Postharvest Dip Research Articles

Effect of calcium propionate dip and spray applications on botrytis blight of ornamental plants

The use of conventional fungicides to control botrytis blight of ornamentals caused by Botrytis cinerea has its limitations due to increasing resistance to site-specific fungicides. Calcium propionate (CaP) has suppressive action against this disease and resistance in B. cinerea to CaP has not been reported. This study evaluated the efficacy of postharvest dip applications of 0.1% CaP (pH 6.0) to control botrytis blight in four cut rose (Rosa ×hybrida) cultivars and analyzed gene expression of CaP-treated rose petals. CaP reduced botrytis blight symptoms in rose ‘Alive’ but not in ‘Freedom’, ‘Momentum’, and ‘Orange Crush’, and no change in gene expression in ‘Orange Crush’ was detected following CaP treatment. Aerial spray applications at 0.1%, 0.2%, 0.3%, 0.4%, and 0.5% CaP made twice a week for 5 weeks caused minimal phytotoxicity damage to calendula (Calendula officinalis), carnation (Dianthus sp), dahlia (Dahlia sp), pansy (Viola ×wittrockiana), and snapdragon (Antirrhinum majus) leaves; however, CaP spray applications generated residues at all CaP concentrations in all species except for dahlia where no residue was observed. The results suggest that CaP will suppress botrytis blight in some but not all rose cultivars and establish a reference for phytotoxicity symptoms and visible CaP residues on ornamental plants.

Pre- and Post-harvest Elicitation with Methyl Jasmonate and Salicylic Acid Followed by Cold Storage Synergistically Improves Red Colour Development and Health-Promoting Compounds in Blood Oranges

Red blush is one of the key quality markers of blood orange fruit (Citrus sinensis L. Osbeck). Therefore, the influence of pre- (1, 2, and 3 mM) and postharvest (0.5, 1, and 1.5 mM) methyl jasmonate (MeJA) and salicylic acid (SA) (1, 2, and 3 mM) treatments on redness, colouring pigments, and health-promoting compounds in cold stored ‘Tarocco Ippolito’ blood oranges was investigated. Preharvest application of 3 mM MeJA significantly increased rind citrus colour index (CCI) by 43.3% and colorimetric coordinate a* (redness) by 3.1% and decreased h° (hue angle, 0 = red), L* (lightness), and b* (yellowness) by 13.7%, 12.6%, and 23.4%, respectively. This treatment also enhanced CCI (57.4%), reduced h° (16.5%) and L* (36.4%), and increased total anthocyanins (88%), monomeric anthocyanins (117%), and flavonoids (77%) in the juice. Postharvest dip of 1.5 mM MeJA (5 min) improved CCI of juice (53.6%) and a* (5.5%), reduced h° (15.9%), L* (19.8%), and b* (19.4%), and increased total anthocyanins (66.7%), monomeric anthocyanins (74%), and flavonoids (23.4%) in the juice. Preharvest application of 1 mM SA increased rind CCI (50.8%) and reduced L* (13.6%), b* (16.4%), and h° (29.5%). All preharvest SA treatments significantly increased total phenolics in the juice. Lycopene was increased (61.7%) by 5 min postharvest dip of 3 mM SA. In conclusion, 3 mM preharvest spray application of MeJA four weeks before harvest and postharvest dip of 1.5 mM MeJA (5 min) are effective in improving red colour of rind and juice and health-promoting compounds in blood orange juice.

