INTERNATIONAL ŒNOLOGICAL CODEX. Caseins. COEI-1-CASEIN: 2015. CASEINS. (Lactic Casein or Caseina acids) (Oeno 12/2003) OIV-OENO 555-2015. 1. OBJECT, ORIGIN AND FIELD OF APPLICATION Casein, a heteroprotein containing phosphorous, is found in milk in the state of calcium salt.