determined according to AOAC (1970)
Skin hue color (h°): Skin color was measured using a hand-held colorimeter (CR-10; Minolta Co., Ltd., Osaka, Japan). Color changes from green to yellow were indicated by calculating the hue angle (h°), from (a*, b*) using the methods described by McGuire (1992)
Fruit firmness (Ib inch-2): It was determined on the two opposite sides of fruit using a hand Effegi-Penetrometers supplemented and the average was estimated as Ib inch-2
Internal browning (IB): For determination of Internal Browning (IB), five fruits were cut longitudinally and the area of the fruit flesh that was affected by a brown core was compared to the total area. The IB assessment was based on five stages, according to the browning area, as follows: No browning (0), slight browning (I, <30% of the area), moderate browning (II, about 30-70% of the area) and severe browning (III, >70% of the area, with only the cortex fraction just underneath the peel not showing browning). The browning index is the sum of the browning score of the five pears divided by 15 and multiplied by 100% and I, II and III refer to the number of pears in the various browning classes. A browning index value of 0% means no browning; 100% means maximal browning. Results were expressed as the browning index (%) calculated using the following equation (Veltman et al., 2000):

Browning index = [I+(2xII)+(3xIII)] 3(0+I+II+III)x100

Soluble solids content (SSC%): Soluble solids content in fruit juice was measured using a Carl-Zeiss hand refractometer according to AOAC (2005)
Titratable acidity (TA %): It was determined in 10 mL of fruit juice as a percentage of malic acid according to AOAC (2005)
SSC/acid ratio: It was calculated by dividing the value of SSC over the value of titratable acidity of each sample
Total sugar (%): The extract was prepared by taking 0.5 g of fresh pulp and extracting with 80% ethanol according to Ranganna (1979)

Statistical analysis: Data of both seasons of the study was analyzed using analysis of variance (ANOVA). Differences among treatment means were statistically compared using Duncan’s multiple tests at a level 0.05, using the CoStat V6.4 program.

RESULTS AND DISCUSSION

Loss in fruit weight percentage: The loss in weight of “Le Conte” pear fruits at cold storage and 5 days during shelf life are presented in Table 1. The data reveal that, the loss in fruit weight increased as storage period advanced under cold storage and at room temperature. Thus, all the applied treatments reduced the loss in fruit weight than the control. Since, the percent of loss in fruit weight of the untreated fruits were 3.22 and 3.44% after 90 days of cold storage and it was 4.69 and 4.93% after five days as marketing in both seasons, respectively. The lowest significant values of weight loss percentage were recorded by the application of AVG at 200 ppm ranged 2.0 and 2.28% after 90 days of cold storage and it were 3.0 and 3.70% after 5 days of marketing in the two seasons, respectively.

Table 1: Effect of AVG and oxalic acid on weight loss, decay and total loss percentage of Le Cont pear fruits during cold storage and under market conditions during 2012 and 2013 seasons
Image for - Improving Storability of Le Conte Pear Fruit Using Aminoethoxyvinylglycine (AVG) and Oxalic Acid (OA) under Cold Storage Conditions
Means followed by the same letters are not significantly different by Duncan’s multiple range test at 0.05 levels

The AVG can strongly inhibit the S-adenosylmethionine (SAM) to ACC conversion and therefore, can inhibit ethylene production, delay ripening and prolong fresh time of fruits (Capitani et al., 2002).

Zheng et al. (2007) showed that oxalic acid treatment delayed fruit ripening and reduced fruit decay incidence compared to the control. It was suggested that the physiological effect of oxalic acid in decreasing ethylene production was an important contributor to delaying the ripening process. Oxalic acid treatment might be a promising method for postharvest storage of mango fruits.

Decay percentage: It is clear from Table 1 that all treatments did not present any decayed fruits till 30 days of cold storage through both seasons. Since, all treatments significantly reduced the percent of decayed fruits than the untreated fruits either after 90 days of cold storage or 5 days during shelf life at room temperature in the both seasons. Thus, the percent of decayed fruits for the control were 7.05 and 7.85% after 90 days of cold storage, but it reached about 31.10 and 32.40% through marketing in both seasons. Yet, dipping “Le Conte” pear fruits in oxalic acid alone at 5 mM significantly reduced decay percentage than all treatments applied after 90 days of cold storage (3.55 and 3.73%) however it were 10.30 and 11.09% during marketing in both seasons, respectively.

