Technical Note: Improved Extraction Method with Hexane for Gas Chromatographic Analysis of Conjugated Linoleic Acids

Abstract

Extraction properties of different solvents (chloroform/methanol, hexane/isopropanol, and hexane) were studied for the gas chromatographic analysis of conjugated linoleic acids (CLA) from probiotic bacteria grown in de Man, Rogosa, and Sharpe medium. As compared with chloroform/methanol and hexane/isopropanol, hexane showed comparable extraction efficiency for CLA from unspent de Man, Rogosa, and Sharpe medium, but showed minimal extraction of oleic acid originated from the emulsifier in broth. The extraction efficiency of CLA by hexane was influenced by the broth pH, showing the optimal pH of 7.0. Repeated extraction with hexane increased the yield. Extraction with hexane showed excellent recovery of spiked CLA from the spent broth with up to 97.2% (standard deviation of 1.74%). This represents the highest recovery of CLA from culture broth ever reported. The sample size was also successfully reduced to 0.5 mL to analyze CLA from the broth without impairment of analytical data. This smaller sample size in the 1.5-mL microcentrifuge tube using a small bench-top centrifuge reduced analytical time significantly.

Antifungal Activity of 2 Lactic Acid Bacteria of the Weissella Genus Isolated from Food

“…The culture was then centrifugated (6000 × g for 10 min at 4 °C). Four microliters CFS were extracted with 6 mL of chloroform/methanol (2:1, v/v), mixed for 3 min and allowed to settle for 30 min as described by Jung and others (2006). The chloroform/methanol phase was harvested and traces of water were removed using sodium sulphate.…”

Production of conjugated linoleic acid by probioticLactobacillus acidophilusLa-5

“…Supernatants were extracted as described by Jung et al (2006) with some modifications. Samples were extracted with 2x 500 ll n-hexane after addition of 1 g NaCl crystals to facilitate diffusion.…”

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

“…Several components may be responsible, although to date investigations have revealed that two do have biological activity: namely, cis9, trans11 CLA and trans10, cis12 CLA (López Bote et al 2004;Bondia-Pons et al 2007). The cis9, trans11 isomer stimulates the growth, reduces the severity of diabetes, strengthens bones, decreases cholesterol levels, and has antiatherogenic properties (Jung et al 2006;Bondia-Pons et al 2007;Silva Hernández et al 2007;Meluchová et al 2008). In contrast, the trans10, cis12 isomer elicits a reduction in fat levels (Park et al 2007).…”