Technical Note: Improved Extraction Method with Hexane for Gas Chromatographic Analysis of Conjugated Linoleic Acids (original) (raw)
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International Journal of Dairy Technology, 2010
Strains of potentially probiotic lactobacilli, propionibacteria, leuconostoc, lactococcus, enterococcus, and pediococcus, were tested for their ability to convert linoleic acid to conjugated linoleic acid (CLA). Growth and CLA production were followed during incubation for 48 h in reconstituted skim milk containing 0.2% lipolysed sesame oil. Lactococcus lactis subsp. lactis biovar diacetylactis and Leuconostoc mesenteroides subsp. mesenteroides gave the highest CLA production. Also, the effect of lipolysed oil concentration on the growth and CLA production of six strains were studied in medium containing 0.0-1% lipolysed oil. Leuconostoc mesenteroides subsp. mesenteroides and Lac. lactis subsp. lactis biovar diacetylactis gave maximum dienes in medium containing 0.6% and 0.8% lipolysed oil respectively.
European Journal of Lipid Science and Technology, 2012
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.
Bacterial production of conjugated linoleic and linolenic acid in foods: a technological challenge
2013
tissues. CLA and CLNA have isomer-specific, health-promoting properties, including anticarcinogenic, antiatherogenic, antiinflammatory, and antidiabetic activity, as well as the ability to reduce body fat. Besides ruminal microorganisms, such as Butyrivibrio fibrisolvens, many food-grade bacteria, such as bifidobacteria, lactic acid bacteria (LAB), and propionibacteria, are able to convert LA and LNA to CLA and CLNA, respectively. Linoleate isomerase activity, responsible for this conversion, is strain-dependent and probably related to the ability of the producer strain to tolerate the toxic effects of LA and LNA. Since natural concentrations of CLA and CLNA in ruminal food products are relatively low to exert their health benefits, food-grade bacteria with linoleate isomerase activity could be used as starter or adjunct cultures to develop functional fermented dairy and meat products with increased levels of CLA and CLNA or included in fermented products as probiotic cultures. However, results obtained so far are below expectations due to technological bottlenecks. More research is needed to assess if bacterial production kinetics can be increased and can match food processing requirements.
The impact of oil type and lactic acid bacteria on conjugated linoleic acid production
2016
Essential fatty acids (EFAs) are fatty acids that cannot be synthesized in the human body and for that reason must be obtained from the diet or other external sources. The two essential fatty acids are α-linolenic acid (ALA) and linoleic acid (LA), which are also known as linseed oil acid [1]. α-linolenic acid is an omega-3 (n-3) fatty acid found in many common vegetable oils, and it has a lipid number of 18:3 with three cis double bonds 9,12,15. The first double bond is located at the third carbon from the methyl end of the fatty acid chain [2]. LA is a polyunsaturated omega-6 (n-6) fatty acid; it has a lipid number of 18:2 with two cis double bonds 9,12 and the first double bond is located at the sixth carbon from the methyl end [3,4]. Linoleic acid is transformed in the human body to the longchain polyunsaturated fatty acids gamma-linolenic acid (GLA) and arachidonic acid (AA) [5]. Conjugated linoleic acid (CLA) is a term used to characterize positional and geometrical isomers of...
Lipids, 1999
Seven methods commonly used for fatty acid analysis of microrganisms and foods were compared to establish the best for the analysis of lyophilized lactic acid bacteria. One of these methods involves fat extraction followed by methylation of fatty acids, while the other methods use a direct methylation of the samples, under different operating conditions (e.g., reaction temperature and time, reagents, and pH). Fatty acid methyl esters were identified by gas chromatography-mass spectrometry and quantified by on-column capillary gas chromatography. Two reliable methods for the analysis of fatty acids in bacteria were selected and further improved. They guarantee high recovery of classes of fragile fatty acids, such as cyclopropane and conjugated acids, and a high degree of methylation for all types of fatty acid esters. These two direct methylation methods have already been successfully applied to the analysis of fatty acids in foods. They represent a rapid and highly reliable alternative to classical time-and solvent-consuming methods and they give the fatty acid profile and the amount of each fatty acid. Using these methods, conjugated linoleic acids were identified and quantified in lactic acid bacteria.