AVG treatment significantly reduced decay development in European pears (CV ‘Camusina di Genova’ and ‘Camusina di Bonarcado’) mainly when it was applied at 250 mg L-1. This effect was related to the delay of ripen and to possible inhibition of ethylene production by the pathogens and/or infected tissues (D’Aquino et al., 2010).

Oxalic acid contributes to induce systemic resistance in plants and this may be due to both an increase in peroxidase (POD) activity and synthesis of new POD isoforms. Also, oxalic acid inhibited the progress of Alternaria rot in harvested pear fruit associated with an increase in defense related enzymes (Tian et al., 2006). Thus, the effect of oxalic acid in decreasing fruit decay incidence might be mainly attributed to the delay of fruit ripening. The application of oxalic acid has already been shown to induce systematic resistance against diseases caused by bacteria, fungi or viruses to affect antioxidant systems in plants (Malencic et al., 2004).

Total loss (%): Total loss in fruit weight is mainly due to loss in fruit weight and decay percentages are presented in Table 1. It is clear from Table 1 that dipping “Le Conte” pear fruits in oxalic acid alone at 5 mM significantly reduced the percentage of total loss in fruit weight in both seasons than the other treatments or the control. Since, oxalic acid application alone at 5 mM presented about 5.95 and 6.50% after 90 days of cold storage whereas, the loss percentage reached 13.70 and 15.14% after 5 days at room temperature in the two seasons, respectively.

Moreover, the percentage of total loss in fruit weight was gradually increased during cold storage or at shelf life as storage period advanced. Since, the percentage of total loss of the untreated fruits were about 10.27 and 11.29% after 90 days of cold storage but reached 35.79 and 37.33% when held 5 days at room temperature at the same period in the both seasons.

Guimaraes and Stotz (2004) investigated the mechanism by which OA affects host cells and tissues and found that guard cells treated accumulated potassium and broke down starch, both of which are known to contribute to stomata opening. In general, disease resistance in fruit decreases during ripening as physiological and biochemical changes increases fruit susceptibility to pathogen infection and the linkage between fruit ripening and increasing disease susceptibility is very strong. Thus, the effect of oxalic acid in decreasing fruit decay incidence might be mainly attributed to the delay of fruit ripening.

Respiration rate (mg CO2/kg/h): Results of Table 2 and Fig. 1 show that, all evaluated treatments succeeded in reducing respiration rate of “Le Cont” pear fruits during durations in comparison with the control treatment. Whereas, fruits dipping in AVG at 200 ppm+OA at 5 mM proved to be the most efficient treatment (20.50 and 19.20 mg CO2/kg/h) till 90 days under cold storage and (26.33 and 26.46 mg CO2/kg/h) 5 days during marketing in both seasons, respectively. On the other hand, the highest respiration rate were obtained by treatments of control (27.60 and 27.20 mg CO2/kg/h) till 90 days under cold storage and (33.23 and 34.70 mg CO2/kg/h) 5 days during marketing in both seasons, respectively.

Table 2: Effect of AVG and oxalic acid on respiration rate (mg CO2/kg/h), firmness (Ib inch-2) and internal browning (%) of Le Cont pear fruits during cold storage and under market conditions during 2012 and 2013 seasons
Image for - Improving Storability of Le Conte Pear Fruit Using Aminoethoxyvinylglycine (AVG) and Oxalic Acid (OA) under Cold Storage Conditions
Means followed by the same letters are not significantly different by Duncan’s multiple range test at 0.05 levels

Image for - Improving Storability of Le Conte Pear Fruit Using Aminoethoxyvinylglycine (AVG) and Oxalic Acid (OA) under Cold Storage Conditions
Fig. 1(a-b): Respiration rate percentage in Le Conte fruits after (a) 90 days of cold storage and (b) 5 days under marketing after each storage period as a mean of 2012-2013 seasons

Aminoethoxyvinylglycine (AVG) inhibits ethylene production during fruit ripening by blocking the conversion of S-adenosylmethionine (SAM) to 1-aminocyclopropane-1-carboxylic acid (ACC). This delay in fruit ripening was mainly due to an inhibition of ethylene biosynthesis, followed by reduced softening in flesh firmness.

