Oxidative Stability and Sensory Attributes of Fermented Milk Product Fortified with Fish Oil and Marine Phospholipids

Marine phospholipids (PL) are potential ingredients for food fortification due to its numerous advantages. The main objective of this study was to investigate whether a fermented milk product fortified with a mixture of marine PL and fish oil had better oxidative stability than a fermented milk product fortified with fish oil alone. Fortification of a fermented milk product with marine PL was performed by incorporating 1 % w/w lipids, either in the form of neat oil or in the form of a pre-emulsion. Lipid oxidation was investigated in the neat emulsions and fortified products by the measurements of primary, secondary volatile oxidation products and tocopherol content upon 32 days storage at 2 °C and 28 days storage at 5 °C, respectively. Analyses of particle size distribution, viscosity and microbial growth were also performed. In addition, sensory attributes such as sour, fishy and rancid flavor/odor were evaluated in fortified products by a trained panel. The results obtained showed that incorporation of a mixture of marine PL and fish oil into fermented milk products decreased the oxidative stability and sensory quality of fortified products. The pH-dependent behavior of iron seemed to be the main factor that influenced the lipid oxidation in the marine PL emulsion and fermented milk system. In addition, both oxidative stability and sensory acceptability of fortified products varied depending on the quality of the marine PL used for fortification.     

Encapsulation of Long-Chain n-3 Polyunsaturated Fatty Acids Using Egg Yolk

Egg yolk is well known for its excellent emulsifying property. In this article, egg yolk was used as the encapsulating matrix to prevent the oxidation of n-3 long-chain polyunsaturated fatty acids from fish oil. A 2 × 2 × 5 complete block design with three replications was used. Two levels of fish oil (1% and 5%) and two levels of esterification type (triglycerides or ethyl esters) of eicosapentaenoic/docosahexaenoic fatty acids were used. Time was considered a fixed factor with five levels. Emulsions were prepared by homogenization and stored for up to 4 weeks at 4–6 °C, with weekly sampling. Emulsions were analyzed for particle size and distribution, encapsulation efficiency, and surface oil. The oxidative stability of the emulsions was evaluated before and after cooking at 150–170 °C for 75 s. The addition of triglycerides resulted in a larger average particle size (234 ± 12.4 nm). All emulsions achieved 100% encapsulation efficiency and showed no significant change in the surface oil concentration during storage. After 4 weeks of storage, the concentration of eicosapentaenoic + docosahexaenoic fatty acids in nonencapsulated fish oil triglycerides and ethyl esters decreased by 20.32% and 14.74%, respectively, while the emulsions showed no significant differences. In addition, no peroxide or propanal formation was detected in raw emulsions over the storage period. Propanal formation was negligible in cooked samples, and the peroxide value showed no differences between the egg yolk control and the emulsions. Therefore, egg yolk was observed to be an efficient encapsulating food matrix that protects n-3 polyunsaturated fatty acids against oxidation and degradation.     

Lymphatic fatty acids from rats fed human milk and formula supplemented with fish oil

Absorption of long-chain polyunsaturated fatty acids from human milk and formula supplemented with fish oil was studied to determine if the distribution route into lymphatic triacylglycerol (TAG) and phospholipid (PL) varies with the dietary source. Rats were intraduodenally infused with human milk or formula containing graded amounts of fish oil (0, 0.5, or 1.0 g/100 mL), and the mesenteric lymph was collected. Arachidonic acid (20∶4n−6) levels in lymphatic TAG and PL were highest from animals fed human milk. In the animals infused with formula containing fish oil, as the amount of eicosapentaenoic acid (EPA, 20∶5n−3) infused increased, there was essentially an equal increase of EPA associated with both lymphatic TAG and PL. Animals intraduodenally infused with human milk or formula without fish oil had only minor levels (less than 1%) of EPA in the lymph. In the fish oil-treated animals, as the amount of docosahexaenoic acid (DHA, 22∶6n−3) infused increased, there was a 16-fold increase in DHA associated with lymphatic TAG, but only a 3-fold increase in DHA associated with lymphatic PL. The highest level of DHA in rats infused with human milk was observed in lymphatic PL. Hence, fish oil can be added to formula as a source of long-chain polyunsaturated fatty acids, but the distribution of fatty acids into lymphatic TAG and PL is not the same as that observed with human milk.     

