• Korean Journal of Food Science and Technology
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• v.35 no.5
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• pp.865-870
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• 2003

The effects of storage atmosphere on the physicochemical and organoleptic properties of Asian pears (Pyrus pyrifolia Nakai cv. Niitaka) were investigated. The pears were stored at $0^{\circ}C$ for up to 8 months under CA conditions (3 kPa $O_2$＋1 kPa $CO_2$, 1 kPa $O_2$+5 kPa $CO_2$, 1 kPa $O_2$+1 kPa $CO_2$) controlled by a static system or air (21 kPa $O_2$+0 kPa $CO_2$). CA conditions retarded the loss of weight, flesh firmness, organoleptic properties (appearance, aroma, sweetness, texture), and the development of injuries in the fruits during storage. Low $O_2$ plus high $CO_2$ conditions maintained the highest flesh firmness. In addition, low $O_2$ reduced injuries more than the other conditions. Skin color (lightness, chroma, hue), soluble solids, titratable acidity, pH and vitamin C were unaffected by storage atmosphere.

• Horticultural Science & Technology
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• v.33 no.5
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• pp.712-721
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• 2015

To improve the breeding efficiency of oriental pear, heritability, correlation and frequency distribution of fruit ripening date were analyzed using 4,035 seedlings obtained from 15 families between 13 parental cultivars. Although variation of fruit ripening time was higher in most early-ripening parental cultivars than in late-ripening parental cultivars, according to analysis of average, standard deviation, and coefficient of ripening variation for ten years, fruit ripening time obtained from all parental cultivars was inherited narrower and more stable variation than others fruit trait, with 0.92-3.41 in coefficient of variation. The heritability of fruit ripening time was calculated to be over 0.8 in almost all crosses and average fruit ripening time of seedlings from cross combinations could be predicted based on that of the parental cultivars due to its superior heritability relative to other fruit traits. The average ripening time was earlier than the mid-parental value in families obtained from cross combinations using at least one late-ripening cultivar as parent, indicating that the early-ripening trait was more likely to be dominant compared to the late-ripening trait. By contrast, average ripening time was clustered in families of crosses not only between mid-season and early-season cultivars, but also between mid-season and mid-season cultivars. There was highly significant relationship (at 0.68) between mid-parental and progeny mean fruit ripening time. The correlation between fruit ripening time and fruit weight was also highly positive and thus, the mid-parental fruit ripening time could be a potent criterion for indirect selection of fruit weight.

• Horticultural Science & Technology
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• v.30 no.5
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• pp.534-542
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• 2012

This study was conducted to investigate the effect of 1-methylcyclopropene (1-MCP) on fruit quality and incidence of physiological disorders for keeping freshness during marketing period in Asian pear (Pyrus pyrifolia Nakai) 'Wonhwang' and 'Whasan'. Fruits were treated with $1{\mu}L{\cdot}L^{-1}$ 1-MCP for 12 hours at $25^{\circ}C$, at two or three stages of ripeness as determined by days after full bloom (DAFB). Fruits were harvested at 130 and 140 DAFB in early season cultivar 'Wonhwang' and 135, 145, and 150 DAFB in mid-season cultivar 'Whasan', respectively. Fruits were stored at $25^{\circ}C$ for 21 days and measured the flesh firmness, weight loss, soluble solids, acidity, ethylene, respiration and severity of physiological disorders at week interval. 1-MCP treatment to 'Wonhwang' pears harvested at 130 and 140 DAFB effectively delayed firmness loss during storage at $25^{\circ}C$. Untreated fruits of 'Wonhwang' pears harvested at 130 DAFB showed 32.3 and 10.1N of firmness after 14 and 21 days of shelf-life at $25^{\circ}C$, respectively, while those of the 1-MCP treated fruits showed 39.4 and 33.1N during same period. In the fruits harvested at 140 DAFB, the firmness of untreated fruit was lowered to 14.8 and 6.6N after 14 and 21 days, respectively, but those of 1-MCP treated fruit were 35.0 and 33.3N, respectively. Whereas, 1-MCP treatment delayed firmness loss only in the fruit harvested late (150 DAFB) in 'Whasan' pears. Higher soluble solids content and acidity during extended shelf-life were apparent in 1-MCP treated 'Wonhwang' pears, while those of 'Whasan' pears were little changed. 'Wonhwang' pears showed a relatively high ethylene production (maximum $0.58{\mu}l{\cdot}L^{-1}$) in the fruits harvested late than early harvested one. 'Whasan' pears showed little amount of ethylene production regardless of extended shelf-life. 1-MCP treatment to 'Wonhwang' pears decreased respiration rate following shelf-life, 42 and 50% reduction were observed at 14 days of shelf-life when compared with those of untreated ones harvested at 130 and 140 DAFB, respectively. No reduction of respiration rate by the treatment of 1-MCP was detected in 'Whasan' pears which showed considerably low respiration rate compared with 'Wonhwang' pears. Harvest time influenced the level of physiological disorders together with extension of shelf-life in both the cultivars. 1-MCP treatment completely blocked the incidence of internal browning of 'Wonhwang' pears harvested at 130 DAFB, and reduced the incidences of pithiness and core browning, while it promoted the flesh spot decay disorder regardless of harvest time. 1-MCP treatment was of little benefit for the prevention of physiological disorders in 'Whasan' pears compared with those of 'Wonhwang'.

