Evaluation of Nitrogen Fractions during the Ripening of Jug Cheese
- *Corresponding Author:
- Fariborz Kianpour
Department of Clinical Microbiology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran.
Received date: 16/06/2014; Accepted date: 19/07/2014
Jug (pot) cheese is a kind of delicious, semi-hard, and salty cheese in Azerbaijan region, Iran, which is traditionally produced from raw sheep's or cow's milk in rural households and then spends its ripening period under soil, which varies from 3 to 6 months. Given that this type of cheese is traditional and originally from Azerbaijan region, in this study for the first time, nitrogen fractions such as total nitrogen, non-casein nitrogen, and non-protein nitrogen were measured during the ripening of jug cheese. In this work, first, the cheese was ripened in two ways: being storing for 45 days in brine at 10°C and being storing for 90 days without brine in the 7±1°C fridge. Results showed that all nitrogen fractions increased during the cheese ripening. Moreover, concentration of tyrosine amino acid as a ripening indicator was determined by preparing of tyrosine standard curve and measuring of its absorption at the wavelength of 650 nm by a spectrophotometer device during the ripening period. It was observed that concentrations of this amino acid gradually increased during ripening, which represented the progress of proteolysis during this period. Also, effect of milk pasteurization on nitrogen fractions was examined and it was concluded that milk pasteurization had a small effect on these factors.