molecular identification of lactic acid bacteria from a close commercial and development of a new consortium for the production of a new raieb without swelling.

摘要

the application of modern technology of food processing, and the application of the principles of quality, the cab - foodborne infections are the basis of 6.5 to 33 million human diseases and more than 9000 deaths every year in the world (mead et al., 1999). the food is the source frequently called into question.the usual means of prevention, such as treatment, high pressure, radiation, pasteurization, sterilization) and chemical (nitrite, sulfite, etc.) often compromise the quality of the food, and it is also the case of dairy products, such as the raieb.the raieb is a fermented milk product, origin, moroccan, obtained by the spontaneous caillement raw milk in 24 to 36 hours at room temperature. the production of lactic acid bacteria raieb involved.in fact, the lactic fermentation may be defined as a fermentation process, which is a group of gram positive nonmotile, nonsporulating, catalase negative, which grow under anaerobic conditions and the use of carbon sources for p roduction of lactic acid as the sole or major organic acid (ketiku and oyenuga, 1970).the lactic acid bacteria are a set of heterogeneous species whose common feature is the production of lactic acid. they belong to different types such as b (fidohacteri11111, enterococc11s, lactohacil / 11s, lactococc11s, le11conostoc, pediococcus, streptococc11s, aerococrns, alloicocc11s and carnohacteri11111 (beuchat, 1995).the action of lactic acid bacteria during the fermentation was associated first with the development of the flavour and texture of the final product, but also in the maintenance of good food with organic acids.therefore, it has been reported that fermented food, help to reduce the duration and severity of diarrhoea in children (mensah et al., 1990; kimmons et al., 1999). the main problem of these traditional methods is at the level of the quality of various foods obtained which is very fluid.in fact, the fermentation process is carried out automatically by the development of the epiphytic microflora may lead to products of the organoleptic quality, microbiological or toxicological reaction.in order to overcome this problem, research is increasingly devoted to the isolation and identification, in the course of fermentation, lactic acid bacteria, characterized by specific physiological and metabolic properties for use as a culture starters (mr. olasupo et al., 1996; agati et al., 1998; el al hounhouigan sanni et al., 1999;2002; kostinek et al., 2005; oguntoyinbo, 2007). these are defined as microbial preparations concentrated at least a microorganism that can achieve a better control of the fermentation process, as well as standardization of the manufacturing process (holzapfel, 2002).in fact, the bacteria of the genus lactococcus are widely used in the dairy industry for the production of a wide variety of fermented milk product (macura and townsley, 1983; oberman and libudzisz, 1998). its importance is mainly in the formation of lactic acid and production of flavour minor (broom and limsowtin, 1998; kieronczyk et al., 2003).cultures of lactococcus play a key role in determining the quality of fermented milk products with regard to the length of life and quality of sensory (smit et al., 2005). so far, two major subspecies of lactococcus are extensively used in the dairy industry, lactococcus lactis subsp. lactis and lactococcus lactis subsp.cremoris, lactococcus cremoris (lc) capable of producing flavor by degradation of bitter peptides (salama et al., 1991; sandine, 1988).it is usually incorporated into dairy products through acid and proteolytic activity of lactococcus lactis and lactococcus diacu00e9tylactis (i) or (ld) are involved in the formation of the flavor diacetyl (formed from citrate metabolism. they are also incorporated in the starter cultures for the head.in some fermented dairy products, ll and ld) play an important role in improving the texture, cerning 1990; the ecsc ob and shin, 2001).