Effects of Preservation Conditions on Peelability, Color Tone, Fruit Cracks, and Physical Properties of the Japanese Chestnut "Porotan"

Abstract

　The Japanese chestnut (Castanea crenata Sieb. et Zucc.) "Porotan" has excellent peelability, but its quality deteriorates during storage and heat-processing. We investigated the effects of storage temperature and peeling timing on chestnut quality after steam treatment of "Porotan". The chestnuts were subjected to five processing strategies with different storage conditions, and their peelability, color tone, fruit cracking, and physical properties after storage were evaluated. First, regarding peelability, no clear differences were observed among the five processing strategies. Second, on measurement of color tone by using a color reader (L^＊, a^＊, and b^＊ values) after steam treatment, discoloration was noted especially after refrigeration storage (R) along with the occurrence, but it hardly occurred under freezing conditions (F), after refrigeration and under freezing conditions (RF), after refrigeration for 1 month followed by peeling and further storage under freezing conditions (RPF). Furthermore, occurrence of mold was observed after R. Third, fruit cracks were observed in all chestnuts at the start of storage (S) and after storage under F, whereas the number of fruit cracks decreased after R and RPF. Finally, with respect to physical properties, chestnuts under RPF tended to soften after steam treatment compared to those under R. Together, these results indicate that RPF is the most suitable storage method.