Some are biological acids produced by wine fermentation itself.
The other part is SO2 added artificially.
But there is a gasket between the metal lid on the bottle and the wine. There should be something wrong with the gasket, or the metal cover is loose, which causes the wine to evaporate and corrode the metal cover.
Pay attention to the wine, please pay attention.
"Ocean" wine
Produced by Yantai Zhangfu Brewing Co., Ltd.