Comparison of methylation methods for fatty acid analysis of milk fat

Effect of Changes in Farm Management on the Yield and Constituents, Microbiological Quality, Somatic Cell Count and Fatty Acid Profile of the Camel Milk

BACKGROUND

The increasing interest in camel milk (CM) worldwide in recent years has increased the need for studies on the properties of CM, which is relatively less studied than other species.

OBJECTIVE

The objective of this study was to determine the effects of changes in farm management on daily milk yield (DMY), milk composition and microbiological quality of CM.

METHODS

Yearly changes in milk fat (MFC), protein (MPC), ash (MAC), totals solid (TSC) contents, total bacteria (TBC), coliform (CC), yeast and mould (YMC), somatic cell (SCC) counts and fatty acid profile of CM were determined by monthly taken milk samples and analyses.

RESULTS

The means of DMY, MFC, MPC, MAC, TSC, TBC, CC, YMC and SCC of milk were 3.53 ± 0.290 kg, 3.80% ± 0.285%, 4.36% ± 0.212%, 0.81% ± 0.013%, 11.95% ± 0.380%, 7.24 × 105 cfu/mL, 1.31 × 105 cfu/mL, 912 cfu/mL and 2.45 × 105 cells/mL, respectively. The effect of the changes (Year 2 vs. Year 1) was statistically significant for MFC, MPC, TSC and Log10TBC (p < 0.05), and significant effects of lactation stage were determined for DMY, MFC, MAC, TSC, Log10TBC and Log10YMC (p < 0.05). The highest fatty acid (FA) amount in CM was found for palmitic (C16:0), oleic (C18:1n9c), stearic (C18:0), myristic (C14:0) and palmitoleic (C16:1) acids with the concentrations of 31.59% ± 0.45%, 21.88% ± 0.81%, 13.43% ± 0.67%, 12.22% ± 0.26% and 12.18% ± 0.34% of fat, respectively. The correlation coefficients of MFC, MPC and TSC with SCFA and MCFA were moderate and negative but with long chain Fas (LCFA) were positive and moderate. Log10SCC was also negatively correlated with total polyunsaturated FAs (PUFA) (-0.414; p < 0.05), SCFA (-0.475; p < 0.01), MCFA (-0.573; p < 0.01) and positively correlated with LCFA (0.588; p < 0.01).

CONCLUSION

Although management causes significant changes in composition, TBC and FA profile, CM has high UFA, low SCFA, high LCFA and better atherogenic index (AI). The high microbiological level at the beginning and middle of lactation and the negative correlation of these traits with milk components reveal that various measures should be taken to improve hygienic conditions to process CM into quality products.

Dry-aged beef quality with the addition of Mucor flavus - Sensory, chemosensory and fatty acid analysis

Dry-aged beef is a premium product known for its unique taste and aroma. These characteristics are thought to partially depend on the composition of the microorganisms present on the meat surface during ageing. Recently several attempts to standardise this process were made. This study aimed to assess the effect of a fungal biostarter application on the profile of volatile compounds, fatty acid composition and sensory quality of dry-aged beef. The Longissimus muscle used in the experiment originated from 20 crossbred (10 heifers and 10 steers) animals from the crossing of Holstein-Friesian cows with beef breed bulls. A fungal biostarter composed of Mucor flavus strain KKP2092p was used for meat inoculation. Half of the material was aged without the use of a biostarter (Control samples). The dry-ageing of the meat was performed at a temperature of 1.5 °C with approximately 80-90 % relative humidity for 28 days. The use of Mucor flavus KKP2092p improved meat quality attributes (aroma liking, flavour and overall liking) as a result of the formation of specific volatile compounds. The profile of volatile compounds in the meat aged with Mucor flavus and control variants was differentiated. This study also indicated that Mucor flavus biostarter had an impact on the specific fatty acid composition. An insignificant effect of Mucor flavus on lipid oxidation expressed as mg/kg of malonaldehyde was also observed.

