Physical properties of starch from two genotypes of Amaranthus cruentus of agricultural significance in China

Abstract

Starches were isolated from the two genotypes of Amaranthus cruentus most widely cultivated in China, R104 and K112. These starches, plus a corn starch standard were mixed with either distilled water or a 1% NaCl solution and characterized for gelatinization parameters by Differential Scanning Calorimetry (DSC), pasting properties using a Rapid Visco-Analyzer (RVA), and texture of the cooled gels. Significant findings were: 1. A. cruentus starches had higher gelatinization temperature and higher endothermic energy than corn starch; 2. Wide differences in pasting properties were found between the two A. cruentus genotypes, although the waxy line R104 had lower hot-paste viscosity and set-back than K112; 3. The pasting properties (peak viscosity and set-back), of K112 were similar to those of corn starch. 4. In 1% NaCl solution, compared to distilled water, corn starch set-back decreased while that of the A. cruentus starches increased. Where Amaranthus starch is to be used in food processing applications, careful selection of genotype is necessary to achieve desired functionality.