| Summary: | 碩士 === 國立屏東科技大學 === 熱帶農業暨國際合作系所 === 97 === The series of studies were conducted to elucidate the changes of physico-chemical characteristics, polyphenol oxidase (PPO) and peroxidase(POD) activities, and total phenolic compounds during fruit growth and development in three cultivars of smooth loofah (Luffa cylindrical Roem.)
fruits (cv. ‘Kaohsiung 2’, ‘Merit’ and ‘Tainung No. 1’). Moreover, the correlation between enzymatic browning, polyphenol oxidase (PPO) and peroxidase (POD) activities, and total phenolic compounds in three cultivars of smooth loofah fruit were investigated. It is possible to determine the optimum stage for harvest from the data. Last but not least, it was also made to find out the best storage temperature for smooth loofah fruit, effects of different storage temperatures (5, 10, and 15°C respectively) on fruit storage life, and symptom of chilling injury was investigated.
The curves of length, width, fresh weight and volume in the three cultivars of smooth loofah showed a linear growth. According to length, width, fresh weight, peel color, total soluble solid content, titratable acidity, and sugar/acid ratio in fruits, these cultivars attained their specific character within 9-11 days after anthesis. The degree of green and yellow of three cultivars of peel increased and the degree of green and yellow of fruits pulp decreased during the growth and development of the cultivars.
The fruit polyphenol oxidase (PPO) activity of ‘Kaohsiung 2’, ‘Merit’and ‘Tainung No. 1’ increased with 5-11th days after anthesis. The peel polyphenol oxidase activity of ‘Kaohsiung 2’ fruit peaked on the 3rd day after anthesis, and the peel polyphenol oxidase activity of ‘Merit’ and ‘Tainung No.1’ fruits peaked on the 11th day after anthesis. The pulp peroxidase (POD) activity of ‘Kaohsiung 2’, ‘Merit’ and ‘Tainung No. 1’decreased with the fruits’ growth and development. The content of total phenolic compounds of the three smooth loofah cultivars peaked on the 5th day after anthesis, and the
total phenolic compounds in pulp increased on 7-11th days after anthesis. Besides, the total phenolic compounds were highest in ‘Tainung No. 1’ fruit pulp than ‘Kaohsiung 2’ and ‘Merit’ throughout the growth and development of the fruits.
The pulp lightness and white index of ‘Tainung No. 1’ was significantly decreased, and ‘Tainung No. 1’ fruit pulp browning existed except for‘Kaohsiung 2’ and ‘Merit’ after cutting at ambient temperature. The pulp PPO activity, POD activity, and total phenolic compounds were
highest for‘Tainung No. 1’ and lowest for ‘Kaohsiung 2’.
The fruit PPO and POD activity of the three cultivars increased with the increase of chilling injury index, and the chilling injury occurred earliest in‘Tainung No. 1’ than ‘Kaohsiung 2’ and ‘Merit’ during 5°C storage. There
were no symptoms of chilling injuries during 15°C storage of three cultivars.The peel PPO activity of the three cultivars increased with the increase of storage duration and the surface yellowing at 25°C. Results of the comparison
of the storage life of three smooth loofah cultivars showed that storage life was longest at 15°C than 5 and 25°C respectively. Moreover, the storage life at 5° and 25°C were lowest in ‘Tainung No. 1’ than ‘Kaohsiung 2’.
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