Growth performance, proximate composition and fatty acid profile of black soldier fly larvae reared on two grape pomace varieties

The black soldier fly (Hermetia illucens) is attracting increasing interest for its ability to convert low-value substrates into highly nutritious feed. This study aimed at evaluating grape pomace from two varieties (Becuet - B; Moscato - M) as rearing substrates for black soldier fly larvae (BSFL), focusing on the related effects on larval growth performance, proximate composition, and fatty acid profile. A total of six replicates per treatment, and 1 000 BSFL per replica, were used. Larval development was assessed by larvae weight, which was recorded eight times during the trial: the day after the beginning of the trial, and then on days 5, 8, 13, 15, 20, 22, and 27 (day in which the 30% of BSFL reached the prepupal stage). Production and waste reduction efficiency parameters, namely the growth rate, substrate reduction and substrate reduction index, were calculated. The two grape pomace varieties were analysed for their proximate composition and fatty acid profile; the same analyses were conducted on BSFL (30 larvae per replica) that were collected at the end of the trial (day 27). The growth rate of BSFL showed a higher value when the larvae were reared on B substrate (4.4 and 3.2 mg/day for B and M, respectively; P < 0.01). The rearing substrate did not significantly affect the proximate composition of BSFL. The percentage of total lipids (TL) in M-fed BSFL was significantly higher than in B ones. Total saturated (P < 0.001) and monounsaturated fatty acids (P < 0.05) were significantly higher in M-fed BSFL, while an opposite trend was observed for total branched-chain (P < 0.001) and total polyunsaturated fatty acids (P < 0.001). Interestingly, some conjugated linoleic acid (CLA) isomers [i.e., C18:2 c9t11(+t7c9+t8c10) and t9t11] were detected in low amounts in both rearing substrates (total CLA equal to 0.085 and 0.16 g/100 g TL in B and M substrate, respectively). Some CLA isomers (i.e., C18:2 c9t11, t7c9, and t10c12) were also found in BSFL, reaching a total CLA concentration equal to 2.95 and 0.052 g/100 g of TL in B-fed and M-fed BSFL, respectively. This study demonstrates that winery by-products from different grape varieties can significantly affect the development and lipid composition of BSFL. The CLA biosynthesis potential of BSFL opens newsworthy perspectives for a new valorisation of winery by-products to produce full-fat black soldier fly meal and black soldier fly oil enriched in specific fatty acids of potential health-promoting interest.

A new isopropyl esterification method for quantitative profiling of short-chain fatty acids in human and cow milk by gas chromatograph-mass spectrometer

Short-chain fatty acids (SCFA) content in milk may have been underestimated due to the neglect of the esterified SCFA content and the lack of an accurate detection method, especially for C1:0, C2:0, and C3:0 SCFA. In this study, an accurate GC-MS profiling method was established for 10 SCFA. A 2-step esterification, including alkaline saponification (60°C for 30 min) and acid-catalyzed esterification (80°C for 150 min) in water/isopropyl/hexane (1:2:1, volume ratio), was found to be the most suitable for the quantification of esterified and nonesterified SCFA analysis. The validation results demonstrate satisfactory linearity, sensitivity, matrix effects, precision, and accuracy. The recoveries of nonesterified and esterified SCFA ranged from 82.78% to 112.49%, respectively. Human milk is distinguished from cow milk by its higher C1:0 and C2:0 content and lower C4:0 and C6:0 content. This method successfully accomplished qualitative and quantitative estimation of all 10 SCFA in milk, including both nonesterified and esterified SCFA. Furthermore, whether our method is applicable for the determination of SCFA in serum, rumen fluid, and feces remains to be explored.

