Bidirectional Solid-State Fermentation of Highland Barley by Edible Fungi to Improve Its Functional Components, Antioxidant Activity and Texture Characteristics

In food industry, the characteristics of food substrate could be improved through its bidirectional solid-state fermentation (BSF) by fungi, because the functional components were produced during BSF. Six edible fungi were selected for BSF to study their effects on highland barley properties, such as functional components, antioxidant activity, and texture characteristics. After BSF, the triterpenes content in Ganoderma lucidum and Ganoderma leucocontextum samples increased by 76.57 and 205.98%, respectively, and the flavonoids content increased by 62.40% (Phellinus igniarius). Protein content in all tests increased significantly, with a maximal increase of 406.11% (P. igniarius). Proportion of indispensable amino acids increased significantly, with the maximum increase of 28.22%. Lysine content increased largest by 437.34% to 3.310 mg/g (Flammulina velutipes). For antioxidant activity, ABTS radical scavenging activity showed the maximal improvement, with an increase of 1268.95%. Low-field NMR results indicated a changed water status of highland barley after fermentation, which could result in changes in texture characteristics of highland barley. Texture analysis showed that the hardness and chewiness of the fermented product decreased markedly especially in Ganoderma lucidum sample with a decrease of 77.96% and 58.60%, respectively. The decrease indicated a significant improvement in the taste of highland barley. The results showed that BSF is an effective technology to increase the quality of highland barley and provide a new direction for the production of functional foods.