PROXIMAL, THERMAL, AND STRUCTURAL CHARACTERIZATION OF STARCH EXTRACTED FROM TWO VARIETIES OF WHITE SORGHUM CULTIVATED IN MEXICO

Abstract

Sorghum (Sorghum bicolor) is a starch source that may contain tannins in red varieties, so white grains are preferred as a better alternative. The hypothesis of this study was that white sorghum starch grown in Mexico has the necessary properties for industrial use. The objective was to evaluate the chemical, thermal and structural characteristics of starch extracted from white sorghum var. Mazatlan-16, and RB-Paloma. Protein, moisture, ash, fiber, fat, water absorption rate, and swelling capacity were evaluated. Thermal properties were determined by calorimetry and viscosity analysis; structural properties by Fourier transform infrared spectroscopy and X-ray diffraction. One-way analysis of variance and Student’s t-test (p ≤ 0.05) were performed. The starch extracted from Mazatlán-16 grain contained the highest moisture (5.47 %), protein (0.72 %) and crude fiber values, and no significant differences (p ≤ 0.05) were found for ash and fat content in both starch varieties. The water absorption rate and swelling power was higher for RB-Paloma variety starch (p ≤ 0.05). Regarding thermal properties, the maximum viscosity temperature was 80.55 and 89 °C for RB-Paloma and Mazatlan-16 starch, respectively; the peak gelatinization temperature was higher for Mazatlan-16 (72.28 °C) and showed differences (p ≤0.05) with RB-Paloma. Structural analysis revealed that the starches of both varieties correspond to the A-type crystalline pattern, with the presence of OH, CH in stretching, H2O and CH2 groups. The starches extracted from the two varieties showed properties suitable for use as a viable alternative in the food industry.