The detoxification of cellular sulfite in table grape under SO₂ exposure: Quantitative evidence of sulfur absorption...

Sulfur dioxide (SO₂) and its derivatives are known to be hazardous but their common application in food, especially the grape industry, is conditionally allowed. Potential hazards to consumers and the environment could occur upon the control-lost SO₂ during grape logistics and storage. Researchers have usually focused on the anti-pathogen role of SO₂ whereas limited efforts were conducted on the sulfur (S) absorption, assimilation patterns, and sulfite detoxification. In this study, short-term, room-temperature, and SO₂-stored grapes were investigated, whose S flux of various forms was quantified through an estimation model. Accordingly, the additional accumulated S (0.50-0.86%) in pulps from atmospheric SO₂ was considered mainly through rachis transport compared to across skin surfaces and the usage arrangement of the absorbed S was included. The first quantitative evidence of induced S assimilation under SO₂ was also provided, which challenged the previous knowledge. In addition, sulfite oxidase and reductase (SiO and SiR) played major roles in sulfite detoxification, being effectively stimulated at multiple levels. The induced S metabolism associated with enhanced reactive oxygen species (ROS) scavenging capacity and alleviated senescence contributed to quality maintenance. Overall, these findings provide novel insights and are valuable supports for developing SO₂-controlling strategies to avoid potential hazards.