Isolation of α-linolenic acid biohydrogenation products by combined silver ion solid phase extraction and semi-preparative high performance liquid chromatography

Silver-mediated separations: A comprehensive review on advancements of argentation chromatography, facilitated transport membranes, and solid-phase extraction techniques and their applications

The use of silver(I) ions in chemical separations, also known as argentation separations, is a powerful approach for the selective separation and analysis of many natural and synthetic organic compounds. In this review, a comprehensive discussion of the most common argentation separation techniques, including argentation-liquid chromatography (Ag-LC), argentation-gas chromatography (Ag-GC), argentation-facilitated transport membranes (Ag-FTMs), and argentation-solid phase extraction (Ag-SPE) is provided. For each of these techniques, notable advancements, optimized separations, and innovative applications are discussed. The review begins with an explanation of the fundamental chemistry underlying argentation separations, mainly the reversible π-complexation between silver(I) ions and carbon-carbon double bonds. Within Ag-LC, the use of silver(I) ions in thin-layer chromatography, high-performance liquid chromatography, as well as preparative LC are explored. This discussion focuses on how silver(I) ions are employed in the stationary and mobile phase to separate unsaturated compounds. For Ag-GC and Ag-FTMs, different silver compounds and supporting media are discussed, often with relation to olefin-paraffin separations. Ag-SPE has been widely employed for the selective extraction of unsaturated compounds from complex matrices in sample preparation. This comprehensive review of Ag-LC, Ag-GC, Ag-FTMs, and Ag-SPE techniques emphasizes the immense potential of argentation separations in separations science and serves as a valuable resource for researchers seeking to learn, optimize, and utilize argentation separations.

New research development on trans fatty acids in food: Biological effects, analytical methods, formation mechanism, and mitigating measures

The trans fatty acids (TFAs) in food are mainly generated from the ruminant animals (meat and milk) and processed oil or oil products. Excessive intake of TFAs (>1% of total energy intake) caused more than 500,000 deaths from coronary heart disease and increased heart disease risk by 21% and mortality by 28% around the world annually, which will be eliminated in industrially-produced trans fat from the global food supply by 2023. Herein, we aim to provide a comprehensive overview of the biological effects, analytical methods, formation and mitigation measures of TFAs in food. Especially, the research progress on the rapid, easy-to-use, and newly validated analytical methods, new formation mechanism, kinetics, possible mitigation mechanism, and new or improved mitigation measures are highlighted. We also offer perspectives on the challenges, opportunities, and new directions for future development, which will contribute to the advances in TFAs research.

Trans-10 18:1 in ruminant meats: A review

Trans (t) fatty acids (TFA) from partially hydrogenated vegetable oils (i.e., industrial trans) have been phased out of foods in many countries due to their promotion of cardiovascular disease. This leaves ruminant-derived foods as the main source of TFA. Unlike industrial TFA where catalytic hydrogenation yields a broad distribution of isomers, ruminant TFA are enzymatically derived and can result in enrichment of specific isomers. Comparisons between industrial and ruminant TFA have often exonerated ruminant TFA due to their lack or at times positive effects on health. At extremes, however, ruminant-sourced foods can have either high levels of t10- or t11-18:1, and when considering enriched sources, t10-18:1 has properties similar to industrial TFA, whereas t11-18:1 can be converted to an isomer of conjugated linoleic acid (cis(c)9,t11-conjugated linoleic acid), both of which have potential positive health effects. Increased t10-18:1 in meat-producing ruminants has not been associated with negative effects on live animal production or meat quality. As such, reducing t10-18:1 has not been of immediate concern to ruminant meat producers, as there have been no economic consequences for its enrichment; nevertheless at high levels, it can compromise the nutritional quality of beef and lamb. In anticipation that regulations regarding TFA may focus more on t10-18:1 in beef and lamb, the present review will cover its production, analysis, biological effects, strategies for manipulation, and regulatory policy.

Transcriptome Analysis of Listeria monocytogenes Exposed to Beef Fat Reveals Antimicrobial and Pathogenicity Attenuation Mechanisms