The potential of postharvest zinc treatment for preservation of pomegranate aril quality

A short shelf life usually limits the distribution and supply of pomegranate arils. Since zinc (Zn) has an indispensable role in the nutrient integrity of our diet and is effective in suppressing pathogens, this study was done as two separate experiments of pre-harvest spraying and postharvest dipping of arils with two zinc supplements, including nano zinc oxide (nZnO) and zinc sulfate (ZnSO4). The optimized concentration of both sources was used in the experiment. The pre-harvest treatment failed to extend the shelf life of arils, and, ultimately, the arils decayed after 15 days. However, the postharvest zinc treatment significantly (P < 0.01) affected all measured indices. Also, zinc sulfate was more effective than nZnO. Zn uptake was higher in postharvest treatments because exogenous Zn was in direct contact with the aril surface. After dissolving in water, Zn ions in sulfate bind to the membrane of microorganisms and thus delay cell division and microbial growth cycle. The solubility of zinc oxide nanoparticles in water is poor. Using the ZnSO4 treatment (0.8%W/V) effectively maintained the values of titratable acidity (TA), total phenolic content (TPC), total soluble solids (TSS), anthocyanin content, and antioxidant activity. Also, this treatment significantly controlled weight loss in the arils.

Potassium Spraying Preharvest and Nanocoating Postharvest Improve the Quality and Extend the Storage Period for Acid Lime (Citrus aurantifolia Swingle) Fruits.

Citrus fruits are one of the most abundant crops globally in more than 140 countries throughout the world. Acid lime (Citrus aurantifolia swingle) is one of the citrus fruits which popularly has rich nutritional and therapeutic features. The storage period is the important factor that affects the economic and quality properties of this fruit. This study aims to demonstrate the enhancing effect of preharvest spraying with potassium, in addition to the postharvest dipping of fruits in some edible coatings, on the quality and storability of acid lime fruits. Preharvest spraying with organic and mineral forms of potassium, namely, potassium thiosulfate 1.75 g/L (S) and potassium tartrate 2 g/L (T), were carried out at three different times, in May, June, and July. On the other hand, postharvest treatments were carried out via dipping fruits in different types of biopolymers (carboxymethyl cellulose (E2) and gum arabic (E3)) and carboxymethyl cellulose/gum arabic composite (E4) as well as nanocoating formulation based on both biopolymers and doped zinc oxide nanoparticles (ZnONPs) (E1), which were prepared via acid lime peel waste extract. Herein, the physiochemical and morphological characterizations confirmed that the nanocoating was prepared at the nanoscale and doped with green synthesis ZnONPs, with recorded sizes of around 80 and 20 nm, respectively. Preharvest spraying with potassium tartrate enhanced fruit traits (Spraying with potassium tartrate at pre-harvest and nanocoating dipping at post-harvest (TE1), spraying with potassium tartrate at pre-harvest and carboxy methyl cellulose dipping at post-harvest (TE2), spraying with potassium tartrate at pre-harvest and gum arabic dipping at post-harvest (TE3) and spraying with potassium tartrate at pre-harvest and carboxymethyl cellulose/gum arabic composite dipping at post-harvest (TE4)), followed by potassium thiosulfate (spraying with potassium thiosulfate at pre-harvest and nanocoating dipping at post-harvest (SE1), spraying with potassium thiosulfate at pre-harvest and carboxy methyl cellulose dipping at post-harvest (SE2), spraying with potassium thiosulfate at pre-harvest and gum arabic dipping at post-harvest (SE3) and spraying with potassium thiosulfate at pre-harvest and carboxymethyl cellulose/gum arabic dipping at post-harvest (SE4)), compared to control. For postharvest treatments, E1 improved fruit quality, followed by E2, E4, and E3, respectively. The integration between pre- and postharvest treatments showed a clear superiority of TE2, followed by TE4, SE1, and SE2, respectively.

Postharvest melatonin and chitosan treatments retain quality of 'Williams' bananas during ripening.

