Investigation on antioxidant activity, protein, and whiteness degree of elicited cowpea sprouts flour prepared with various drying technique

Abstract

Cowpea (Vigna unguiculata) is a protein source legumes that exerted several advantages compared to the other legumes, such as rich in antioxidants and dietary fiber as well as provide various health benefits, can help restore soil fertility and more tolerant to the environmental stresses. Cowpea has a higher level of dietary fiber, productivity, and lower fat content than soybean. Germination prepared with elicitation techniques has been proved to be able to increase protein levels and antioxidant activity of legume sprouts. Previous author's research showed that elicitation using both NaCl as abiotic and Na-alginate as biotic elicitors effectively increased radical scavenging activity (RSA) and ferric reducing antioxidant power (FRAP) of cowpea sprouts. However, sprouts have a short shelf life due to the higher moisture content. A strategy to overcome this problem is by drying followed by milling sprouts to produce sprouts flour. This study aims to examine antioxidant activity (RSA, FRAP), nutrition (dissolved protein) and the whiteness degree of elicited cowpea sprouts flour prepared with various drying techniques (50ºC for 5 hours, 60ºC for 4 hours, 70ºC for 3 hours, and 80ºC for 2 hours). Cowpea sprouts were prepared by elicitation using 50 mM NaCl and 250 ppm Na-alginate solutions. The results showed that the drying technique had a significant effect on RSA, FRAP, dissolved protein levels and the whiteness degree of the flour. The drying technique using temperature of 80ºC for 2 hours resulted in elicited cowpea sprouts flour with higher RSA, FRAP, dissolved protein levels and whiteness degree than other drying techniques. These results have an important implication for the development of local legumes sprouts flour as a functional food.