Optimization of Processing Parameters for Camel Milk Cheese Production

Abstract

Pakistan share is one million heads of the world’s 20 million camel population. Although camel is not considered the major milk source in Pakistan, it has been utilized to support the growing demand of milk products and fresh milk. Camel cheese is gaining popularity due to their nutritional and therapeutic potential, hence to manufacture camel milk cheese (CMC) is not an easy task. The main problems faced by researchers and processors for camel milk cheese production is the longer coagulation time and low yield of cheese. The hypothesis of this study was there is a potential to increase the yield and reduce the coagulation time camel milk, and consequently the quality of cheese, by optimizing the processing conditions. To select the optimum processing conditions, preliminary trials were conducted using pasteurization temperatures (60, 65, 70°C), pH (5.3, 5.5, 5.7), CaCl2 (0.04, 0.06, 0.08%) and buffalo milk (0, 10, 20%) using yield and coagulation time as criterion for the evaluation of the process’s sucess. The whole research work was divided in two studies. In study-I, eighty one combinations of these selected processing parameters were used for cheese production at laboratory scale, and evaluation was done for the yield, coagulation time, texture, acidity, fat, protein and moisture contents. It was concluded from this study that coagulation time can be reduced to 50 min and yield increased to 20% when the milk is pasteurized at 65°C, pH is reduced to 5.5 and CaCl2 is added at 0.06% before the coagulation of milk. The fat, moisture, proteins and texture were 16%, 65%, 17%, and 6 N respectively. Quality attributes were improved with the increase of buffalo milk addition, but the addition of only 10% was chosen to facilitate the coagulation process. Study-II was performed to assess the influence of starter culture for the CMC quality attributes. Four cheese samples designated as camel (milk) cheese by using mesophilic cultures (CM), camel (milk) cheese with thermophilic cultures (CT), camel + buffalo milk (10%) cheese with mesophilic cultures (CBM) and camel milk + buffalo milk (10%) with thermophilic cultures were prepared and stored at 4°C for 60 days, evaluated for physico-chemical, sensory and proteolytic aspects. The results showed significant (p<0.01) influences for cheese samples and storage days on the pH, acidity, moisture, protein and fat contents. The interactive effect of these variables was insignificant (p>0.05) except the (p<0.05) pH. Results showed that highest moisture content (70.19%) was in CM treatment whereas the lowest was found in CBT treatment (55.19%). Lower acidity value was observed in CM (0.63%) and CBM (0.66%) compared to CT (0.78%) and CBT (0.83%), however the more protein (21.04, 21.57%) and fat (17.65, 17.70%) was retained in the CBM and CBT, respectively during storage. All the quality parameters decreased significantly during storage except of acidity. Results of sensory analyses showed a significant (p<0.01) impact of processing conditions on all sensory attributes. CBT treatment was the preferred cheese by the panelist followed by CBM and CT. All CMC samples were acceptable for sensory attributes up to 30 days of storage. In a proteolytic study (Urea-PAGE and RP-HPLC) of the samples, it was noted that level of intact caseins (s,  and k-caseins) were decreased with the increase of storage time, addition of buffalo milk and thermophilic cultures. A higher extent of proteolysis was observed in CBT followed by CBM, CT and CM. From both studies, it is concluded that 65°C/30 min temperature of pasteurization, pH 5.5, CaCl2 0.06%, addition of buffalo milk (10%) with thermophilic starter cultures (L. bulgaricus and Strep. Thermophillus) produced CMC with good characteristics.