Optimization of enzymatic hydrolysis of cucurbitin using response surface methodology: Improvement of the functional properties

Abstract

Optimization of enzymatic hydrolysis of cucurbitin, extracted from pumpkin (Cucurbita pepo) oil cake with bromelain, was carried out by response surface methodology (RSM). Second-order polynomial model (R2=0.791) has been proposed for the effect of time (t), and enzyme/substrate ratio (E/S) on degree of hydrolysis (DH). Conditions for obtaining maximal value of DH were determined (E/S= 0.0132 (w/w), t= 42 min). Furthermore, according to the regression equation, conditions for production of hydrolysates with target DH values were chosen. Comparison of the functional properties of cucurbitin and its hydrolysates (DH= 10%, 20% and 30%) were carried out. The solubility of the hydrolysates gradually increased with the increase of DH, in pH range of 6-8. The hydrolysate with DH=10% had the best emulsifying properties (EA=0.632 ± 0.02 A500nm, ES= 44.2min), and extent of hydrolysis decreased both emulsifying activity and emulsifying stability. All studied hydrolysates exhibited higher oil-holding capacity and have improved foaming properties compared to the original protein. DH has influence on foam capacity. The highest foam capacity has hydrolysate with DH=20% (150.3±3.66 %). Obtained results suggest that limited protease hydrolysis of cucurbitin with bromelain produces the hydrolysates with improved functional properties and indicate their possible use in different food systems. © 2011 De Gruyter. All rights reserved.