A Novel Method for Simultaneous Monitoring of 2-MCPD, 3-MCPD and Glycidyl Esters in Oils and Fats

The availability of a reliable methodology for the quantification of fatty acid esters of monochloropropropanediol (MCPD) and glycidol is essential for understanding the mechanism of formation of these process contaminants and for developing effective mitigation strategies. While several analytical methods for the determination of MCPD esters have already been developed and evaluated, only very few procedures are currently available for the analysis of glycidyl esters. This work presents a new indirect method for the simultaneous quantification of fatty acid esters of 2-MCPD, 3-MCPD and glycidol. The method is based on the acid-catalyzed conversion of glycidyl esters into 3-monobromopropanediol (3-MBPD) monoesters which, owing to the structural similarity to MCPD esters, are quantified by using the procedure we previously optimized for the analysis of MCPD esters. The critical step of the method, which is the conversion of glycidyl esters, was optimized by testing different reagent concentrations and varying other condition settings. The novel method showed good repeatability (RSD <2.5 %) and between-day reproducibility (RSD ≤5 %). The limit of detection was 0.04 mg/kg for bound 2-MCPD and 3-MCPD and 0.06 mg/kg for bound glycidol. The trueness of the method was evaluated by the analysis of spiked samples and by interlaboratory comparison.     

Generation of 3‐monochloro‐1,2‐propanediol and related materials from tri‐, di‐, and monoolein at deodorization temperature

Heating tests of pure tri‐, di‐, and monoolein (TO, DO, and MO, respectively) with and without the addition of tetrabutylammonium chloride as a chloride source at 240°C revealed the characteristic reactions that generate 3‐monochloro‐1,2‐propanediol‐related materials (3‐MCPD‐RM) in each acylglycerol. 3‐MCPD‐RM were formed mainly from DO and MO, with only a small amount from TO. Glycidyl ester was the predominant class of 3‐MCPD‐RM generated from both DO and MO, and was increased continuously throughout the heating period with comparable rates in both DO and MO, which also generated 3‐MCPD esters with chloride in a short completion time with an achieved level that was fourfold higher for MO than for DO. The production of free glycidol and 3‐MCPD was confirmed only in heated MO, but not from TO and DO, in a closed heating system, although these compounds were never detected in oils heated under simulated distillation conditions using a gas stream. In a closed system, both free glycidol and 3‐MCPD were increased throughout the heating period, which differed from the esters. Since an interesterification reaction, which produced free glycerol, was observed only in heated MO, free glycerol might be one of the precursors for those free forms. For clarification, further investigation is required.     

Factors Impacting the Formation of 3-MCPD Esters and Glycidyl Esters During Deep Fat Frying of Chicken Breast Meat

The effect of the frying temperature, frying duration and the addition of NaCl on the formation of 3‐monochloropropane‐1,2‐diol (3‐MCPD) esters and glycidyl esters (GE) in palm olein after deep frying was examined in this study. The eight frying systems were deep‐fat frying (at 160 and 180 °C) of chicken breast meat (CBM) (with 0, 1, 3 and 5% sodium chloride, NaCl) for 100 min/day for five consecutive days. All oil samples collected after each day were analyzed for 3‐MCPD ester, GE, and free fatty acid (FFA) contents, specific extinctions at 232 and 268 nm (K₂₃₂ and K₂₆₈), p‐anisidine value (pA), and fatty acid composition. There was a significant (p < 0.05) decrease in the 3‐MCPD esters and a significant (p < 0.05) decrease in the GE with the increasing of the frying duration. There were significant (p < 0.05) increases in the 3‐MCPD esters formed when the concentration of NaCl increased from 0 to 5%. The addition of NaCl to the CBM during deep frying had no significant effect on the GE generation. The FFA contents, K₂₃₂ and K₂₆₈ and pA showed that all the frying oils were within the safety limit.     