In red delicious apple, Silverman et al. (2004) observed that AVG reduced ethylene production and starch degradation but had no significant effect on organic acids, color and sugar. It also reduced ethylene and protein biosynthesis and delayed fruit maturation in Cox’s Orange Pippin apples (Johnson and Colgan, 2003).

Zheng et al. (2007) proved that mango fruits dipped in 5 mM OA solution for 10 min showed lower ethylene production, lower incidence of decay and slowed the respiration of fruits, while increased the activities of antioxidant enzymes, maintained membrane integrity and delayed the fruit ripening process.

Firmness (lb inch-2): Fruit firmness testing is currently the main method used to determine pear maturity. Data from Table 2 and Fig. 2 show clearly that, fruit firmness was reduced as storage period advanced under cold storage or through shelf life at room temperature. The data also confirm that all treatments used significantly reduced changes in fruit firmness than the control at cold storage or during shelf life at room temperature through the two seasons. However, the reduction in fruit firmness was higher during shelf life at room temperature than under cold storage. Thus, fruit firmness for the control was 8.89 and 8.15 lb inch-2 after 90 days of cold storage, but it reached about 4.59 and 4.10 lb inch-2 through marketing in both seasons. Furthermore, treated fruits with AVG at 200 ppm alone maintained a higher fruit firmness (11.69 and 11.20 lb inch-2) after 90 days of cold storage while, reached 7.75 and 7.99 lb inch-2 from fruits held 5 days at room temperature of two seasons, respectively.

Application of AVG to stark red gold nectarines fruits delayed flesh softening. The delay in flesh softening caused by AVG could be one of the consequences of reduced ethylene production (Torrigiani et al., 2004). In ‘Bartlett’ pear, pre-harvest AVG treatments either 14 or 7 days before harvest did not affect ethylene production at harvest, but delayed changes in skin color, softening and starch content (Clayton et al., 2000). Arctic snow nectarines also exhibited delayed ripening, lower ethylene production and extended firmness after treatment with AVG (McGlasson et al., 2005). During fruit ripening, oxalate also plays important roles such as in the oxalate-soluble pectin which is related to firmness of banana (Emaga et al., 2008).

Image for - Improving Storability of Le Conte Pear Fruit Using Aminoethoxyvinylglycine (AVG) and Oxalic Acid (OA) under Cold Storage Conditions
Fig. 2(a-b):
Firmness (lb inch-2) in Le Conte fruits after (a) 90 days of cold storage and (b) 5 days under marketing after each storage period as a mean of 2012-2013 seasons

Image for - Improving Storability of Le Conte Pear Fruit Using Aminoethoxyvinylglycine (AVG) and Oxalic Acid (OA) under Cold Storage Conditions
Fig. 3(a-b):
Internal browning in Le Conte fruits after (a) 90 days of cold storage and (b) 5 days under marketing after each storage period as a mean of 2012-2013 seasons

Internal browning (%): The flesh browning index of all fruits increased after 3 months of storage plus 5 days of shelf life (Table 2 and Fig. 3). Pears treated by AVG+OA showed slight browning (2.90 and 2.30%) after 90 days of cold storage while, ranged 3.13 and 3.16% after 5 days at marketing in both seasons, respectively. On the other hand, the highest browning index was observed in control fruits, increasing to 7.60 and 7.90% at cold storage while ranged 8.53 and 8.56% after 5 days at marketing during both seasons, respectively.

Toal and Jones (1999) has reported that oxalic acid contributes to induced systemic resistance in plants and this may be due to both an increase in peroxidase (POD) activity and synthesis of new POD isoforms. Furthermore, oxalic acid is considered to be a natural anti-oxidant for artificial preservation of oxidized materials and under consideration to replace synthetic alternatives to minimize the risk of residues in bee products (Moosbeckhofer et al., 2003).

