Assessment of physicochemical characteristics and modifications of pasting properties of different varieties of maize flour using additives

Effects of konjac glucomannan on pasting, rheological, and structural properties of low-amylose rice starch

Blend of starch and polysaccharide is a secure and feasible modifying method for starch. Effects of konjac glucomannan (KGM) on pasting, retrogradation, rheological and structural properties of low-amylose rice starch were evaluated. KGM addition reduced the pasting temperature, breakdown and setback values, but raised the peak viscosity. When KGM concentration increased, the storage and loss moduli showed an upward trend. Fourier transform infrared spectroscopy (FTIR) showed redshifts at 3450 and 1640 cm−1 and suggested the formation of intermolecular hydrogen bond between KGM and starch molecules. X-ray diffraction (XRD) indicated that KGM decreased the relative crystallinity from 11.88 to 3.10%. Scanning electron microscopy (SEM) of KGM induced samples showed looser network structures, and confocal laser scanning microscopy (CLSM) detected less cloud-like blurry pastes surrounding around the starch ghosts. KGM addition suppressed the starch retrogradation. These results could be used to broaden the application of KGM in the food industry.

Changes in starch structures and in vitro digestion characteristics during maize (Zea mays L.) germination

This study analyzed changes in the starch structures and in vitro digestion profiles of a specific maize cultivar, Jike 728 (JK728), in Jilin, China, after 0-5 days of germination. The total starch, amylose, and amylopectin contents decreased significantly during germination. The average molecular weight of the starch compounds also decreased significantly during germination. The proportion of amylopectin with a degree of polymerization (DP) of 13-24 significantly decreased, while the relative abundance of amylopectin with DP values of 6-12, 25-36, and 37-60 significantly increased. The X-ray diffraction (XRD) patterns of all samples were characteristic of A-type starch, and the starch relative crystallinity decreased over time. The proportions of slowly digestible starch and resistant starch decreased significantly, while the proportion of rapidly digestible starch increased significantly during germination. Germination is an easy, inexpensive, and low-carbon processing method. This study indicates that germination is an effective way to control the physical properties and digestibility of starch in maize. The changes observed in the physical properties and digestibility of maize starch after germination provide scientists with a platform to understand starch modification mechanisms that might have potential applications on an industrial scale.