• Korean Journal of Agricultural Science
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• v.45 no.4
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• pp.601-614
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• 2018

Chitosan with a natural antimicrobial property has been introduced to protect horticultural crops from diseases as an environmentally friendly method. The purpose of this study was to investigate the effects of the pre-harvest application of chitosan on growth and quality during the late stage of fruit development and on the simulated marketing of the peach fruit (Prunus persica L.). The application of chitosan with calcium chloride ($100mg{\cdot}L^{-1}$) three times at one week intervals 4 weeks before the harvest significantly increased the fruit weight, changed the fruit shape, and reduced the fruit length/diameter ratio giving the peach fruits a round oblate shape. The calcium treatment contributed to enhancing or maintaining the storage potential by increasing the flesh firmness. However, at higher concentrations of $CaCl_2$, i.e., > $600mg{\cdot}L^{-1}$, the positive effects of the chitosan application were offset, and fruit growth was not affected by calcium alone. The application of the chitosan/calcium mixture delayed fruit softening; however, this effect was shortened when the storage temperature was $20^{\circ}C$ rather than $15^{\circ}C$. The internal quality of the fruit was profoundly affected by the concentration of calcium added to the chitosan, and delayed fruit maturation was observed at a higher concentration of calcium. The pre-harvest application of chitosan with calcium contributes to the enhancement of food safety by inhibiting the occurrence of diseases during postharvest handling. Considering the above results, chitosan has the potential to improve both the yield of peach fruits and their storability. Because chitosan can enhance the freshness and shelf-life of fresh produce, it is necessary to examine its effects on other horticultural crops.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.20 no.2
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• pp.59-63
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• 2014

The quality changes of 'Fuyu' persimmon fruits chill-injured on tree with different time periods were evaluated during storage of 6 weeks at $0^{\circ}C$. There was no significant difference among treatments in the weight loss, which increased with storage time. Firmness was found to be very important factor determining the quality level of persimmon fruit during the storage. The increased chill-injured period decreased the firmness, indicating the rapid fruit softening. While the firmness of the persimmons not exposed to chill-injured condition was not changed significantly during the storage period, the firmness of persimmon fruits chill-injured for 1, 3, and 5 days decreased from 26.7, 16.1, 10.8 N to 18.2, 12.22, and 5.8 N for 6 weeks. The total solids content and total acidity did not significantly change during the storage period. The amount of ethylene production from the chill-injured fruits was almost 2 times higher than that without low temperature injury. The results indicated that persimmon fruit injured by low temperature exposure directly affected to the changes of its ethylene production and firmness during storage.

• Journal of the Korean Society of Food Science and Nutrition
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• v.26 no.2
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• pp.180-185
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• 1997

This work was carried out to investigate change of polygalacturonase activities and polygalacturonase patterns by gel filtration chromatography during softening of persimmon and jujube fruits. During softening of two kinds of fruit, polygalacturonase activities of water-soluble and salt-soluble proteins were increased, but that of cell wall-bound proteins was decreased. In water-soluble and salt-soluble proteins of persimmon fruits, two peaks of polygalacturonase activity were separated in mature stages, but one peak in soft stages. During softening of those fruits, the peaks of polygalacturonase activity in water-soluble and salt-soluble proteins appeared on the same fraction with the peaks of polygalacturonase activity in cell wall-bound proteins.

• Food Science and Preservation
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• v.23 no.1
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• pp.7-11
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• 2016

In order to develop a sprayable ethylene antagonist, unlike 1-methylcyclopropene (MCP), we synthesized 2-decylcyclopropene-1-carboxylic acid ethyl ester (DCPE) as a derivative of cyclopropene and tested its effect on the flesh softening of 'Fuyu' persimmon fruits. The fruits on trees were sprayed with $4{\cdot}10^{-4}$ M DCPE solution before harvest. After harvest, the persimmon fruits were stored at a low temperature for 1.5 months. The ripening progress of the fruits was then evaluated during storage at ambient temperature ($20^{\circ}C$). Flesh softening, a measure of ethylene response, was considerably delayed up to 7 days after DCPE treatment. However control fruits was rapidly softened after 3-day storage. The treatment effect of DCPE at $4{\cdot}10^{-4}$ M was also compared to that of 1-MCP at 1 ppm. DCPE was storable at refrigerated conditions for at least one month without any loss. The results show that DCPE could be a potential sprayable agent for the prevention of flesh softening of persimmon fruit.