Rapid quantification of 50 fatty acids in small amounts of biological samples for population molecular phenotyping

Efficient quantification of fatty-acid (FA) composition (fatty-acidome) in biological samples is crucial for understanding physiology and pathophysiology in large population cohorts. Here, we report a rapid GC-FID/MS method for simultaneous quantification of all FAs in numerous biological matrices. Within eight minutes, this method enabled simultaneous quantification of 50 FAs as fatty-acid methyl esters (FAMEs) in femtomole levels following the efficient transformation of FAs in all lipids including FFAs, cholesterol-esters, glycerides, phospholipids and sphingolipids. The method showed satisfactory inter-day and intra-day precision, stability and linearity (R2 > 0.994) within a concentration range of 2-3 orders of magnitude. FAs were then quantified in typical multiple biological matrices including human biofluids (urine, plasma) and cells, animal intestinal content and tissue samples. We also established a quantitative structure-retention relationship (QSRR) for analytes to accurately predict their retention time and aid their reliable identification. We further developed a novel no-additive retention index (NARI) with endogenous FAMEs reducing inter-batch variations to 15 seconds; such NARI performed better than the alkanes-based classical RI, making meta-analysis possible for data obtained from different batches and platforms. Collectively, this provides an inexpensive high-throughput analytical system for quantitative phenotyping of all FAs in 8-minutes multiple biological matrices in large cohort studies of pathophysiological effects.

Goat milk powder supplemented with branched-chain fatty acid: influence on quality and microstructure

BACKGROUND

Branched-chain fatty acid (BCFA) is effective in preventing and helping to treat neonatal necrotizing enterocolitis. It is essential to supplement goat-milk powder for formula-fed preterm infants with BCFA. In this study, the quality and microstructures of milk powders supplemented with different concentrations of BCFA were evaluated, using goat milk powder without BCFA as the control group (CG).

RESULTS

In comparison with the CG, goat milk powder supplemented with BCFA exhibited smaller fat globules and a significant drop in overall particle size. During 16 weeks of storage, BCFA-supplemented groups showed suitable moisture content and viscosity and good solubility. The BCFA also helped reduce the number of folds on the surface of the milk powder particles.

CONCLUSION

The findings of this study indicate that goat milk powders with BCFA exhibit differences in quality and microstructure in comparison with ordinary goat milk powder, which is relevant for the future development and application of BCFA in foods. © 2022 Society of Chemical Industry.

Comparison of the Effectiveness and Environmental Impact of Selected Methods for the Determination of Fatty Acids in Milk Samples

Determination of the fatty acid profile in milk samples is one of the most important in food analysis. There are many methodologies for FA determination. The conventional procedure for determining the FA composition of milk is isolation of fat or indirect methylation, trans-methylation, extraction of fatty acids, and analysis by gas chromatography. In this study, eight methods based on alkaline methylation were compared for the analysis of fatty acids in cow's milk. The response factors (RF) for GC analysis using FID were calculated. For most acids, RFs were close to 1, with the exception of short-chain fatty acids (C4:0-C8:0). To facilitate the selection of the method for the determination of fatty acids in milk samples, the methods were assessed using the environmental assessment tools of the analytical procedure: the Analytical Eco-Scale, Green Analytical Procedure Index (GAPI), and Analytical Greenness for Sample Preparation (AGREEprep). The method based on direct milk methylation received the highest scores. Omitting the lipid separation step has an impact on reducing the quantity of used toxic chemicals and reagents, and produces a smaller amount of waste, a much higher throughput, and a reduced cost analysis.

AMPK-ChREBP axis mediates de novo milk fatty acid synthesis promoted by glucose in the mammary gland of lactating goats

