Assessment of the Functional and Nutritive Properties of Thermally Modified Maize Biopolymer

Abstract

Cereal grains are important because of their abundance and readily available biopolymer made up of mainly digestible starch, proteins and other minor components like lipids and non-starch polysaccharides which is present only in small concentrations but affect the properties of the biopolymer considerably. In its native form cereal starch is neither suitable for direct human consumption nor industrial processes, and must therefore, be modified to develop specific properties such as digestibility, palatability, solubility and texture for food applications. In this research maize grain biopolymer were thermally modified and their functional and nutritive
properties were determined. Significant reduction was observed in water absorption capacity (WAC), least gelling concentration (LGC), gelatinisation temperature (GT) and swelling capacity (SC), but the process led to significant increase (p ˂ 0.05) the bulk density (BD). Final moisture, ash and fat contents recorded significant reduction as a result of thermal modification, while protein and carbohydrate contents were significantly increased by 5.7% and 2.8%. Essential amino acids (EAA) recorded some increments as a result of the
biopolymer modification ranging from 1.5% to 26.7% depending on the amino acid. Histidine, tryptophan and methionine showed highest increments with 26.7%, 17.5% and 13.6% respectively. Leucine, phenylalanine and isoleucine are next in percentage increase with 9.4%, 7.4% and 6.1% respectively. it is noted that nutritional index (Ni), total aromatic essential amino acid (TAEAA) and total sulphur-containing amino acids (TSAA) are statistically significant, while essential amino acids index (EAAI), essential amino acids ratio (TEAA⁄TAA) and protein efficiency ratio (PER) are not.