Natural fermentation as a tool to enhance the functionality of agricultural crops: a case study on Carica papaya leaf and Garcinia mangostana pericarp

The effect of natural fermentation on enhancing the antioxidant activity and cultivation of probiotics of Carica papaya leaf (CPL) and Garcinia mangostana pericarp (GMP) was evaluated to enhance the functionality of agricultural yields. To have better production, the antioxidant activity was estimated in terms of 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity (radical model) by Trolox (antioxidant model) and expressed as Trolox equivalent (mg TE) per dried extract mass (g), i.e., mg TE/g. The antioxidant activity of fermented CPL and GMP extracts were 1,117 ± 10.2 mg TE/g and 34.3 ± 0.7 mg TE/g respectively which are significantly higher (i.e., 68.8 ± 0.8 mg TE/g and 7.8 ± 0.3 mg TE/g) than the antioxidant activity of unfermented extracts of the respective materials. The study findings indicate that Lactobacillus plantarum and Lactobacillus brevis are obvious in the probiotics component which naturally fermented to CPL and GMP. The presence of yeasts such as Pichia kudriavzevii, Hanseniapora meyeri and Saccharomyces cerivisiae may improve the flavour of the naturally fermented CPL and GMP. The outcomes of this study will be helpful for stakeholders in enhancing the functionality of medicinal (agricultural) crops in Malaysia.