Combined volatile compounds and non‐targeted metabolomics analysis reveals variation in flavour characteristics, metabolic profiles and bioactivity of mulberry leaves after Monascus purpureus fermentation
Biao Wang, Yichen Duan, Chengmo Wang, Chun Liu, Jun Wang, Junqiang Jia, Qiongying Wu- Nutrition and Dietetics
- Agronomy and Crop Science
- Food Science
- Biotechnology
Abstract
Background
Mulberry leaves (MLs) are widely used in food because of their nutritional and functional characteristics. However, plant cell walls and natural bitterness influence nutrient release and flavor properties of MLs. Liquid‐state fermentation using Monascus purpureus (LFMP) is a common processing method used to improve food properties. This study used headspace solid‐phase micro extraction gas chromatography‐mass spectrometry (HS‐SPME‐GC‐MS) and non‐targeted metabolomics to examine changes in volatile and non‐volatile metabolites in MLs. The transformation mechanism of LFMP was investigated by microscopic observation and dynamic analysis of enzyme activity, and changes in the biological activity of MLs were analyzed.
Results
LFMP significantly increased total phenolics, total flavonoids, free amino acids, and soluble sugars in MLs, while decreasing phytic acid levels. A total of 92 volatile organic compounds (VOCs) were identified and quantified in this study. VOCs such as (2R,3R)‐(‐)‐2,3‐butanediol, terpineol, and eugenol showed some improvement in the flavour characteristics of MLs. By using non‐targeted metabolomics, 124 unique metabolites in total were examined. LFMP altered the metabolic profile of MLs, mainly in plant secondary metabolism, lipid metabolism and amino acid metabolism. Microscopic observation and dynamic analysis of enzyme activity indicated that LFMP promoted MLs' cell wall degradation and biotransformation. In addition, LFMP significantly increased the ACE, α‐glucosidase inhibitory activity of MLs.
Conclusion
LFMP altered the flavour characteristics, metabolite profile and biological activity of MLs. These findings will provide ideas for the processing of MLs into functional foods. In addition, they also provide useful information for biochemical studies of fermented MLs.
This article is protected by copyright. All rights reserved.