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-An overview of the present knowledge on the influences of dairy processing and storage on the content of conjugated linoleic acids (CLA) and to possible differences between organic and standard products is given. In organic dairy products CLA was reported to be from not significantly up to 135% higher. Newer studies on the effect of heating steps show no changes in CLA content or isomer profiles, with the exception of microwaving, where CLA was decreased by up to 53%. In commercial dairy products no effects of fermentation on CLA content were observed. Recent studies on cheese showed no changes in the CLA content during manufacturing or ripening. CLA content was stable during butter-making out of CLA-enriched milk. In several more recent investigations with probiotic bacteria (lactic acid bacteria such as Lactobacillus rhamnosus or Lactobacillus acidophilus, and propionibacteria and bifidobacteria such as B. breve and B. dentium) or other strains of these bacteria groups on a laboratory scale, an increase in CLA could be observed under the condition that free linoleic acid (LA) was available in the culture medium. Conversion rates reached up to 87% with Propionibacteria freudenreichii ssp. shermanii. In cultivated form, B. breve reached a comparably high concentration of 398 mg CLA·L -1 broth. Especially high concentrations of up to 40 g CLA·L -1 broth could be produced with resting cells of Lactobacillus plantarum and Lb. acidophilus or with immobilised cells of Lb. delbrueckii ssp. bulgaricus. CLA formation in yoghurt could be observed under the condition that free LA was added. After 14 days of storage the increase was 77%. Specific procedures allow one to increase the content of CLA in a fraction. These procedures are dry fractionation (63% increase), fractionation using supercritical carbon dioxide (89% increase) and crystallisation (concentration 2.5 times). Numerous studies on the shelf-life stability of CLA-enriched dairy products showed no significant differences in flavour quality parameters. conjugated linoleic acid / dairy product / processing / shelf-life stability / organic product 共轭亚油酸 / 乳制品 / 加工 / 货架稳定性 / 有机的Résumé -Influence de la fabrication sur la composition des acides gras et la concentration en acides linoléiques conjugués dans des produits laitiers biologiques et standards. La présente étude donne une vue d'ensemble des connaissances concernant l'influence de la fabrication et du stockage des produits laitiers sur la concentration en acides linoléiques conjugués (CLA) et les différences possibles entre les produits biologiques et les produits standards. Dans les produits laitiers bio, il est reporté que la concentration en CLA est plus élevée dans des proportions allant de non significatif à 135 %. Il ressort de nouvelles études conduites sur l'effet du chauffage que celui-ci n'entraîne aucune modification au niveau de la concentration en CLA ou de la répartition des isomères, à l'exception du chauffage par micro-onde avec lequel la concentration en CLA pouvait être inférieure ...

-The influence of typical feeds from five mountain regions of Switzerland (altitude of grass-based feed (GBF) during the summer and winter seasons: 1247 (± 465) m and 1136 (± 310) m, respectively) on the fatty acid (FA) composition of bovine milk fat was studied over one year (from May 2004 to April 2005. Compared with winter, summer milk had a significantly lower concentration of saturated FA (SFA) (-8.6%) and significantly higher contents of monounsaturated FA (MUFA) (+19.9%), polyunsaturated FA (PUFA) (+21.7%), conjugated linoleic acid (CLA) (+70.1%), and trans FA other than CLA (+56.7%). Summer and winter milk from mountains did not significantly differ with respect to the contents of branched, n-3 and n-6 FA. However, the content of the main n-3 FA (α-linolenic acid) was significantly higher in summer than in winter milk and its content was positively correlated with increasing percentages of GBF and altitude. milk fat / fatty acid / mountain milk / winter milk / summer milk