Sodium bisulfate is a type of chemical compound made up of sodium, hydrogen, and sulfur. It is commonly used as an acidic agent in cleaning products and pool chemicals to remove dirt, bacteria, and other impurities. Full definition
This indicates that chemicals such as sodium bisulfate has been used on the shrimp. (theeverythingdogsite.com)
One of the more obscure ingredients found in many pet foods are menadione derivatives - in the form of menadione sodium bisulfate, menadione sodium bisulfite, menadione dimethylprimidinol sulfate, menadione dimethylprimidinol sulfite or menadione dimethylpyrimidinol bisulfite, often listed as «a source of vitamin K activity» or «vitamin K supplement». (dogfoodproject.com)