The effect of postharvest dipping treatments with 0.5mM melatonin (MT) and 1% chitosan (CT) either alone or in combination on quality of pre-climacteric 'Williams' bananas during ripening at ambient conditions were investigated. MT or CT treatments delayed ripening by retaining greener peel, higher firmness, titratable acidity (TA), but lower total soluble solids (TSS) and TSS/TA, weight loss, browning and electrolyte leakage than the control. Total phenol (TPC) and flavonoid contents (TFC) in both peel and pulp increased up to 6days and then decreased and was higher in treated fruit than the control. Vitamin C content decreased up to 3days, then increased and was higher in treated fruit than control. MT and CT combination exhibited the highest TPC, TFC and vitamin C contents compared to other treatments. Radical scavenging capacity (RSC) of peel and pulp increased up to 6days, then decreased and was higher in treated fruit than the control. The treated fruit exhibited lower polyphenoloxidase (PPO) and hydrolytic enzymes but higher peroxidase (POD) activities in both peel and pulp than the control. Postharvest treatments with 0.5mM MT and 1% CT alone or in combination could be used to retain quality of 'Williams' bananas during ripening.

Post-harvest melatonin application reduced browning in minimally processed lettuce (Lactuca sativa L.) during low temperature storage

The investigation was carried out to assess the effect of post-harvest dipping of minimally processed fresh cut lettuce with various concentrations (10, 100 and 1000 μmolL-1) of melatonin on shelf-life and sensory quality of lettuce stored at 6±2ºC for 8 days. Melatonin treatment was found effective in maintaining freshness and sensory quality of lettuce during storage. Browning was reduced by 45% and visual quality index increased by 44.10% compared to control in 100 μmol L-1 melatonin treated samples on the 6th day of storage. Maximum total chlorophyll, total phenol and total antioxidants and least activity of browning related enzyme i.e., peroxidase (POD) was observed in 100 μmol L-1 melatonin treated samples during storage. No significant variation was observed between 10 μmol L-1 melatonin treated and control samples. Browning index value had significant negative correlation with total chlorophyll, total phenol and total antioxidants whereas POD activity had significant positive correlation. It can be inferred from the present investigation that post-harvest treatment of 100 μmol L-1 melatonin extended shelf-life of minimally processed lettuce for 6 days by preserving phenols, chlorophyll, antioxidants and inhibiting POD activity.

Maintenance of postharvest storability and overall quality of 'Jinshayou' pummelo fruit by salicylic acid treatment.

The loss of postharvest storability of pummelo fruit reduces its commodity value for long run. To maintain its storability, the effects of postharvest dipping treatment by salicylic acid (SA) with different concentrations (0, 0.1, 0.2, or 0.3%) were investigated on pummelo fruit (Citrus maxima Merr. cv. Jinshayou) during the room temperature storage at 20 ± 2°C for 90d. Among all treatments, pre-storage SA treatment at 0.3% demonstrated the most significant ability to reduce fruit decay incidence, decrease weight loss, delay peel color-turned process, and inhibit the declines in total soluble solids (TSS) as well as titratable acid (TA) content. The increases in electrolyte leakage, hydrogen peroxide (H2O2), and malondialdehyde (MDA) content of the 0.3% SA-treated pummelo fruit were reduced compared to the control (dipped in distilled water). Pummelo fruit treated with 0.3% SA exhibited the most outstanding ability to excess reactive oxygen species (ROS) accumulation, as evidenced by promoted the increases in glutathione (GSH), total phenolics and flavonoids contents, delayed the AsA decline, and enhanced the activities of antioxidant enzymes and their encoding genes expression. Pre-storage treatment dipped with SA, particularly at 0.3%, can be used as a useful and safe preservation method to maintain higher postharvest storability and better overall quality of 'Jinshayou' pummelo fruit, and thus delaying postharvest senescence and extend the storage life up to 90d at room temperature.

