Microbial production of conjugated linoleic and linolenic acids in fermented foods: Technological bottlenecks

Several food-grade bacteria are known to produce conjugated linoleic acid (CLA) and conjugated linolenic acid (CLNA) from linoleic acid (LA) and a-linolenic acid (ALA), respectively. Therefore, bifidobacteria and a Lactobacillus sakei strain, able to produce CLA and CLNA in vitro, were applied as starter cultures for the fermentation of milk and meat, respectively. However, for both the fermented milk and meat no increase in CLA and CLNA content was obtained. Although LA and ALA were present in sufficient amounts in milk, their availability as free fatty acids was likely too low. During meat fermentation, the prevailing temperature and pH conditions most probably were the limiting factors for conversion of LA and ALA.