Effect of different cooking treatments on sugar profile and sweetness of sweet-potato root
Owusu-Mensah1,2, E., Oduro1, I., Ellis1, W.O., Adofo3, K, and Carey2, E.E.
1) Food Science and Technology Department, College of Science, Kwame Nkrumah, University of Science and Technology, Kumasi, Ghana.
2) International Potato Centre (CIP), c/o CSIR-CRI, P.O. Box 3785, Kumasi, Ghana
3) Crops Research Institute, CSIR-CRI, P.O. Box 3785, Kumasi, Ghana
*Corresponding author: email: /
Cooking can significantly alter sugar content of sweet-potato roots. Sweet-potato breeding efforts in Ghana target the development of low-sugar, staple-types preferred by consumers. Eleven sweet-potato varieties were cooked using three different treatments, baking, microwaving and steaming, with the aim of investigating the effects of these methods on sugar profile and sweetness levels. Sugars (sucrose, glucose, fructose and maltose) were determined prior to and after cooking. Significant contribution of the cooking treatment and genotype, and their interaction on levels of the sugars were also investigated. Moreover, sugar values were converted to relative sweetness per sucrose equivalent to measure the sweet perceptions of the varieties. Amylase activity of the raw roots was also evaluated. The results revealed that cooking treatment produced the highest effect on maltose, sucrose, and glucose contents of the roots. Genotypic effect was profound on fructose content. Variability due to the interactions ranged from 2.60% to 11.74%. Whilst sucrose was the predominant in the raw form, maltose increased dramatically and became the principal sugar after cooking. Increased in sugar concentration was highly correlated with amylase activity in the raw roots. Sweetness level increased substantially upon cooking in most of the varieties, and was highly dependent on initial sugar content, amylase activity and cooking treatment. Thus, evaluation of sweetness levels in sweet-potato clones should not only be on the uncooked samples but should take into account the cooking methods employed.
Keywords: cooking treatments, sugar profile, sweetness level, amylase activity, maltose.