Mohammed Zyarah Eskander*⁽¹⁾

(1). Department of Food Science, Faculty of Agriculture, Basra University, Basra, Iraq.

(*Corresponding author: Dr. Mohammed Eskander. E-Mail: mohamed_alklom@yahoo.com).

Received: 19/08/2017                                 Accepted: 03/10/2017

Abstract

The study included the extraction of pepsin EC: 3.4.23.1 chicken gizzard lining type Broiler, using extraction solution (4% boric acid, 0.5% sodium benzoate and pH 5.6) at a rate of 4:100 (w/v). Enzyme was precipitated with ammonium sulphate at 20-60% saturation. The proteolytic activity and milk-clotting activity of pepsin were 23.786, 2.653 (units/ml) respectively, and the rate of (milk-clotting activity/proteolytic activity) was 8.965. The effects of pH and temperature on the milk-clotting activity were also evaluate. The extracted pepsin showed the highest milk-clotting activity at pH 5 and 50 ^oC. The results indicated that milk-clotting activity decreased with the increment in NaCl concentration. The partially purified and chicken gizzard lining immobilized pepsin were utilized in soft cheese manufacture and compared with calf rennet, the results showed an increase in the percentage of soluble nitrogen/total nitrogen in the partially purified pepsin cheese, compared to the immobilized pepsin and calf rennet during the storage periods of 1, 3 and 7 days at 5 ^o C. Also, the results of the chemical composition and sensory evaluation of cheese produced by the immobilized pepsin was compatible with calf rennet.

Key words: Pepsin, Chicken gizzard, Milk-clotting activity, Soft white cheese.

Full paper in Arabic: PDF