Optimization of enzyme treatment conditions for extraction of dietary fiber from Opuntia humifusa stem

Abstract

This study aimed to optimize the hydrolysis conditions required for extraction of dietary fiber from Opuntia humifusa stem using Viscozyme ® (MilliporeSigma, St. Louis, MO, USA) with response surface methodology (RSM). A central composite design was applied to examine the effects of the independent variables, enzyme concentration (0.5-2.5%, X 1) and reaction time (1-5h, X 2). The hydrolysis conditions were optimized using total yield, total dietary fiber (TDF), water-soluble dietary fiber (SDF), and water-insoluble dietary fiber (IDF) contents of hydrolysates as dependent variables. The total yield was 39.9-53.2% and the coefficient (R 2) of the derived equation from the response surface regression for total yield was 0.9073. The TDF and SDF contents in all hydrolysates were 29.02-43.82% and 27.25-40.68%, respectively, which were within the 1% level. The IDF contents in all hydrolysates were 0.98-3.80% (R 2 0.8886) and with in 5% significance. The optimal hydrolysis conditions comprised 1.0-1.8% Viscozyme ® and an incubation period of 1.0-1.8 h. Our results suggested that O. humifusa could be a source that might extend the application of dietary fiber in functional food industries.