Improvement in physicochemical characteristics, bioactive compounds and antioxidant activity of acerola (Malpighia emarginata D.C.) and guava (Psidium guajava L.) fruit by-products fermented with potentially probiotic lactobacilli

Abstract

The effects of a submerged fermentation with a mixed inoculum composed of potentially probiotic Lactobacillus isolates, namely L. casei L-26, L. fermentum 56, L. paracasei 106 and L. plantarum 53, on physicochemical characteristics, bioactive compounds and antioxidant activity of acerola (ACE) and guava (GUA) fruit industrial by-products were measured. Viable counts of probiotic lactobacilli in ACE and GUA after a 120 h-fermentation were of ≥5.5 log CFU/mL. Fermented ACE and GUA had increased luminosity and decreased contrast. Contents of total soluble solids and pH decreased and titrable acidity increased in ACE and GUA during fermentation. Ascorbic acid contents decreased in ACE and increased in GUA during fermentation. Different phenolic compounds were found in ACE and GUA during fermentation. Fermented ACE and GUA had increased contents of total flavonoids and total phenolics and antioxidant activity. Contents of total flavonoids and total phenolics were correlated with antioxidant activity in fermented ACE and GUA. These results indicate that submerged fermentation with probiotic lactobacilli could be a strategy to improve the contents of bioactive compounds and antioxidant activity of ACE and GUA.