Effect of starter culture on the quality and yield of karish cheese made from buffalo's milk

Karish cheese was made from fresh buffaloes' skim milk (0.5% fat) using a commercial starter culture DOM 1® (Lactococcus lactis subsp.lactis and lactococcus lactis subsp cremoris (1:1)) and with natural starter from good quality karish cheese. Four treatments were made by using 1 and 2% natural starter culture (YS-1 and YS-2, respectively) and with 1 and 2% of DOM 1® starter culture (DS-1 and DS-2, respectively). Yield of the resultant cheeses were calculated. Chemical, microbiological and sensory characteristics of cheeses were monitored when fresh and during 60 days of storage at 5±2°C. Gross composition of all resultant cheeses was within the Egyptian legal limits for Karish cheese. The highest cheese yield (25.4%) was obtained when 2% of DOM 1® starter culture was added (DS-2). This increase in the cheese yield of DS-2 was associated with an increase in the cheese moisture content by 2.7% compared with YS-1 and 1.1% compared with YS-2 treatments. The pH values were decreased during storage period, but both YS-1 and YS-2 treatments had lower pH-values than DS-1 and DS-2 treatments. The highest values of SN and SN/TN were observed in the DS-2 cheese treatment. This could be an indication of more proteolysis occurred when 2% of the DOM 1® starter culture was used. DS-1 and DS-2 treatments showed a reduction in the losses of TS and TN contents in the pickling solution during storage compared with YS-1 and YS-2 treatments. It was also observed that YS-1 and YS-2 treatments had higher total viable bacterial and mold and yeast counts than that in DS-1 and DS-2 treatments. On the other hand, there was a slight increase in the total sensory score of the DS-2 treatment It can be concluded that manufacture of karish cheese by using 2% DOM 1® improved cheese yield, organoleptic properties and decreased losses of cheese components in pickling solution.