Influence of fermentation on the nutritional value of two varieties of Vigna sinensis

Cowpeas ( Vigna sinensis) are a good source of protein and energy. They are widely consumed all over the world, mainly in rural populations, and satisfy a considerable proportion of the protein requirements. However, like other pulses, cowpeas contain several antinutritional factors, which limit their consumption and affect the digestibility and bioavailability of nutrients. Fermentation seems to enhance the nutritive value of legumes. The present work studies the effect of natural fermentation and subsequent cooking process of two varieties of Vigna sinensis on the content of protein, minerals, ash, fat, soluble and insoluble dietary fibre, α-galactosides, inositol phosphates, trypsin inhibitor activity (TIA), water-soluble vitamins (thiamin and riboflavin) and protein quality parameters, in vivo digestibility and PER (protein efficiency ratio). The processes applied caused a significant increase of vitamin B2, and significant reductions in the contents of TIA (40%) and phytates (100%), main antinutritional factors present in cowpeas. Likewise, the soluble fibre and α-galactosides compounds that produce flatulence diminished (67 and 100%, respectively). Protein digestibility for Orituco variety was adequate among legumes (82.8–88.4%), although only Vigna sinensis var. Orituco showed an acceptable PER value (1.63).