# Metabolomic insights into Monascus ‐fermented rice products: Implications for monacolin K content and nutritional optimization

## TL;DR

This study explores how different monacolin K levels and sterilization methods affect the metabolism of fermented rice products, offering insights for improving their nutritional and medicinal value.

## Contribution

The study provides novel metabolomic insights into how monacolin K levels and sterilization methods influence the metabolic profile of Monascus-fermented rice products.

## Key findings

- Variations in monacolin K levels significantly alter metabolite profiles, including organic acids, lipids, and nucleosides.
- Sterilization methods and use of highland barley as a fermentation substrate induce distinct metabolic changes.
- Key metabolic pathways affected include those related to longevity, cGMP-PKG signaling, and unsaturated fatty acid biosynthesis.

## Abstract

This study aims to elucidate the detailed metabolic implications of varying monacolin K levels and sterilization methods on Monascus‐fermented rice products (MFRPs), acclaimed for their health benefits and monacolin K content. Advanced metabolite profiling of various MFRP variants was conducted using ultrahigh‐performance liquid chromatography coupled with tandem time‐of‐flight mass spectrometry (UHPLC‐Q‐TOF MS). Statistical analysis encompassed t‐tests, ANOVA, and multivariate techniques including PCA, PLS‐DA, and OPLS‐DA. Notable variations in metabolites were observed across MFRPs with differing monacolin K levels, particularly in variants such as MR1‐S, MR1.5‐S, MR2‐S, and MR3‐S. Among the 524 identified metabolites, significant shifts were noted in organic acids, derivatives, lipids, nucleosides, and organic oxygen compounds. The study also uncovered distinct metabolic changes resulting from different sterilization methods and the use of highland barley as a fermentation substitute for rice. Pathway analysis shed light on affected metabolic pathways, including those involved in longevity regulation, cGMP‐PKG signaling, and the biosynthesis of unsaturated fatty acids. The research provides critical insights into the complex metabolic networks of MFRPs, underscoring the impact of fermentation substrates and conditions on monacolin K levels and their health implications. This study not only guides the nutritional optimization of MFRPs but also emphasizes the strategic importance of substrate choice and sterilization techniques in enhancing the nutritional and medicinal value of these functional foods.

Monascus‐fermented rice products (MFRPs) are widely used in traditional and modern medicinal practices for their health benefits and monacolin K content, which is a natural statin that can lower cholesterol levels. However, the comprehensive metabolic impact of varying monacolin K levels and sterilization methods on MFRPs has not been fully elucidated.