Alpha amylase inhibition and roasting time of local vegetables and herbs prepared for diabetes risk reduction chili paste

Abstract

Consumption behaviour of carbohydrate and sucrose rich food is one of main causes of noninsulin ependent diabetes mellitus (diabetes type II). This results in an increase in the number of diabetes patients in Thailand in recent years. Potent inhibitors of mammalian alpha-amylase found in some vegetables and herbs have been known as effective antidiabetic treatment for diabetes. Therefore, this research was aimed to investigate the change of alpha amylase inhibition in chili paste prepared from vegetables and herbs with different roasting time. Local vegetables and herbs which show high potential for diabetes risk reduction used in this study were Gynura divaricata DC., Coccinia grandis Voigt, Thunbergia laurifolia Linn.., Piper retrofractum Vahl and Cyperus rotundus Linn.. They were added into the paste to make up 20% in the form of fresh (0 min) and roasted (5-15 min) materials. Other ingredients and preparation rocesses correspondingly followed the production of a raditional roasted chili paste with dried fish. Alpha amylase inhibition of the products were then determined. The result found that all of the studied vegetables and herbs showed more than 80% alpha amylase inhibitory activity and this may contribute to the enzyme inhibition effect of chili paste, resulting in this high level of inhibition. Despite the added portion of these vegetables and herbs being quite high, the products were mostly accepted by 30 untrained panelists. The correlation study of enzyme inhibition and roasting time was found to be second order polynomial regression type. Chili paste containing Gynura divaricata DC, Piper retrofractum Vahl and Cyperus rotundus Linn. showed a decrease of alpha amylase inhibitory activity the longer the time of roasting. This was in contrast to enzyme inhibition of chili paste prepared from Coccinia grandis Voigt which increased from 23.16% to 45.02% during 15 min roasting. Alpha amylase inhibition of chili paste added with roasted Thunbergia laurifolia Linn. tended to decrease after 10 min roasting time. This will be further studied to develop design models for application in a decision support system for development of Thai food that could be applied to diabetes patients and consumed as healthy food for diabetes risk reduction.