Sauerkraut is finely shredded white cabbage (Brassica oleracea var. capitata) salted and packed tight so it ferments under its own brine. Lactic-acid bacteria turn it sour, tangy, briny and lightly fizzy while it keeps a firm, crunchy bite — a German and Central and Eastern European staple, the French choucroute, eaten with pork, sausage and rye, and prized as a source of vitamin C and live bacteria that helped keep sailors free of scurvy.