SHELF-LIFE AND RHEOLOGICAL PROPERTIES OF COTTAGE CHEESE MADE FROM CAMEL MILK

Abstract

This study was aimed to investigate the shelf-life and rheological properties of cottage cheese made from camel milk as physicochemical properties, microbial counts and texture. The experiment was laid out in completely randomized design (CRD) with eight treatments. The general chemical composition of milk including fat, solids-not-fat (SNF), protein, total solid, casein and lactose were determined using MilkoScan. Cheeses were made in the dairy technology laboratory of Haramaya University using Streptococcus thermophilus and Lactobacillus delbrṻeckii spp. bulgaricus as starter culture and chymosin as coagulant. The cheeses were stored in refrigerator (4 C) and at room temperatures (18 C) for periods of 1, 8, 15 and 22 days. Then, analyzed following standard procedures at each storage periods and temperatures. Results in this study indicated that storage period significantly (P<0.05) affected the physicochemical properties of cheese. Total protein, fat and total solids of the cheese significantly (P<0.05) increased during storage. Storage temperature also significantly (P<0.05) affect crude protein, fat, pH and titratable acidity. However ash contents showed not significant difference in both storage temperatures. Microbial quality of the cheese was significantly (P<0.05) affected by storage periods and storage temperatures. Cheese sample kept at room temperature was higher in total bacterial count, coliform count, yeast and mould counts (6.79 log cfu/gram, 7.21 log cfu/g and 6.41 log cfu/g) than sample kept at refrigerator temperature (4.76 log cfu/g, 4.09 log cfu/g and 4.84 log cfu/g counts), respectively. Hardness of the cheese were significantly (P<0.05) affected by storage temperature and storage time. The cheese sample stored at refrigerated temperature significantly (P< 0.05) increased from 3.77±0.17 N at day one to 6.67±0.12 N at day 22, while adhesiveness was not significantly (P 0.05) affected. It is concluded that cottage cheese stored at refrigerator had acceptable shelf-life till days 22 of storage period but cheese that kept at room temperature (18 C) had 5 to 6 days of shelf-life based on standard recommended limit bacterial contamination of food. Therefore, to increase cottage cheese shelf-life, stored at 4 C is recommended and pre-contamination at processing stage could be avoided.