21 C.F.R. § 172.180 Stannous chloride.
Title 21 - Food and Drugs
The food additive stannous chloride may be safely used for color retention in asparagus packed in glass, with lids lined with an inert material, in an amount not to exceed 20 parts per million calculated as tin (Sn).
Title 21: Food and Drugs
PART 172—FOOD ADDITIVES PERMITTED FOR DIRECT ADDITION TO FOOD FOR HUMAN CONSUMPTION
Subpart B—Food Preservatives
§ 172.180 Stannous chloride.

