Quality and Shelf Life Enhancement of Domiati Cheese From Heat Treated Milk Using Starter Culture

Abstract

Domiati cheese was made from heated cow's milk with tow levels of salt (5% or 10%) with adding 1% activated commercial starter cultures of YC-X11 (Str. thermophilus and Lb. delbruekii ss. bulgaricus, T1), Bio Profit (Lb rhamnosus and Propio. freudenreichii ss. shermanii, T2) and LC 705 (Lb. casei, T3). Resulting cheeses were pickled into its own whey. The low-salted cheese was pickled for 6 months and the high-salted cheese after 9 months. Moisture, salt and yield of low and high-salt cheeses decreased with adding starter culture, while an increase was noticed in the acidity, soluble nitrogen (SN) and total volatile fatty acids (TVFA). High salt cheeses had significantly higher values for moisture, salt and yield with significantly lower acidity, SN and TVFA than low salt cheeses. The values of moisture, salt and yield gradually decreased during pickling while acidity, SN and TVFA significantly increased. Domiati cheese with starter culture had higher total bacterial count (TBC) than that of control being highest in T3. Increasing the salt in cheese milk resulted in lower TBC. Values of TBC increased in all samples during early pickling and then sharply decreased till the end. There was a remarkable inhibition in the growth of sporeforming bacteria and yeasts & moulds with adding starter culture. Sensory quality attributes of cheese improved with adding starter culture. Pickling of cheese up to different periods led to better flavour as well as body & texture but extending the period beyond caused lower quality. The rate of improvement was faster in cheese of low salt than that from 10% salted milk. Starter culture of Bio Profit (T2) produced cheese with typical ripened cheese flavour and texture and can be recommended for low or high-salt cheeses.