We observed from Fig. 1, 2 and 3 great relationship among the rate of respiration, firmness and internal browning of Le Conte pear fruits during cold storage and through marketing at room temperature, as soon as increasing the fruit respiration rate resulting decreases in fruits firmness and raising the internal browning. So, this association may be due to the effect of aminoethoxyvinylglycine (AVG) to inhibit ethylene production during fruit ripening by blocking the conversion of S-adenosylmethionine (SAM) to 1-aminocyclopropane-1-carboxylic acid (ACC). Also, oxalic acid led to increase peroxidase (POD) activity and synthesis of new POD isoforms which aid to delay ripening.

Soluble solids content (SSC%): Data from Table 3 showed that, the percent of SSC in fruit juice was gradually increased as storage periods advanced either a cold storage or during marketing in both seasons. Since, all treatments gave somewhat lower values of SSC in fruit juice than the control fruit which ranged 14.93 and 15.92% after 90 days of cold storage and it were 14.70 and 15.35% after five days as marketing in both seasons under the study. The data also disclose that, OA at 5 mM gave a somewhat increment in SSC values in fruit juice compared with other treatments conducted averaged 14.75 and 15.64% after 90 days of cold storage and it were 14.51 and 15.17% after five days as marketing in both seasons, respectively.

Pears is a climacteric fruits that tend to have increased SSC until maximum is reached at the fully ripe stage, followed by a decreasing trend when the fruits reaches full senescence (Xiao et al., 2011).

Zheng et al. (2007) found that mango fruits dipped in 5 mM oxalic acid L-1 for 10 min and stored at controlled atmospheres (6% CO2, 2% O2 and 14±1°C) were more firm and had lower total soluble solid contents, disease index and decay incidence compared with control. It was suggested that the effects of exogenous oxalic acid on the enhancement of antioxidant capacity helps to retardation of the ripening process and decrease in decay incidence during storage and that oxalic acid treatment is an alternative method for prolonging the storage life of mango fruits.

Titratable acidity (TA): From Table 3, it’s clear that the content of total acidity in fruit juice was decreased with the progress in storage period from harvest till 90 days at cold storage or during shelf life at room temperature, which may be attributed to the use of acids as substrate for respiration. The values of total acidity in fruit juice were almost lower during shelf life than those obtained at cold storage.

Significant differences began to appear at the end of cold storage. The highest value was obtained with AVG at 200 ppm in the first season (0.240) while untreated ones gave higher values of total acidity in the second season (0.260%) after 90 days of cold storage. Moreover, control treatment produced higher acidity after 5 days as marketing in the two seasons ranged 0.233 and 0.255%, respectively.

On the other hand, AVG treatment at 200 ppm gave lower acidity after 5 days as marketing in the two seasons ranged 0.229 and 248% respectively, but the reduction was unpronounced. Acidity is an important component of fruit flavor and in combination with SSC, contributes to overall quality. Total organic acid content declines in fruit as they mature, ripen and storage. However, fruit acidity should be considered in conjunction with other quality parameters, especially firmness and SSC as consumer studies show a strong relationship between the three (Harker et al., 2008). In addition, reduction in acidity during ripening may be due to their conversion into sugars and further utilization in the metabolic process of the fruit respiration (Abbasi et al., 2009). Softening of flesh, decreased acidity, increased carotenoid pigments among the recognized parameters of maturity and ripening in mango.

SSC/acid ratio: Considering to the effect on SSC/acid ratio, data in Table 3 reveal that the values of SSC/acid ratio were progressively increased by the storage period advanced from harvest till 90 days either at cold storage or during marketing at room temperature.

With regard to the effect of these treatments on SSC/acid ratio the data reveal that, control treatment produced a higher value of SSC/acid ratio at cold storage in the first season since the values averaged about 64.08 while, in the second one AVG at 200 ppm treatment presented higher value 62.04%.

