Effects of storage temperature of potato tubers on sprouting, respiration rate, sugar content, and polyphenol oxidase activity

Potato tubers were stored at 4, 20, or 33 degrees C, and the sprouting time, respiration rate, sugar content, and polyphenol oxidase activity were examined. Sprouting was observed after about 70 days of storage at 20 degrees C but was not found when storage was at 4 or 33 degrees C after 160 days. Tubers transferred to 33 degrees C after 70 days of storage at 20c did not sprout during the next 160 days. When tubers were stored at 33 degrees C for 42 days and then transferred to 20 degrees C, sprouting was observed after 27 days. The respiration rates of potato tubers stored at 4 or 20 degrees C were low. At 33 degrees C, the respiration rate was initially high, but decreased during storage. The total sugar content of tubers stored at 22 degrees C was low. At 4 or 33 degrees C, however,this content increased rapidly to about 2%. The reducing-sugar content of tubers stored at 33 degrees C was lower than when storage was at 4 degrees C. Polyphenol oxidase activity in potato tubers stored at 20 degrees C increased twofold during storage, but rapidly decreased during storage at 33 degrees C