616 Bulletin USAMV-CN, 63/2007 THE EVOLUTION OF SOME PHYSICAL-CHEMICAL AND BIOCHEMICAL PARAMETERS DURING MATURATION OF THE SEMI-HARD CHEESES Jimborean Mirela 1 , C. Laslo 1 , D. łibulcă 1 1 University of Agricultural Sciences and Veterinary Medicine, Faculty of Agriculture, 3-5 Mănăştur Street, 3400 Cluj-Napoca, Romania, mirelajimborean2004@yahoo.com Key words: ammoniac nitrogen, amine nitrogen, protein splitting indexes. SUMMARY Two experimental options for the obtaining of Holland Type cheese were studied: 1 st option: product obtained through seeding with lactic mesofile bacteria and Pseudomonas, adding of CaCl 2 , and coagulation with microbial curd. The samples were marked: M 1 – the witness sample after la obtaining; M 2 - the witness sample 14 days after obtaining; M 3 – the witness sample 30 days after maturation. 2 nd option 2: product obtained through seeding with lactic mesofile bacteria and Pseudomonas, adding of CaCl 2 , papain and coagulation with microbe curd. The samples were marked as follows: P 1 – the sample with proteolytic enzymes at production; P 2 – the sample with proteolytic enzymes 14 days from production; P 3 – the sample with proteolytic enzymes 30 days from production; P 4 – the sample with proteolytic enzymes 45 days from production. The sample harvest was made according to STAS 6343/81. Following methods were used for the analyses: - protein determination – through the Kjeldahl method, according to STAS 6355/89; - easy hydrolysable nitrogen according to STAS 9065/7-74. The protein contents of the cheeses recorded a reduction during maturation, thus:  in the witness sample the protein contents has fallen from 25.51% right after production, to 20.92% at the end of maturation, and total nitrogen has decreased from 4% to 3.28%;  in the proteolytic enzymes sample the protein contents has fallen from 27.14% right after the production, to 20.65% at the end of maturation, and total nitrogen has decreased from 4.25% to 3.24%. The contents of amine nitrogen has increased during maturation, from 168 mg% to 308 mg% in the witness sample and from 280 mg% to 532 mg% after 30 days, then a decrease to 448 mg% was found, after 45 days, in the cheese with addition of proteolytic enzymes. The proteic splitting index (N-NH 2 /N total ) has grown from 4.2 to 9.39 in the witness sample from 6.59 to 16.42 in the cheese with addition of proteolytic enzymes. The contents of amine nitrogen has grown during maturation. The increase was from 38.44 mg% to 109.02 mg% in the witness sample and from 48.9 mg% to 81.1 mg% after 30 days of maturation has reached the value of 91.87 mg% after 45 days of maturation, in the cheese with addition of proteolytic enzymes. The protein splitting index (N-NH 3 /N total ) has grown from 0.96 to 3.32 in the witness sample and from 1.15 to 2.5 in the cheese with addition of proteolytic enzymes. BIBLIOGRAPHY 1. Costin, G. &CO, 2003, The science and engineering of cheese make, Academic Publishing House, GalaŃi; 2. Fox, P.F., O’Connor, T.P., McSweeney, P.L., Guinee, T.P., O’Brien, N.M., 1996, Cheese: physical, biochemical, and nutritional aspect, Adv. Food Nutrit. Res., 3, 163-328.