The skin of Boerewors is also know as the casing. So what is the skin of the Boerewors made of? Some casings are made of intestines that have been well trimmed and properly cleaned. You also get casings made from things like collagen and alginate. You’ll find collagen in bones as the main protein of connective tissue, and alginate is a viscous gum that comes from seaweed. The casing is quite important. If there was no casing, it would be boeremince.