Healthy cheese: Influence of milk fat components on microbial activity and development of bioactive components in fat reduced cheese.

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Consumers often regard cheese with reduced fat content of inferior quality; since it often obtains a too elastic and cohesive texture and a deficient flavour. An increased intake of fat-reduced dairy products is recommended by the health authorities. Rece nt research has shown the potential of cheese as a carrier of probiotic bacteria in addition to its content of conjugated linoleic acid (CLA), fat globule membrane components and bioactive peptides. In order to develop healthy cheeses with reduced fat con tent it is essential to understand the influence of the milk fat on cheese ripening and quality. Since proteolysis has had the main focus in cheese research, there is not, at present, sufficient knowledge on the influence of milk fat on cheese ripening. R esent research has shown that some bacteria important for cheese ripening live on the fat globule interface, most probably they utilise fat globule membrane components for survival. In fat reduced cheese a lower number of some of these bacteria have been shown and in these cheeses the development of typical flavour compounds diverge from full fat cheese. Three lines of research will be followed in this project: Line A: The growth, selection and metabolism of lactic acid bacteria will be characterised by m olecular methods in cheese differing in fat content, milk fat composition and the amount of fat globule components. Line B: The utilisation of milk fat and fat globule membrane components and their metabolic products produced by selected strains of lacti c acid bacteria (LAB) and propionic acid bacteria (PAB) will be studied in vitro (under cheese like conditions) and in cheese. Line C: The probiotic potential of LAB and PAB strains important for cheese ripening will be evaluated in vitro by testing thei r acid resistance, bile tolerance and ability to adhere to human cell lines.