Changes in fatty acid, simple sugar, and oligosaccharide content of cowpea ( Vigna unguiculata) flour as a result of soaking, boiling, and fermentation with Rhizopus microsporus var. oligosporus

Abstract

Changes in fatty acid, simple sugar, and oligosaccharide content of cowpea flour as a result of soaking, boiling, and fermentation with Rhizopus microsporus var. oligosporus were investigated. The major fatty acids in flour made from both nonfermented and fermented cowpeas were linoleic, palmitic, and linolenic. With the exception of lower amounts of lauric, palmitic, linoleic, and linolenic acids and slightly higher amounts of lignoceric acid, the remaining fatty acids in flour made from soaked cowpeas were essentially unchanged from the control flour made from cowpeas that were not soaked, boiled or fermented. Soaking followed by boiling generally increased amounts of fatty acids in flour compared to the control. Rhizopus microsporus did not utilize lipid during 24 h of fermentation. Soaking decreased the amount of sucrose and stachyose by 39% and 18.4%, respectively, whereas soaking followed by boiling caused decreases of 58.3% and 49.3%. Complete elimination of sucrose, raffinose, and stachyose was achieved after 15 h of fermentation.