Listeria monocytogenes is a deadly intracellular pathogen mostly associated with consumption of ready-to-eat foods. This study investigated the effectiveness of total beef fat (BF-T) from flaxseed-fed cattle and its fractions enriched with monounsaturated fatty acids (BF-MUFA) and polyunsaturated fatty acids (BF-PUFA), along with commercially available long-chain fatty acids (LC-FA), as natural antimicrobials against L. monocytogenes BF-T was ineffective at concentrations up to 6 mg/ml, while L. monocytogenes was susceptible to BF-MUFA and BF-PUFA, with MICs at pH 7 of 0.33 ± 0.21 mg/ml and 0.06 ± 0.03 mg/ml, respectively. The MIC of C14:0 was significantly lower than those of C16:0 and C18:0 (P < 0.05). Fatty acids c9-C16:1, C18:2n-6, and C18:3n-3 showed stronger inhibitory activity than c9-C18:1 and conjugated C18:2, with MICs of <1 mg/ml. Furthermore, global transcriptional analysis by transcriptome sequencing (RNA-seq) was performed to characterize the response of L. monocytogenes to selected fatty acids. Functional analysis indicated that antimicrobial LC-UFA repressed the expression of genes associated with nutrient transmembrane transport, energy generation, and oxidative stress resistance. On the other hand, upregulation of ribosome assembly and translation process is possibly associated with adaptive and repair mechanisms activated in response to LC-UFA. Virulence genes and genes involved in bile, acid, and osmotic stresses were largely downregulated, and more so for c9-C16:1, C18:2n-6, and C18:3n-3, likely through interaction with the master virulence regulator PrfA and the alternative sigma factor σ^B IMPORTANCE Listeria monocytogenes is a bacterial pathogen known for its ability to survive and thrive under adverse environments and, as such, its control poses a significant challenge, especially with the trend of minimally processed and ready-to-eat foods. This work investigated the effectiveness of fatty acids from various sources as natural antimicrobials against L. monocytogenes and evaluated their potential role in L. monocytogenes pathogenicity modulation, using the strain ATCC 19111. The findings show that long-chain unsaturated fatty acids (LC-UFA), including unsaturated beef fat fractions from flaxseed-fed cattle, could have the potential to be used as effective antimicrobials for L. monocytogenes through controlling growth as well as virulence attenuation. This not only advances our understanding of the mode of action of LC-UFA against L. monocytogenes but also suggests the potential for use of beef fat or its fractions as natural antimicrobials for controlling foodborne pathogens.

Safflower seed supplementation in lamb feed: effects upon fatty acid profile and quality of meat patty formulations

The aims of this study were to determine the fatty acid profile of meat from lambs fed with different levels of safflower seed (0%, 7.5%, and 15%) and, also, to compare the characteristics of the meat patties prepared from this lamb meat (LMP) with beef meat patties (BMP). The safflower seed-supplemented diet did not change the contents of polyunsaturated and unsaturated fatty acids, except for C22:1. All meat patty formulations were considered safe for consumption. The values of cooking yield, shrinkage, water absorption index, luminosity (L*), and redness (a*) were similar for the LMP and BMP tested. While the safflower seed-supplemented diet did not alter the moisture, ash, and protein levels of LMP, the lipid content was lower than that in BMP. The incorporation of 15% safflower seed into lamb feed contributed to promoting better sensory attributes of the meat patties. Most of the physicochemical properties evaluated were similar among LMP and BMP. However, to improve the sensory properties of the product, dietary supplementation with 15% safflower seed is recommended.

Bioactivity and health effects of ruminant meat lipids. Invited Review

Ruminant meat (RM) is an excellent source of high-quality protein, B vitamins and trace minerals and plays an important role in global food and nutrition security. However, nutritional guidelines commonly recommend reduced intake of RM mainly because of its high saturated fatty acid (SFA) content, and more recently because of its perceived negative environmental impacts. RM is, however, rich in heart healthy cis-monounsaturated fatty acids and can be an important source of long-chain omega-3 (n-3) fatty acids in populations with low fish consumption. In addition, RM is a source of bioactive phospholipids, as well as rumen-derived bioactive fatty acids including branched-chain, vaccenic and rumenic acids, which have been associated with several health benefits. However, the role of bioactive RM lipids in maintaining and improving consumers' health have been generally ignored in nutritional guidelines. The present review examines RM lipids in relation to human health, and evaluates the effectiveness of different feeding strategies and possibilities for future profile and content improvement.

Preparative separation of liquiritigenin and glycyrrhetic acid from Glycyrrhiza uralensis Fisch using hydrolytic extraction combined with high-speed countercurrent chromatography