Application of Indirect Enzymatic Method for Determinations of 2-/3-MCPD-Es and Gly-Es in Foods Containing fats and Oils

Because of the potential health risks, fatty acid esters of 3‐chloro‐1,2‐propanediol (3‐MCPD‐Es), 2‐chloro‐1,3‐propanediol (2‐MCPD‐Es) and glycidol (Gly‐Es) in foods are drawing the attention of public health authorities. To assess applicability of the rapid indirect method developed earlier by using a Candida rugosa lipase for the analyses of refined fats and oils was applied to the analyses of various foods. Mayonnaise, vegetable oil margarine and fat spread could be analyzed with the hydrolysis condition of 30 min at room temperature. Analyses of 3‐MCPD‐Es in margarines and fat spreads containing milk fat could be analyzed by increasing the hydrolysis temperature to 40 °C. The results in a mayonnaise, four fat spreads and five margarines analyzed by the enzymatic method were 0.10–0.98 mg/kg for 3‐MCPD, 0.05–0.41 mg/kg for 2‐MCPD and 0.15–0.59 mg/kg for Gly, and correlated well with the results obtained by AOCS Cd 29a with Cd 30–15 with slopes of 0.99–1.13, and R²s of 0.87–0.99. Further, by adding a simple fat extraction step using a solvent mix at 60 °C, foods high in protein and carbohydrate, such as infant formulas, could also be successfully analyzed with >90 % recovery in 1 day. Because the enzymatic method requires only 30 min for hydrolysis, the method is considered suitable for routine analyses of 2‐/3‐MCPD‐Es and Gly‐Es in foods.     

Determination of total 3‐chloropropane‐1,2‐diol (3‐MCPD) in edible oils by cleavage of MCPD esters with sodium methoxide

A method for the determination of total 3‐chloropropane‐1,2‐diol (3‐MCPD) in edible fats and oils was presented. 3‐MCPD was released from 3‐MCPD fatty acid esters by transesterification with NaOCH₃/methanol. After derivatization with phenylboronic acid, 3‐MCPD was determined by GC‐MS. Deuterium‐labeled 3‐MCPD was used as internal standard. In a model experiment, it was shown that acidic hydrolysis with methanol/sulfuric acid, which is normally used for the release of 3‐MCPD from its esters, can cause problems because under acidic conditions additional 3‐MCPD can be formed. No additional 3‐MCPD was formed using NaOCH₃/methanol for transesterification. Eleven samples of cold‐pressed and refined safflower oils were analyzed with this method. Levels of total 3‐MCPD were in the range from <100 up to 3200 µg/kg.     

Relationship Between Oil Uptake and Water Content During Deep-Fat Frying of Potato Particulates Under Isothermal Temperature

The purpose of this study is to correlate water content and oil uptake with the structural changes of potato particulates during deep-fat frying. Raw potato particulates were sliced to form cylinders of 0.006 m diameter × 0.006 m length and subjected to deep-fat frying at isothermal oil temperatures of 160, 190 and 220 °C. The microstructure properties were assessed using a field emission scanning electron microscope (FESEM). Previous results showed that a simultaneous two first-order kinetic model adequately predicted water loss of potato particulates during isothermal frying. In this study, a simple rational model with two parameters in which regression squared (Rsqr) reaches 0.983 shows that oil uptake can be expressed by water content. The cross-sectional structure of potato particulates observed using FESEM is different from the surface structure. Regardless of the frying temperature, pores not only become larger but also increase in number after the transition time. The observations of structural changes at the surface and inner section of potato particulates through the pictures of FESEM are critical. This physical evidence supports our previous assumption that the mechanisms of water loss (two-stage rate processes) before and after transition time are different.     

Detection of 430 Fatty Acid Methyl Esters from a Transesterified Butter Sample

Milk fat is known to contain one of the highest number of fatty acids of all edible oils. Some of these fatty acids are known to be valuable (e.g. conjugated linoleic acids, furan fatty acid) and other as undesirable (e.g. saturated and some trans-fatty acids) food ingredients. However, a comprehensive picture on the presence of many trace fatty acids has not been achieved. For this reason we have developed an analysis scheme based on the conversion of the fatty acids into methyl esters. The fatty acid methyl esters were then fractionated by urea complexation. Both the filtrate of the urea complexation (~4 % of the sample weight) and the original sample were fractionated by high-speed counter-current chromatography (HSCCC). The resulting fractions were analyzed by GC/MS analysis. With this method 430 fatty acids were detected in one single butter sample. More than 230 fatty acids had two or more double bonds. In addition to the widely known spectrum of fatty acids we also detected a range of cyclohexyl fatty acids (five homologues) and methyl-branched fatty acids (including short chain and even-numbered anteiso-fatty acids), conjugated tetradecadienoic acids along with the novel ω-oxo-fatty acids (seven homologues). The reported relative retention time on the polar column may serve as a data base for the screening of other samples for this profusion of fatty acids.     

