DEVELOPMENT OF A NEW METHOD FOR THE DETERMINATION OF RENNIN ACTIVITY

Abstract

Dairy products take an important place in food industry all over the world, especially, cheese industry that has more than a thousand product variety. Millk and rennin are the most important constituents of the cheese production. Rennin can be obtained by different ways, however, animal based rennin is usually used in cheese industry. This kind of rennin is obtained from stomach region of young calfs and lambs. Rennin consists of 75 % chymosin and 25 % pepsin enzyme. When rennin is added to milk, casein particles, that are in milk, get an unstable situation. As a result k-casein divides into two parts. These parts are named as calciumparacaseinate and caseinomacropeptide (CMP). This reaction is the basic of cheese production. One of the important parameters in cheese industry is the determination of milk clotting activity of rennin. Because, knowing that how much milk can be coagulated by how much rennin is a parameter that should be taken into account due to economic reasons. Currently using methods for determining standard rennin power include some weak points. A new method is studied that is based on devices in order to remove these weak points which increase fault probability. In this new method, caseinomakropeptid molecule that emerge from proteolysis of milk with effecting rennin (chymosin) is adsorped by Amberlite IRC86 weak asidic cation exchanger resin and then eluated with sodium chloride solution. After that, increasing of the primary amine nitrogen proportion in post coagulation of milk is analysed by using Harding and MacLean's (ninhydrin) method. A formulation is obtained between this increase and coagulation period. Thus, rennin activity can be analyzed by spectrophotometric technique. This innovated process has been compared with the determination method for the classical rennin activation, and it has been understood that there are not any significant Standard deviation between them.