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

Abstract

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 13month-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-ll-/t-9,c-lland t-9,t-ll-/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.

Conjugated linoleic acid contents in cheeses of different compositions during six months of ripenin

“…In contrast, others have described that the period of ripening does not alter CLA contents (Werner 1992;Luna et al 2007), because, on one hand, a longer time for the bacteria to act involves an increase in the CLA contents, whereas, on the other, oxidising reactions could lead to the destruction of the double bonds, thus decreasing CLA levels (Lin et al 1995;Domagala et al 2010).…”

Derivatization of fatty acids and its application for conjugated linoleic acid studies in ruminant meat lipids

“…54,57 It has been reported that CLA exhibits conversion from c, t or t, c isomers to t, t isomers or unknown substances as a consequence of BF 3 methylation. 38 The use of the milder BCl 3 -methanol reagent in place of the BF 3 -methanol reagent has similar results. 54 …”

“…57,61,62 Lowering the methylation temperature can decrease CLA isomerization, but these milder conditions may not be sufficient to methylate all lipids. 38,60,63 …”

“…For example, CLA can easily be isomerized by boron trifluoride (BF 3 ), thus changing the profile of the original isomer content. 38 Gas chromatography (GC) with the use of a flame ionization detector (FID), a large split flow (>30:1) and preferably hydrogen as carrier gas at a flow rate of 1.2 ml min −1 is the suggested method for the analysis and quantification of fatty acids and their isomers, particularly if high resolution, polar capillary columns are employed (eg 100 m Chrompak CP-Sil88, 100 m Supelco SP-2560, 120 m SGE BPX-70). GC exhibits rapidity, high resolution and sensitivity.…”

Influence of processing on the fatty acid composition and the content of conjugated linoleic acid in organic and conventional dairy products - a review

“…Also Ha et al [26] and Prandini et al [63] reported higher CLA contents in the fat of cheese than in the fat of milk. Werner et al [82], Jiang et al [29], Gnädig et al [22], Nudda et al [54] and Ryhänen et al [73] observed no significant effect of processing on the CLA content in cheese, including blue cheese, Edam cheese, Swedish Swisstype cheese, French Emmental and other hard cheeses, and Pecorino Romano cheese and Ricotta cheese made from the corresponding sheep's milk. Gnädig et al [22] investigated different processing factors such as raw or mildly heated milk (68 °C/20 s), cooking/moulding temperatures of 52 °C/50 °C or 48 °C/48 °C or 50 °C/ 50°C and different strains of Propionibacterium freundenreichii, and found no effect on CLA content in French Emmental cheese.…”