61A-28 |
Characterization of starch in 10 genotypes of three Amaranthus species |
A. S. M. CHAN and H. Corke. Botany, University of Hong Kong, Pokfulam Road, Hong Kong Grain Amaranthus has been rediscovered and extensively researched as a high potential new crop in the past two decades. Its starch has also been studied since the 1970's and the general properties of some Amaranthus starches have been revealed. However, in order to fully utilize Amaranthus starches in today's demanding food applications, knowledge of the basic properties of starch from more genotypes is necessary. The objective was to characterize the starch properties of different genotypes and to compare the properties among the three Amaranthus species. The starches were isolated from grains by using an alkali wet-milling method. Amylose content was determined by Megazyme Assay Method. The starch pasting properties were determined by Rapid Visco Analyzer. The starch thermal properties were determined by Differential Scanning Calorimetry. Relatively wide variation was observed in the amylose content of different genotypes with values ranging from 1.4% to 10.9%. A. hybridus had the highest mean amylose content generally, 6.8%, compared to 4.8% in A. cruentus and 2.8% in A. hypochondriacus. The results showed there was wide variation in pasting and thermal properties among the genotypes and within the species. The viscosity increase during the cooling of the starch paste is probably due to amylose molecule reassociation during cooling, overcoming the effect of continued shearing. The correlation between amylose content and setback (SB) was significant (r=0.71). The wide variation among and within Amaranthus species in all the starch properties shows that careful selection of proper genotypes for specific uses must be made. The wide diversity of properties of Amaranthus starch provides a range of types for the possible replacement of some current commercial starches.
Session 61A, Carbohydrate
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