Physiological responses and quality attributes of table grape fruit to chitosan preharvest spray and postharvest coating during storage

The effects of preharvest chitosan spray (PCS) or/and postharvest chitosan coating (PCC) treatments on the quality and physiological response of table grape fruit stored at 20 or 0 °C was evaluated, respectively. PCS/PCC treatment showed the best control effect on decay. PCC or PCS/PCC treatment significantly decreased the weight loss of fruit stored at 20 °C. Additionally, all chitosan treatments inhibited the increase in rate of soluble solid content to titratable acid in fruit, stored at 20 °C, while enhancing the rate at 0 °C and affecting the content of total phenolic compounds in the fruit. Furthermore, the activities of superoxide dismutase decreased in all chitosan treatments and PCS or/and PCC treatments also changed the activities of polyphenol oxidase, peroxidase and phenylalanine ammonia-lyase. The results indicated the beneficial effect of chitosan by preharvest spray and/or postharvest coating on fruit quality and resistance to fruit decay.     

Effects of preharvest application of antagonistic yeast combined with chitosan on decay and quality of harvested table grape fruit

BACKGROUND: Decay caused by fungal pathogens is responsible for significant economic loss of grape fruit in vineyards worldwide. However, postharvest treatment is not advisable for this fruit owing to its thin waxy pericarp and succulent flesh, which are easily damaged. Therefore preharvest treatment even at 1 day before harvest has been considered as a promising method to control postharvest decay of table grape fruit in storage. Integrative effects of preharvest application of Cryptococcus laurentii combined with low‐concentration chitosan on decay and quality of table grape fruit during storage were investigated in this study. RESULTS: Spraying of antagonistic yeast combined with chitosan before harvest significantly reduced natural decay of fruit stored at 0 °C. Preharvest treatment stabilised polyphenol oxidase activity, increased peroxidase and phenylalanine ammonia‐lyase activities and decreased superoxide dismutase activity compared with control fruit. There was a higher ratio of soluble solid content to titratable acidity in treated fruit than in control fruit during storage. In addition, preharvest treatment affected the total phenolic content in fruit during storage. CONCLUSION: The results suggest that integrative application of C. laurentii and low‐concentration chitosan before harvest may be a promising technology to control decay of table grape fruit in storage. Copyright © 2009 Society of Chemical Industry     

Methyl jasmonate enhances biocontrol efficacy of Rhodotorula glutinis to postharvest blue mold decay of pears

The effect of Rhodotorula glutinis treatment alone or in combination with methyl jasmonate (MeJA) in controlling blue mold decay, the natural fungal decay of pears and the postharvest quality parameters including fruit firmness, total soluble solids, titratable acidity, and ascorbic acid were investigated. The combination of methyl jasmonate (200 μM) and R. glutinis (1 × 10⁸ CFU/ml) was a more effective approach to reduce the disease incidence and lesion diameter of blue mold decay of pears than the application of MeJA or R. glutinis alone after incubation for 7 d at 20 °C. The natural fungal decay of pears treated with the application of R. glutinis combined with MeJA resulted in reduced average decay incidence of 10.42% or 4.16%, respectively, compared with 27.17% or 20.83% in the control fruits following storage at 20 °C for 15 d or 4 °C for 60 d followed by 20 °C for 15 d. The combined treatment did not impair quality parameters of fruits under both conditions.     

Changes in anthocyanins in arils of chitosan-coated pomegranate (Punica granatum L. cv. Rabbab-e-Neyriz) fruit during cold storage

Edible coatings as chitosan treatments (0%, 1% and 2%) were applied to ‘Rabbab-e-Neyriz’ pomegranate (Punica granatum L.). The effect of chitosan coating on individual anthocyanins and colour parameters of the juice during storage at 2 °C or 5 °C was examined. Six predominant anthocyanins were identified in the juice, with up to 935 mg/L total anthocyanins at the time of harvest. Cyanidin 3,5-diglucoside (402 mg/L) was the major pigment. The total anthocyanin content and chroma decreased with storage time in all applied treatments, although lightness and hue angle increased. These changes were reduced with chitosan treatments and at lower storage temperature (2 °C as compared to 5 °C). Based on the obtained results, the diglucoside anthocyanins were more stable than the monoglucosides. Chitosan coating followed by cold storage delayed anthocyanin degradation and prevented colour deterioration in the pomegranate arils.     

