Das Lab und seine Wirkung auf das Casein der Milch. IX. Über die Abspaltung von Nicht‐Protein‐Stickstoff (NPN) aus isoliertem α‐ und β‐Casein durch Lab

Abstract

AbstractDuring the action of crystalline rennin on solutions of α‐casein, Non Protein Nitrogen (NPN) soluble in 12% trichloroacetic acid is split off. The NPN/time curves greatly resemble the ones obtained by Alais, Mocquot, Nitschmann & Zahler for whole casein. Both primary reaction and general proteolysis are clearly recognizable. β‐casein under the same conditions shows only the general proteolysis (straight NPN/time curve). As is known, the α‐casein alone is responsible for the curdling of milk under the action of rennet. These results, therefore, support the assumption that the specific splitting reaction, which sets free a small amount of NPN very quickly, is directly responsible for the milk clotting.