Table 3: Effect of AVG and oxalic acid on SSC (%), acidity (%) and SSC/acid ratio (%) of Le Cont pear fruits during cold storage and under market conditions during 2012 and 2013 seasons
Image for - Improving Storability of Le Conte Pear Fruit Using Aminoethoxyvinylglycine (AVG) and Oxalic Acid (OA) under Cold Storage Conditions
Means followed by the same letters are not significantly different by Duncan’s multiple range test at 0.05 levels

Moreover, in the first season after 5 days during marketing AVG 200 ppm+OA at 5 mM treatment gave a higher value of SSC/acid ratio (63.23%) while, oxalic acid application alone produced higher value of this trend ranged 60.69% in the second seasons.

In the ripening fruits, the alcohol dehydrogenase (ADH), a main enzyme responsible for catalyzing the reduction of acetaldehyde to ethanol during the fermentation of sugars (glycolysis) plays an important role in the development of sugar compounds (Speirs et al., 2002). Exogenous OA application decreased ADH activity in jujube fruit during storage periods at 20°C (Wang et al., 2009).

Skin hue color (h°): From Table 4 data presented that all applied treatments delayed the development of fruits skin color when compared with the untreated fruit. The loss of the green color in pear skin was expressed as lower hue angle (h°). In control fruit, hue angle decreased rapidly during storage indicating a losing green color, either at cold storage (83.00 and 89.00 h°) or during shelf life (72.00 and 75.00 h°). Furthermore, green color in pear fruits decreased with storage period advanced during cold storage or under room temperature. Whereas, the values of green color during shelf life were almost lower than those obtained at cold storage during the both seasons of study.

Table 4: Effect of AVG and oxalic acid on sugar (%) and hue angle (h°) of pear fruits during cold storage and under market conditions during 2012 and 2013 seasons
Image for - Improving Storability of Le Conte Pear Fruit Using Aminoethoxyvinylglycine (AVG) and Oxalic Acid (OA) under Cold Storage Conditions
Means followed by the same letters are not significantly different by Duncan’s multiple range test at 0.05 levels

Moreover, AVG at 200 ppm maintained a higher green color than all treatments or thecontrol after 90 days of cold storage and 5 days during shelf life in both season, because the hue angle decreased slowly during all of the storage period.

The increment due using these treatment reached about 109.66 and 111.00 h° after 90 days of cold storage, respectively during both seasons. While, after 5 days during shelf life in the same period the values averaged 103.00 and 106.66 h° in both seasons, respectively. Maintaining the coloring of fruits increase its market values so, AVG generally delays ripening and undesirable color formation on fruit (Greene and Schupp, 2004; Rath and Prentice, 2004).

Total sugar: Concerning to the effect on total sugar, Data from Table 4 showed that total sugar content in fruit juice of “Le Conte” pear was gradually increased as storage period prolonged either after cold storage or during shelf life at room temperature.

Since, the untreated fruits produced higher significant values of total sugar in pear fruits than all treatments which ranged 11.34 and 11.80% after 90 days of cold storage and it were 10.44 and 10.83% after five days as marketing in both seasons under the study. The data also disclose that, application of AVG 200 ppm+OA at 5 mM presented lower values of total sugars compare to the applied treatments averaged 10.15 and 10.84% after 90 days of cold storage and it were 9.17 and 9.66% after five days as marketing in both seasons, respectively. Sugars are the most important constituent of fruit product and are essential factor for the flavor of the food product and also act as a natural food preservative.

In red delicious apple, Silverman et al. (2004) observed that AVG reduced ethylene production and starch degradation but had no significant effect on organic acids, color and sugar.

Guimaraes and Stotz (2004) investigated the mechanism by which OA affects host cells and tissues and found that guard cells treated with OA accumulated potassium and broke down starch, both of which are known to contribute to stomatal opening.

CONCLUSION

This study reveals that AVG and/or OA materials were relatively more effective in delaying respiration rate and ripening, since it play an integrated role in many of the biochemical changes occur during ripening such as, firmness, sugar, color and internal browning. Besides, AVG+OA were more effective on reduced respiration rate, showed slight browning and produced a lower fruit sugar. AVG considered a material with promising future in prolonging the storability of Le Conte pear fruits and maintaining the highest possible quality during marketing.