The objective of this paper was to develop a preparative method for the isolation and purification of liquiritigenin and glycyrrhetic acid from Glycyrrhiza uralensis Fisch using hydrolytic extraction combined with high-speed countercurrent chromatography (HSCCC). Liquiritigenin and glycyrrhetic acid were well hydrolyzed from liquiritin and glycyrrhizic acid by hydrochloric acid, respectively. The optimal extraction conditions were obtained by single-factor and orthogonal experiments, which were 100% ethanol, 1.5 mol/L hydrochloric acid, 1:25 ratio of solid to liquid, and extracted 2 h for one time. Using the two-phase solvent system of n-hexane-ethyl acetate-methanol-water (4:5:4:5, v/v), 2.1 mg liquiritigenin (the purity was 96.5% with a recovery of 87.6%) and 12.3 mg glycyrrhetic acid (the purity was 97.1% with a recovery of 74.4%) were obtained from 315-mg crude extraction by HSCCC. The retention ratio of stationary phase was 47.2%. Their structures were identified by HPLC, melting points, UV, Fourier-transform infrared, Electrospray ionization-MS, ¹ H nuclear magnetic resonance (NMR), and ¹³ C NMR spectra. According to the antioxidant activity assays, liquiritigenin and glycyrrhetic acid had some scavenging abilities on 1,1-diphenyl-2-picrylhydrazyl free radicals; liquiritigenin had stronger scavenging ability on hydroxyl radicals.

Nutritional enhancement of sheep meat fatty acid profile for human health and wellbeing

Dietary fatty acids (FA) consumed by sheep, like other ruminants, can undergo biohydrogenation resulting in high proportions of saturated FA (SFA) in meat. Biohydrogenation is typically less extensive in sheep than cattle, and consequently, sheep meat can contain higher proportions of omega (n)-3 polyunsaturated FA (PUFA), and PUFA biohydrogenation intermediates (PUFA-BHI) including conjugated linoleic acid (CLA) and trans-monounsaturated FAs (t-MUFA). Sheep meat is also noted for having characteristically higher contents of branched chain FA (BCFA). From a human health and wellness perspective, some SFA and trans-MUFA have been found to negatively affect blood lipid profiles, and are associated with increased risk of cardiovascular disease (CVD). On the other hand, n-3 PUFA, BCFA and some PUFA-BHI may have many potential beneficial effects on human health and wellbeing. In particular, vaccenic acid (VA), rumenic acid (RA) and BCFA may have potential for protecting against cancer and inflammatory disorders among other human health benefits. Several innovative strategies have been evaluated for their potential to enrich sheep meat with FA which may have human health benefits. To this end, dietary manipulation has been found to be the most effective strategy of improving the FA profile of sheep meat. However, there is a missing link between the FA profile of sheep meat, human consumption patterns of sheep FA and chronic diseases. The current review provides an overview of the nutritional strategies used to enhance the FA profile of sheep meat for human consumption.

Dietary linseed oil increases trans-10,cis-15 18:2 in caprine milk fat

Trans-10,cis-15 18:2 has been recently detected and characterized in digestive contents and meat and adipose tissue of ruminants, but its presence in milk and dairy products is hardly known. The aim of this study was to quantify trans-10,cis-15 18:2 in milk fat, better understand its metabolic origin, and help to elucidate the mechanisms of rumen biohydrogenation when the diet composition might affect ruminal environment. To address these objectives, 16 dairy goats were allocated to 2 simultaneous experiments (2 groups of goats and 2 treatments in each experiment). Experimental treatments consisted of basal diets with the same forage-to-concentrate ratio (33/67) and 2 starch-to-nonforage neutral detergent fiber (NDF) ratios (0.8 and 3.1), which were supplemented or not with 30 g/d of linseed oil for 25 d in a crossover design. Trans-10,cis-15 18:2 contents in milk fat were determined by gas chromatography fitted with an extremely polar capillary column (SLB-IL111). Levels of trans-10,cis-15 18:2 in individual milk fat samples ranged from 0 to 0.2% of total fatty acids, and its content in milk fat increased 8 fold due to linseed oil supplementation, substantiating the predominant role of α-linolenic acid in its formation. The trans-10,cis-15 18:2 levels in milk fat were similar in both experiments, despite the fact starch-to-nonforage NDF ratio of their respective basal diets greatly differed. In conclusion, trans-10,cis-15 18:2 was clearly related to linseed oil supplementation, and its increase in milk fat was comparable when the basal diets were rich in either nonforage NDF or starch.