• Horticultural Science & Technology
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• v.32 no.5
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• pp.645-654
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• 2014

This study was conducted to investigate the effect of 1-methylcyclopropene (1-MCP, $1.0{\mu}L{\cdot}L^{-1}$), a known ethylene action inhibitor, on fruit quality and incidence of physiological disorders during a simulated marketing period at $25^{\circ}C$ for 20 days in early-season Asian pear (Pyrus pyrifolia Nakai) 'Hanareum' that had been treated with 0, 0.5, 1.2 or 2.4% $GA_{4+7}$. Weight loss of stored fruits increased with $GA_{4+7}$ concentration, and the 1-MCP treatment slightly reduced the weight loss rates during the marketing period. Flesh firmness decreased abruptly in all 1-MCP-untreated fruits as the storage period extended to 10 d, whereas the firmness of 1-MCP-treated fruits remained high (> 30 N) during 15 days shelf-life. The effect of 1-MCP was significantly reduced when fruits were subjected to increased GA concentration. Higher soluble solids content and acidity during extended shelf-life were also apparent in 1-MCP-treated 'Hanareum' pears. The L-values (lightness) and hue angles of 1-MCP treated samples were higher than those of controls during 20 days shelf-life, but the a-value (redness) was lower in 1-MCP treated fruits. 1-MCP treatment did not decrease the level of ethylene evolution regardless of $GA_{4+7}$ concentration during shelf-life in early-season Asian pear 'Hanareum'. By contrast, 1-MCP treatment decreased the respiration rate significantly during shelf-life. The efficacy of 1-MCP was greatest in the GA-untreated fruit and was reduced as the $GA_{4+7}$ concentration increased. 1-MCP treatment influenced the severity of physiological disorders including core browning and mealiness: 1-MCP treatment completely blocked the incidence of core browning of during 15 days shelf-life, and reduced the severity of mealiness during 20 days shelf-life regardless of $GA_{4+7}$ concentration. Based on our results, we conclude that the use of $1{\mu}L{\cdot}L^{-1}$ 1-MCP can be of great benefit for maintaining quality and preventing physiological disorders in early-season pear cultivar 'Hanareum' pear, whereas its efficacy decreases with the concentration of $GA_{4+7}$ whereas its efficacy gradually decreases when the concentration of $GA_{4+7}$ paste increased.

• Journal of Bio-Environment Control
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• v.26 no.4
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• pp.378-385
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• 2017

In this study, we evaluated the changes of fruit quality indices during fruit development and ripening in Korean new pear cultivar 'Changjo', developed from a cross between 'Tama' and '81-1-27' ('Danbae' ${\times}$ 'Okusankichi') in 1995 and named in 2009, to determine appropriate harvest time and to enhance the market quality and broaden the cultivation area. The fruits of 'Changjo' pears harvested from 132 days after full bloom (DAFB) to 160 DAFB. Fruit growth and quality indices were monitored at 1 week interval by measuring fruit weight, length, diameter, firmness, and taste related quality indices. The calculated fruit fresh weight increased continuously with fruit development and reached to an average of 594g on Sep. 20 (160 DAFB). The ratio of length to diameter declines as fruit maturation progress, resulting in 0.898 for ripe fruit stage as a round oblate shape. Flesh firmness of 'Changjo' pears showed over 30N until 153 DAFB and then decreased abruptly with fruit ripening, reaching a final level of about 26.44N on 160 DAFB. Starch content of fruit sap was also decreased abruptly after 146 DAFB which decreased almost half of the fruits harvested at 139 DAFB. In parallel with the decrease of flesh firmness, ethanol insoluble solids (EIS) content decreased sharply with fruit ripens, only 50% of EIS was detected on the fruits harvested on 160 DAFB when compared to that of the fruits harvested on 139 DAFB (Aug. 30). The maximum value of soluble solids contents was observed in the fruits harvested on 153 DAFB, resulting in $14.2^{\circ}Brix$. The changes of skin color difference $a^*$ which means loss of green color occurred only after 139 DAFB, coincide with the decrease of SPAD value of the fruit skin. The sugars of the 80% ethanol soluble fraction consisted mainly of fructose, sorbitol, glucose and sucrose, also increased during maturation and ripening. Fructose and sucrose contents were larger than those of glucose and sorbitol in flesh tissues. These results were explained that stored starch is converted to soluble sugars during fruit maturation, mainly in fructose and sucrose increasing the sweetness of this cultivar. Total polyphenols were increased up to middle of fruit maturation (146 DAFB) and then decreased continuously until the end of fruit maturation. Consequently, our results suggested that the commercial harvest time of 'Changjo' pears should not be passed 153 DAFB and late harvest of this cultivar would not good for quality maintenance during shelf-life. As a result of the post-harvest low-temperature acclimation experiment during the short-term transportation period, fruits harvested at 146 DAFB tended to maintain higher firmness after 14 days of simulated marketing at $25^{\circ}C$ compared to fruits harvested at 153 DAFB regardless of temperature set. And, the slower the rate of decrease to the final transport temperature of $5^{\circ}C$, the higher the incidence of internal browning and ethylene production. Therefore, in order to suppress the physiological disorder and to maintain the fruit quality when exporting to Southeast Asia in the 'Chanjo' pears, it is desirable to lower the temperature of the fruits within a short time after harvest and to set the harvest time before 146 days after full bloom.