Rate of Cooling Alters Chip Color, Sugar Contents, and Gene Expression Profiles in Stored Potato Tubers

When stored at temperatures below 10 A degrees C, potatoes accumulate sucrose and the reducing sugars glucose and fructose. This process, cold-induced sweetening, has been studied extensively because potatoes with elevated reducing sugar contents produce undesirable, dark-colored products and acrylamide, a suspected carcinogen, during high-temperature cooking. Potatoes in commercial storages are cooled slowly, but many research studies have used potatoes cooled rapidly. In this study, effects of cooling rate and variety on chip color, sugars, and gene expression were examined. Sucrose and reducing sugar contents were substantially lower in slowly cooled than in rapidly cooled tubers of 'Snowden' and MegaChip' for the first 11 weeks after cooling to 3 A degrees C began. Differences in gene expression for VInv, beta-amylase, SPS, AGPase and GBSS were observed between cooling treatments and varieties. Overall, the data showed that cooling rate, time in storage, and variety influenced multiple aspects of cold-induced sweetening.