In the hope of increasing the availability of different strains for cheese manufacture, it is proposed to isolate and classify the starter bacteria found in these natural fermentations and to determine their genetic relatedness, their metabolic and physiological properties and their ability to produce flavour compounds. Cheese will be made with those strains with the best technological properties. An additional hope is the possibility of producing new fermented dairy products if strains with different flavour profiles are isolated.
Many cheeses and fermented milks in Southern Europe are made by natural fermentation in which the lactic acid bacteria adventiously present in the milk, grow and produce acid. The major objective of this project has been to isolate and preserve strains of lactic acid bacteria from these natural fermentations for possible use as industrial cultures. Strains with unusual flavour profiles have also been isolated which may ultimately result in the development of new fermented dairy products with different flavours. A third objective was to develop a suitable probe for distinguishing the different subspecies of lactococci and for use in isolating strains with commercially significant properties.
A starter culture containing lactic acid bacteria which grow rapidly in milk is an absolute requirement for cheese manufacture where their main functions are to produce lactic acid, flavour compounds and protein hydrolysis products during cheese ripening. In most cheese manufactured in the EC commercial starters are used. Many of the strains in these cultures are fairly closely related, especially in terms of their phage sensitivity and their ability to produce lactic acid and flavour compounds. In the use of these cultures, inhibition of acid production by phage is the major industrial problem. However, in particular areas of some EC countries (eg France, Greece, Spain, Italy and Portugal) the starters used are produced by allowing raw milk or whey to sour naturally or by using raw milk without souring. In the latter case, the lactic acid bacteria present in the milk grow during manufacture and ripening to produce the necessary amounts of lactic acid. Little or nothing is known about the bacteria present i these 'natural' cultures but it is believed that the indigenous lactic acid bacteria found in them are quite different from those found in commercial cultures.
Funding SchemeCSC - Cost-sharing contracts
20060 Zelo Buon Persico Milano
2745 Queluz De Baixo
6710 Ede Gld