Enrichment of Omega-3 Polyunsaturated Fatty Acid Methyl Esters by Ionic Liquids Containing Silver Salts

Abstract

In this paper, we demonstrate that the hydrophobic ionic liquid (IL) such as 1-hexyl-3-methyl imidazolium hexafluorophosphate, [hmim][PF₆], with silver salt, e.g. AgBF₄, is an excellent extraction phase to separate and enrich omega-3 polyunsaturated fatty acid methyl esters (PUFAMEs) from the mixed solution containing closely related saturated, monounsaturated or diunsaturated fatty acid methyl esters. With this silver salt-ionic liquids extraction phase, the health-beneficial omega-3 PUFAMEs such as methyl ester of all-cis-5,8,11,14,17-eicosapentaenoic acid (20:5 or EPA) and methyl ester of all-cis-4,7,10,13,16,19-docosahexaenoic acid (22:6 or DHA) were largely enriched from 18% (wt %) in the original cod liver oil to greater than 80% in the 1-hexene stripping solvent. The unique properties of nonvolatility and adequate polarity allow ILs to dissolve or suspend silver salts and to be conveniently adopted as extraction phase in separating PUFAMEs. The ILs with different hydrophobicities and different silver salts were screened to obtain an optimal combination of IL and silver salt with the highest extraction capability and selectivity. The screening results showed that AgBF₄ exhibited high extraction capability in the hydrophobic ILs but little or no extraction capability in the hydrophilic ILs. Furthermore, the high extraction capability of AgBF₄ in hydrophobic ILs was much greater than that of AgBF₄ in traditional silver-water or silver-alcohol extraction systems. Pretreating the silver-ILs extraction phase with steric hindered short chain olefins could significantly enhance its extraction selectivity for PUFAMEs. Nine runs of the IL-silver extraction phase showed no obvious decrease in its extraction capabilities and selectivities.     

Enzymatic removal of 3‐monochloro‐1,2‐propanediol (3‐MCPD) and its esters from oils

3‐Monochloro‐1,2‐propanediol (3‐MCPD) is a contaminant in processed food well known for about 30 years. More recently, this compound has observed attendance due to its occurrence as fatty acid esters in edible oils and products derived from them. In this study, the first enzymatic approach to remove 3‐MCPD and its esters from aqueous and biphasic systems by converting it into glycerol is described. First, 3‐MCPD was converted in an aqueous system by an enzyme cascade consisting of a halohydrin dehalogenase from Arthrobacter sp. AD2 and an epoxide hydrolase from Agrobacterium radiobacter AD1 with complete conversion to glycerol. Next, it could also be shown, that the corresponding oleic acid monoester of 3‐monochloropropanediol‐1‐monooleic‐ester (3‐MCPD‐ester) was converted in a biphasic system in the presence of an edible oil by Candida antarctica lipase A to yield free 3‐MCPD and the corresponding fatty acid. Hence, also 3‐MCPD‐esters can be converted by an enzyme cascade into the harmless product glycerol. Practical applications: Since several reports have been recently published on the contamination of foods with 3‐MCPD and its fatty acid esters, there is a great demand to remove these compounds and an urgency to find useful methods for this. In this contribution, we present an easy enzymatic way to remove 3‐MCPD and its esters from the reaction media (i.e., plant oil) by converting it to the nontoxic glycerol. The method requires neither high temperature nor organic solvents.     

Improvement of accuracy in quantification of 3‐monochloropropane‐1,2‐diol esters by Deutsche Gesellschaft für Fettwissenschaft standard methods C‐III 18

By Deutsche Gesellschaft für Fettwissenschaft (DGF) standard methods C‐III 18 for the determination of 3‐monochloropropane‐1,2‐diol (3‐MCPD), the minimum limit of detection was lower in the case of actual oil samples compared to the calibration samples. The problem was found to be lied in the low recovery of 3‐MCPD derivatives from the aqueous phase to the organic phase at the extraction step of the standard procedure. The substitution of the conventional solvent, n‐hexane, with n‐butanol, chloroform, and ethyl acetate increased the recovery to the relative extent of 5.6, 4.7, and 3.9, respectively. The modification contributed to improve the accuracy of the method, especially at lower concentration (<1 ppm) of 3‐MCPD. Practical applications: This paper provides the modification of DGF standard methods C‐III 18 in order to improve the accuracy to quantify 3‐MCPD at lower concentration. It might be important for estimation and control of our daily intake of 3‐MCPD, and for the product control in the fat and oil processing.     

