Fermentation-Induced antioxidant properties by lactic acid bacteria from fresh African indigenous leafy vegetables consumed in Cameroon

Abstract

InformationThis study aimed to identify lactic acid bacteria (LAB) from fresh African indigenous leafy vegetables (AILVs) consumed in Cameroon and screen them for total phenolic content and antioxidant capacity upon fermentation.The LAB were isolated from four AILVs; Solanum scabrum (African nightshade, AN), Telfeiria occidentalis (fluted pumpkin, FP), Amaranthus hybridus (Amaranthus vegetable, AL) and Talinum triangulaire (Waterleaf, WL).The LAB isolates were identified biochemically and molecularly.The LAB strains were then preserved in 20% glycerol at -20°C and later reactivated to carry out fermentation of the AILVs.Fermentation trials using a systematic replicate screening design, were conducted at 27°C with each LAB strain over a period of 0-4 days.The pH, total phenolics (FrP and BF), and antioxidant activities; ferric reducing antioxidant power (FRAP), 2,2-diphenyl-1-picrylhydrazyl(DPPH) and total antioxidant capacity (TAC) were assessed using standard methods.The LAB isolates were identified by 16S rRNA gene sequencing as Lactiplantibacillus plantarumL52, Lactiplantibacillus plantarumL31, Leuconostoc mesenteroidesL33, Leuconostoc mesenteroidesL2 and Lactiplantibacillus pentosusL7.Fermentation with L. plantarumL52 strain significantly (p ≤ 0.05) decreased the pH from 6.39±0.006 to 3.82±0.006in the AILVs.L. plantarumL31 fermented AILVs significantly increased (by 56.6% and 140.2%)FrP content and TAC activity respectively while L. mesenteroidesL33 significantly recorded the highest percentage DPPH (7.7%) and FRAP (106.9%)activities after 4 days.The most improved active metabolite trend was observed at 3 days of fermentation after screening.Overall, L. plantarumL31 and L. mesenteroidesL33 were the most functionally effective strains, and AN emerged as the most potent substrate among the vegetables.examined.