Off-campus UMass Amherst users: To download dissertations, please use the following link to log into our proxy server with your UMass Amherst user name and password.
Non-UMass Amherst users, please click the view more button below to purchase a copy of this dissertation from Proquest.
(Some titles may also be available free of charge in our Open Access Dissertation Collection, so please check there first.)
The effects of preharvest factors on the accumulation of antioxidants in fruit peel, and their relationships to superficial scald development after cold storage of apples (Malus domestica Borkh.)
Abstract
Superficial scald, a physiological disorder of apples, develops during storage, and is believed to result from the oxidation of $\propto$ farnesene to conjugated trienes. Antioxidants are believed to protect against this oxidation, thus providing scald resistance. The hypothesis examined in this study was that temperatures below 10$\sp\circ$C before harvest facilitate the accumulation of antioxidants in the apple peel, and that this effect is enhanced by ripening and light. Cortland and Delicious apples were harvested following exposure to increasing hours below 10$\sp\circ$C during three years. Cortland apples were sprayed with ethephon to induce ripening at warm temperatures, and were bagged in late August to produce ripening at low light intensities, both during two years. Percent inhibition of oxidation and water-soluble reducing activities, as well as concentrations of $\propto$ tocopherol, ascorbic acid, glutathione, $\propto$ farnesene, conjugated trienes and several pigments, were determined at harvest and following intervals of storage. Scald development was determined after 3 to 5 months of storage at 0$\sp\circ$C. Correlations and regressions demonstrated that increasing exposure to temperatures below 10$\sp\circ$C was the primary factor in development of scald resistance. Less resistance developed when low light intensity existed during cool periods. Ripening alone was only a small factor in development of scald resistance. Cool preharvest temperatures slightly increased the concentrations of $\propto$ tocopherol and carotenes, and slightly increased water-soluble reducing capacity and percent inhibition of oxidation. Ripening increased both percent inhibition of oxidation and total water-soluble reducing activities, and increased concentrations of $\propto$ tocopherol, carotenes and ascorbic acid. Reduced light intensity (bagging) decreased concentrations of $\propto$ tocopherol, carotenes, and ascorbic acid, as well as total water-soluble reducing capacity. However, percent inhibition of oxidation and glutathione were not significantly influenced. During storage, as conjugated trienes accumulated, the $\propto$ tocopherol and carotene concentrations increased, while total water-soluble reducing capacity, ascorbic acid, and glutathione decreased. Although some support is given to the widely accepted model of scald development, it was concluded that while antioxidants play a role in scald resistance, they are probably not the key factor.
Subject Area
Plant sciences
Recommended Citation
Barden, Cynthia Louise, "The effects of preharvest factors on the accumulation of antioxidants in fruit peel, and their relationships to superficial scald development after cold storage of apples (Malus domestica Borkh.)" (1992). Doctoral Dissertations Available from Proquest. AAI9233029.
https://scholarworks.umass.edu/dissertations/AAI9233029