Effect of chitosan coating combined with postharvest calcium treatment on strawberry (Fragaria × ananassa) quality during refrigerated storage

Strawberries (Fragaria × ananassa Duch.) were coated with either 1% or 1.5% chitosan (CS) or chitosan combined with calcium gluconate (CaGlu). Following treatment, strawberries were stored at 10 °C and 70 ± 5% RH for one week. The effectiveness of the treatments in extending fruit shelf-life was evaluated by determining fungal decay, respiration rate, quality attributes and overall visual appearance. No sign of fungal decay was observed during the storage period for fruit coated with 1.5% CS (with or without the addition of CaGlu) or 1% CS + 0.5% CaGlu. By contrast, 12.5% of the strawberries coated with 1% CS lacking calcium salt were infected after five days of storage. The chitosan coating reduced respiration activity, thus delaying ripening and the progress of fruit decay due to senescence. Chitosan coatings delayed changes in weight loss, firmness and external colour compared to untreated samples. Strawberries coated with 1.5% chitosan exhibited less weight loss and reduced darkening than did those treated with 1% chitosan, independently of the presence or absence of CaGlu. However, addition of calcium to the 1% chitosan solution increased the firmness of the fruit. Coated samples had greater visual acceptability than had untreated fruits. The addition of calcium gluconate to the chitosan coating formulation increased the nutritional value by incrementing the calcium content of the fruit.     

Comparative shelf life study of blackberry fruit in bio-based and petroleum-based containers under retail storage conditions

The shelf life of blackberries is relatively short, 2–3 days at 0 °C. Different marketing strategies like packaging can be used to retain blackberry quality during postharvest. This study compares the blackberry retail shelf life performance of different packaging materials, bio-based versus petroleum-based using the same packaging design. ‘Cancaska’ and ‘Chester’ blackberries were packaged in snap-fit closed packages made from oriented poly(lactic acid), OPLA, and oriented poly(styrene), OPS, and stored at 3 °C and 85% RH for three weeks. Both cultivars exhibited an increase in pH, weight loss, SSC to TA ratio, and fungal count, and a reduction in firmness, anthocyanin content, TA, and SSC during storage. The changes in TA, SSC, SSC to TA ratio, and weight loss significantly depended on the packaging material while no such effect was observed on firmness, anthocyanin content, pH and fungal growth. Both cultivars demonstrated better quality in the OPS container with less weight loss, and decrease in SSC and TA. Blackberries in both OPS and OPLA containers met the “US standard No 1” grade for commercialisation for more than 12 days at 3 °C.     

采前涂膜处理对宣化牛奶葡萄贮藏生理及品质的影响

研究采前涂膜处理对宣化牛奶葡萄的采后贮藏生理及保鲜效果。经采前挂蔓涂膜处理的牛奶葡萄在0℃条件贮藏100d,贮藏期间测定了果实的呼吸强度、乙烯释放量、总酚含量、叶绿素含量、可滴定酸含量等生理和品质指标。结果表明：采前涂膜处理可以显著抑制宣化牛奶葡萄果实在贮藏过程中的呼吸强度,处理组果实的呼吸强度比对照低42.5%～53.8%、并在一定程度上减少果实的乙烯释放量;采前涂膜能有效控制葡萄腐烂,贮藏结束时(100d)对照组腐烂率达75.3%,而涂膜处理组的腐烂率只有5.2%。同时可以减少褐变,贮藏75d时处理组的褐变指数比对照低81.6%。保持果实鲜绿色,处理组果实果皮叶绿素含量在50d和75d时为0.04mg/g和0.33mg/g,而对照组则为0.02mg/g和0.015mg/g;也可以保持葡萄果实可溶性固形物、可滴定酸含量,保持感官品质,延长保鲜期约50d。     

Changes in microbial and postharvest quality of shiitake mushroom (Lentinus edodes) treated with chitosan-glucose complex coating under cold storage

The effect of chitosan, glucose and chitosan-glucose complex (CGC) on the microbial and postharvest quality of shiitake (Lentinus edodes) mushroom stored at 4 ± 1 °C for 16 days was investigated. Mushroom weight loss, respiration rate, firmness, ascorbic acid, total soluble solids, microbial and sensory quality were measured. The results indicate that treatment with CGC coating maintained tissue firmness, inhibited increase of respiration rate, reduced microorganism counts, e.g., pseudomonads, yeasts and moulds, compared to uncoated control mushroom. The efficiency was better than that of chitosan or glucose coating treatment. In addition, CGC coating also delayed changes in the ascorbic acid and soluble solids concentration. Sensory evaluation proved the efficacy of CGC coating by maintaining the overall quality of shiitake mushroom during the storage period. Our study suggests that CGC coating might be a promising candidate for maintaining shiitake mushroom quality and extending its postharvest life.     