Effect of Silver Nitrate (AgNO3) and Nano-Silver (Ag-NPs) on Physiological Characteristics of Grapes and Quality during Storage Period

The aim of this study was to evaluate the effects of silver nitrate (AgNO3) and nano-silver (Ag-NPs) on the physiological and biochemical characteristics, and quality of grape bunches during a cold storage period. For investigations, two varieties of grapes were used, Shine Muscat and Kyoho, with different concentrations of AgNO3 and Ag-NPs on post-harvest dipping. The data indicated that AgNO3 and Ag-NPs enhanced the fruits’ longevity and quality. Depending on the data analysis, it was found that the lowest weight loss value was obtained from Ag-NP treated grapes, followed by AgNO3 treated grapes, while the highest loss occurred in the control grapes. Immersion of grape bunches in Ag-NPs was the best application for maintenance of overall storage quality for both cultivars. In the same trend, treatment with Ag-NPs produced the best results for soluble solids content (SSC), titratable acidity (TA), malondialdehyde (MDA) content, polyphenol oxidase (PPO), pyrogallol peroxidase (POD), and pectin methylestraese activity (PME). It was concluded that Ag-NPs and AgNO3 were helpful in maintaining the quality of grape bunches up to 30 days, while grape bunches under control conditions were spoiled with 30 days of cold storage.

Improving the quality of ‘Keitt’ Mango using pre-harvest calcium lactate treatment and post-harvest applications of kojic and ascorbic acids

ABSTRACT This study intended to enhance fruit quality, extend shelf life and maintain quality of ‘Keitt’ mango (Mangifera indica L.) by using edible compounds without affecting quality or taste. Pre-harvest foliar treatment using calcium lactate (CaL) was applied at 1 and 2% alone or in combination with one of the post-harvest dipping treatments of 2% ascorbic acid (AsA) or 0.3% kojic acid (KA), before storage at 4°C for 12 days during two successive seasons. Pre-harvest treatment with calcium lactate at 2% significantly enhanced the quality of ‘Keitt’ mango fruits at harvest. It was observed that all the conducted treatments were effective in maintaining the quality of the pre-prepared ‘Keitt’ mango as compared to the untreated ones. Pre-harvest application of 2% CaL + post-harvest 2% AsA was the most effective treatment under experimental conditions in terms of total phenols, ascorbic acid, TSS/acid ratio, overall appearance, colour purity, browning incidence, and decay percentage. CaL at 2% showed the lowest significant values of CPLW and it maintained the highest significant firmness compared with control.

Hexanal application reduces postharvest losses of mango (Mangifera indica L. variety "Kent") over cold storage whilst maintaining fruit quality

Mango (Mangifera indica L.) is a widespread crop that is affected by many factors that promote deterioration and limit its shelf life. This study aims to evaluate the effect of hexanal treatment and cold storage conditions on mango quality and postharvest losses. Mangoes var "Kent" were harvested from a commercial orchard located in Korhogo in the northern area of Ivory Coast. The fruit was then dipped in an aqueous hexanal formulation and stored at a cold temperature (13 ºC) before ripening at laboratory temperature (30 °C). Their quality was assessed during storage and after ripening. The results showed that hexanal reduced postharvest losses by 22.85% and spoilage by 12% after four weeks of cold storage. Furthermore, the results revealed that hexanal treatment increased fruit firmness and ascorbic acid content compared to control fruit. However, there was no difference in soluble solids content, titratable acidity, pH, dry matter, and colour between treated and control fruit. Sensory analysis showed that hexanal treatment improved some sensory descriptors such as overall likeability, chewiness, sweetness, and colour of the mango flesh. Therefore, our study suggests that postharvest dipping of mangoes in the hexanal solution, combined with cold storage conditions, extends the shelf life of the fruit while maintaining or even improving its organoleptic features.

