Changes in physicochemical and functional properties of Opuntia humifusa during fermentation with cellulolytic enzyme and lactic acid bacteria

Eastern prickly cactus (Opuntia humifusa) has a substantial therapeutic and dietary value. In this study, O. humifusa plants were fermented at 25 °C with cellulolytic enzymes (E, Viscozyme), lactic acid bacteria (LAB), Lactobacillus paraplantarum (Lp), Streptococcus salivarius (Ss), and Weissella confusa (Wc) in various combinations: E, LWS (Lp:Wc:Ss = 1:1:1, v/v/v), and E with LAB (E-Lp, E-Ss, E-Wc, and E–LWS). Significantly lower viscosity (14.5 cP) and higher yield (>97.4%) were observed in O. humifusa extracts containing E (P < 0.05), whereas the extract with LWS showed the highest viscosity (36.9 cP) and lowest yield (58.8%). Total polyphenol content and antioxidant activity of O. humifusa extract were enhanced, and flavonoid glycosides (isorhamnetin-3-O-rutinoside and isorhamnetin-3-O-glucoside) were effectively converted to aglycones when fermentation was performed with E and LAB. The isorhamnetin and quercetin contents were highest in the E-Wc and E-LWS extracts fermented for 60 h. This study shows that the physical and functional properties of O. humifusa extract may be modulated by fermentation with selected LAB and cellulolytic enzymes.