A combination of marine yeast and food additive enhances preventive effects on postharvest decay of jujubes (Zizyphus jujuba)

We investigated the effects of marine yeast Rhodosporidium paludigenum in combination with a food additive, carboxymethylcellulose sodium (CMC-Na), on prevention of postharvest decay and food quality of Chinese winter jujubes. R. paludigenum (1 × 10⁸ cells/ml) combined with CMC-Na (0.3%) significantly increased the inhibition of black rot on jujubes at 25 °C when compared with R. paludigenum-alone treatment (5.8% vs. 20%, p < 0.05). The combination also reduced natural rot from 86% (control) to 56%. The combination caused transient changes in enzyme activities or contents of some oxidation reactive markers such as peroxidase (POD), superoxide dismutase (SOD), and malondialdehyde (MDA) of jujubes. The combination had no significant effect on the food qualities such as colour (chroma and hue angle), total soluble solid (TSS) and titratable acidity (TA) of the fruit. While enhancing these effects, CMC-Na did not affect the survival of R. paludigenum in nutrient yeast dextrose agar (NYDA) culture. Thus, we conclude that the combination of R. paludigenum and CMC-Na is a promising formulation to control postharvest decay of Chinese winter jujubes.     

Coating citrus (Murcott tangor) fruit with low molecular weight chitosan increases postharvest quality and shelf life

This study investigates the effects of coating with low molecular weight chitosan (LMWC, Mw = 15 kDa) and high molecular weight chitosan (HMWC, Mw = 357 kDa) on the decay of Murcott tangor and the maintenance of its quality. A 0.1% LMWC coating substantially slowed the decay of Murcott tangor stored at 15 °C in relation to a control sample and reduced decay by over 20% as compared to the fungicide TBZ. A concentration of 0.2% LMWC was more effective in controlling the growth of fungus on citrus fruits caused by Penicillium digitatum and Penicillium italicum, exhibiting effective antifungal activity. LMWC coating improved firmness, titratable acidity, ascorbic acidity and the water content for Murcott tangor stored at 15 °C for 56 days. Consequently, Murcott tangor coated with LMWC exhibited greater antifungal resistance than TBZ and its quality was maintained for longer.     

The influence of light and maturity on fruit quality and flavonoid content of red raspberries

The effects of various fruit maturities and different light intensities on berry fruit quality, antioxidant capacity and phytonutrient levels in red raspberries (Rubus ideaus L.) were determined. At harvest, immature berries contained significantly lower levels of sugars and acids than ripe berries. When berries were harvested at 5% or 20% maturity, they never developed the levels of soluble solids content (SSC) and titratable acid (TA) values observed in ripe berries at harvest. However, fruit harvested at 50% or more advanced maturity had the capacity of attaining comparable levels of SSC, TA and sugars as those harvested at 100% maturity. When 5% and 20% berries were stored under light, higher level of SSC and lower levels of TA values were observed than those kept in the dark. However, light condition showed little effect in 50% and 80% maturity fruit after 4 days at 24/16 °C (day/night). Ripe raspberries (100%) had stronger antioxidant activities and higher total anthocyanin content when compared with the pink stage (50% maturity). Fruit harvested at greener stages (5% and 20%) also consistently showed higher antioxidant activities and total phenolics than those harvested at 50%. Cyanindin-based anthocyanins increased during postharvest period. On the other hand, other polyphenols such as ellagic acid, quercetin 3-glucoside, quercetin derivative, and kaempferol 3-glucuronide were initially present at high levels but decreased drastically during storage. Red raspberries harvested at different developmental stages continued their development during storage even under the dark conditions. The antioxidant activity of red raspberries was directly related to the total amount of phenolics and flavonoids. Results of this study indicate that red raspberries harvested at 50% or more advanced maturity could develop comparable quality and antioxidant levels as those harvested at full maturity.     

