Effects of Variation in Activities of Starch-Sugar Metabolic Enzymes on Reducing Sugar Accumulation and Processing Quality of Potato Tubers

The experiment was designed, via storing potato tubers of cv. E-Potatol and E-Potato3 in different temperatures, to explore the variation patterns of reducing sugar (RS) and total sugar (TS) contents and enzyme activities that are involved in the pathway of starch-sugar metabolism aiming at identifying the main factors that influence the chip color. The results showed that low temperature in storage was a main factor that accelerated the accumulation of RS of the stored tubers and a very significant linear relationship existed between RS content and chip color index (CCI) of the tubers. Further analysis elucidated that when tubers stored at 4℃, the activities of ADP glucose pyrophosphorylase (AGPase), UDP glucose pyrophosphorylase (UGPase) and sucrose synthase (SuSy) were negatively exponential to the RS content significantly while that of acid invertase and alkaline invertase was significantly linear to RS content. It suggested that these enzymes could play main roles in the cold sweetening of potato tubers through regulating starch-sugar metabolism.