Secalins are the major storage proteins of rye grain. Unlike wheat glutenins and gliadins, they form only weak, non-elastic networks, which is why rye breads are dense rather than airy. They also contain the protein fractions that make rye unsafe for people with coeliac disease. Understanding secalins helps bakers predict dough behaviour and helps clinicians explain why rye must be avoided in gluten-free diets. Rye’s distinctive flavour owes much to these proteins. Bakers work with them, not against them. They define rye’s character.