Effects of microwave and conventional heating on physicochemical, digestive and structural properties of debranched quinoa starch-oleic acid complexes with different water addition.

Abstract

Starch-lipid complex is a new type of resistant starch, which is of great significance for the prevention of chronic diseases such as diabetes. Most of starch-lipid complexes usually need to be treated by heating in order to make them ideal for a variety of application and starch based foods are generally not edible without heat treatment process. However, the digestion and structural properties of starch-lipid complex will be changed after heating. In this study, microwave and conventional heating were used to treat debranched quinoa starch-oleic acid complexes (DQS-OA) with different water addition, and the effects of the two methods on the physicochemical, digestive and structural properties of DQS-OA were compared. The results of in vitro digestibility showed that the resistant starch content (235.34-269.55 g kg-1 ) of the conventional heating-treated samples was significantly higher than that the microwave-treated samples (141.51-157.99 g kg-1 ). Moreover, after microwave treatment, the short-range molecular order and crystalline structure of DQS-OA were destroyed and the particle size became smaller. In contrast, the thermal stability, enthalpy and crystallinity of the complexes after conventional heating were improved. The ratio at 1047/1022 cm-1 of complexes has also been increased. This study demonstrated that conventional water-bath heating was better than microwave heating in increasing the digestion resistance, improving the short-range and long-range molecular order and promoting the formation of DQS-OA. In addition, with the increase of water addition, the influence of microwave or water bath treatment on the properties of DQS-OA became greater. This article is protected by copyright. All rights reserved.