[Effect of a differentiated additive KNO3 on the quality of Zuławski cheese. I. Nitrate changes in maturing Zuławski cheese].

18 gyle of cheese in three experimental variants were produced: O variant--control product without additive KNO3; 1 variant--with 0.01% of additive KNO3; 2 variant--with 0.02% of additive KNO3. It was found that raw and pasteurized milk was not an essential source of nitrates. During the summer and autumn cycles of production it was noted respectively: 0.0-0.8 mg NO3-/kg and 0.0-7.4 mg NO3-/kg. Content of NO3- ions in cheese starter approximated their content in raw milk. However, content of nitrates in milk after preparing depended mostly on the quantity of added saltpeter. The cheese made without saltpeter was characterized by low level of nitrates, not exceeding 4.2 mg NO3-/kg, and by vestigial presence nitrites. Whereas the cheese made with additive KNO3 included to 40 mg NO3-/kg for 0.01% of additive KNO3 and to 80 mg NO3-/kg for 0.02% of additive KNO3. It was found that the most intense reduction of nitrates in cheese (to 75%) occurred between the phase of pressing and up to the first two weeks of its ripening. After four weeks' ripening process the level of nitrates in cheese became stabilized independently of the quantity of additive KNO3. After six weeks' ripening process, that is when the cheese is sent into consumption, the level of nitrates and nitrites was quite low and did not exceed 3.0 mg NO3-/kg and 1.2 mg NO2-/kg. Manufactured cheese met the requirements of FIL/IDF while taken into consideration the content of nitrates and nitrites.