Feasibility of replacing waxy rice with waxy or sweet-waxy corn viewed from the structure and physicochemical properties of starches

Abstract

To explore the feasibility of substituting waxy rice with waxy or sweet-waxy corn, eight varieties of waxy and sweet-waxy corns were selected, including three self-cultivated varieties (Feng nuo 168, Feng nuo 211, and Feng nuo 10). Their starches were isolated and used as research objects, and commercially available waxy rice starch (CAWR) and waxy corn starch (CAWC) were used as controls. X-ray diffraction, scanning electron microscopy, differential scanning calorimetry, rapid viscosity analyzer, and rotational rheometer were used to analyze their physicochemical and structural characteristics. The morphologies of all corn starch granules were generally oval or round, with significant differences in particle size distributions. All ten starches exhibited a typical A-type crystal structure; however, their relative crystallinity varied from 20.08% to 31.43%. Chain length distribution analysis showed that the A/B ratio of Jing cai tian nuo 18 and Feng nuo 168 was similar to that of CAWR. Peak viscosities of corn starches were higher than that of CAWR, except for Feng nuo 10, while their setback values were lower than that of CAWR. Except for Feng nuo 10, the paste transparency of corn starches was higher than that of CAWR (10.77%), especially for Jing cai tian nuo 18 (up to 24%). In summary, Jing cai tian nuo 18 and Feng nuo 168 are promising candidates to replace CAWR in developing various rice-based products.