INFLUENCE OF INDIGENOUS CULTURES AND RIPENING TEMPERATURES ON CHEDDAR CHEESE QUALITY

Abstract

Cheddar cheese cultures were isolated and purified from indigenous sources using various microbiological techniques and characterized on basis of sugar fermentation, biochemical and enzyme activity tests, growth at various temperatures, pH and NaCl concentrations and using API identification kits. Raw milk and sour cream were found the most suitable indigenous sources for isolation and purification of Lactococcus lactis ssp. lactis and Lactococcus lactis ssp. cremoris. The later was differentiated from the former by no acid production from maltose, ribose, mannitol, arabinose, inositol, trehlose, negative arginine hydrolysis test, no growth either in 4% w/v NaCl or at 40°C and pH 9.2. Commercially available and locally isolated strains of Lactococcus lactis ssp. cremoris and Lactococcus lactis ssp. lactis were propagated in combination of 95:5 to prepare the mother cultures. These mother cultures were employed in standardized buffalo and cow’s milks to manufacture Cheddar cheese and ripened at 4°C and 12°C for 120 days. During ripening, cheese was evaluated for physico-chemical composition and sensory quality. Buffalo milk cheese contained significantly higher fat, protein, ash, lactose, sodium, calcium, potassium and organic acids contents; particularly lactic, citric and butyric acid contents as compared to cow. Cheddar cheese prepared from indigenous cultures had significantly lower lactose and pH and higher acidity than commercial cultures. The concentrations of all the organic acids produced by indigenous cultures were distinctly higher than commercial cultures. During ripening, lactose and pH decreased while acidity increased significantly. The concentrations of all the organic acids increased highly significantly during ripening and elevated temperature considerably accelerated the production of all organic acids except pyruvic acid. Starter cultures and ripening temperatures substantially influenced the aldehydes, ketones and alcohols, while milk composition considerably affected the alcoholic and sulphur compounds. Descriptive sensory evaluation indicated that cheese samples prepared from buffalo milk using indigenous cultures were scored significantly higher for most of the attributes. Elevated temperature perceptibly accelerated the development of odor, flavor and texture characteristics during ripening. Hence, it is concluded that indigenous starter cultures and buffalo milk produced the cheese with improved quality and elevated temperature accelerates the process of ripening.