Thermal Stability of β-Amylase Activity and Sugar Profile of Sweet Potato Varieties during Processing

Abstract

Sweet-potato root is a good source of β-amylase for food applications. β-amylase catalyses the conversion of soluble starch to sugars thus increasing the free sugar composition and sweetness of processed sweet-potato products. This study was undertaken to determine effects of temperature, time and their interactions on thermal stability of β-amylase and sugar profile of sweet-potato roots. Moreover, percentage variability of temperature, time, genotype and interactions on β-amylase was assessed. Temperature, genotype, time, and genotype x temperature interaction accounted for 50%, 26%, 11% and 8% of the variation respectively. Increasing temperature and heating time generally reduced β-amylase activity and enhanced maltose formation. Heating sweet-potato roots up to 75°C reserve relatively higher percentage of the endogenous amylases required for starch conversion and free sugar formation in the tempered product. The relatively high β-amylolytic potential of Santom Pona makes it a good raw material for the brewery and sugar syrup industry.