Marine phospholipids as dietary carriers of long‐chain polyunsaturated fatty acids

Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are polyunsaturated fatty acids (PUFA) of the n‐3 series. Fish oil is a classical source of n‐3 PUFA, where they occur in the form of triacylglycerols (TAG). However, new sources of n‐3 PUFA esterified in phospholipids (PL) are emerging. We prepared liposomes from a natural marine lipid extract and examined their behaviour under conditions mimicking that of the gastrointestinal tract. This physicochemical approach proved that liposomes could be used as an effective oral PUFA delivery system. In vivo studies in rats were performed to examine the metabolic fate of EPA (20:5 n‐3) and DHA (22:6 n‐3) delivered either in PL from liposomes or in TAG from oil. Liposome ingestion increased PUFA bioavailability in lymph compared with fish oil. The proportion of n‐3 PUFA esterified in the sn‐2 position of chylomicron TAG depended on the dietary lipid source. Complex time‐course profiles were observed for plasma lipids with liposome supplementation over a 2‐week period, suggesting time‐dependent regulations. Taken together, the type of PUFA, EPA or DHA, as well as its intramolecular distribution in chylomicron TAG seemed to influence the metabolic fate of the fatty acids and their physiological activities.     

Delivery of Omega-3 Fatty Acids into Cake Through Emulsification of Fish Oil-in-Milk and Encapsulation by Spray Drying with Added Polymers

Fortification of cakes with fish oil encapsulates was performed to enhance the consumption of health-beneficial polyunsaturated fatty acids like eicosapentaenoic acid and docosahexaenoic acid. Fish oil-in-milk emulsions prepared by ultrasonication at different amplitudes were encapsulated by spray drying using different wall materials. The oxidative stability of fish oil encapsulates was determined for 32 days at room and refrigerated temperatures. Oxidatively stable encapsulates and organoleptic quality of fortified cakes reveal that emulsification of fish oil-in-milk and encapsulation by spray drying are potential processes to produce fish oil encapsulates suitable for fortification of bakery products with omega-3 fatty acids.     

Feeding rats with liposomes or fish oil differently affects their lipid metabolism

Two n‐3 polyunsaturated fatty acid (PUFA)‐rich diets differing in their chemical and physical forms were given to rats during 2 wk. Liposomes [phospholipids (PL) organized in bilayer structures] made from a natural marine lipid extract or a mixture of fats containing fish oil [similar fatty acids esterified in triacylglycerols (TAG)] were used. The influence of n‐3 PUFA dietary sources on plasma parameters, i.e. TAG, cholesterol and PL concentrations, was investigated. A similar hypotriglyceridemic effect of n‐3 PUFA from liposomes or fish oil was observed. In contrast, feeding rats with liposomes led to different PL and cholesterol patterns. In the plasma of rats fed liposomes, total cholesterol amounts were positively correlated with PL levels. Liposome and fish oil feedings caused a marked increase in the amounts of n‐3 PUFA, which occurred mainly at the expense of n‐6 PUFA. However, the enrichment in n‐3 PUFA in the different plasma lipid classes differed substantially when ingested in the form of fish oil or liposomes. These results were interpreted in terms of different lipid bioavailability and metabolic fate during the digestive steps and in the liver, with the dietary source.     

Oxidative stability of natural and randomized high-palmitic-and high-stearic-acid oils from genetically modified soybean varieties

The oxidative stability of soybean oil triacylglycerols (TAG) obtained from genetically modified soybeans was determined before and after chemical randomization. Soybean oil oxidative studies were carried out under static oxygen headspace at 60°C in the dark and oxidative deterioration was monitored by peroxide value, monometric and oligomeric oxidation products, and volatile compounds. Randomization of the soybean oil TAG improved the oxidative stability compared to the natural soybean oil TAG. Oxidative stability was improved by three factors. Factor one was the genetic modification of the fatty acid composition in which polyunsaturated acids (such as linolenic and linoleic acids) were decreased and in which monounsaturated fatty acids (such as oleic) and saturated acids (palmitic and stearic) were increased. Factor two was the TAG compositional modification with a decrease in linolenic and linoleic-containing TAG and an increase in TAG with stearic and palmitic acids in combination with oleic acid. Factor three was the TAG structure modification accomplished by an increase in saturated fatty acids and a decrease in linoleic and linolenic acids at the glycerol moiety carbon 2. Presented at the AOCS Annual Meeting & Expo, Chicago, IL, May 10–13, 1998.     

Oxidative flavour deterioration of fish oil enriched milk

The oxidative deterioration of milk emulsions supplemented with 1.5 wt‐% fish oil was investigated by sensory evaluation and by determining the peroxide value and volatile oxidation products after cold storage. Two types of milk emulsions were produced, one with a highly unsaturated tuna oil (38 wt‐% of n‐3 fatty acids) and one with cod liver oil (26 wt‐% of n‐3 fatty acids). The effect of added calcium disodium ethylenediaminetetraacetate (EDTA) on oxidation was also investigated. Emulsions based on cod liver oil with a slightly elevated peroxide value (1.5 meq/kg) oxidised significantly faster than the tuna oil emulsions, having a lower initial peroxide value (0.1 meq/kg). In the tuna oil emulsions the fishy off‐flavour could not be detected throughout the storage period. Addition of 5—50 ppm EDTA significantly reduced the development of volatile oxidation products in the cod liver oil emulsions, indicating that metal chelation with EDTA could inhibit the decomposition of lipid hydroperoxides in these emulsions. This study showed that an oxidatively stable milk emulsion containing highly polyunsaturated tuna fish oil could be prepared without significant fishy off‐flavour development upon storage, provided that the initial peroxide value was sufficiently low.     

