Studying the effect of pH, different concentrations of glutamic acid and salt on non-protein nitrogen compounds, survival and overall acceptance of low-fat probiotic cheese

Today, the demand for low-fat dairy products such as cheese has increased. Reducing fat in cheese reduces the sensory properties of cheese. The use of probiotic bacteria, fat alternatives and changes in production methods can improve the sensory properties of low-fat cheeses. The aim of this research is to investigate the effect of three independent variables including pH (4.7, 4.9 and 5.1), glutamic acid (1, 2, 3 mgg-1) and salt (2, 2.5 and 3%) on the amount of non-protein nitrogen compounds to total nitrogen, survival and overall acceptance of low-fat probiotic cheese during for 30 days’ storage. According to the results, the amount of non-protein nitrogen compounds to total nitrogen is increased during the ripening period in all samples, but this increase in the sample containing 2 mgg-1 glutamic acid, 2% salt and at pH 4.7 is significantly higher than other tested samples. The results are shown that with increasing the amount of glutamic acid and decreasing the amount of salt, the sensory properties and survival of probiotic bacteria is significantly increased. Probiotic bacteria are survived in all tested samples up to 30 days, but this survival is significantly more than other samples in the treatment containing 3 mgg-1 glutamic acid, 2% salt and at pH 4.9. The highest general acceptance score is belonged to the treatment containing 3 mgg-1 glutamic acid, 2% salt and pH 4.9, which was selected as the best treatment in terms of sensory and nutritional characteristics.