Purification of high-purity glycyrrhizin from licorice using hydrophilic interaction solid phase extraction coupled with preparative reversed-phase liquid chromatography

Glycyrrhizin (GA), a major bioactive compound in licorice, has been extensively used throughout the world as a medicine to treat chronic viral hepatitis and allergic dermatitis. In this study, a new method based on hydrophilic interaction solid phase extraction (HILIC-SPE) and preparative reversed-phase liquid chromatography (prep-RPLC) was developed to purify GA with high purity from the complex licorice extract. Via evaluation of retention behavior of GA and flavonoids in different commercially available columns, a hydrophilic column--Click XIon was finally chosen for the purification due to its excellent resolution toward GA and flavonoids under HILIC mode. To optimize the SPE elution conditions, relative factors including water content, pH and ionic strength had been investigated in chromatographic condition. The result indicated that the most appropriate water content was 30% and pH at 4.00, as well as salt concentration should be controlled at 5mM. In addition, the optimization revealed that GA experiences both hydrophilic interaction and ion-exchange interaction on the Click XIon material. According to the chromatographic evaluation, the optimized conditions were applied to HILIC-SPE to enrich GA from licorice, which leads to an increased content of GA from 13.67% to 64.22%. Finally, prep-RPLC was performed to obtain GA with purity higher than 99.00%，which demonstrating great prospect in large-scale preparation of GA.

Feeding steers hay with extruded flaxseed together or sequentially has a profound effect on erythrocyte trans 11-18:1 (vaccenic acid)

Extruded flaxseed and ground hay [25% and 75%; dry matter (DM) basis] were fed in a total mixed ration (TMR) or sequentially (non-TMR) to three pens of eight crossbred steers per diet. At 112 d, erythrocytes from non-TMR steers had 65% more vaccenic acid (trans 11-18:1) than TMR steers (P < 0.05).

A trans10-18:1 enriched fraction from beef fed a barley grain-based diet induces lipogenic gene expression and reduces viability of HepG2 cells

Beef fat is a natural source of trans (t) fatty acids, and is typically enriched with either t10-18:1 or t11-18:1. Little is known about the bioactivity of individual t-18:1 isomers, and the present study compared the effects of t9-18:1, cis (c)9-18:1 and trans (t)-18:1 fractions isolated from beef fat enriched with either t10-18:1 (HT10) or t11-18:1 (HT11). All 18:1 isomers resulted in reduced human liver (HepG2) cell viability relative to control. Both c9-18:1 and HT11were the least toxic, t9-18:1had dose response increased toxicity, and HT10 had the greatest toxicity (P<0.05). Incorporation of t18:1 isomers was 1.8-2.5 fold greater in triacylglycerol (TG) than phospholipids (PL), whereas Δ9 desaturation products were selectively incorporated into PL. Culturing HepG2 cells with t9-18:1 and HT10 increased (P<0.05) the Δ9 desaturation index (c9-16:1/16:0) compared to other fatty acid treatments. HT10 and t9-18:1 also increased expression of lipogenic genes (FAS, SCD1, HMGCR and SREBP2) compared to control (P<0.05), whereas c9-18:1 and HT11 did not affect the expression of these genes. Our results suggest effects of HT11 and c9-18:1 were similar to BSA control, whereas HT10 and t-9 18:1 (i.e. the predominant trans fatty acid isomer found in partially hydrogenated vegetable oils) were more cytotoxic and led to greater expression of lipogenic genes.

Metabolism ofα-linolenic acid during incubations with strained bovine rumen contents: products and mechanisms

Description ofα-linolenic acid (cis-9,cis-12,cis-15-18 : 3, ALA) metabolism in the rumen is incomplete. Ruminal digesta samples were incubated with ALA and buffer containing water or deuterium oxide to investigate the products and mechanisms of ALA biohydrogenation. Geometric Δ9,11,15-18 : 3 isomers were the main intermediates formed from ALA. An increase in then+1 isotopomers of Δ9,11,15-18 : 3 was due to2H labelling at C-13. Isomers of Δ9,11,13-18 : 3,cis-7,cis-12,cis-15-18 : 3 andcis-8,cis-12,cis-15-18 : 3 were also formed. No increase inn+1 isotopomers of Δ7,12,15-18 : 3 or Δ8,12,15-18 : 3 was detected. Enrichment inn+2 isotopomers of 18 : 2 products indicated that ALA metabolism continued via the reduction of 18 : 3 intermediates. Isomers of Δ9,11,15-18 : 3 were reduced to Δ11,15-18 : 2 labelled at C-9 and C-13. ALA resulted in the formation of Δ11,13-18 : 2 and Δ12,14-18 : 2 containing multiple2H labels. Enrichment of then+3 isotopomer of Δ12,15-18 : 2 was also detected. Metabolism of ALA during incubations with rumen contents occurs by one of three distinct pathways. Formation of Δ9,11,15-18 : 3 appears to be initiated by H abstraction on C-13. Octadecatrienoic intermediates containingcis-12 andcis-15 double bonds are formed without an apparent H exchange with water. Labelling of Δ9,11,13-18 : 3 was inconclusive, suggesting formation by an alternative mechanism. These findings explain the appearance of several bioactive fatty acids in muscle and milk that influence the nutritional value of ruminant-derived foods.