Process optimization for the production of ghee residue protein hydrolysates

Abstract

The nutritional potential of ghee residue (GR) still remains untapped. Hydrolysis of proteins is known to decrease allergenicity, improve their functionality, and also induces bitterness. Present investigation was aimed to optimize the production process of GR proteins hydrolysates through two stage enzymatic hydrolysis of 5× ultrafiltered (UF) retentate (12.56% total solids and 8.77% protein). First stage hydrolysis was optimized at 42°C temperature, 8.0 pH using 4% papain with 5 h hydrolysis time (14.48 degree of hydrolysis, %DH). Increased hydrolysis time, significantly increased the DH % without any bitterness in the hydrolysate. Second stage hydrolysis was carried out using three food grade enzymes viz. trypsin (0.2%), alcalase 2.4L (0.25%) and flavourozyme 1000L (0.25%), by adjusting pH of 5× UF retentate to 8.0, 7.0 and 7.0 at 38, 50 and 50°C, respectively. Period of hydrolysis was optimized for each enzyme to 8 h with 26.99, 29.22 and 37.44 (%DH), respectively. Increase in hydrolysis time (optimized 13 h), significantly increased the %DH and bitterness in optimized hydrolysate. Further, period of hydrolysis, type of enzymes and their interaction, significantly effected % DH. Optimized hydrolysate obtained with papain (fist stage hydrolysis), trypsin (0.2%), and flavourozyme 1000L enzymes (second stage) was slightly bitter (3.68 on 4-point sensory scale). This optimized process can be adopted for commercial production of GR protein hydrolysates to meet the ever growing demand of easily digestible foods that will also be helpful to combat the problem of protein energy malnutrition.