Using Biological Elicitation to Improve Type 2 Diabetes Targeted Food Quality of Stored Apple

Food quality improvements of fresh fruits targeting both food preservation and human health is essential to advance healthy dietary options and to mitigate imbalanced nutrition-linked non-communicable chronic disease (NCDs) challenges globally. Specifically, protective phenolic bioactives of fruits with dual functional benefits can be harnessed to advance innovations for improving nutritional quality and post-harvest shelf-life of perishable fruits. Based on this rationale the dual functional benefits of plant phenolics were harnessed using novel biological elicitation strategies to modulate phenolic bioactive-linked protective responses in apple during storage in two interrelated studies. Bioprocessed food-grade elicitors [water soluble chitosan oligosaccharide -(COS) and phenolic enriched oregano extracts-(OX)] were targeted as post-harvest dipping treatments (2 &amp;amp; 4 g/ L) and compared with diphenylamine (DPA) (1 &amp;amp; 2 g/L) to enhance phenolic-linked antioxidant and anti-diabetic (type 2 diabetes) relevant properties of Cortland apple during 3 months of storage (4°C). The selection of bio-elicitors and respective doses were based on the foundations of the previous related study, which resulted in reduction of superficial scald of Cortland apple during storage. Apples sampled over 3 months as aqueous and ethanol (12%) extracts of peel and pulp were analyzed separately for total soluble phenolic content, phenolic profile, antioxidant activity, and glucose metabolism relevant α-amylase and α-glucosidase enzyme inhibitory activities using in vitro assay models. Enhanced soluble phenolic content and associated antioxidant activity were observed in ethanol (12%) extracts of apple peel with 4 g/L COS elicitor treatments after 2 and 3 months of storage. High chlorogenic acid and quercetin derivatives were found in peel extracts of Cortland apple, while pulp extracts had high chlorogenic and gallic acids. Additionally, high α-glucosidase enzyme inhibitory activity, which is relevant for managing post-prandial hyperglycemia of type 2 diabetes was also observed in bio-elicited apple peel and pulp extracts. Therefore, results of these two interrelated studies indicate that bioprocessed food grade elicitor such as OX and COS can be recruited as a novel tool to enhance protective phenolic responses for improving type 2 diabetes targeted food quality and post-harvest storage quality of apple.

​Effect of Different Post-harvest Treatments of Fungicides, Botanical Oils, Food Preservatives and Packaging on Black Mould Fruit Rot of Pomegranate

Background: Pomegranate is an important favourite fruit of tropical, subtropical and arid regions. In India, it is grown in almost all the states but a commercial orchard exists in Maharashtra and Gujarat. Some pathogens only attack the fruit from the inside, while the external surface of the fruit remains asymptomatic. Diseased fruit display poor shelf life and flavour quality attributes. Changes include losses in sugars, acids, characteristic aroma and development of off flavours. Therefore, identifying and quick characterization of these disease symptoms is paramount to their effective control and management. Since there is a lack of research work on pomegranate black mould fruit rot diseases caused by Aspergillus niger. Realizing the gaps concerns the environmental factors affecting the prevalence of disease development and management of disease, the present investigation was undertaken with the objective: Management of post-harvest black mould fruit rot diseases of pomegranate by different methods. Methods: The experiments were carried out at Division of Horticulture, UAS, GKVK, Bengaluru by using the variety Bhagwa with 11 treatments which are replicated four times in Completely Randomized Design (CRD). Different chemical, physical methods, food preservatives and packaging were used to control the black mould fruit rot. Result: The epidemiological studies revealed that injury to the pomegranate fruits was found to be a prerequisite for infection. All the fruits inoculated by cork-wounding, pin-pricking, scrapping and rubbing method exhibited symptoms of rot. Cork-wounding proved to be the most efficient method of inoculation. Post-harvest dipping in hot water, fungicides, oils and food preservatives provided effective control of the rot. Oil suspensions were found effective in preventing the rot. Food preservatives were also found effective in preventing rot, potassium metabisulphite (KMS) 0.5 percent followed by sodium benzoate 0.5 percent proved most effective against the rot in both pre-and post-inoculation treatments. Packaging for postharvest storage showed very good performance in maintaining the quality of pomegranate fruits up to 12 weeks.

