Enrichment of Ewe's Milk with Dietary n-3 Fatty Acids from Palm, Linseed and Algae Oils in Isoenergetic Rations.

Increasing the levels of n-3 fatty acids (FA) in dairy products is an important goal in terms of enhancing the nutritional value of these foods for the consumer. The purpose of this research was to evaluate the effects of linseed and algae oil supplements in ovine isoenergetic diets on healthy milk fatty acid composition, mainly n-3. Seventy-two Churra dairy ewes were divided and randomly assigned to four experimental treatments for 6 weeks. The treatments consisted of a TMR (40:60 forage:concentrate ratio) that varied according to the inclusion of different types of fat (23 g/100 g TMR): hydrogenated palm oil (control), linseed oil (LO), calcium soap of linseed oil (CaS-LO) and marine algae oil (AO). The most effective lipid supplement to increase n-3 FA in milk was AO. 22:6 n-3 and total n-3 PUFA content increased from 0.02 and 0.60% (control) to 2.63 and 3.53% (AO), respectively. All diets supplemented with n-3 FA diminished the content of saturated FA in milk and its atherogenic index, while the levels of trans-11 18:1 and cis-9 trans-11 18:2 significantly increased. Overall, the enhancement of n-3 FA in ewe's milk would be advantageous for the manufacture of nutritionally improved cheeses.

Feeding Algae Meal to Feedlot Lambs with Competent Reticular Groove Reflex Increases Omega-3 Fatty Acids in Meat.

The aim of this study was to compare the effects of supplementing marine algae as a source of omega-3 fatty acids (FA) in the diet, mixed in the concentrate or bottle-fed, on intramuscular fat FA composition of lambs with competent reticular groove reflex (RGR). Forty-eight feedlot lambs were distributed in three equal groups: one group did not consume marine algae nor had competent RGR, the second group received a daily dose (2.5%) of algae meal in the concentrate and the last group consumed the same dose of algae meal emulsified in milk replacer and bottle-fed. Marine algae raised the contents of EPA, DPA, and mainly DHA in the intramuscular fat, but the increase was significantly higher when algae meal was administered with a bottle via RGR. This strategy could contribute to improvements in the marketing of lamb meat by optimizing its status as a healthier food.

Fast capillary electrophoresis method for determination of docosahexaenoic and eicosapentaenoic acids in marine oils omega-3 supplements.

Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are essential omega-3 fatty acids (FA) in human nutrition. Dietary supplements containing these FA are available in the market and there is a need to assess their quality to prevent frauds. The purpose of this work was to optimize and validate a fast capillary electrophoresis (CE) method to determine EPA and DHA content in marine oils omega-3 supplements. Sample preparation comprised only a saponification step and analysis time was 8 min. Validation was performed according to limits of detection and quantification, linearity, accuracy and repeatability. Ten real samples of marine oil supplements were analyzed by CE and compared to conventional gas chromatography method. No significant differences between both methods were found within 95% confidence interval. Overall, CE method was successful to FA quantification and it could be used for fast FA monitoring during omega-3 supplement manufacture, final product quality assurance and labelling.

Application of a linear regression model to study the origin of C17 branched-chain fatty acids in caprine milk fat.

This research communications addresses the hypothesis that a part of iso 17:0 and anteiso 17:0 in milk fat could come from endogenous extraruminal tissue synthesis. In order to confirm this a linear regression model was applied to calculate the proportions of iso 17:0 and anteiso 17:0 in milk fat that could come from elongation of their putative precursors iso 15:0 and anteiso 15:0, respectively. Sixteen dairy goats were allocated to two simultaneous experiments, in a crossover design with four animals per treatment and two experimental periods of 25 d. In both experiments, alfalfa hay was the sole forage and the forage to concentrate ratio (33 : 67) remained constant. Experimental diets differed on the concentrate composition, either rich in starch or neutral detergent fibre, and they were administered alone or in combination with 30 g/d of linseed oil. Iso 15:0, anteiso 15:0, iso 17:0 and anteiso 17:0, the most abundant branched-chain fatty acids in milk fat, were determined by gas chromatography using two different capillary columns. The regression model resolved that 49% of iso 17:0 and 60% of anteiso 17:0 in milk fat was formed extraruminally from iso 15:0 and anteiso 15:0 elongation.

Oxidomics on the omega-3 volatile degradation pattern to determine differences between vegetable and marine oils.

