An integrated study using ultrasonic-assisted enzymatic extraction of hydrolysates from rice based distillery byproduct and its characterization

Abstract

The present study aim is to establish a greener approach by integrating an ultrasonic process that is amalgamated with enzymes for distillers dried grains with solubles (DDGS), a distillery by-product, into an improved value-added product. A good synergistic effect is recorded by applying ultrasonication in conjunction with enzymatic extraction of protein from rice-based DDGS. The ultrasonic-assisted extraction (UAE) method was examined for optimum conditions using Box-Behnken design (BBD) based response surface methodology (RSM). The optimized parameters viz. amplitude, solid loading and extraction time, were obtained as 90.01%, 10% and 18.06 min, respectively which yielded 65.76% of DDGS protein. The coefficient of determination (R2) for extracted protein (%) and degree of hydrolysis (DH) were 0.981 and 0.976, respectively validating a good fit of the model with the experimental data. The protein hydrolysates obtained after ultrasonic-assisted enzymatic hydrolysis were found to exhibit significantly (P < 0.05) improved functional properties in comparison to untreated DDGS. Additionally, the effects of applied treatment was evaluated by a reduction in the particle size, structural changes (XRD and FE-SEM) and their functional properties (solubility, water holding capacity, oil holding capacity, emulsification, and foaming properties). The obtained results reveal that ultrasonic-assisted enzymatic hydrolysis was capable of enhancing the functional properties of extracted protein hydrolysate. Therefore, ultrasonic-assisted enzymatic hydrolysis can be applied as a promising technology for improving protein yield and functionalities of rice DDGS protein, which could facilitate the potential application of distillery by-products in the food industry.