EVOLUTION OF THE MICROFLORA AND PROTEOLYSIS DURING RIPENING OF HALLOUMI CHEESE AND A NEW HALLOUMI-TYPE CHEESE USING THERMOTOLERANT STARTERS Lactobacillus paracasei 0196 AND Enterococcus faecium 0165 AND PROTEASE OF Mucor miehei

摘要

Halloumi is the traditional cheese of Cyprus. The special characteristic in Halloumi technology is the heating of the blocks of pressed curd in whey at 90°C for 30 min. The heating of the curd destroys rennet and some of the microbes and this in combination with the fact that starters are not added to the milk lead to Halloumi cheese with a high pH grade and a low degree of proteolysis. The first aim of this study was the creation of a new production method for ovine Halloumi based on traditional Halloumi production technology which could enable intense ripening and better cheese preservation. For this purpose Halloumi cheese using traditional technology was produced and used for comparison with a new Halloumi-type cheese produced after the the following alterations to the production method: 1) Pasteurization of milk at 68°C for 10 min and addition of thermotolerant starters instead of using fresh milk without of starters. 2) Replacement of the rennet with Mucor meihei protease which is more thermotolerant than the classical rennet for the coagulation of milk. 3) Reheating the blocks of pressed curd in hot whey at 62°C for 30 min, instead of at 90°C for 30 min. 4) Preservation of the new cheese in whey which contained 10% NaCl at ambient temperature, compared with traditional cheese which was preserved at 4°C in sterilized brine containing 10% NaCI. The second aim of this study was to determine the changes in the total microbial flora, psychrotrophic bacteria, yeast moulds, coliforms, pH and soluble nitrogen, and a comparison of caseins in the traditional and new cheeses by electrophoresis. According to the results we succeeded in producing a new Halloumi-type cheese in which thermotolerant bacteria used as starters were not destroyed during the heating of the curd and thus contributed to the augmentation of the lactic acid microflora, reducing the pH grade and improving cheese preservation. Consequently, the use of the thermotolerant coagulant enzyme of Mucor miehei in combination with the suggested alterations in traditional technology enabled intense proteolysis of the caseins and a rise in soluble nitrogen during the preservation of the new Halloumi-type cheese compared to the traditional one.