Effect of Drying Method on Sulfur Dioxide Content in Edible Mushrooms and Endogenous Transformation Factors

In this study, dietary risk assessment of sulfur dioxide content in both fresh and dried commercially available edible mushrooms (Tremella fuciformis, Lentinus edodes, and Agaricus blazei) was conducted through risk quotient and point assessment methods. Furthermore, to elucidate the factors governing endogenous sulfur dioxide transformation in edible mushrooms, the effects of different drying methods (hot air drying, natural air drying, and vacuum freeze drying) on key parameters such as sulfur dioxide content, glutamic acid-oxaloacetate aminotransferase activity, sulfur-containing amino acids content, and sulfur-containing volatile compounds content, were further analyzed. The results revealed that the sulfur dioxide levels in fresh commercially available edible mushrooms adhered to the national standard (50 mg/kg), while the dried varieties of Tremella fuciformis, Lentinus edodes, and Agaricus blazei exceeded the national standard by 16.54%, 30.00%, and 26.67% respectively, and the dietary risk of these edible mushrooms were found to be an acceptable risk. Post-treatment with various drying techniques, the sulfur dioxide residues in the dried edible mushrooms conformed to the standard and were significantly elevated compared to their fresh counterparts (P<0.05). The levels of glutamate-oxaloacetate transaminase, sulfur-containing amino acids, and sulfur-containing volatile compounds in dried edible mushrooms all increased, which suggested that different drying methods could promote the conversion of sulfur-containing amino acids and the formation of sulfur-containing volatile compounds, leading to an increase in sulfur dioxide content in dried edible mushrooms. This study provides solid theoretical guidance for industrialized processing technology and high-quality sustainable development of edible mushrooms.