• Korean Journal of Agricultural Science
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• v.41 no.1
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• pp.9-16
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• 2014

This experiment was conducted to examine the effects of a short-term treatment of high pressure $CO_2$ on shelf-life of strawberry fruit. A short-term treatment (12 hr) of 100% $CO_2$ resulted in the increase of fruit firmness up to 71.9% compared to that at harvest. The firmness of $CO_2$ treated fruit remained a significantly higher than that of control (air) up to 15 days. The alteration of pectic polymers was observed by $CO_2$ treatment such as an increase of EDTA soluble pectins and decrease of water soluble ones. The $CO_2$ treatment resulted in the increase of total amount of wall bound calcium. Pectate lyase activity, an important agent of strawberry fruit softening, was also significantly reduced by $CO_2$ treatment. Contents of soluble solids and acids of $CO_2$ treated fruit were higher than those of control fruit. Short-term treatment of high pressure $CO_2$ affected shelf-life through firmness increase whereas the visual quality and decay incidence of strawberry fruit were not affected.

• Horticultural Science & Technology
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• v.32 no.5
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• pp.614-622
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• 2014

Melons (Cucumis melo L.) are generally grafted onto Cucurbita rootstocks to manage soilborne pathogens such as Monosporascus root rot and v ine decline (MRR/VD) and Fusarium wilt. However, g rafting onto Cucurbita rootstocks reportedly results in the reduction of fruit quality. In this study, the resistance to MRR/VD, yield, and fruit quality of melons grafted onto melon rootstocks were evaluated under greenhouse conditions. Eight melon rootstocks (R1 to R8) were used and the inodorus melon 'Homerunstar' was used as scion. Melon rootstocks R1 to R6 were selected based on resistance to MRR/VD under greenhouse conditions. Non-grafted 'Homerunstar' and plants grafted onto squash interspecific hybrid 'Shintozwa' rootstock (Cucurbita maxima D. ${\times}$ C. moschata D.) served as controls. Grafted melons were cultivated in the greenhouse infested with Monosporascus cannonballus during two growing seasons (summer and autumn). The responses to MRR/VD, yield, and fruit quality differed depending on the rootstocks and growing season. The melons grafted onto 'Shintozwa' exhibited less severe disease symptoms and higher survival rates than non-grafted melons in both seasons. While the melon rootstocks in the summer cultivation did not increase the survival rate compared to non-grafted melons, the melon rootstocks R1 and R2 in the autumn cultivation led to higher survival rates. The melon rootstocks resistant to MRR/VD increased the percentage of marketable fruits and marketable yields. Grafting onto the melon rootstocks caused little or no reduction of fruit quality such as low calcium content, fruit softening, and vitrescence, especially in lower-temperature autumn season. Accordingly, these results suggest that grafting onto the melon rootstocks may increase the tolerance to MRR/VD and the marketable yield without a reduction of fruit quality.

