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

Abstract

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.Practical applications: The market interest in CLA and CLNA has increased because of their potential health-promoting properties. It has been suggested that increased levels of CLA and CLNA isomers in fermented food products might be obtained through the use of appropriate starter cultures. From the present study, it became clear that this approach is not straightforward and more research is needed to investigate the possibility of using selected bacterial strains to increase the levels of CLA and CLNA in fermented foods.

Dietary CLA supplementation of pigs confers higher oxidative stability to Ciauscolo and Fabriano salami produced from their meat with no negative impact on the physico‐chemical, microbiological and sensorial characteristics

“…The introduction of CLA into the diet did not significantly ( P > 0.01) affect the salami chemical composition, pH and a w both in Fabriano e Ciauscolo (Table ). These results are in agreement with previous studies who found that the incorporation of CLA into heavy pig diet did not modify the chemical composition of dried cured ham .…”

“…The administration of CLA‐enriched diets to pigs did not seem to interfere with the microbial evolution of the products. Furthermore, many strains of Lactobacilli , Lactococci and Streptococci are able to produce CLA from linoleic acid , therefore, improving functionality through CLA microbial biosynthesis in dry‐fermented meat products needs further consideration .…”

Conjugated Linoleic Acid in Milk and Fermented Milks: Variation and Effects of the Technological Processes

“…lactis in combination with S. thermophilus, was slightly higher than the CLA concentration of the starting milk (88,93,94). In contrast, there was no formation of CLA in fermented milks with strains of Bifidobacterium, despite having been chosen for their ability to produce CLA in vitro, and being cultured in substrates rich in linoleic acid (89).…”

Selection of Lactic Acid Bacteria for the Optimized Production of Sheep’s Milk Yogurt with a High Conjugated Linoleic Acid Content

“…As stated by Van Nieuwenhove et al (2007), different strains tolerate different concentrations of LA. Additionally, the inhibitory dose depends on the availability of the FA (Gorissen, Raes, De Smet, De Vuyst, & Leroy, 2012;Trigueros & Sendra, 2015). According to Kim and Liu (2002), the growth of Lactococcus lactis was completely inhibited at LA concentrations higher than 0.50 mg/mL.…”

“…According to Gorissen et al (2011), the conversion of CLA depends on the amount of free LA in the medium. Gorissen et al (2012) used Bifidobacteria and Lactobacillus sakei strains, which are able to produce CLA in vitro, as starter cultures for milk fermentation, and no significant increase in CLA content was observed, even with sufficient amounts of LA. This result is in accordance with the prior study (Gorissen et al, 2011), suggesting that the availability of free FA was likely too low.…”