Effect of Particle Size Distributions on the Amino Acid Composition and In-vitro Protein Digestibility of Two Varieties of Bean

Abstract

The study examined the alterations in the proximate composition, in-vitro protein digestibility and amino acid composition of two varieties of bean with respect to particle size distributions. Brown and white beans were processed and milled to obtain flour samples of fine particles. The flour samples were subjected to particle size analyses using Endecott sieve with pore sizes of 300, 315, 500 and 600 µm. The bean flours with different particle sizes were evaluated for proximate composition, protein digestibility and amino acid composition. The results showed that the highest yields obtained for the brown and white flours were 40 % (315 micron) and 35 % (600-micron) respectively. The ash, protein and fibre contents of the samples varied between 4.51 to 4.61 % and 3.72 to 3.78 %; 24.74 to 24.87% and 22.76 to 22.95 %; 3.24 to 5.23 % and 2.11 to 5.15 % for brown and white bean varieties respectively. The highest values for the protein digestibility were obtained in 315µ for both the brown and white bean flours. The results also showed that the amino acid composition of the samples varied with respect to the particle size and the variety of bean flour. The study concluded that particle size of flour should be considered as a quality factor of flours to enhance derivation of nutritional benefits of flours.