MICROBIAL PRODUCTION OF CONJUGATED LINOLEIC ACID (CLA) : DEVELOPMENT OF FUNCTIONAL DAIRY PRODUCT: AN OVERVIEW
Conjugated linoleic acid (CLA) is a generic name for a group of positional and geometric isomers of linoleic acid (LA), cis 9, cis 12,octadecadienoic acid) in which the double bonds are conjugated instead of the methylene interrupted configuration of LA. Of these isomers, cis-9, trans-11 and Trans 10, cis12 octadecadienoic acid (C 18: 2) has been reported as the most biologically active fatty acids that confer beneficial health effects on human. CLA isomers are found mostly in milk, dairy products and meat of ruminant animals.
Interest in the beneficial health effects of CLA was reported over the years since nineties of the 20thcentury. Such benefits are: increase metabolic rate, decrease abdominal fat, enhance muscle growth, lower cholesterol and triglycerides, lower insulin resistance, reduced risk of vascular diseases and anticarcinogenic effect.
Microbiological production of CLA has been recently attracted considerable research studies. The capability of several bacterial genera to convert linoleic acid in the forage of ruminants into CLA has been highlighted in many studies .The major CLA producing bacteria are: lactic acid bacteria (LAB), bifidobacteria, and propionibacteria.
Lactic acid bacteria (LAB) comprised 13 genera namely,Carnobacterium,Enterococcus, Lactobacillus,Lactococcus,Lactosphaera,Leuconostoc,Melissococcus,Oenococcus, Pediococcus,Streptococcus,Tetragenococcus,Vagococcus and Weissellaamong phylum Firmicutes. LAB were isolated from milk, fermented milk, cheese and other plant sources. They inhabit human and animal intestinal tracts and play a significant role positively affect the health of the host. LAB are regarded as a unique group of bacteria having probiotic effect due to its capability to produce bioactive compounds such as peptides including antimicrobials , fatty acids , vitamins, and antioxidants. Probiotics refer to a live microbial feed or food supplement which beneficially affects the host by improving its intestinal microbial balance . LAB metabolites play a significant role in metabolism and detoxification of foreign substances and free radical entering the body of the host.
Recently, manufacture of functional dairy products such as cheese and yogurt rich in CLA, using unique adjunct probiotics, as vehicles provide adequate dietary CLA for human consumption has received considerable interest by dairy processors. The aim of the present overview was to highlight some aspects in the production of functional dairy products to satisfy modern consumer interest looking for their life betterment through increased tendency toward functional food consumption.
Keywords: Microbial CLA, probiotic bacteria, functional foods, LAB