To investigate the role of glucose in regulating milk fatty acid synthesis, 6 lactating Guanzhong dairy goats were infused with 0, 60, or 100 g/d glucose via the external pubic artery in a 3 × 3 repeated Latin square experiment. A concomitant in vitro experiment was conducted to investigate possible mechanisms whereby glucose regulates milk fatty acid synthesis. RNA sequencing was used for cellular transcriptome analysis. Drugs, MK-2206, rapamycin, and dorsomorphin were used to block cellular mammalian AMP-activated protein kinase (AMPK), AKT serine/threonine kinase 1, and mechanistic target of rapamycin kinase signaling pathways, respectively. Carbohydrate response element binding protein (ChREBP) was knockdown and overexpressed to investigate its role in regulating milk fatty acid synthesis in mammary epithelial cells. Glucose infusion linearly elevated the concentration of C8:0 (P = 0.039) and C10:0 (P = 0.041) in milk fat while it linearly decreased (P = 0.049) that of C16:0. This result was in agreement with the upregulation of genes related to de novo synthesis of fatty acids and lipid droplet formation, including adipose differentiation-related protein, butyrophilin subfamily 1 member A1, fatty acid synthase (FASN) and ChREBP. Their expression increased (P < 0.05) linearly in the lactating goat mammary gland. In vitro, glucose linearly stimulated the expression of genes related to de novo synthesis of fatty acids and cellular triacylglycerol in cultured mammary epithelial cells. RNA sequencing and inhibition studies revealed that glucose induced transcriptomic changes increasing lipogenic pathways, with AMPK responding to glucose by controlling ChREBP and FASN. Knockdown and overexpression of ChREBP highlighted its essential role in lipogenesis. The knockdown and overexpression of ChREBP protein also revealed an essential role in regulating the de novo synthesis of fatty acids. Collectively, our data highlight that glucose supplementation promotes de novo fatty acid synthesis via the AMPK-ChREBP axis, hence increasing milk fat yield in the goat mammary gland. Results from the current study provide possible strategies to manipulate the fatty acid composition as well as improve ruminant milk quality.

Antioxidant and Antibacterial Activities of a Purified Polysaccharide Extracted from Ceratonia siliqua L. and Its Involvement in the Enhancement Performance of Whipped Cream

The main objective discussed in this research was to determine the structural characteristics of carob kibble water-soluble polysaccharide (KWSP), extracted from Ceratonia siliqua L., and to assess its in vitro antioxidant activities, as well as its effect on whipped cream. The results obtained through 13C, 1H, and the hetero-nuclear single quantum coherence (HSQC) nuclear magnetic resonance (NMR) and Fourier transform infrared spectroscopy (FT-IR) analysis indicated that KWSP had the characteristic bands of polysaccharides. Thin layer chromatography (TLC) and high performance liquid chromatography (HPLC) suggested that KWSP is a hetero-polysaccharide composed of glucose and fructose, with an average molecular weight (Mw) amounting to 65 KDa. In addition, KWSP showed a good water holding capacity (WHC), a good oil holding capacity (OHC), and an emulsification stability, rated as 3.14 ± 0.05 g/g, 0.87 ± 0.02 g/g, and 71 ± 0.01%, respectively. The antioxidant activity of KWSP was investigated in vitro, demonstrating important DPPH and ABTS⋅+ radical scavenging activities and a good total antioxidant capacity. KWSP exhibited antibacterial activity against Listeria monocytogenes, Staphylococcus aureus, and Salmonella enterica. On the other hand, the incorporation of KWSP in whipped cream was investigated, to enhance its antioxidant capacity and consequently to extend its expiration date. Moreover, KWSP reduces the formation of conjugated dienes and trienes in cream fat.

Simultaneous Determination of C18 Fatty Acids in Milk by GC-MS

The determination of C18 fatty acids (FAs) is a key and difficult aspect in FA profiling, and a qualified method with good chromatographic separation and high sensitivity, as well as easy methylation, is required. A GC-MS method was established to simultaneously determine C18 FAs in milk. To simplify the methylation protocol for milk samples, besides a base-catalyzation methylation (50 °C for 20 min), the necessity of an additional acid-catalyzation was also studied using different temperatures (60 °C, 70 °C, 80 °C, and 90 °C) and durations (90 min and 150 min). The results showed that the chromatographic resolution was improved, although three co-eluted peaks existed. The base-catalyzation was sufficient, and an additional acid-catalyzation was not necessary. The proposed method was validated with good sensitivity, linearity, accuracy, and precision, and then applied in determining C18 FAs in 20 raw milk and 30 commercial milk samples. UHT milk presented a different profile of C18 FAs from raw milk and PAS milk samples, which indicated that excessive heating could change the profile. Overall, the proposed method is a high-throughput and competent approach for the determination of C18 FAs in milk, and which presents an improvement in chromatographic resolution and sensitivity, as well as a simplification of methylation.

