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

BACKGROUND

Little information is available on α- and β-amylase activity and their associations with starch, sugars and other culinary qualities in sweetpotato. The present study aimed to assess sweetpotato storage root α- and β-amylase activity in relation to starch, sugars, β-carotene content and storage root flesh color.

RESULTS

α- and β-amylase activity (α-AA and β-AA) were assayed from a Tanzania (T) × 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 α-AA and β-AA, respectively. Storage root dry matter, starch, glucose, fructose, sucrose and β-carotene content were predicted using near infrared reflectance spectroscopy. There was little relationship (r = 0.02-0.08, P ≤ 0.05 in 2016 and r = 0.05-0.11, P ≤ 0.05 in 2017) between α-AA and β-AA. We observed negative linear associations between α-AA and dry matter content and generally no correlations between β-AA and dry matter content. β-AA and sugars were weakly positively correlated. β-AA and β-carotene content were positively correlated (r = 0.3-0.4 in 2016 and 0.3-0.5 in 2017).

CONCLUSION

Generally, 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 α- and β-amylase activity are inter-associated with several culinary quality attributes. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.