In this work, oxidation assessment of vegetable and marine oils was performed based on their quantitative volatile profile and data analysis by 3-way partial least square chemometrics. Classification models were obtained using broad-spectrum isotopically labelled standards on the analysis of 25 volatile compounds from omega-3 fatty acid (FA) degradation by headspace solid phase microextraction gas chromatography time-of-flight mass spectrometry. Our oxidomic approach was performed on edible oils that differed in their origin (marine or vegetable) and in their omega-3 FA profile. In order to achieve a 3D matrix, every oil was oxidized at 6 different time-points. The obtained models classified edible oils according to their volatile degradation pattern. Oxidation of eicosapentaenoic/docosahexaenoic FA was mainly related to 2-propenal, butanal and 2-ethylfuran while α-linolenic acid oxidation was linked to 1-hydroxy-2-butanone and 5-ethyl-2(5H)-furanone. The present research provides valuable information on the degradation differences of omega-3 oils and proposes specific oxidation markers that could be used to ensure their quality assurance and avoid intentional adulterations.

Quick changes of milk fatty acids after inclusion or suppression of linseed oil in the diet of goats.

BACKGROUND: Lipid supplementation of ruminant diet is an excellent tool to improve the nutritional quality of dairy fat. The purpose of this research was to monitor in detail the goat milk fatty acid (FA) profile during the first 24 h after linseed oil (LO) supplementation or suppression in the diet. Particular emphasis was placed in the changes of FA with bioactive properties. Milk fat was analysed by gas chromatography from milkings at 0, 1, 3, 6, 12 and 24 h after diet shift. RESULTS: The α-linolenic acid levels increased 12 h after LO incorporation in the diet and decreased 3 h after oil suppression. Most of the milk 10:0 to 16:0 saturated FA decreased 24 h after LO supplementation, whereas oil suppression raised their levels after 6 h. Similarly, raising of mono- and polyunsaturated trans-FA after LO inclusion was delayed in comparison with their decrease after oil suppression. CONCLUSION: This study supports that ruminal bacteria and mammary glands would exhibit a fast responsiveness after the inclusion or suppression of LO in ruminant rations. Milk with an improved FA profile could be collected between 12 h after LO supplementation and the last milking before LO suppression in the diet. © 2018 Society of Chemical Industry.

Associations between major fatty acids in plant oils fed to dairy goats and C18 isomers in milk fat.

Relationships between fatty acids (FAs) in plant oils included in goat diets and milk fat C18 isomers were determined by Principal Factor Analysis (PFA). The three first principal factors (PF1, PF2 and PF3) accounted for 64.5% of the total variation in milk FAs contents. Fatty acids with a double bond at carbons 13, 14, 15 or 16 had high (>0.6) and positive loadings for PF1, trans-4 to trans-8 C18:1 for PF2, whereas trans-10 C18:1, trans-11 C18:1 and cis-9 trans-11 C18:2 showed high and positive loadings for PF3. Pearson's correlations supported that PF1, PF2 and PF3 were related to α-linolenic, oleic and linoleic acid intakes, respectively. Our results show that the quantitatively main FAs in plant lipids supplemented to dairy ruminants are often the main cause of the observed changes in milk C18 isomer contents. However, sometimes the observed changes are caused, or at least are influenced, by other FAs present in lower quantities in the plant lipids. Thus, using mixtures of plant oils with differently unsaturated main FAs could be a way of tailoring milk fat composition to a pre-designed pattern.

Quantitative analysis of volatiles in edible oils following accelerated oxidation using broad spectrum isotope standards.

Analysis of food volatiles generated by processing are widely reported but comparisons across studies is challenging in part because most reports are inherently semi-quantitative for most analytes due to limited availability of chemical standards. We recently introduced a novel strategy for creation of broad spectrum isotopic standards for accurate quantitative food chemical analysis. Here we apply the principle to quantification of 25 volatiles in seven thermally oxidised edible oils. After extended oxidation, total volatiles of high n-3 oils (flax, fish, cod liver) were 120-170 mg/kg while low n-3 vegetable oils were <50mg/kg. Separate experiments on thermal degradation of d5-ethyl linolenate indicate that off-aroma volatiles originate throughout the n-3 molecule and not solely the n-3 terminal end. These data represent the first report using broad-spectrum isotopically labelled standards for quantitative characterisation of processing-induced volatile generation across related foodstuffs, and verify the origin of specific volatiles from parent n-3 fatty acids.

Production of isotopically labeled standards from a uniformly labeled precursor for quantitative volatile metabolomic studies.