3-碘-6-卤代咪唑并[1,2-a]吡啶-8-甲酸酯的合成

标题化合物是一类重要杂环化合物,具有较高的生物活性,广泛应用于抗肿瘤药物、抗菌、抗病毒等药物的生产.以2-氨基烟酸为起始原料,经过浓硫酸催化与醇类生成2-氨基烟酸酯,再与N-卤代丁二酰亚胺反应制备2-氨基-5-卤代烟酸酯,再与氯乙醛成环缩合生成6-卤代咪唑并[1,2-a]吡啶-8-甲酸酯,最后和N-碘代琥珀酰亚胺发生碘...     

n-3 Fatty Acid Distribution of Commercial Fish Species Components

For application of n-3 fatty acids, distribution of the fatty acid compositions of different parts of (head, tail, fins and skin = HTFS, liver, viscera and muscle tissue) five commercially important fish species from the Persian Gulf (Scomberomorus commersoni, Thunnus tonggol, Euthynnus affinis, Scomberomorus guttatus and Dussumieria acuta) as good sources of n-3 PUFA were studied. The richest source of n-3 were HTFS in S. guttatus and S. commersoni, liver in S. guttatus, total body of D. acuta, liver of E. affinis and T. tonggol, followed by viscera of E. affinis. The content of these fatty acids were the same in viscera of tonggol, liver of S. commersoni, and HTFS of E. affinis. Moreover, muscle of E. affinis and HTFS of T. tonggol and also muscle of S. guttatus and T. tonggol had the same n-3 contents as the viscera of S. commersoni. So, it was concluded that HTFS and viscera (which are discarded as residues) are as useful as muscle and liver and can be a source of economically available n-3 PUFA. Muscle had the lowest proportion of n-3 in E. affinis, T. tonggol, and S. guttatus in comparison with other organs of these fish species. The highest n-3:n-6 ratio was observed in D. acuta. Finally, the cluster analysis showed that with respect to n-3 and other PUFA contents, HTFS of S. commersoni and D. acuta with S. guttatus on the one hand, and HTFS of T. tonggol and E. affinis on the other hand were similar to each other. In addition, viscera of S. commersoni and S. guttatus were similar followed by T. tonggol and different from E. affinis and D. acuta. In the case of muscle, T. tonggol and S. guttatus had good similarity followed by E. affinis and had no significant similarity with S. commersoni and D. acuta. With regard to liver, the highest similarity was observed between T. tonggol and E. affinis followed by D. acuta and S. guttatus, while S. commersoni did not show similarity with the others.     

Short‐Chain Fatty Acids Enhance the Lipid Accumulation of 3T3‐L1 Cells by Modulating the Expression of Enzymes of Fatty Acid Metabolism

Short‐chain fatty acids (SCFA) such as acetic acid, propionic acid, and butyric acid are produced by fermentation by gut microbiota. In this paper, we investigate the effects of SCFA on 3T3‐L1 cells and the underlying molecular mechanisms. The cells were treated with acetic acid, propionic acid, or butyric acid when cells were induced to differentiate into adipocytes. MTT assay was employed to detect the viability of 3T3‐L1 cells. Oil Red O staining was used to visualize the lipid content in 3T3‐L1 cells. A triglyceride assay kit was used to detect the triacylglycerol content in 3T3‐L1 cells. qRT‐PCR and Western blot were used to evaluate the expression of metabolic enzymes. MTT results showed that safe concentrations of acetic acid, propionic acid, and butyric acid were less than 6.4, 3.2, and 0.8 mM, respectively. Oil Red O staining and triacylglycerols detection results showed that treatment with acetic acid, propionic acid, and butyric acid accelerated the 3T3‐L1 adipocyte differentiation. qRT‐PCR and Western blot results showed that the expressions of lipoprotein lipase (LPL), adipocyte fatty acid binding protein 4 (FABP4), fatty acid transporter protein 4 (FATP4), and fatty acid synthase (FAS) were significantly increased by acetic acid, propionic acid, and butyric acid treatment during adipose differentiation (p < 0.05). In conclusion, SCFA promoted lipid accumulation by modulating the expression of enzymes of fatty acid metabolism.     

Enantioselective Hydrogenation of α‐Dehydroamino Acid Esters Catalyzed by Rhodium Complexes with Chiral Bisaminophosphine Ligands

A highly efficient strategy for the synthesis of a series of chiral bisaminophosphine ligands was well established with several remarkable features. The synthetic utility of these ligands was explored for rhodium‐catalyzed asymmetric hydrogenations of α‐dehydroamino acid esters. Up to 98% ee values were achieved for the enantioselective synthesis of aminocarboxylic acids and their derivatives, which are very important chiral building blocks for the synthesis of a variety of natural products and biologically active molecules.     

