Effect of fermentation on the bioactive compound composition and antioxidant potential of opuntia sp. Fruit juices

ALLENDEZ, G.; LÓPEZ ALSOGARAY, S.; NAZARENO, M. A.

Coquimbo

Congreso; IX International Congress on Cactus Pear and Cochineal; 2017

The effect of fermentation of fruit juices of two types of Opuntia sp. (purple and green pulp fruits) on bioactive compounds and antioxidant potential was evaluated. The fermentation was performed with previously isolated yeast from naturally fermented juice of Opuntia sp. fruits. Ethanol tolerance of yeast to different concentrations of fortified wine (10-12-15 % v/v) was evaluated for 7 days at 28°C, sealed with vaspar plug. Yeast previously activated for 48 hours at 30°C in potato dextrose broth (PG) broth was inoculated at 0.2% v/v of pasteurized juice in a 125 ml Erlenmeyer flask. Thereafter, it was incubated for 5 days at 28°C. Total soluble solids (TSS), pigment (betaxanthins and betacyanins) concentrations, phenolic contents and antioxidant properties were determined at the beginning and at the end of fermentation process. Yeast showed excellent growth in the fortified musts at 10 and 12% v/v but it was scarce at 15% v/v. The CO2 pressure generated during fermentation indicated that the strain was able to grow in the alcoholic medium. The phenolic content was higher in the purple fruit juice than in the green one (2.29 and 1.90 mg gallic acid/g of juice, respectively). The same was the case for the antioxidant capacity. Opuntia juice fermentation slightly increased the phenolic content as well as the antiradical capacity. TSS reduced due to fermentation from 15 to 12° Brix in the green juice and from 13 to 9° Brix in the purple one. Initially, the betacyanin contents were 23.7 and 116.0 mg betanin/g juice and betaxanthin contents were 6.4 and 71.1 mg/g juice for the green variety and the purple one, respectively. After fermentation, betacyanin contents were 18.1 and 113.3 mg/g juice and betaxanthin contents were 4.9 and 78.7 mg/g juice, for green and purple variety, respectively. Fermentation did not significantly affect the bioactive compound contents and properties of Opuntia fruit juices.