REFERENCES

1:  AOAC, 2005. Official Methods of Analysis. 16th Edn., AOAC, Washington, DC., USA

2:  Clayton, M., W.V. Biasi, S.M. Southwick and E.J. Mitcham, 2000. ReTainTM affects maturity and ripening of Bartlett pear. HortScience, 35: 1294-1299.
Direct Link  |  

3:  D'Aquino, S., M. Schirra, M.G. Molinu, M. Tedde and A. Palma, 2010. Preharvest aminoethoxyvinylglycine treatments reduce internal browning and prolong the shelf-life of early ripening pears. Sci. Hortic., 125: 353-360.
CrossRef  |  Direct Link  |  

4:  Garner, D., C.H. Crisosto and E. Otieza, 2001. Controlled atmosphere storage and aminoethoxyvinylglycine postharvest dip delay post cold storage softening of Snow King peach. HortTechnology, 11: 598-602.
Direct Link  |  

5:  Greene, D.W. and J.R. Schupp, 2004. Aminoethoxyvinylglycine (AVG) on preharvest drop, fruit quality and maturation of McIntosh apples. II. Effect of timing and concentration relationships and spray volume. HortScience, 39: 1036-1041.
Direct Link  |  

6:  Emaga, T.H., C. Robert, S.N. Ronkart, B. Wathelet and M. Paquot, 2008. Dietary fibre components and pectin chemical features of peels during ripening in banana and plantain varieties. Bioresour. Technol., 99: 4346-4354.
CrossRef  |  Direct Link  |  

7:  Harker, F.R., E.M. Kupferman, A.B. Marin, F.A. Gunson and C.M. Triggs, 2008. Eating quality standards for apples based on consumer preferences. Postharvest Biol. Technol., 50: 70-78.
CrossRef  |  

8:  Johnson, D.S. and R.J. Colgan, 2003. Low ethylene controlled atmosphere induces adverse effects on the quality of Cox's Orange Pippin apples treated with aminoethoxyvinylglycine during fruit development. Postharvest Biol. Technol., 27: 59-68.
CrossRef  |  Direct Link  |  

9:  Kayashima, T. and T. Katayama, 2002. Oxalic acid is available as a natural antioxidant in some systems. Biochimica Biophysica Acta, 1573: 1-3.
CrossRef  |  Direct Link  |  

10:  McGlasson, W.B., A.C. Rath and L. Legendre, 2005. Preharvest application of aminoethoxyvinylglycine (AVG) modifies harvest maturity and cool storage life of Arctic Snow nectarines. Postharvest Biol. Technol., 36: 93-102.
CrossRef  |  Direct Link  |  

11:  McGuire, R.G., 1992. Reporting of objective color measurements. HortScience, 27: 1254-1255.
CrossRef  |  Direct Link  |  

12:  Rath, A.C. and A.J. Prentice, 2004. Yield increase and higher flesh firmness of arctic snow nectaries both at harvest in Australia and after export to Taiwan following pre-harvest application of ReTain plant growth regulator (Aminoethoxyvinylglycine, AVG). Aust. J. Exp. Agric., 44: 343-351.

13:  Silverman, F.P., P.D. Petracek, M.R. Noll and P. Warrior, 2004. Aminoethoxyvinylglycine effects on late-season apple fruit maturation. Plant Growth Regul., 43: 153-161.
CrossRef  |  Direct Link  |  

14:  Swindeman, A.M., 2002. Fruit packing and storage loss prevention guidelines. Postharvest Information Network, Tree Fruit Research and Extension Center, USA., pp: 1-9. http://postharvest.tfrec.wsu.edu/REP2002D.pdf.

15:  Tian, S., Y. Wan, G. Qin and Y. Xu, 2006. Induction of defense responses against Alternaria rot by different elicitors in harvested pear fruit. Applied Microbiol. Biotechnol., 70: 729-734.
CrossRef  |  Direct Link  |  

16:  Toal, E.S. and P.W. Jones, 1999. Induction of systemic resistance to Sclerotinia sclerotiorum by oxalic acid in oilseed rape. Plant Pathol., 48: 759-767.
CrossRef  |  Direct Link  |  