PROLONGING THE SHELF LIFE AND MAINTAINING FRUIT QUALITY OF NAOMI MANGO CULTIVAR

Mango fruits being climacteric have a short shelf life; and post-harvest dipping is considered as one of the most popular techniques to prolong its shelf life dipping based on starch, olive oil, beeswax and sodium benzoate have been evaluated with reference to the shelf life and quality of mango Naomi cultivar fruit harvested at full stage of maturity. The dipped and undipped (control) fruits were stored on the lab’s tables in the room conditions (25±5 &lt;C and 65-70% R.H.), samples of each treatment were randomly taken every 4 days to evaluate after harvest dipping treatments effect during shelf life of fruits. Results indicated that every dipping treatment has a significant impact on the quality and shelf life of the fruit. The beeswax and olive oil treated mango fruits had the longest shelf life with good quality, while the shelf life of untreated (control) fruit was the shortest. The total soluble solids and sugar contents were also high in starch-treated fruit. The overall data conclude that beeswax was the best post-harvest dipping material, which might be due to the fact that beeswax is an antioxidant and antimicrobial as well as hydrophobic in nature.

Efficacy of postharvest sodium nitroprusside application to extend storability by regulating physico-chemical quality of pear fruit

Quality loss in pear fruit during storage reduces its marketability for long run. To increase its storability, the efficacy of postharvest dip treatment donor sodium nitroprusside (SNP) 0.000, 0.001, 0.002 and 0.003 mol L−1 were investigated on pear fruit cv. Patharnakh under storage conditions (low temperature 0–1 °C and relative humidity (90–95%). SNP effectively lowered fruit mass loss, retained colour and higher firmness, suppressed browning and respiration rate and sustained soluble solids content, titratable acidity, total phenol content and ascorbic acid thus conserved the fruit quality for longer period. SNP treatments suppressed the activity of polyphenol oxidase and increased activity of superoxide dismutase enzyme. Additionally, the SNP treated fruit exhibited lesser activities of fruit softening enzymes like pectin methylesterase, polygalacturonase and cellulase. Among all, 0.002 mol L−1 SNP concentration was superior to lengthen storability and sensory quality of pear up to 60 d under cold storage.

Postharvest Dip Application of Putrescine and Salicylic Acid Delayed Postharvest Quality Deterioration and Extended the Storage Life of Lime (Citrus Aurantifolia Swingle) Fruit

ABSTRACT Potential of putrescine (PUT) and salicylic acid (SA) as postharvest dip treatments on maintaining quality and extending the shelf life of lime (Citrus aurantifolia Swingle) fruit cv. Local was investigated. Fruit harvested at commercially mature stage were dipped in different concentrations of PUT (0.5, 1.0, and 1.5 mmolL−1), SA (1.0, 2.0, and 3.0 mmolL−1), and control (0.0 mmolL-1) for 15 minutes and stored in cold room (13 ± 1°C, 90 ± 5% RH). Evaluation of peel color (L*, a*, b*), total chlorophyll content (TCC), TSS, TA, physiological weight loss (PWL), visual quality, and decay incidence were carried out at 0 day (before treatment) and at 14, 28, 42–56 days of storage. Out of two reagents examined, PUT showed promising effect compared to SA on maintaining quality and extending the postharvest life of lime cv. Local during cold storage (13 ± 1°C, 90 ± 5% RH). The lowest dose of PUT (0.5 mmolL−1) and the middle dose of SA (2 mmolL−1) effectively suppressed the degradation of peel color, retarded the rate of deterioration of TSS and TCC while reducing the rate of increase in PWL. The lowest concentrations of both PUT (0.5 mmolL−1) and SA (1.0 mmolL−1) exhibited higher efficacy in preventing the deterioration of TA. In conclusion, exogenous treatment of PUT at the dose of 0.5 mmolL−1or SA at the concentration of 2 mmolL−1for 15 min could be recommended as an effective tool for maintaining quality and extending the shelf life of lime cv. Local.

