M.Sc. Tezi Görüntüleme

      In this study, changes in the activities of polyphenol oxidase (PPO), peroxidase (POD), and in the levels of soluble protein, soluble sugars, and ascorbic acid during development and ripening stages of medlar and blackberry fruits were investigated.

       For this purpose, activities of PPO and POD and the other organic substances in the medlar fruits harvested every month from the mid of July to the mid of November while the blackberry fruits harvested different times from the end of June to the mid of July were spectrophotometrically analysed and, these analyses were begun after two months of pollination and continued until the fruits are mature. At the end of analyses, PPO activity and the level of ascorbic acid gradually decreased during development of the medlar fruits, but PPO activity increased in the post-ripening stage and ascorbic acid level increased pre-ripening stage finally decreased post-ripening period. Similarly POD activity decreased during development of the fruits and increased in the pre-ripening stages. The level of glucose gradually increased during the fruit development and ripening. Pentose, hexose, and soluble protein levels decreased during the fruit development but increased in the stage of ripening.

      On the other hand, PPO and POD activities and the level of ascorbic acid gradually increased during the development of blackberry fruits then decreased in the stage of ripening. The amount of protein and soluble sugars gradually increased during development and ripening of the fruits. These observations indicate the changes of PPO and POD activities and sugars and protein contents has an important role to reduce astringency taste of the medlar and blackberry fruits.

      Keywords: Medlar, Blackberry, Polyphenol Oxidase, Peroxidase, Development and Ripening, Organic Substance .