Metabolomic Studies for the Evaluation of Toxicity Induced by Environmental Toxicants on Model Organisms

Environmental pollution causes significant toxicity to ecosystems. Thus, acquiring a deeper understanding of the concentration of environmental pollutants in ecosystems and, clarifying their potential toxicities is of great significance. Environmental metabolomics is a powerful technique in investigating the effects of pollutants on living organisms in the environment. In this review, we cover the different aspects of the environmental metabolomics approach, which allows the acquisition of reliable data. A step-by-step procedure from sample preparation to data interpretation is also discussed. Additionally, other factors, including model organisms and various types of emerging environmental toxicants are discussed. Moreover, we cover the considerations for successful environmental metabolomics as well as the identification of toxic effects based on data interpretation in combination with phenotype assays. Finally, the effects induced by various types of environmental toxicants in model organisms based on the application of environmental metabolomics are also discussed.

Bovine Milk Triacylglycerol Regioisomer Ratio Shows Remarkable Inter-Breed and Inter-Cow Variation

Regioisomers (or positional isomers) of triacylglycerols (TAGs) of milk are known to show differential outcome in relation to human absorption. Quantitation of TAG regioisomers remains a big challenge due to the lack of facile chromatographic separation technique. The feasibility of using fragment ion intensity ratio to determine the ratio of co-eluting AAB/ABA-type regioisomer pairs was confirmed in this study. The ability of C30 stationary phase in resolving interfering TAG isomers was demonstrated for the first time. This allowed us to reveal the complexity of using fragment ion intensity to quantify 1,2-olein-3-palmitin (OOP), 1,3-olein-2-palmitin (OPO), 1,2-olein-3-stearin (OOS), and 1,3-olein-2-stearin (OSO) regioisomers in milk samples. A novel algorithm was proposed to consider the contribution of OPO/OOP and OSO/OOS double bond (DB)-isomers and to eliminate the interference of isobaric ions from other isomers, an aspect overlooked in previous studies. This liquid chromatography-mass spectrometry method that requires no pre-fractioning and a moderate chromatographic separation time of 36 min is simple and, thus, suitable for screening a large number of samples for genetic analysis of this trait. Preliminary results using a small cohort of animals showed that OPO/OOP ratio differs significantly between Jersey and Holstein cows, and a large variation was also observed across individual Holstein cows.

Short-chain fatty acid (SCFA) and medium-chain fatty acid (MCFA) concentrations in human milk consumed by infants born at different gestational ages and the variations in concentration during lactation stages

This study aimed to quantify the short-chain fatty acids (SCFAs) and medium-chain fatty acids (MCFAs) in human milk triacylglycerols (TAGs) and investigate their concentrations in human milk consumed during lactation by infants born at different gestational ages. One hundred and eighty milk samples from the mothers of 30 full-term, 10 early-preterm (≤32 weeks), 10 mild-preterm (32-34 weeks), and 10 near-term (34-37 weeks) infants were collected from the colostrum, transitional, and mature milk. The human milk TAGs were transferred into fatty-acid methyl esters via potassium methoxide in methanol and determined using gas chromatography (GC). The total SCFA (4:0) and MCFA concentrations (6:0 and 8:0) were highest in the mature milk (1.47 ± 0.66 mg g-1 fat from full-term infant milk), approximately 42.18% higher than those in transitional milk. Significantly higher SCFA and MCFA concentrations were found in full-term milk than in preterm milk (p = 0.001). The milk TAGs were analyzed using ultra-high-performance supercritical fluid chromatography with quadrupole-time-of-flight mass spectrometry (UHPSFC-Q-TOF-MS), which showed that the SCFAs and MCFAs were mainly esterified with long-chain fatty-acid groups (16:0, 18:1 n-9, and 18:2 n-6) at the glycerol backbone. The infants' daily SCFA intake from human milk was estimated; this was highest from mature milk for full-term infants (∼14 mg d-1) which was significantly different from that of preterm infants from colostrum and transitional milk (p < 0.001). The correlation between dietary SCFAs and MCFAs in human milk and nutrition in newborns, especially in the gut microbiotas of preterm infants, requires further study.

