Effect of Soaking and Salt-Water Blanching on the Proximate, Antinutrients and Amino Acid Profile Composition of Cream Coloured Pigeon Pea Flours

Abstract

The study was on the effect of processing: soaking and salt-water blanching and cooking on the proximate, anti-nutrient and amino-acid composition of cream coloured pigeon pea seeds’ flours. The proximate composition analysis showed significant (p>0.05) differences between the values obtained for crude protein, ash, fat, crude fibre, carbohydrates and moisture, in the raw/untreated and the processed pigeon pea. Healthy cleaned pigeon pea seeds (2.5kg) were divided into five portions of 500 g each. They were subjected to five different processing methods and coded AOP, BXY, CZK, DRN and EVT respectively. AOP represented the untreated flour; BXY represented salted and 1h boiled pigeon pea flour; CZK represented salted and 2h boiled pigeon pea flour; DRN represented 24h soaked and 1h boiled pigeon pea flour while EVT represented 2h boiled pigeon pea flour sample. The flours’ crude protein contents ranged from 19.54 to 21.68%, crude fat ranged from 2.40 to 3.96%; ash ranged from 3.48 to 5.20 %; fibre ranged from 9.45 to 10.19%, moisture ranged from 4.70 to 6.46 % while carbohydrates ranged from 50.48 to 57.49%. In the anti-nutrients’ assays, processing significantly reduced the levels of oxalate, saponins, alkaloids, tannins, cyanide and phytate. In addition to the significant differences, straight cooking without salt blanching or soaking yielded the highest levels of leucine, lysine, phenylaline, tryptophan, valine, methionine and histidine, 7 out of the 8 essential amino acids. The result of essential amino acid indices of the sample flours revealed that the flours are of good protein quality. This result also showed that straight-cooking yielded highest crude protein and highest levels of the essential amino acids. Also, processing generally lowered the levels of anti-nutrients in the pigeon pea seeds’ flours, thus making them safer for consumption. Salt-blanching yielded more softening and pastry product.