[Functional and thermal properties of chickpea and soy-protein concentrates and isolates]

ABSTRACT

In the last few years there has been a growing trend to use chickpea as a good protein source. Chickpea protein products, such as chickpea flour, concentrate and isolate, are considered as functional food supplements, alternatives to soy protein. The objective of this study was to determine and compare the functional and thermal properties of chickpea and soy-protein concentrates and isolates. Chickpea protein concentrate and isolate were prepared from defatted chickpea flour by applying alkaline extraction and isoelectric precipitation. Chemical composition [protein, fat, ash, crude fiber, and water contents], functional properties [water and fat absorptions, gelation, foaming capacity, and foam stability], and thermal properties [glass transition and denaturation temperatures] of chickpea protein concentrate and isolate were determined and compared with those of the soy protein products. The protein contents of the concentrate and isolate obtained from defatted chickpea flour were 80% and 88.6%, respectively; the corresponding proportions for soy concentrate and isolate were 83.1% and 90.2%. There were no statistically significant differences as regards water and oil absorptions between soy and chickpea proteins. The gelation properties and foaming capacity of all the samples increased with an increase in protein concentration. However, soy protein had a higher foaming capacity and foam stability as compared to chickpea protein [P chickpea and soy-protein isolates had a semi-crystalline structure, while soy protein showed a higher thermal stability than chickpea protein. The results reveal that some functional properties of chickpea protein are similar to those of soy protein. Its high nutritional value, the high indispensible amino acid content and good functional properties of chickpea, makes it ideal substitutes for other dietary proteins