Interrelations of α- and β-amylase activity with starch, sugars, and culinary and nutritional quality attributes in sweetpotato storage roots

BACKGROUNDLittle information is available on & alpha;- and & beta;-amylase activity and their associations with starch, sugars and other culinary qualities in sweetpotato. The present study aimed to assess sweetpotato storage root & alpha;- and & beta;-amylase activity in relation to starch, sugars, & beta;-carotene content and storage root flesh color. RESULTS & alpha;- and & beta;-amylase activity (& alpha;-AA and & beta;-AA) were assayed from a Tanzania (T) x Beauregard (B) genetic mapping population in their uncured (raw), cured and stored (approximately 11 weeks) forms during 2016 and 2017. Ceralpha and Betamyl methods, with modifications to suit a high-throughput microplate assay format, were used to quantify & alpha;-AA and & beta;-AA, respectively. Storage root dry matter, starch, glucose, fructose, sucrose and & beta;-carotene content were predicted using near infrared reflectance spectroscopy. There was little relationship (r(2) = 0.02-0.08, P & LE; 0.05 in 2016 and r(2) = 0.05-0.11, P & LE; 0.05 in 2017) between & alpha;-AA and & beta;-AA. We observed negative linear associations between & alpha;-AA and dry matter content and generally no correlations between & beta;-AA and dry matter content. & beta;-AA and sugars were weakly positively correlated. & beta;-AA and & beta;-carotene content were positively correlated (r = 0.3-0.4 in 2016 and 0.3-0.5 in 2017). CONCLUSIONGenerally, the correlation coefficient for amylase enzyme activity and sugar components of storage roots at harvest increased after curing and during post-harvest storage. The present study is a major step forward in sweetpotato breeding in terms of providing a better understanding of how & alpha;- and & beta;-amylase activity are inter-associated with several culinary quality attributes. & COPY; 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.