1-Methylcyclopropene delays arazá ripening and improves postharvest fruit quality

Six different experiments were conducted to give some practical recommendation to apply 1-MCP during the postharvest handling chain of arazá fruit (Eugenia stipitata McVaugh). Fruit were harvested in three stages of maturity (mature-green primarily, turning and mature) and treated for 1 to 12 h with 0 (control in air) or 1 μL L⁻¹ 1-Methylcyclopropene (1-MCP) at 20 °C. The mature-green fruit were subjected to different storage conditions (7, 10, 12, 13, 20 or 27 °C). The treatment of mature-green fruit with 1-MCP for 1 h, and storage at 12 °C for up to 2 weeks prolonged the shelf-life about one week by delaying or reducing the respiration and ethylene production rates, skin colour changes, the loss of organic acids, and softening, with or without a further shelf-life period of 3 days at 20 °C. At 7 °C, 1-MCP also reduced mature-green fruit weight loss and shrivelling. Extending 1-MCP treatment periods at 20 °C to 6 or 12 h caused partial and uneven ripeness. Treating fruit in their post-climacteric stage of maturity had little effect on ripening compared with the mature-green stage. 1-MCP increased the respiration rate and/or the ethylene production in certain combinations of advanced harvest maturities and/or unfavourable storage temperatures. Recommendations for maintaining postharvest quality are harvesting at the mature-green stage, treatment with 1 μL L⁻¹ of 1-MCP for 1 h, and storage at 12 °C for up to 2 weeks.     

Biocontrol of postharvest gray and blue mold decay of apples with Rhodotorula mucilaginosa and possible mechanisms of action

The efficacy of Rhodotorula mucilaginosa against postharvest gray mold, blue mold and natural decay development of apples and the possible mechanisms involved were investigated. The decay incidence and lesion diameter of gray mold and blue mold of apples treated by R. mucilaginosa were significantly reduced compared with the control fruits, and the higher concentration of R. mucilaginosa, the better the efficacy of the biocontrol. R. mucilaginosa also significantly reduced the natural decay development of apples following storage at 20 °C for 35 days or at 4 °C for 45 days followed by 20 °C for 15 days. Germination and survival of spores of Penicillium expansum and Botrytis cinerea were markedly inhibited by R. mucilaginosa in an in vitro test. Rapid colonization of the yeast in apple wounds was observed whether stored at 20 °C or 4 °C. In apples, the activities of peroxidase (POD) and polyphenoloxidase (PPO) were significantly induced and lipid peroxidation (malondialdehyde (MDA) content) was highly inhibited by R. mucilaginosa treatment compared with those of the control fruits. All these results indicated that R. mucilaginosa has great potential for development of commercial formulations to control postharvest pathogens on fruits. Its modes of action were based on competition for space and nutrients with pathogens, inducement of activities of defense-related enzymes such as POD, PPO and inhibition of lipid peroxidation (MDA content) of apples, so as to enhance the resistance and delay the ripening and senescence of apples.     

Effects of chitosan coating on postharvest life and quality of longan fruit

The effects of chitosan coating in extending postharvest life of longan fruits and maintaining their quality were investigated. The fruits were treated with aqueous solutions of 0.5, 1.0 and 2.0% chitosan, respectively, and then stored at 2°C and 90% relative humidity. Changes in respiration rate, polyphenol oxidase (PPO) activity, colour, eating quality, and weight loss were measured. The effect of chitosan coating on disease incidence was also evaluated. The application of chitosan coating reduced respiration rate and weight loss, delayed the increase in PPO activity and the changes in colour, and eating quality, and partially inhibited decay of fruit during storage. Furthermore, increasing the concentration of chitosan coating enhanced the beneficial effects of chitosan on postharvest life and quality of the fruit.     

Combination of heat treatment and chitosan coating to improve postharvest quality of wolfberry (Lycium barbarum)

The synergistic application of hot water dip at 42 °C for 30 min and 1% chitosan coating on differentiation in postharvest quality traits, microstructure as well as microbiological evolution of wolfberry fruits was investigated. Fresh wolfberry fruits were stored at 2 ± 0.5 °C and 90% relative humidity (RH) for 28 days. Results indicated the combination of prestorage heat treatment and chitosan coating maintained higher levels of ascorbic acid, total phenolic contents and antioxidant capacity as well as lower decay, compared with untreated wolfberry fruits. The possible mechanism was that the heat treatment almost sealed open stomata to limit the sites of pathogen penetration into fruits independently, followed by the biofilm formed by chitosan which controlled secondary infections as well as slowed changes in fruit respiration and metabolic activity in wolfberries. The synergistically treated fruit also exhibited a higher acceptability obtained by sensory analysis after cold storage. In this sense, the integrated application of heat treatment and chitosan coating could be regarded as an effective strategy to extend storage life and maintain the postharvest quality of wolfberry fruits.     

