Articles
Determination of optimum temperature for long-term storage and analysis of ripening-related genes in ‘Rainbow Red’ kiwifruit
Article number
1218_71
Pages
517 – 524
Language
English
Abstract
Kiwifruit is considered a climacteric fruit since exogenous ethylene induces ripening-associated changes.
However, we previously reported that low temperature modulated ripening in kiwifruit since ripening occurred faster during storage at 5°C compared to 20°C, in the absence of any detectable ethylene.
It is therefore not clear which temperature is suitable for long-term storage of kiwifruit.
The purpose of this study was to determine the optimum temperature for long-term storage, and analysis of ripening-related genes in ‘Rainbow Red’ kiwifruit.
Kiwifruit were harvested at commercial maturity, and stored at either 0, 2, 5 or 22°C in ethylene-free chambers.
During storage, incidence of fruit deterioration and changes in fruit firmness, soluble solids concentration (SSC) and titratable acidity (TA) were monitored at 4-week intervals.
Real-time PCR was also conducted to analyze the changes in expression of selected ripening-related genes.
Incidence of fruit fast senescence and deterioration was high at 22°C, so kiwifruit could only be stored for a maximum of 8 weeks.
Nevertheless, healthy fruit at 22°C remained firm and maintained high TA for 8 weeks.
The incidence of ethylene-producing fruit, and consequent fast senescence, was greatly reduced at 5°C, while it was completely suppressed at 0 and 2°C. Fruit at 5°C decreased in firmness and TA faster, attaining eating-ripe quality within 8 weeks.
At 2°C, fruit decreased in firmness and TA gradually, achieving eating-ripe quality after 12 weeks.
Conversely, fruit at 0°C maintained higher firmness and TA, and did not attain eating-ripe quality even after 12 weeks.
SSC increased at all storage temperatures, although the lowest levels were observed in fruit at 0°C. Real-Time PCR analysis revealed that cell-wall-modifying genes (AcPG, AcPL2, AcEXP1 and AcXET2) and carbohydrate-metabolism-associated genes (Acβ-AMY1 and Acβ-AMY2) were markedly induced in fruit at 5°C. Overall, these results indicate that 0°C is the suitable temperature for long-term storage of kiwifruit, while 2°C is suitable for medium-term storage.
For short-term storage, 5°C can be recommended.
However, we previously reported that low temperature modulated ripening in kiwifruit since ripening occurred faster during storage at 5°C compared to 20°C, in the absence of any detectable ethylene.
It is therefore not clear which temperature is suitable for long-term storage of kiwifruit.
The purpose of this study was to determine the optimum temperature for long-term storage, and analysis of ripening-related genes in ‘Rainbow Red’ kiwifruit.
Kiwifruit were harvested at commercial maturity, and stored at either 0, 2, 5 or 22°C in ethylene-free chambers.
During storage, incidence of fruit deterioration and changes in fruit firmness, soluble solids concentration (SSC) and titratable acidity (TA) were monitored at 4-week intervals.
Real-time PCR was also conducted to analyze the changes in expression of selected ripening-related genes.
Incidence of fruit fast senescence and deterioration was high at 22°C, so kiwifruit could only be stored for a maximum of 8 weeks.
Nevertheless, healthy fruit at 22°C remained firm and maintained high TA for 8 weeks.
The incidence of ethylene-producing fruit, and consequent fast senescence, was greatly reduced at 5°C, while it was completely suppressed at 0 and 2°C. Fruit at 5°C decreased in firmness and TA faster, attaining eating-ripe quality within 8 weeks.
At 2°C, fruit decreased in firmness and TA gradually, achieving eating-ripe quality after 12 weeks.
Conversely, fruit at 0°C maintained higher firmness and TA, and did not attain eating-ripe quality even after 12 weeks.
SSC increased at all storage temperatures, although the lowest levels were observed in fruit at 0°C. Real-Time PCR analysis revealed that cell-wall-modifying genes (AcPG, AcPL2, AcEXP1 and AcXET2) and carbohydrate-metabolism-associated genes (Acβ-AMY1 and Acβ-AMY2) were markedly induced in fruit at 5°C. Overall, these results indicate that 0°C is the suitable temperature for long-term storage of kiwifruit, while 2°C is suitable for medium-term storage.
For short-term storage, 5°C can be recommended.
Publication
Authors
O.W. Mitalo, S. Tokiwa, Y. Kasahara, Y. Tosa, Y. Kondo, W.O. Asiche, I. Kataoka, K. Suezawa, K. Ushijima, R. Nakano, Y. Kubo
Keywords
low-temperature-modulated ripening, eating quality, cell-wall-modifying genes, carbohydrate-metabolism-associated genes
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