Abstract:
As a rare and valuable edible fungus native to Guizhou Province, challenges in industrial upgrading due to the impact of drying temperatures on the retention of functional components during dry product processing were faced by
Dictyophora rubrovalvata (DR). In this study, the investigation on air-source heat pump-dried DR samples at 40, 45, 50, and 55 ℃ (labeled as DR40, DR45, DR50, and DR55, respectively) was conducted using liquid chromatography-mass spectrometry (LC-MS)-based non-targeted metabolomics. By using principal component analysis (PCA), orthogonal partial least squares discriminant analysis (OPLS-DA), KEGG pathway enrichment analysis, and differential abundance (DA) score analysis, dynamic metabolic changes and network responses under varying drying temperatures were systematically characterized. The detection of a total of 4470 metabolites was conducted, primarily distributed across 21 major classes (88.46% of total), including lipids, fatty acyls, and steroids. At 40~45 ℃, metabolic stability was high, with only 1071 differential metabolites (DR45 vs. DR40), in which a small disparity between upregulated (757) and downregulated (314) metabolites was shown. At 50 ℃, differential metabolites increased to 1,219 (DR50 vs DR40), with significantly more upregulated (993) than downregulated (226) metabolites, indicating metabolic system activation to maintain homeostasis. At 50~55 ℃, differential metabolites sharply decreased to 577 (DR55 vs DR50), with downregulated metabolites (328) surpassing upregulated ones (249), so metabolic system damage beyond the temperature threshold was presented. From KEGG enrichment analysis, high temperatures (≥50 ℃) were shown to significantly affect lipid, flavonoid, and antioxidant-related pathways, so metabolic network reconstruction was caused. Based on the study, a temperature-sensitive threshold of~50 ℃ for DR drying was confirmed, with 40~45 ℃ preserving original metabolic characteristics, thus offering a theoretical basis for optimizing industrial drying processes, recommending temperatures below 50 ℃ to minimize functional component loss.