Studies on the Harvest Maturity and Storability of ‘Jong-Shan Yueh Bar’ Guava (Psidium guajava L.) Fruit

• Main Authors: Yu-Yen Shen, 沈妤晏
• Other Authors: Chun-Teh Kuo
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/61236424509178202252

碩士 === 國立宜蘭大學 === 園藝學系碩士班 === 102 === In this thesis, ‘Jong-Shan Yueh Bar’ (Psidium guajava L.) from Ilan was adopted for the following study, including fruit growth and development and harvest maturity, the impact of harvest maturities and storage temperatures on the fruit’s respiration rate, ethylene production, fruit quality and storability, and the influences on fruit decay rate and peel color of guava by 1-Methylcyclopropene (1-MCP) postharvest treatment. The study is expected to contribute to the study and promotion of the guava industry. The fruit materials used in this experiment were grown by a fruit farmer Mr. Lin in Toucheng, Ilan (north latitude+24° 51' 49.48", east longitude +121° 48' 26.63"). The growth curve of the fruit can be divided into three stages: first stage: fruit development significantly increased; second stage: steady growth; third stage: rapid fruit growth, during which period the transversal diameter increases at a faster length than the longitudinal diameter. Fruit growth follows a double-sigmoid curve. The fruit shape index during the early development is greater than 1, indicating that the fruit has an elongated shape; the fruit shape index subsequently becomes less than 1, indicating the shape as oblate sphere. The fruit drop rate per week and accumulate fruit drop rate were lower than 15% from 13 to 76 days after anthesis (DAA), a significant fruit drop occurred 83 to 104 DAA, reaching 100% on 104 DAA. The abovementioned fruit in the growth and development was harvested on 34, 62, 76, 83, 90, and 97 DAA. That increases days after anthesis increased the mass of the fruit. The fruit firmness quickly dropped from 65N (75 DAA) to 10 N (97 DAA). The L value of the peel color increased as the number of days after anthesis increased, but decreased on 97 DAA. The a* value of the peel color was the highest on 90 DAA and it was the lowest on 83 and 97 DAA, thus reaching significant differences. The b* value of the peel color increased as the number of days after anthesis increased. The total soluble solids content from 83 to 97 DAA increased with increases in the number of days after anthesis, with 97 DAA (11 °Brix) being the highest and 83 DAA (9 °Brix) and 90 DAA (9 °Brix) reaches significant differences. The titratable acidity content, sugar-acid ratio, and ascorbic acid content showed no significantly different. In consideration to the characteristics of fruit growth and development, fruit quality requirements, and economic benefits, it is recommended that the 97 DAA be selected as the harvestable maturity. The mass of the fruit showed an upward trend with increase in harvest maturity (the number of days after anthesis), but the fruit firmness showed the opposite results. The fruit peel color on 90 DAA had the highest L and a* values, the b* value of the peel color was the highest on 102 DAA. The total soluble solids content on 84 DAA was the lowest and the highest on 102 DAA. That an increase harvest maturity decreased the titratable acidity content. The ascorbic acid content was the highest in 96 DAA and was the lowest in 90 DAA. As for harvest maturity (84, 90, 96, and 102 DAA), the results of the fruit stored under 20 and 5℃ for 12 days showed that after 9 days under 20℃, the decay rate of the fruit 102 days after flowering was the highest (100%). The L value of the treatment group on day 84, 90, and 96 first decreased and then increased, on 102 DAA, the fruit continued to increase as storage time increased, but it slightly decreased after 12 days of storage; the a* value of the peel color on 102 DAA turned from a negative value to appositive value on the sixth day of storage. On the other hand 90 and 96 DAA turned from negative values to positives values on day ninth; 84 DAA turned from a negative value to a positive value on day twelfth; the b* value of the peel color increased in the storage period increased. With increases in harvest maturity, the fruit firmness, total soluble solids content, and ascorbic acid content all decreased. During the period of storage at 5℃,the fruit on 102 DAA and stored for 9 days had the highest decay rate (66%). The L values of the peel color on 84, 90, and 96 DAA all significantly decreased after storage for 3 days, but the fruit on 102 DAA showed no significant changes, except for the fruit stayed for ninth days that decreased; the a* values of the peel color in various treatment groups did not turn to positive values during the storage period; all the treatment groups showed no significant changes in b* values, but the 84 DAA was decreased during storage. In terms of fruit firmness, it decreased with an increase in harvest maturity. The total soluble solids content of various treatment groups showed no significant changes, except for the one stored for 102 DAA that decreased. As of the titratable acidity content only 84 DAA was significantly higher than the other treatment groups. The ascorbic acid content decreased with increases in maturity. It is recommended that the 96 DAA be selected as the maturity for harvest. On 84 DAA, the respiration rate of the fruit climacteric peaked on day eighth. As the days increased to 102 DAA, the respiration rate reached the climacteric peak on the second day of storage. As for the peak of ethylene, the fruit 84 DAA also peaked on the eighth day of storage. As the number of days after anthesis increased to 102 DAA, the peak of the fruit ethylene was reached on the fourth day. As for the impact of storage temperature on the respiration rate and ethylene production of ‘Jong-Shan Yueh Bar’ guava fruit, findings show that the respiration rate of the fruit stored under 25℃ began to increase on the third day, while the respiration rate of the fruit stored under 20℃ increased with increases in the number of storage days, both peaking on fifth day. For the treatment groups stored under 5 and 10℃, the respiration rates were steady until seventh day of storage, but the respiration rate began to increase on first day of temperature transfer to 20℃. The ethylene production of the treatment group stored under 25℃ began to increase on first day and peaked on second day. The treatment group stored under 20℃ peaked after 3 days and gradually decreased afterwards. The treatment groups stored under 5 and 10℃ showed steady ethylene production until seventh day of storage, on the first day of temperature transfer to 20℃, the ethylene production reached the peak. While fruit peel browning was more serious in the fruit stored under 5℃ compared to the fruit peel stored under 10℃, thus the inference that the fruit stored under 10℃ had the best shelf life. The harvested mature green fruits were treated using 1-methylcyclopropene (1-MCP) of varying concentrations (0, 300 and 600 nL˙L−1) under 20°C for a period of 12 hours. The results showed that an increase in 1-MCP concentration decreased the decay rate, where the 600 nL˙L−1 1-MCP featured the lowest decay rate, which was followed by the 300 nL˙L−1 1-MCP, and significant differences were observed. The weight loss percentage increased with the storage duration, but no significant differences between three concentrations. An increase in the storage period (after fourth day) decreased the L value. For guavas treated using the 0 nL˙L−1 or 300 nL˙L−1 1-MCP, the a* value moved from negative to positive on the fourth and fifth day, respectively. For guavas treatment using the 600 nL˙L−1 1-MCP, the a* value remained in the negative even on the sixth day. Concerning the b* value for guavas processed using the 0 , 300, and 600 nL˙L−1 1-MCP, significant differences were observed only between the second and fifth day, and the difference between the 300 nL˙L−1 or 600 nL˙L−1 1-MCP were no significant differences.