Recent Techniques in Nutrient Analysis for Food Composition Database

Food composition database (FCD) provides the nutritional composition of foods. Reliable and up-to date FCD is important in many aspects of nutrition, dietetics, health, food science, biodiversity, plant breeding, food industry, trade and food regulation. FCD has been used extensively in nutrition labelling, nutritional analysis, research, regulation, national food and nutrition policy. The choice of method for the analysis of samples for FCD often depends on detection capability, along with ease of use, speed of analysis and low cost. Sample preparation is the most critical stage in analytical method development. Samples can be prepared using numerous techniques; however it should be applicable for a wide range of analytes and sample matrices. There are quite a number of significant improvements on sample preparation techniques in various food matrices for specific analytes highlighted in the literatures. Improvements on the technology used for the analysis of samples by specific instrumentation could provide an alternative to the analyst to choose for their laboratory requirement. This review provides the reader with an overview of recent techniques that can be used for sample preparation and instrumentation for food analysis which can provide wide options to the analysts in providing data to their FCD.

Breast milk n-3 long-chain polyunsaturated fatty acids and blood pressure: an individual participant meta-analysis

Purpose

It is controversial whether a higher intake of n-3 long-chain polyunsaturated fatty acids (n-3 LC PUFA) through breastfeeding is associated or not to a lower blood pressure (BP) during childhood. We aimed to clarify this point by undertaking a meta-analysis involving the data from seven European birth cohorts.

Methods

We searched https://www.birthcohort.net for studies that had collected breast milk samples, and had at least one BP measurement in childhood. Principal investigators were contacted, and all agreed to share data. One additional study was identified by contacts with the principal investigators. For each cohort, we analyzed the association of breast milk n-3 LC PUFAs with systolic and diastolic BP with linear mixed effects models or linear regression, and pooled the estimates with a random effects model. We also investigated age-specific and sex-specific associations.

Results

A total of 2188 participants from 7 cohorts were included. Overall, no associations between breast milk n-3 LC PUFAs and BP were observed. In the pooled analysis, each 0.1 wt% increment in breast milk docosahexaenoic acid (DHA) was associated with a 1.19 (95% CI − 3.31, 0.94) mmHg lower systolic BP. Associations were similar for boys and girls and at different ages.

Conclusion

In this individual participant meta-analysis, we found no evidence for an association between breast milk n-3 LC PUFAs and BP.

Electronic supplementary material

The online version of this article (10.1007/s00394-020-02310-4) contains supplementary material, which is available to authorized users.

Development of one-step sample preparation methods for fatty acid profiling of milk fat

Determination of the fatty acid (FA) profile of milk fat generally involves total lipid extraction from liquid milk, transesterification and GC analysis. The lipid extraction step is time consuming and often employs toxic solvents such as chloroform. Two alternative methods are presented here that skip the lipid extraction step and allow the determination of FA composition via direct transesterification of dried milk and liquid milk respectively. We have shown that dried milk can be used directly in alkaline-catalysed methylation, whereas direct transesterification of both dried milk and fresh milk is feasible with acidic methanol. Both methods generate similar results as compared to the classical two-step method (i.e. lipid extraction and FA methylation) when optimised methylation parameters (temperature, time, milk and reagent volume) are followed. By omitting the lipid extraction step, these simplified one-step methods offer a much higher throughput and a reduced cost in FA composition analysis of milk samples.

Development of a Liquid Chromatography-High Resolution Mass Spectrometry Method for the Determination of Free Fatty Acids in Milk

The determination of free fatty acids (FFAs) in milk is of importance for quality control, legislative purposes, authentication and product development. We present herein a liquid chromatography–high resolution mass spectrometry method for the direct determination of FFAs in milk. The method involves mild sample preparation, avoids time-consuming derivatization and allows the direct quantification of twenty-two FFAs in a 10-min single run. It was validated and applied in thirteen cow milk and seven goat milk samples. Saturated fatty acids C16:0, C18:0 and unsaturated C18:1 (n-9) were found to be the major components of milk FFAs at concentrations of 33.1 ± 8.2 μg/mL, 16.5 ± 5.3 μg/mL and 14.8 ± 3.8 μg/mL, respectively, in cow milk and at concentrations of 22.8 ± 1.8 μg/mL, 12.7 ± 2.8 μg/mL and 13.3 ± 0.3 μg/mL, respectively, in goat milk. Other saturated and unsaturated FFAs were found in significantly lower quantities. Saturated fatty acids C6:0, C8:0 and C10:0 were found in higher quantities in goat milk than in cow milk. The levels of the important (for human health) odd-chain FFAs C15:0 and C17:0 were estimated in cow and goat milk.

