Effect of different pre-soaking technique on physicochemical properties of canavalia ensiformis protein hydrolysate

Abstract

Canavalia ensiformis or Kacang Koro (Jack Beans) is one of the under-exploited tropical beans that contains between 25-35% crude protein content. Pre-treatments such as soaking helps to maintain the desired properties of protein hydrolysate, such as antioxidants, structure, high water capacity, oil-water capacity, and removing antinutrients. However, there is little information on the effect of soaking using different solvents on physicochemical properties of C. ensiformis. The main objectives of this study are to determine the effect of pre-treatments (A= lime juice, B=in 50% w/v tamarind solution (1:2) for 15 min and rinsed in distilled water, C=3% salt solution (1:3) and 50% (w/v) activated carbon solution (1:2), D= in distilled water (1:2) as control.) on physicochemical properties of C. ensiformis protein hydrolysate. The hydrolysates were evaluated based on moisture content, protein content, water holding capacity (WHC), oil holding capacity (OHC), emulsifying properties, solubility, degree of hydrolysis (DH), foam stability, foaming capacity and antioxidant properties using 2,2-diphenyl-2-picrylhydrazyl (DPPH) assay for antioxidant activities. The highest protein content (6.89±0.71%) was observed in treatment D. Treatment C exhibited the highest degree of hydrolysis water, oil holding capacity, emulsifying stability index (ESI), solubility and DPPH. The size of C. ensiformis protein hydrolysate analysed using scanning electron microscope (SEM) varies due to different pH soaking treatments between pH 5 to pH 10. C. ensiformis protein hydrolysate treated in treatment B showed the highest inhibition towards DPPH (27.23±4.65%). Overall, this study showed that the best technique for extracting a high quality C. ensiformis protein hydrolysate that can be used in food or pharmaceutical products was pre-soaking in salt and activated carbon, thus promoting the use of this under-utilized legume.