Biodiesel Production from Rubber Seed Oil by Transesterification Using a Co‐solvent of Fatty Acid Methyl Esters

Rubber seed oil (RSO) is a high‐potential feedstock for the production of biodiesel fuel (BDF) in Asia. Transesterification using fatty acid methyl esters (FAMEs) as co‐solvents was developed for BDF production from RSO with high content of free fatty acids (FFAs). The homogeneous system (FAMEs/triglyceride/methanol) was attained when the FAME content was more than 30 wt %. After esterification of RSO, the crude RSO obtained was transesterified with FAMEs as a co‐solvent. The quality of BDF with high FAME content satisfied the criteria of the EN 14214/JIS K2390 standards. These results suggest that FAMEs converted from FFAs can be applied as a co‐solvent and, thus, reused for BDF production.     

The Effects of Omega‐3 Polyunsaturated Fatty Acid Consumption on Mammary Carcinogenesis

The consumption of omega‐3 polyunsaturated fatty acids (n‐3 PUFA) is associated with a reduced risk of breast cancer. Studies in animals and in vitro have demonstrated mechanisms that could explain this apparent effect, but clinical and epidemiological studies have returned conflicting results on the practical benefits of dietary n‐3 PUFA for prevention of breast cancer. Effects are often only significant within a population when comparing the highest n‐3 PUFA consumption group to the lowest n‐3 group or highest n‐6 group. The beneficial effects of n‐3 PUFA eicosapentaenoic and docosahexaenoic on the risk of breast cancer are dose dependent and are negatively affected by total n‐6 consumption. The majority of the world population, including the most highly developed regions, consumes insufficient n‐3 PUFA to significantly reduce breast cancer risk. This review discusses the physiological and dietary context in which reduction of breast cancer risk may occur, some proposed mechanisms of action and meaningful recommendations for consumption of n‐3 PUFA in the diet of developed regions.     

Excellent Properties of Dimer Fatty Acid Esters as Biolubricant Produced by Catalyst‐ and Solvent‐Free Esterification

Currently most technologies available to produce esters require acid or base catalysts for esterification or transesterification reactions. Production of dimerate esters (DE) exhibiting potential as a biolubricant for low temperature applications using catalyst‐ and solvent‐free approaches is presented in this article. Hydrogenated C₃₆ dimer acid and alcohol are reacted under the following conditions: dimer acid/alcohol (1:4.5 molar ratio), 150–200 °C, 24 h, 3Å molecular sieve (15% w/w). The performances of four DE species—dibutyl, dihexyl, di‐(2‐ethylhexyl), and dioctyl dimerate—as lubricant base stocks are evaluated by kinematic viscosity, viscosity index, cloud and pour point (cold flow properties) as well as oxidative stability, and compared with commercial synthetic lubricant base stock and DE, Radialube 7121. High viscosity indexes ranging between 129 and 138 are observed for the synthesized DEs, which are comparable with two commercial base stock, polyalpha olefin (PAO), and polyolester (POE). Significantly low pour point, less than ?42 °C, is observed for di‐(2‐ethylhexyl) dimerate attributed to the branching of the side chain. The DEs are categorized as ISO VG 68 based on their viscosity according to ISO 3448 classification and show potential as biolubricant with high viscosity index and excellent cold flow properties. Practical Applications: DFAE obtained have high potential to be used as lubricant base stock for equipment and machinery operating at extremely low temperature.     

Incorporation of Alpha‐Linolenic Acid and Enhancement of n‐3 Fatty Acids in Nile Tilapia: a Factorial Design

A 2² factorial design (two factors at two levels, in triplicate) was performed to investigate the influence of factors A (time of treatment, 15 and 30 days) and B (chia oil content in a supplemented diet, at 2.1 and 4.2 %) in three responses of interest referring to: (a) the incorporation of alpha‐linolenic acid (LNA) in lipids of Nile tilapia fillet; (b) the enhancement of n‐3 fatty acids; and (c) the decrease in the omega‐6/omega3 (n‐6/n‐3) ratio in fish. Factors A and B were significant in the three regression models obtained and the interaction AB was a significant contributor to the LNA and n‐6/n‐3 ratio. Analysis of variance suggested three significant and predictive mathematical models. Response surfaces analyses from designs indicated higher LNA and n‐3 contents and a lower n‐6/n‐3 ratio using both factors A and B in the higher levels (30 days of treatment and 4.2 % of chia oil in the diet for fish) chosen for this study.