Optimization of Anti-nutritional Removal, Protein Extraction of Cowpea (Vigna unguiculata L.) and Characterization of Its Functional Properties
Bambang Dwi Wijatniko, Chelsea Rie Eliza, Agnes Murdiati

Department of Food and Agricultural Product Technology, Faculty of Agricultural Technology, Universitas Gadjah Mada, Yogyakarta
corresponding email: nicodw92[at]gmail.com

Abstract

Cowpea is a local legume that is rich in protein while it is often used widely as vegetable dish. The high protein content in cowpeas makes it is potential to be utilized as protein isolate. However, cowpeas also contain some anti-nutritional compounds which can lower the nutritional quality of the cowpeas. It is necessary to reduce the antinutritional contents from the cowpea by combination of treatments. The objective of this study was to investigate the optimum treatments for antinutritional removal and protein extraction to produce protein isolate. Removal of antinutritional was performed by combination of soaking treatment with duration of 24, 48 and 72 hours with 5 percent NaHCO3 solution and boiling for 0, 2.5 and 5 minutes. The protein extraction was conducted by adjusting the pH to optimum protein solubility of cowpea according to various pH at 2, 4, 6, 8, 10, 11 and 12.
The results showed that soaking of cowpeas seeds for 48 hours with 5 percent NaHCO3 enabled to significantly reduce the HCN levels into 0.72 ppm, phytic acid of 9.62 mg/g, and trypsin inhibitor of 7.02 mg/g. The protein concentrate was obtained from protein extraction by using optimum pH at 12 while precipitation of protein by using pH 4 with protein concentration at 70.9 percent. The cowpea protein concentrate has water holding capacity of 3,99 ml water/g sample, oil holding capacity of 3,49 ml oil/g sample, emulsion capacity of 38,33 percent, emulsion stability of 78,57 percent, foaming capacity of 59,22 percent and foaming stability of 94,29 percent. The functional properties of the cowpeas protein concentrate indicated a promising potency for utilizing as binder in food system.

Keywords: Anti-nutrition- removal- cowpea protein- protein extraction- functional properties

Topic: Food Chemistry