Object A new fermentation process of longan pulp with added Ganoderma lucidum was developed to generate a desirable polysaccharide profile of the finished product.

Method Being a valuable functional ingredient in food, polysaccharides were used as the evaluation indicator to optimize the ganoderma-longan fermentation (GLF) of longan pulp by incorporating Ganoderma lucidum. Carbohydrate metabolomics and polysaccharide contents of the broth before and after fermentation were analyzed to decipher the process mechanism.

Result The co-fermentation of non-spore Ganoderma lucidum with longan significantly increases the accumulation of polysaccharides, with the optimal fermentation conditions being: longan pulp concentration at 6.5%, longan pulp at pH 5.5, and shaking speed at 150 rpm. Under these fermentation conditions, the polysaccharide accumulation of GLF is (8.94±0.10) mg·mL⁻¹. The metabolic sugar compositions of the longan pulp and GLF showed 17 differential metabolites, of which 11 were up-regulated that included D-pineol, sucrose, and mannose.

Conclusion It appeared that GLF significantly accentuated the polysaccharide contents in the longan pulp due to the incorporation of G. lucidum.