Physicochemical Properties of Gels Obtained from Corn Porous Starches with Different Levels of Porosity

Preparation and properties of cationic starch-carrageenan‑sodium alginate hydrogels with pH and temperature sensitivity

In this study, cationic starch-carrageenan‑sodium alginate (CAS/CR/SA) hydrogels with different weight ratios of carrageenan and sodium alginate were prepared and their properties such as scanning electron microscopy (SEM), rheological properties, Fourier transform infrared spectroscopy (FTIR), 1H nuclear magnetic resonance (1H NMR), X-ray diffraction (XRD), and methylene blue adsorption test were measured. The results showed that the viscosity and the shear strain resistance of the CAS/CR/SA hybrid hydrogels positively correlated with their sodium alginate contents. The hybrid hydrogels with high carrageenan contents exhibited a high energy storage modulus (G') and a high loss modulus (G"). The swelling and methylene blue adsorption experiments showed that the CAS/CR/SA hydrogels had pH and temperature sensitivity. The hydrogels reached adsorption equilibrium in 12 h (alkaline conditions) and 24-36 h (acidic conditions). The adsorption kinetics of the hybrid hydrogels showed that their adsorption process was mainly controlled by chemisorption and that adsorption was exothermic (ΔH° < 0).

The effect of lactic acid bacteria fermentation on physicochemical properties of starch from fermented proso millet flour

A waxy and a non-waxy proso millet flour were each fermented by Lactobacillus amylovorus, Lactobacillus fermentum, and Lactobacillus plantarum. The samples were fermented for one to five days, and starch was isolated from the fermented flours. The pH of fermented proso millet flour ranged from 3.27 to 3.6. The starch morphology of fermented samples differed from that of raw starches, with surface indentations and small pores leading to granule channels observed on the granule. The gelatinization temperatures were significantly decreased, whereas the enthalpies were not affected by fermentation. Peak and final viscosities were decreased after fermentation. The hardness of Lb. fermentum and Lb. plantarum fermented waxy starch gels was decreased, but the non-waxy samples fermented by Lb. amylovorus had significantly increased hardness. The adhesiveness of the starch gels from fermented samples was significantly increased. Lactic acid fermentation had significant effects on the morphology and physicochemical properties of proso millet starch.

Use of flour from cormels of Xanthosoma sagittifolium (L.) Schott and Colocasia esculenta (L.) Schott to develop pastes foods: Physico-chemical, functional and nutritional characterization

The corms of cocoyams, specifically Colocasia esculenta (L.) Schott and Xanthosoma sagittifolium (L.) Schott are usually consumed as pastes. Nevertheless, the secondary corms, also named cormels, are not fully exploited. In this study, the chemical composition and functional properties of cormels from different botanical sources were evaluated, and the digestibility of the resulting pastes investigated. Colocasia spp. flour contained significantly higher protein (10.32% vs 9.65%), ash (5.65% vs 5.05%) and oxalates (0.32% vs 0.22%) content, and exhibited lower Amylab gel strength (773 g vs 1040 g) than Xanthosoma spp. flour. In the resulting pastes, micrographs revealed that starch gelatinization depended on cocoyam variety. Indeed, the very tight and closed microstructure of pastes containing Colocasia spp. flour led them to better stability during storage with lower syneresis. Lower protein digestibility was obtained in Colocasia spp. gels (67.56% vs 70.91%), but they showed faster (higher k) in vitro starch hydrolysis (0.0140 vs 0.0050) with lower estimated glycemic index (61.29 vs 65.84) than Xanthosoma spp. gels. The present findings offer ways to develop cocoyam based foods by using cormels, enhancing the applicability of cocoyams.