Physiological and biochemical responses of grapefruit seed extract dip on ‘Redglobe’ grape

Table grapes (Vitis vinifera cv. Redglobe) were immersed in 1 g L⁻¹ grapefruit seed extract (GSE) for 60 s at 15 °C and then stored at 2 ± 1 °C, and the related physiological effects were investigated. The results showed that GSE treatment lowered the respiration rate and ethylene evolution in the whole cluster. The activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) were increased and extended by GSE treatment, however, polyphenol oxidase (PPO) activity was suppressed. Furthermore, increase of malondialdehyde (MDA) as well as membrane permeability was delayed in GSE-treated grapes. Total phenolic compounds degradation was substantially lower in GSE-treated grapes than in control. The soluble solids content (SSC) in GSE-treated grapes was always higher than in control, although there was no significant difference at the level of P < 0.05. Our study suggests that GSE might be a promising candidate for extending the postharvest storage time of table grapes.     

Effects of stage II and postharvest deficit irrigation on peach quality during maturation and after cold storage

Effects of regulated deficit irrigation (RDI) on the quality of a mid–late maturing peach (Prunus persica L Batsch cv Andross) were determined at commercial harvest as well as 1 week before (early pick‐up) and after 1 week of cold storage. Respiration and ethylene evolution were measured during 96 h on fruits sampled at early pick‐up and at harvest. Fruits from a well‐watered irrigation treatment (Control) were compared with a treatment of RDI during stage II of fruit growth (RDI‐SII) and with RDI applied postharvest (RDI‐PH). A fourth treatment received a combination of deficit irrigation applied during stage II and postharvest (RDI‐SII‐PH). Higher soluble solids content (SSC) amd SSC/titratable acidity (TA) ratio for RDI‐SII were already noted at early pick‐up and these differences were enhanced after cold storage (RDI fruits having higher SSC, lower TA and higher SSC/TA ratio than Control fruits). This improvement in quality (high SSC/TA ratio) was also correlated with a more reddish colouration in the fruit skin. Moreover, ethylene production indicated different behaviour of the physiological evolution for fruits from the different treatments. Copyright © 2004 Society of Chemical Industry     

Effects of 1-methylcyclopropene(1-MCP) on ripening and resistance of jujube (Zizyphus jujuba cv. Huping) fruit against postharvest disease

The effects of 1-methylcyclopropene (1-MCP) on senescence and induction of resistance against postharvest decay in jujube (Zizyphus jujuba cv. Huping) fruit were investigated in this study. The results indicated that, compared to control, 1-MCP at 1 μL L^?l depressed ethylene production by 28% and respiration rate by 30% at 24 h after treatment, resulting in effective delay in fruit senescence. 1-MCP treatment was beneficial for maintaining quality of jujube fruit stored both at 25 and 0 °C, retarding decline of firmness, vitamin C, titratable acidity (TA) and soluble solids content (SSC) which are important parameters for fruit quality evaluation during the storage periods. Moreover, 1-MCP effectively limited the development of lesion diameter of blue mold rot and significantly reduced the incidence of natural decay. The activities of phenylalanine ammonia-lyase (PAL), polyphenol oxidase (PPO), catalase (CAT) and superoxide dismutase (SOD) were significantly induced after 1-MCP treatment. These findings indicate that the induced resistance in jujube fruit by 1-MCP is related with the increase of enzymes involved in scavenging of reactive oxygen species and enzymes associated with phenolics metabolism which produces highly toxic products against pathogen invasion. Our results suggest that 1-MCP has potential effect on maintaining the quality and extending postharvest life of jujube fruit.     

Effect of sucrose‐based polymers on quality of Satsuma mandarin fruit (Citrus unshiu Marc. cv. Miyagawa Wase)

In this study, the effects of an edible coating (sucrose‐based polymers, SBP) on postharvest fruit quality of Satsuma mandarin (Citrus unshiu Marc. cv. Miyagawa Wase) were investigated. All the fruit except the control was sprayed with SBP solution at a concentration of 0.1%, 0.3%, 0.5% and 1.0% (v/v), respectively, and then stored at room temperature (25 °C, 85% relative humidity) for 25 days. Results showed that 0.1%, 0.3% and 0.5% SBP treatment could significantly increase the soluble solids concentrations (SSC), vitamin C (Vc), total sugars, total carotenoids, the ratio of SSC to titratable acidity (TA) (SSC/TA), catalase (CAT), peroxidase (POD) and superoxidase dismutase (SOD) activities, while the decay rate, TA and polyphenol oxidase (PPO) activity were greatly reduced. In contrast, 1.0% SBP treatment resulted in fruit browning, despite maintaining fruit quality. Our present study provided the theoretical data for the practical application of the SBP on the citrus fruit quality of during postharvest storage.