Biochemical and Flavour Profile of Lingzhi (Ganoderma lucidum) Mycelium Fermented by Lactiplantibacillus plantarum: A Dual-Modelling Approach to Umami Synergy and Antioxidant Capacity

The broader application of Lingzhi (Ganoderma lucidum) in functional foods is fundamentally restricted by its intense, triterpenoid-driven bitterness. This study investigated the biochemical changes in Lingzhi mushroom mycelium (LMM) over a 10-day controlled fermentation with Lactiplantibacillus plantarum. To evaluate bioactivity enhancement, a dual predictive modelling strategy (Partial Least Squares Regression [PLSR] and elastic-net) was applied to the non-volatile metabolite matrix, identifying model-supported candidate contributors to TPC and FRAP antioxidant responses. Concurrently, fermentation significantly transformed the matrix, yielding an estimated 24-fold increase in synergistic umami intensity, with Equivalent Umami Concentration (EUC) increasing from 0.27 to 6.49 g MSG/100 g fermented LMM by Day 10. This increase was primarily driven by the accumulation of glutamic acid (Taste Activity Value [TAV] = 1.27) and its potent synergy with 5'-GMP (TAV = 2.82). Furthermore, Principal Component Analysis (PCA) of GC-MS volatile data revealed a distinct temporal transition from lipid-derived aldehydes to microbially generated 'mushroom' alcohols and mid-fermentation esters, suggesting enhanced aromatic complexity. These findings indicate that targeted L. plantarum fermentation can convert raw LMM into a bioactive ingredient with enhanced umami and antioxidant capacity suggesting potential for improved palatability that warrants sensory confirmation.