Extrusion assisted interaction of rice starch with rice protein and fibre: Effect on physicochemical, thermal and in-vitro digestibility characteristics.

Rice starch has high digestibility due to its large carbohydrate content. Macromolecular enrichment of starch has the tendency to retard rate of starch hydrolysis. Hence, the current investigation was aimed to check the combined effect of extrusion assisted addition of rice protein (0, 10, 15 and 20 %) and fibre (0, 4, 8 and 12 %) to rice starch on physico-chemical and in-vitro digestibility characteristics of starch extrudates. It was observed from the study that 'a' and 'b' values, pasting temperature and resistant starch of starch blends and extrudates increased with the addition of protein and fibre. However, lightness value, swelling index, pasting properties and relative crystallinity of blends and extrudates decreased with the addition of protein and fibre. Maximum increase in thermal transition temperatures was observed for ESP3F3 extrudates due to absorption capacity of protein molecules which led to late onset of gelatinization. Therefore, enrichment of protein and fibre to rice starch during extrusion can be considered as a novel approach to reduce rate of rice starch digestion for catering nutritional requirements of diabetic population.

In-vitro digestibility of rice starch and factors regulating its digestion process: A review.

Rice is consumed as staple food by more than half of the world's population. However, it has high glycemic index because of high starch content and is associated with the development of diabetes. Therefore, it is important to devise strategies that could lower the digestibility of rice starch. Keeping this fact into consideration, the present study includes a review of factors that are known to regulate in-vitro digestibility of rice starch. This review also includes an overview of some previous and current in-vitro starch digestion methods along with their advantages and limitations. Regarding factors regulating in-vitro digestibility, physical encapsulation of starch within cell wall/macro-capsule, protein or dietary fibres retard rate of starch digestion. Also, interaction of polyphenols with rice starch results in formation of V-type inclusion complexes, resistant to digestion. This review provides sufficient information that can help food industries to develop suitable strategies for mitigating digestibility of rice starch.