Phenolic content, antioxidant activity and biodiversity changes during spontaneous fermentation of Carica Papaya leaf

Abstract

The spontaneous fermentation was carried out on Carica papaya leaf (CPL) in view of its potential improvement on antioxidant functionality and cultivation of lactic acid bacteria. The effect of the spontaneous fermentation on the total phenolic content and antioxidant activity of CPL, as well as biodiversity profiling were evaluated in this study. Total phenolic content and antioxidant capacity of the fermented CPL were 31.14 mg GAE g-1 and 405.8 mM TE g-1 respectively, higher than the unfermented CPL (5.71 mg GAE/g and 130.5 mM TE g-1) respectively. Microbial community was predominantly lactic acid bacteria (LAB) and yeasts, both populated at 104 to 108 CFU/mL during most part of the fermentation. Presumptive Enterobacteriaceae showed up briefly at the onset of the fermentation before disappearing. PCR-DGGE fingerprinting revealed Lactobacillus plantarum (Lb. plantarum) as the sole dominant bacterial species. More diverse yeasts community was detected by PCR-DGGE where succession of Zygosaccharomyces, Saccharomyces, Candida and Aspergillus genera were detected along fermentation time. Spontaneous fermentation successfully enhanced the total phenolic content and antioxidant capacity of the CPL. The cultivation of lactic acid bacteria was indicated by the presence of Lb. plantarum, whereas the disappearance of Enterobacteriaceae conferred a safe consumption of the fermented CPL.