Impact of post-harvest processing techniques on the glycemic index of millets

Abstract

The processing techniques on millets have a significant impact on the nutritional and functional qualities of millets, especially their glycemic behavior is often overlooked. Therefore, this work aims to serve as a resource covering the state-of-the-art known information about the effects of both conventional and emerging processing techniques on the glycemic index of millets. Structural interaction of starch with polyphenols or lipids tends to alter the semi-crystalline layer leading to the formation of V-type starch thereby decreasing the GI. Heat treatment in general results in depolymerisation of dietary fibres resulting in more alcohol soluble fragments and decreased dietary fibre content increasing the GI. However, when moisture is involved, the amylose gets solubilized and forms a gel network which strengthens the fiber content. In the case of novel processing methods, pressure-treated starch shows higher compactness than heat-treated starch which decreases the GI. Alternative non-thermal processing techniques can harm starch structures, leading to elevated GI. However, this impact is contingent on the dosage and treatment duration, suggesting that hurdle technology may offer the potential to achieve a different GI outcome. Understanding structural alterations while lowering the GI of millet can link with increased consumer demand, market share, and health claims. Overall, the field remains underexplored, and future research on the development of value-added products from millets must consider this aspect.

Keywords

• Processing
• Starch hydrolysis
• Digestibility
• Starch modification
• Starch morphology