Effect of processing methods on anti-nutritional factors and protein digestibility of cowpea

Abstract:

Think of cowpea as a protein vault with the lock still on anti-nutritional factors like phytate, tannins, and trypsin inhibitors bind minerals and block enzyme access, locking away much of the grain's 23-25% protein from human digestion. This research compared five processing methods (soaking, boiling, soaking+boiling, germination, fermentation) for their ability to reduce six anti-nutritional factors and improve in vitro protein digestibility (IVPD) in cowpea variety Caupí Rojo at Instituto de Ciencias Agrarias del Llano, Villavicencio, Colombia. Fermentation (72 hours, natural lactic) achieved the greatest overall reduction: tannins by 77.4%, phytate by 68.6%, trypsin inhibitor by 85.3%, and lectins by 94.9%. IVPD improved from 64.2% (raw) to 86.1% (fermented), a 34.1% gain. Germination (72 hours) ranked second with 72.2% tannin and 61.9% phytate reduction. Simple boiling alone removed only 38-53% of most ANFs. These results confirm fermentation as the most effective single-step processing method for maximising cowpea nutritional quality in Colombian food systems.