Submitted to: Journal of Food Chemistry
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/22/2007
Publication Date: 5/24/2007
Citation: Anderson, A.K., Guraya, H.S. 2007. Effects of microwave heat-moisture treatment on properties of waxy and non-waxy rice starches. Journal of Food Chemistry. 97(2):318-323. Interpretive Summary: Chemically altered starch and starch products have gradually become undesirable. Food industry desires naturally altered starches. The breakdown of starches during digestion of food results in glucose. This released glucose is rapidly absorbed into the body. There are desirable limits of blood glucose. Overeating of starchy foods could result in weight gain. Starch can be modified to release glucose slowly in blood. This would result in satiety and reduced weight gain. We naturally altered starches by a small addition of water and heating using microwaves. This heat moisture treatment results in modification of starches. These naturally altered starches can be used in food products instead of chemically altered starches. No significant reduction in digestibility of starches was observed.
Technical Abstract: Waxy and non-waxy rice starches adjusted to 20% moisture (wet basis, w.b.) were heat-moisture treated in a microwave oven to determine the effects of the microwave heating characteristics on digestibility, pasting, and morphological properties of the heated starches. Microwave heating produced only minimal changes in digestibility, as well as the physical characteristics of heated starches. Significant changes in viscosity properties after microwave heat treatment were observed for both waxy and non-waxy starches heat-treated in a microwave oven, relative to non-treated samples. Non-waxy starch heated in a microwave oven showed an increase in breakdown viscosity from 29.8 RVU (non-treated starch) to 35.8 RVU after heating for 60 minutes. However, for waxy starch, breakdown viscosity decreased from 112.7 to 35.9 RVU after 60 minutes of microwave heat treatment, reflecting an increased stability of microwave heat-treated starch under cooking. The data obtained in this study indicates that there was much higher re-aggregation of starch granules in waxy starch after microwave heat treatment than occurred in non-waxy starch, suggesting a re-association of amylopectin branch chains in the heat-treated waxy starch.