Changes in invertase activities and reducing sugar content in sweetpotato stored at different temperatures

Cured sweetpotato roots were stored at different temperatures (4.5, 15.6, and 24 degrees C) for 7 weeks and assayed for invertase activities and reducing sugar levels during two separate years. Invertase activities and reducing sugar concentration significantly increased in the roots kept at low temperature. Of the three types of invertases assayed, acid invertase specific activity was the highest. Acid invertase was the most influential in determining reducing sugar levels in stored sweetpotato. Cultivar differences were found in invertase specific activities and reducing sugar concentration. Reducing sugar content was highly correlated to acid and total invertase activity, regardless of cultivar.