• Korean Journal of Agricultural Science
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• v.43 no.3
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• pp.340-345
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• 2016

The kiwi fruit (Actinidia deliciosa cv. 'Hayward') should be ripened at any step during postharvest handling before consumer consumption. This is essential for freshly harvested kiwi fruit. But, this requires correct temperatures and ethylene concentrations. More testing of a newly developed ethylene generator using charcoal for commercial purposes is needed. This study was conducted to investigate the optimum storage temperatures and the effect of ethylene on the postharvest quality of kiwi fruit. Three different ethylene concentrations of 10, 50, and $100{\mu}L{\cdot}L^{-1}$ were used on fresh kiwi fruit stored at different temperatures of 10, 15, and $20^{\circ}C$. The quality changes of the fruits were assessed by sensory evaluation and by measuring firmness, soluble solids content, titratable acidity, and ethylene production. Higher storage temperatures and ethylene concentrations softened the kiwi fruit quickly and led to the rapid loss of acidity while soluble solid contents of fruit increased to a significant extent during the same storage period. Similarly, the firmness of ethylene-treated fruits stored at 20 and $15^{\circ}C$ dramatically decreased in the experiment while treated fruits stored at $10^{\circ}C$ decreased only slightly. Quality characteristics of kiwi fruits stored at 15 and $20^{\circ}C$ were better than those of fruits at $10^{\circ}C$. With regards to the effect of temperature, fruits stored at lower temperatures took a longer time to ripen and retained their quality longer. The newly developed ethylene generator maintained the ethylene concentration in the 5 kg box at $40-400{\mu}L{\cdot}L^{-1}$. The ethylene generator could also be used to soften persimmons.

• Horticultural Science & Technology
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• v.19 no.4
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• pp.545-549
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• 2001

The relationship between ethylene action and flesh softening in post-storage persimmon fruits was investigated by treating the fruits with 1-MCP. The patterns of firmness change caused by various treatments with 1-MCP and ethylene were similar to those of changes in cell wall-degrading enzyme activities, including cellulase, PG, PME, and ${\beta}$-galactosidase. Moreover, the activities of these enzymes were inhibited by 1-MCP treatment. These results show that the cell wall-degrading enzymes influenced by ethylene account for the flesh softening process of post-storage persimmon fruit. The ethylene production of fruits, as measured by ACC content and ACC oxidase activity, nevertheless, was not influenced by 1-MCP treatments. It is suggested that the flesh softening phenomena in post-storage persimmon fruits is correlated to the ethylene responsiveness of tissue rather than the ethylene production rate per se.

• Horticultural Science & Technology
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• v.29 no.5
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• pp.441-446
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• 2011

The effects of UV irradiation, as a hormetic stimulus, on the postharvest persimmon fruits (Diospyros kaki cv. Fuyu) were investigated in regards to the change of carotenoid contents and flesh softening, when the UV irradiation was combined with or without the pretreatment of 1-methylcyclopropene (1-MCP) as an ethylene action inhibitor. The major carotenoid pigments in persimmon fruits were ${\beta}$-carotene, lycopene and ${\beta}$-cryptoxanthin. Of them, the lycopene was a pigment, which increased markedly after harvest. UV irradiation increased the contents of ${\beta}$-carotene and lycopene, enhancing the skin color to scarlet. The treatment accelerated however also the softening of fruit flesh. But the softening of UV irradiated fruits could be delayed significantly by pretreatment with 1-MCP without reducing the advantageous effect of UV irradiation on the carotenoid increase.

• Korean Journal of Food Science and Technology
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• v.20 no.1
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• pp.95-99
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• 1988

The changes of texture, composition of cell wall polysaccharides, polygalacturonase (PG) activity and soaking effect during preserving of persimmon at various tempoeratures were estimated for the purpose of investigating the softening characteristics of persimmon fruit. The softening of persimmon was most promoted at $25^{\circ}C$, where in the higher temperature, at $45^{\circ}C$ it was inhibited. During softening adhesiveness increased, cohesiveness and gumminess decreased. This phenomenon was obvious at $25^{\circ}C$. By soaking in water at $50^{\circ}C,\;70^{\circ}C$ for 30 minutes PG activity and softening was inhibited. Ionically associated pectin (IAP) and covalently bounded pectin (CBP) fractionated from crude cell wall of fresh persimmon were respectively degraded about 60% by PG curde enzyme of softened persimmon. And the degraded ratio of polysaccharides composed of pentose and hexose was very similar to that of polyuronide.