Influence of the strains of Loctococcus used as a starter on the characteristics and ripening properties of Turkish white cheese

ABSTRACT PhD THESIS INFLUENCE OF THE STRAINS OF Lactococcus USED AS A STARTER ON THE CHARACTERISTICS AND RIPENING PROPERTIES OF TURKISH WHITE CHEESE Ali Adnan HAYALOGLU DEPARTMENT OF FOOD ENGINEERING INSTITUTE OF NATURAL AND APPLIED SCIENCES UNIVERSITY OF ÇUKUROVA Supervisor : Prof. Dr. Mehmet GÜVEN Year: 2003, Pages: 170 Jury Prof. Dr. Mehmet GÜVEN Prof. Dr. Celalettin KOÇAK Prof. Dr. Harun UYSAL Assoc. Prof. Dr. Nuray SAHAN Assist. Prof. Dr. Işıl VAR In this study, Turkish White-brined cheese was manufactured by either using some Lactococcal strains {Lc. lactis subsp. lactis NCD0763 plus Lc. lactis subsp. cremoris SKI 1 and Lc. lactis subsp. lactis UC317 plus Lc. lactis subsp. cremoris HP) or without starter culture, and the experimental cheeses were ripened for 90 days. It was found that the usage of starters have significantly influenced the physical, chemical, biochemical and sensory properties of the cheese (p<0.01). Chemical composition, pH values and sensory properties of starter added cheeses were not affected by different starter bacteria. In addition, water-soluble fractions and urea-PAGE of the pH 4.6-insoluble fractions were found to be significantly different in some stages of ripening. Urea- PAGE patterns of the pH 4.6-insoluble fractions of the cheeses showed that there was a considerable degradation of oCsj-caseins and it was found that p-casein were more resistant to hydrolysis. The use of different starter bacteria significantly influenced the 12% TCA-soluble nitrogen, 5% PTA- soluble nitrogen, total FAA, total FFA, amino acid composition and RP-HPLCs of pH 4.6-soluble, 70% ethanol-soluble or -insoluble fractions of the cheeses. The peptide concentration of cheeses were increased during ripening. The PCA plots or HCA dendrograms of electrophoretic and chromatographic results indicated that the cheeses were found to be significantly different and they were grouped based on the usage and types of starters and ripening stages. Free amino acid levels of the cheeses were different and, Leu, Glu, Phe, Lys and Val were the most abundant amino acids. Nitrogen fractions, total FAA, total FFA and peptide concentrations detected by RP-HPLC increased during ripening, and the effect of ripening was significant on above parameters. There were no significant differences found between the sensory properties of starter-added cheeses, but the cheese with no starter received lower points than starter added cheeses during ripening. However, the cheese made with NCD0763 plus SKI 1 was voted as the best cheese during ripening by the tasters. It was concluded that the use of different starter bacteria significantly cause a difference on the quality of cheeses, and each starter bacteria contributes to cheese proteolysis in different manners. Key Words: White Cheese, Lactococcus, ripening, peptide, amino acid. II