Post-harvest dip of enhanced freshness formulation (EFF) to extend the shelf-life of Sapota (Achras sapota Mill.) Cv. PKM-1

Post-harvest dip of enhanced freshness formulation (EFF) to extend the shelf-life of Sapota (Achras sapota Mill.) Cv. PKM-1

Effect of Packaging and Coating Technique on Postharvest Quality and Shelf Life of Raphanus sativus L. and Hibiscus sabdariffa L. Microgreens.

Microgreens are highly respiring produce characterized by a relatively short shelf-life. In this study, the efficacy of two types of macro-perforated packaging, PET clamshell (PET–CS) and LDPE self-seal bag (LDPE–SSB), was assessed on the postharvest quality and shelf life of radish (RaS) and roselle (HbS) microgreens stored at 5 °C. Pre-harvest spray treatment (AGSC) was compared with postharvest dip coating (AGDC) using Aloe vera gel (AG) for the first time in microgreens for postharvest quality improvement. PET–CS had a lower physiological loss in weight (PLW), respiration rate (RR), electrolyte leakage (EL), microbial counts (MCs), and higher overall acceptability (OA) than LDPE–SSB. AG-coated microgreens had significantly (p ≤ 0.05) lesser deteriorative postharvest changes and higher ascorbic acid content than uncoated control. AGSC maintained better OA and postharvest quality than AGDC, especially at the end of the study period in terms of reducing EL, retaining greenness (−a*), and chroma value in HbS microgreens. In RaS microgreens, AGSC helped to maintain lower PLW, MC, and higher ascorbic acid levels. AGSC could be suggested as an eco-friendly ergonomic pre-harvest treatment along with PET–CS for enhancement of postharvest quality and shelf life in RaS and HbS microgreens, with a tremendous potential to be extended to other microgreens.

Physiological responses of Indian jujube (Ziziphus mauritiana Lam.) fruit after postharvest hot water dipping

Physiological responses of Indian jujube (Ziziphus mauritiana Lam.) fruit after postharvest hot water dipping

Putrescine application reduces softening and maintains the quality of pear fruit during cold storage

To enhance the storage potential of pear cv. Punjab Beauty fruit, the effect of putrescine (PUT) treatments was evaluated by analysing various physico-chemical characteristics and enzymatic activities. Postharvest dip treatments of PUT (1, 2 and 3 mM) were given to uniform and healthy fruit, while tap water was used for the control fruit. Treated fruit were stored at 0–1 °C and 90–95% RH for 75 days. Evaluation of fruit quality parameters was made on the 0th, 15th, 30th, 45th, 60th, 67th and 75th days of storage. The PUT treatments (2 and 3 mM) proved to be effective to diminish the softening and enhance the storage potential with acceptable quality. These treatments also suppressed the pectin methyl esterase and cellulase activity, reduced the weight loss and spoilage compared with control. Moreover, 2 and 3 mM PUT applications delayed colour changes, retained higher soluble solids content, starch content and titratable acidity at the end of storage than in control. These findings suggested that exogenous PUT application of 2 and 3 mM could effectively maintain fruit quality and prolong the storage potential of pear cv. Punjab Beauty fruit by reducing the softening during storage.

Chitosan oligosaccharides induced chilling resistance in cucumber fruit and associated stimulation of antioxidant and HSP gene expression

Cucumber (Cucumis sativus L.) fruit is susceptible to chilling injury. The effect of postharvest dipping of cucumber fruit in 1 % chitosan oligosaccharides (COS) solution was examined for its inhibition of chilling symptoms and effects on biochemical and molecular factors associated with chilling injury. Results showed that COS treatment of cucumbers before cold storage at 4 °C reduced pitting and decay, suppressed membrane lipid oxidation, and increased expression of SOD, GR, APX, CAT, HSP45.9 and HSP70 genes. In view of the critical role of antioxidant system and HSPs in protecting plants from stress induced damage, we suggest that the stimulation of antioxidant and HSP gene expression by COS contributed to enhanced chilling tolerance in cucumbers.