A Comparative Study on the Physicochemical Properties of Aqueous-Ethanol-Annealed Starches From Pea, Chickpea, and Mung Bean and Their Applications as Edible Films.

This study investigated the aqueous-ethanol-assisted annealing of starches from pea, chickpea, and mung bean to enhance their functional properties for industrial applications. The effects of ethanol concentration (40%, 55%, and 70%) on the physicochemical properties of annealed starches were systematically evaluated, with particular focus on the water solubility (WS) and mechanical performance of resulting starch films. Compared to native starches, treatment with 40% and 55% ethanol significantly reduced the gelatinization and pasting properties, while increasing the cold water absorption capacity (cold WAC). These results are attributed to microstructural agglomeration and transformation to V-type or mixed V + C-type crystalline structures. However, compared to 40% and 55% ethanol-annealed starches, the 70% ethanol-annealed starches retained the basic morphology of starch granules and their original C-type crystal structure. Consequently, the gelatinization properties and viscosity parameters increased, while the cold WAC decreased accordingly, resulting in overall properties that are closer to those of native starch. Starch films derived from mung bean exhibited superior mechanical properties, likely due to higher amylose content. Films prepared from 70% ethanol-annealed starches demonstrated optimal characteristics, including WS (21.68%-23.55%), elongation at break (30.00%-33.71%), and tensile strength (4.63-7.37 MPa). Furthermore, the two-way ANOVA results indicated that the effects of ethanol concentration during annealing on the properties of both the legume starches and its corresponding films varied among different cultivars. These findings indicate that ethanol concentration during annealing critically modulates starch properties, showing significant potential for developing edible films with tailored functionality.