Determination of conjugated linoleic acid content and isomer distribution in three Cheddar-type cheeses: effects of cheese culture, processing, and aging

Conjugated linoleic acid (CLA) is a mixture of positional and geometric isomers of linoleic acid with conjugated double bonds. Several investigators have suggested that CLA has anticarcinogenic properties. This study describes the quantification of CLA isomers in three Cheddar-type cheeses relative to the effects of different cheese cultures, processing conditions, and aging periods. An improved method was developed for quantifying CLA isomers in cheese such that isomerization did not occur. Three 13-month-aged cheeses and one unaged cheese were analyzed for CLA concentration and isomer distribution. The CLA concentration in the fat of the aged and unaged cheeses ranged from 5.05 to 5.39 mg of CLA/g of fat. Isomers c-9,t-11-/t-9,c-11- and t-9,t-11-/t-10,t-12-octadecadienoic acids accounted for 82-88 and 8-11% of the total CLA, respectively. These results suggest that different starter cultures, processing conditions, and aging periods had negligible effects on the total CLA concentration but did influence the CLA isomer distribution in the cheeses studied