Postharvest ripening of two varieties of corns: Structure, antioxidant activities and physicochemical properties of zein

•Postharvest ripening resulted in more disordered and less compact structure of zein.•Radical scavenging capacity of zein was promoted by controlling postharvest ripening.•Postharvest ripening improved zein's emulsifying, foaming and rheological properties.•Structural changes of zein affected its antioxidant and physicochemical properties.