Microwave-Assisted, Base-Catalyzed Synthesis of Fatty Acid Methyl Esters from Seeds and Fish Oil Supplements

Growing health awareness has resulted in the increased use of dietary supplements derived from plants and marine sources, leaving consumers unsure of their best options. There were three objectives of the present study. The first was to design and evaluate an efficient derivatization procedure. The second was to perform a comparative analysis of liquid oils and their corresponding capsules of hemp, chia, and flax seeds. The final objective was to determine the fatty acid (FA) composition of six fish oil products and compare it to the one provided on the label. For the FA profiling, we implemented two efficient, one-step, sustainable methods with high percentage recovery for the synthesis of FA methyl esters (FAME), which use base catalysis and microwave-assisted heating. Our results found no difference in nutritional value between liquid oils and capsules of the seed supplements, with flaxseed and chia offering a higher, beneficial n-3:n-6 ratio compared to hemp oil. Four of the fish oils analyzed contained significantly less eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) than their reported label, and the other two not only agreed with the manufacturers' declaration but were able to fulfill the daily adequate intake (AI) with fewer capsules.

Comprehensive Evaluation of Parameters Affecting One-Step Method for Quantitative Analysis of Fatty Acids in Meat

Despite various direct transmethylation methods having been published and applied to analysis of meat fatty acid (FA) composition, there are still conflicting ideas about the best method for overcoming all the difficulties posed by analysis of complex mixtures of FA in meat. This study performed a systematic investigation of factors affecting a one-step method for quantitative analysis of fatty acids in freeze-dried animal tissue. Approximately 280 reactions, selected using factorial design, were performed to investigate the effect of temperature, reaction time, acid concentration, solvent volume, sample weight and sample moisture. The reaction yield for different types of fatty acids, including saturated, unsaturated (cis, trans and conjugated) and long-chain polyunsaturated fatty acids was determined. The optimised condition for one-step transmethylation was attained with four millilitres 5% sulfuric acid in methanol (as acid catalyst), four millilitres toluene (as co-solvent), 300 mg of freeze-dried meat and incubation at 70 °C for 2 h, with interim mixing by inversion at 30, 60 and 90 min for 15 s. The optimised condition was applied to meat samples from different species, covering a broad range of fat content and offers a simplified and reliable method for analysis of fatty acids from meat samples.

Total and Free Fatty Acids Analysis in Milk and Dairy Fat

Dairy fat is one of the most complex natural fats because of its fatty acid (FA) composition. Ruminant dairy fat contains more than 400 different FA varying in carbon chain length, and degree, position and configuration of unsaturation. The following article reviews the different methods available to analyze FA (both total and free) in milk and dairy products. The most widely used methodology for separating and analyzing dairy FA is gas chromatography, coupled to a flame ionization detector (CG-FID). Alternatively, gas chromatography coupled to a mass spectrometer (GC-MS) is also used. After lipid extraction, total FA (TFA) are commonly converted into their methyl esters (fatty acid methyl esters, FAME) prior to chromatographic analysis. In contrast, free FA (FFA) can be analyzed after conversion to FAME or directly as FFA after extraction from the product. One of the key questions when analyzing FAME from TFA is the selection of a proper column for separating them, which depends mainly on the objective of the analysis. Quantification is best achieved by the internal standard method. Recently, near-infrared spectroscopy (NIRS), Raman spectroscopy (RS) and nuclear magnetic resonance (NMR) have been reported as promising techniques to analyze FA in milk and dairy products.