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CREATION OF A LACTIC ACID CULTURES COLLECTION MODELLING AND CONTROL TECHNICS OF THERMOPHILIC CULTURES

Objective

MATHEMATICAL MODELS OF MIXTES BACTERIAL CULTURES FROM THE BASIS FOR THE DEVELOPMENT OF ALGORITHMS FOR THE CONTROL OF FERMENTATION PROCESSES SUCH AS THE PRODUCTION OF YOGOURTH. THE ALGORITHMS ISSUE OF THE PRESENT RESEARCH SHOULD HELP TO RATIONALISE PRODUCTION PROCESSES IN THE DAIRY INDUSTRY AND SHOULD PERMIT A BETTER CONTROL OF THE PRODUCT QUALITY.
Lactic acid bacteria culture collections do not exist in Greece. Pure cultures used in the production of traditional cheese and yogurt products made from ewe's and goat's milk must be imported and do not adapt easily to growth in these substrates. On the other hand, mixed microbial cultures are widely used in the production of dairy products, wine, bread, etc, but knowledge of these cultures is still very poor. Their modelling and control may improve this situation.

A thermophilic lactic acid bacteria culture collection from traditional Greek dairy products was created. Common studies on biochemcial properties (enzyme activities, antibiotic resistance, etc), genetic material (plasmid deoxyribonucleic acid (DNA)) and technological properties (acidification, viscosity, flavour compounds) enabled classification of strains and selection of the most interesting for yogurt manufacture. Selection was completed by developing mixed cultures of previously defined strains. All streptococcal strains had urease activity and 8 strains contained 1 or 2 plasmids, which made them suitable for genetic studies.
An automated method for online determination of the acidification characteristics of the strains was developed. It is called a CINAC system.
Polynomial models describing the effect of pH and temperature on kinetics and production characteristics of the strains were established for pure and mixed cultures. A diagram was developed enabling the determination of pH and temperature in order to maximize the final bacterial population with respect to the ratio of each population.
EXCHANGE OF LACTIC ACID BACTERIA WITH ESA, ATHENS, AND IDENTIFICATION OF WILD STRAINS FROM MEDITERRANEAN DAIRY PRODUCTS.

STUDIES OF THE METABOLIC PATHWAYS OF MIXED MICROBIAL CULTURES USED IN FERMENTED DAIRY PRODUCTS. MODELLING AND IDENTIFICATION OF CONTROL PARAMETERS, ELABORATION OF CONTROL ALGORITHMS. EXPERIMENTAL VERIFICATION OF THE MODELS AND CONTROL ALGORITHMS.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

Institut National de la Recherche Agronomique (INRA)
Address
11 Rue Jean Nicot
75007 Paris
France

Participants (1)

AGRICULTURAL COLLEGE OF ATHENS
Greece
Address

Athens