Which substance is used both for caustic peeling in fruit and vegetable canning and in food-preservation processes that inhibit microbial growth?

Explanation

Sodium hydroxide, also called caustic soda or lye, is used for caustic peeling during fruit and vegetable processing. It also has a role in food-preservation processes: strongly alkaline conditions can inhibit microbial growth. This identifies both uses described in the question; it does not mean that sodium hydroxide is an all-purpose preservative for every food.