Changes and Correlations of Chemical Components and Quality of Moringa oleifera Leaf Tea at Different Stages of Four Fermentation Methods

Moringa oleifera leaf tea were fermented by natural fermentation, yeast fermentation, Rhizopus fermentation and Aspergillus niger fermentation. Color indexs, sensory quality and chemical components of Moringa oleifera leaf tea samples in different fermentation stages were determined, and correlations among chemical components were analyzed. Results showed that the main chemical components and quality of Moringa oleifera leaf tea samples in different fermentation stages were converted obviously. When Moringa oleifera leaf tea was fermented for 16 days, its sensory quality had been improved, and the contents of soluble protein and caffeine increased, while the contents of polyphenol, flavonoid, polysaccharide and water extract decreased. The color indexes △E^* value, a^* value and b^* value of soups of Moringa oleifera leaf tea fermented samples increased with the increase of pile-up times. The fourth pile-up sample of Moringa oleifera leaf tea fermented by Aspergillus niger had the best sensory quality, the contents of its polyphenol, flavonoid, soluble protein, polysaccharide, caffeine and water extract were 13.48, 10.99, 16.46, 27.38, 2.39 and 342.70 mg/g, and the color indexes a^* value, △E^* value and b^* value of its soup were 15.66, 28.48 and 36.42, respectively. The contents of water extracts (Y) of different fermented samples of Moringa oleifera leaf tea were significantly positively correlated with the contents of polyphenol (X₁), soluble protein (X₃) and polysaccharide (X₄), their correlation coefficients were 0.8821, 0.7598 and 0.7240, respectively, and the regression equation was Y=15.8337+0.6793X₁+0.2360X₃+0.0897X₄. The results of this study can provide the references for exploitation of Moringa oleifera leaf fermentation tea and utilization of this resource.