2015
2 Abstract: This study investigated the potential factors affecting conjugated linoleic acid (CLA) production by 24 candidate probiotic Bifidobacterium and Lactobacillus strains. Strains were cultured in de Man, Rogosa and Sharpe (MRS) medium, MRS with cysteine hydrochloride, or skim milk with 1% hydrolyzed soybean oil (SO) at 37°C for 24h. Quantitative and qualitative analyses of CLA were performed by UV spectrometry and gas chromatography/mass spectrometry, respectively. Of the strains examined, 10 were CLA producers, with two strains each of B. bifidum and L. casei producing the highest amounts of CLA in skim milk, ranging from 80-90 and 125-153 µg CLA/g lipid, respectively. CLA isomers produced by the two species were qualified as C18:2 cis-9,trans-11 and C18:2 trans-10, cis-12, respectively. B.bifidum was characterized as a C18:3 conjugated linolenic acid producer. CLA production was significantly affected by 1.5%SO, while extending the fermentation time was detrimental. Charac...
Bioproduction of Conjugated Linoleic Acid in Yogurt by Probiotic Bacteria
International Journal of Biotechnology for Wellness Industries, 2014
Conjugated linoleic acid as unique fatty acid of milk fat has beneficial properties including antioxidant‚ anticarcinogen‚ antidiabetic‚ antiblood pressure‚ stimulating the body immune system and reducing cholesterol. The aim of this study was assessing ability of some probiotics for biotransformation of linoleic acid to conjugated linoleic acid. Effect of process variables were investigated on production of conjugated linoleic acid in probiotic yogurt. An 8 run Plackett-Burman design was used to study the effect of 7 variables included: addition of supplements (whey powder‚ the amount of added grape seed oil), fermentation (temperature, pH, incubation time) and inoculum condition (age and size) on biomass and conjugated linoleic acid production in probiotic yogurt containing strains of Lactobacillus acidophilus La5, Bifidobacterium bifidum and Propionibacterium freudenerchii grown in medium containing free linoleic acid. The highest amount of conjugated linoleic acid was obtained by addition of 8% w/v whey powder, addition of 4%v/v grape seed oil in pH=6.0, inoculation of 0.7%v/v Inoculum of 36 h age and fermentation at temperature of 35°C for 27 h. This research showed that at the optimized conditions‚ the amount of conjugated linoleic acid in probiotic yogurt was increased by 40% from an average of 8.01 mg/g fat in non-treated yogurt to 11.03 mg/g fat of probiotic yogurt containing grape seed oil.
Production of conjugated linoleic acid by probiotic Lactobacillus acidophilus La-5
Journal of Applied Microbiology, 2009
Aims: To study the ability of the probiotic culture Lactobacillus acidophilus La-5 to produce conjugated linoleic acid (CLA), which is a potent anti-carcinogenic agent. Methods and Results: The conversion of linoleic acid to CLA was studied both by fermentation in a synthetic medium and by incubation of washed cells. Accumulation of CLA was monitored by gas chromatography analysis of the biomass and supernatants. While the fermentation conditions applied may not be optimal to observe CLA production in growing La-5 cells, the total CLA surpassed 50% of the original content in the washed cells after 48 h under both aerobic and micro-aerobic conditions. The restriction of oxygen did not increase the yield, but favoured the formation of trans, trans isomers. Conclusions: The capability of L. acidophilus La-5 to produce CLA is not dependant on the presence of milk fat or anaerobic conditions. Regulation of CLA production in this strain needs to be further investigated to exploit the CLA potential in fermented foods. Significance and Impact of the study: Knowledge gained through the conditions on the accumulation of CLA would provide further insight into the fermentation of probiotic dairy products. The capacity of the nongrowing cells to produce CLA is also of great relevance for the emerging nonfermented probiotic foods.
Microbiology and molecular biology reviews : MMBR, 2018
SUMMARYConjugated linoleic acids (CLAs) and conjugated linolenic acids (CLNAs) have gained significant attention due to their anticarcinogenic and lipid/energy metabolism-modulatory effects. However, their concentration in foodstuffs is insufficient for any therapeutic application to be implemented. From a biotechnological standpoint, microbial production of these conjugated fatty acids (CFAs) has been explored as an alternative, and strains of the genera , , and have shown promising producing capacities. Current screening research works are generally based on direct analytical determination of production capacity (e.g., trial and error), representing an important bottleneck in these studies. This review aims to summarize the available information regarding identified genes and proteins involved in CLA/CLNA production by these groups of bacteria and, consequently, the possible enzymatic reactions behind such metabolic processes. Linoleate isomerase (LAI) was the first enzyme to be d...