17:  Tonutti, P., C. Bonghi, B. Ruperti, G.B. Tornielli and A. Ramina, 1997. Ethylene evolution and 1-aminocyclopropane-1-carboxylate oxidase gene expression during early development and ripening of peach fruit. J. Amer. Soc. Horticult. Sci., 122: 642-647.
Direct Link  |  

18:  Torrigiani, P., A.M. Bregoli, V. Ziosi, S. Scaramagli and T. Ciriaci et al., 2004. Pre-harvest polyamine and aminoethoxyvinylglycine (AVG) applications modulate fruit ripening in Stark Red Gold nectarines (Prunus persica L. Batsch). Postharv. Biol. Tech., 33: 293-308.
CrossRef  |  Direct Link  |  

19:  Veltman, R.H., R.M. Kho, A.C.R. van Schaik, M.G. Sanders and J. Oosterhaven, 2000. Ascorbic acid and tissue browning in pears (Pyrus communis L. cvs Rocha and Conference) under controlled atmosphere conditions. Postharvest Biol. Technol., 19: 129-137.
CrossRef  |  

20:  Wang, Q., T. Lai, G. Qin and S. Tian, 2009. Response of jujube fruits to exogenous oxalic acid treatment based on proteomic analysis. Plant Cell Physiol., 50: 230-242.
CrossRef  |  Direct Link  |  

21:  Yoruk, R., M.O. Balaban, M.R. Marshall and S. Yoruk, 2002. The inhibitory effect of oxalic acid on browning of banana slices. Proceedings of the IFT Annual Meeting on Food Expo, June 15-19, 2002, Anaheim, California, USA., pp: 74-

22:  Zheng, X., S. Tian, M.J. Gidley, H. Yue and B. Li, 2007. Effects of exogenous oxalic acid on ripening and decay incidence in mango fruit during storage at room temperature. Posthar. Biol. Technol., 45: 281-284.
Direct Link  |  

23:  Capitani, G., D.L. McCarthy, H. Gut, M.G. Grutter and J.F. Kirsch, 2002. Apple 1-Aminocyclopropane-1-carboxylate synthase in complex with the inhibitor l-aminoethoxyvinylglycine. Evidence for a ketimine intermediate. J. Biol. Chem., 227: 49735-49742.
CrossRef  |  PubMed  |  Direct Link  |  

24:  Malencic, D.J., D. Vasic, M. Popovic and D. Devic, 2004. Antioxidant systems in sunflower as affected by oxalic acid. Biol. Plant., 48: 243-247.
CrossRef  |  Direct Link  |  

25:  Moosbeckhofer, R., H. Pechhacker, H. Unterweger, F. Bandion and A. Heinrich-Lenz, 2003. Investigations on the oxalic acid content of honey from oxalic acid treated and untreated bee colonies. Eur. Food Res. Technol., 217: 49-52.
CrossRef  |  Direct Link  |  

26:  Speirs, J., R. Correll and P. Cain, 2002. Relationship between ADH activity, ripeness and softness in six tomato cultivars. Sci. Horticult., 93: 137-142.
CrossRef  |  Direct Link  |  

27:  Abbasi, N.A., Z. Iqbal, M. Maqbool and I.A. Hafiz, 2009. Postharvest quality of mango (Mangifera indica L.) fruit as affected by chitosan coating. Pak. J. Bot., 41: 343-357.
Direct Link  |  

28:  AOAC., 1970. Official Methods of Analysis. 10th Edn., Association of Official Analytical Chemists, Washington, DC., USA

29:  Ranganna, S., 1979. Manual of Analysis of Fruit and Vegetables Produts. 2nd Edn., Tata MeGraw-Hill Publ. Co. Ltd., New Delhi, India, Pages: 634

30:  Guimaraes, R.L. and H.U. Stotz, 2004. Oxalate production by Sclerotinia sclerotiorum deregulates guard cells during infection. Plant Physiol., 136: 3703-3711.
CrossRef  |  Direct Link  |  

31:  Xiao, Z., Y. Luo, Y. Luo and Q. Wang, 2011. Combined effects of sodium chlorite dip treatment and chitosan coatings on the quality of fresh-cut d'Anjou pears. Postharvest Biol. Technol., 62: 319-326.
CrossRef  |  Direct Link  |  

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