Amino acid profile, microbiological and farinographic properties of African locust bean pulp flour

Abstract

Flour was prepared from African locust bean (Parkia biglobosa) fruit pulp and evaluated for the amino acid composition, microbiological and farinographic characteristics. The locust bean pulp flour contained 4.8% total crude protein and 17 amino acids. The major amino acids in the locust bean pulp flour protein were glutamin acid, aspartate acid, leucine and arginine. Leucine, lysine and phenylalanine were the major essential amino acids. Methionine had the lowest concentration and tryptophan was the second limiting amino acid in the locust bean pulp flour protein. The bacteria isolated from the pulp included Bacillus cereus, Leuconostoc and Streptococcus species .The yeasts and moulds found in the pulp were Rhizopus and Saccharomyces species. Colifoms were not detected in the pulp. The total bacteria count was 4.6 x 104 cfu/g. The Bacillus cereus, Streptococcus aureus, yeasts and moulds counts were 0.5 x 104, 3. 2 x 104 and 2.4 x 104cfu/g, respectively. The farinographic water absorptions were 60 % and 68% for wheat flour and the African locust bean pulp flour, respectively. The water absorption increased with increase in the level of locust bean pulp flour in the blends. The dough development time was higher for the locust bean pulp flour (3.0 min) than for wheat flour (1.7 min).The dough development time increased steadily with increase in the level of African locust bean pulp flour addition. The mixing tolerance index decreased from 79 BU (Brabender unit) in wheat flour to 42 BU in the blend containing 90 % locust bean pulp flour. The dough stability also decreased with increased level of the locust bean pulp flour in the blends. African locust bean pulp flour and wheat flour blends have the potential for use in baked food products.