Transformations in Properties of Indian Barnyard Millet Starch as Induced by Ultra‐Sonication and Gamma Irradiation

Abstract

This study aims to assess the effect of physical modification techniques on the properties of millet starch. The starch isolated from barnyard millet (Echinochloa frumentacea) is subjected to ultrasonication (20 kHz; 30 and 60 min) and gamma irradiation (5 and 10 kGy). The protein content decreases slightly (by 2.5–3.8%) with gamma irradiation and significantly (by 5.7–6.9%) with ultrasonication. As compared to the native starch (20.56%), the amylose content of ultrasonicated starch is significantly higher (21.42% and 21.88%), while it is significantly lower (19.73% and 19.18%) for gamma‐irradiated starch. The swelling power of the native starch (13.57%) increases significantly with ultrasonication (14.21% and 14.33%) treatment; while it decreases significantly with gamma irradiation (13.17% and 12.25%) treatment. The solubility increases to 11.23%, 11.19%, 12.09%, and 13.31% from 10.45%, with both modifications. The peak viscosity of modified starches decreases significantly (2872 and 2700 cP) as compared to the native starch (3832 cP). The starches exhibit a greater value for storage modulus (G′) as compared to loss modulus (G″), reflecting their elastic nature. These transformations in the microstructure, gelatinization, and physicochemical properties of native starch can further be explored for food and textile industrial applications.