Optimal accuracy and precision in small-molecule profiling by mass spectrometry generally requires isotopically labeled standards chemically representative of all compounds of interest. However, preparation of mixed standards from commercially available pure compounds is often prohibitively expensive and time-consuming, and many labeled compounds are not available in pure form. We used a single-prototype uniformly labeled [U-(13)C]compound to generate [U-(13)C]-labeled volatile standards for use in subsequent experimental profiling studies. [U-(13)C]-α-Linolenic acid (18:3n-3, ALA) was thermally oxidized to produce labeled lipid degradation volatiles which were subsequently characterized qualitatively and quantitatively. Twenty-five [U-(13)C]-labeled volatiles were identified by headspace solid-phase microextraction-gas chromatography/time-of-flight mass spectrometry (HS-SPME-GC/TOF-MS) by comparison of spectra with unlabeled volatiles. Labeled volatiles were quantified by a reverse isotope dilution procedure. Using the [U-(13)C]-labeled standards, limits of detection comparable to or better than those of previous HS-SPME reports were achieved, 0.010-1.04 ng/g. The performance of the [U-(13)C]-labeled volatile standards was evaluated using a commodity soybean oil (CSO) oxidized at 60 °C from 0 to 15 d. Relative responses of n-decane, an unlabeled internal standard otherwise absent from the mixture, and [U-(13)C]-labeled oxidation products changed by up to 8-fold as the CSO matrix was oxidized, demonstrating that reliance on a single standard in volatile profiling studies yields inaccurate results due to changing matrix effects. The [U-(13)C]-labeled standard mixture was used to quantify 25 volatiles in oxidized CSO and low-ALA soybean oil with an average relative standard deviation of 8.5%. Extension of this approach to other labeled substrates, e.g., [U-(13)C]-labeled sugars and amino acids, for profiling studies should be feasible and can dramatically improve quantitative results compared to use of a single standard.

Comparison of the fatty acid profiles in cheeses from ewes fed diets supplemented with different plant oils.

The purpose of this work was to obtain a cheese from ewes milk with a healthier fatty acid (FA) profile. To achieve our aim, 48 ewes (12 per treatment) were fed diets supplemented with 3% of plant oils: palm (used as control), olive (OO), soybean (SO), and linseed (LO). Milk samples from each treatment were collected to manufacture cheeses. The cheesemaking process did not modify the dairy fat FA profile, but OO, SO, and LO did reduce the C12:0 + C14:0 + C16:0 content in dairy fat, thus decreasing the atherogenic index value in the cheeses. Percentages of cis-9 trans-11 C18:2 in cheeses ranged from the 0.43 control value to 0.92, 1.64, and 2.71 with OO, LO, and SO respectively, following the same pattern as trans-11 C18:1. In contrast, trans-10 C18:1 levels were always below 1%. The lowest n-6/n-3 ratio obtained with LO (1.43) suggests that such lipid supplementation would be the most effective nutritional strategy for improving cheese FA profiles.

Acute oral safety study of dairy fat rich in trans-10 C18:1 versus vaccenic plus conjugated linoleic acid in rats.

The acute oral toxicity of a trans-10 C18:1-rich milk fat (T10, 20% of total FA), and a trans-11 C18:1+cis-9 trans-11 C18:2-rich milk fat (T11-CLA, 14% and 4.8% of total FA, respectively) was studied in rats receiving a single oral dose of 2000 mg/kg body weight (BW). T10 and T11-CLA milk fats were well tolerated; no adverse effects or mortality were observed during the 2-week observation period. Two weeks following a single oral dose of 2000 mg/kg BW of T10 and T11-CLA milk fats there were no changes in haematological and serum chemistry parameters (excepting plasma lipid) organ weights, gross pathology or histopathology. In rats treated with T10 milk fat a significant increase of triglycerides was observed. In contrast, in rats treated with T11-CLA milk fat significantly decreased triglycerides were detected. It was concluded that dairy fats rich in T10 and T11-CLA have a low order of acute toxicity, the oral lethal dose (DL50) for male and female rats are in excess of 2000 mg/kg BW. Our results suggest that the T10 milk fat treatment tended to increase triglycerides concentrations, whereas the T11-CLA milk fat treatment tended to reduce it.

Characterization of cis-9 trans-11 trans-15 C18:3 in milk fat by GC and covalent adduct chemical ionization tandem MS.

Rumen biohydrogenation of dietary alpha-linolenic acid gives rise in ruminants to accumulation of fatty acid intermediates, some of which may be transferred into milk. Rumelenic acid [cis-9 trans-11 cis-15 C18:3 (RLnA)] has recently been characterized, but other C18:3 minor isomers are still unknown. The objective of this work was to identify a new isomer of octatridecenoic acid present in milk fat from ewes fed different sources of alpha-linolenic acid. Structural characterization of this fatty acid was achieved by GC-MS. Analysis of dimethyloxazoline and picolinyl ester derivatives allowed for location of the double bond positions. Covalent adduct chemical ionization tandem mass spectrometry confirmed the positional structure 9-11-15, identical to RLnA, and helped to establish double bond geometry (cis-trans-trans). This new C18:3 isomer could be formed by isomerization of cis-15 bond of RLnA and subsequently converted by hydrogenation to trans-11 trans-15 C18:2, an octadecadienoic acid also detected in this study.