Oxidative stability of polyunsaturated fatty acids and soybean oil in an aqueous solution with emulsifiers

The oxidative stability of polyunsaturated fatty acids (PUFA) and soybean oil homogenized with emulsifiers was investigated. Model emulsions were prepared from PUFA, including linoleic acid (LA), arachidonic acid (AA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA), and from soybean oil emulsified with different emulsifiers: three Tween emulsifiers (Tween 20, Tween 60, Tween 80) and two sucrose esters (S-1170 and S-1570) were used. The results showed that the emulsions prepared from LA and the various emulsifiers, oxidized at 40°C, were unstable. However, the corresponding AA, EPA, and DHA emulsions were stable, indicating that PUFA with a higher degree of unsaturation were more stable with emulsifiers than without the emulsifiers. In the soybean oil-in-water model system, the oxidation of soybean oil with various emulsifiers was less than without the emulsifiers.     

Marine lipid-based liposomes increase <Emphasis Type="Italic">in vivo</Emphasis> FA bioavailability

Liposomes made from an extract of natural marine lipids and containing a high n-3 PUFA lipid ratio were envisaged as oral route vectors for FA supplements in order to increase PUFA bioavailability. The absorption of FA in thoracic lymph duct-cannulated rats, after intragastric feeding of dietary fats in the form of liposomes or fish oil, was compared. Lipid and FA analyses were also performed on feces. Five mole percent α-tocopherol was added to fish oil and incorporated into the liposome membrane. The influence of α-tocopherol on FA lymph recovery was also investigated. In vivo, FA absorption in rats was favored by liposomes (98±1%) compared to fish oil (73±6%). In the same way, the DHA proportion in lymph was higher after liposome ingestion (78%) than after fish oil ingestion (47%). However, phospholipid (PL) concentration in lymph was not affected by the kind of dietary fat ingested, suggesting a PL regulation due to de novo TAG synthesis. The influence of the intramolecular distribution of n-3 PUFA in dietary lipids (TAG and PL) on the intramolecular FA distribution in TAG of chylomicrons was also investigated. The results obtained showed that the distribution of n-3 PUFA esterified on the sn-2 of chylomicron TAG depended on the lipid source administered. All these results correlated, at least partly, with in vitro liposome behavior under conditions that mimic those of the gastrointestinal tract. As a whole, this study pointed out that marine PL may constitute an attractive material for the development of liposomes as oral PUFA supplements.     

Oxidative Stabilities of Enzymatically Interesterified Fats Containing Conjugated Linoleic Acid

Interesterified fat was produced from soybean oil (SBO) and palm stearin (PS) using two different weight ratios of substrates. Conjugated linoleic acid (CLA; 10?wt% on the weight of SBO and PS) was used as a functional fatty acid. Interesterification and acidolysis was simultaneously carried out to exchange fatty acids and incorporate CLA in the triacylglycerol (TAG) backbone, respectively, using immobilized lipase. Comparative study was carried out between interesterified fats and blends (before interesterification) for the quantification of physical properties (i.e., solid fat content, melting and crystallization behavior) and oxidative stability. In the interesterified fat 5.2–6.1?% CLA was incorporated in the TAG backbone. Blends showed higher solid fat content (SFC) and melting point than interesterified fat at each measured temperature. The Rancimat test was performed for the oxidative stability where the interesterified fat showed significantly lower induction time than physical blends. After the addition of antioxidants such as butylated hydroxytoluene (BHT), rosemary extract, tertiary butylhydroquinone (TBHQ), propyl gallate (PG), etc. into the interesterified fat, the induction time was significantly increased. On the other hand, different deacidification methods (alkaline, batch deodorized and short path distillation) were performed after interesterification to remove the free fatty acids. After deacidification, oxidative stability of alkaline deacidified sample showed significantly (P?≤?0.05) longer induction time compared to short path distillation (SPD) and physically deacidified samples. In this study, interesterified functional fat that may have a potential functionality for the margarines and shortenings were produced and their oxidative stability was observed.     

Effects of droplet size on the oxidative stability of oil-in-water emulsions

The effects of droplet size and emulsifiers on oxidative stability of polyunsaturated TAG in oil-in-water (o/w) emulsions with droplet sizes of 0.806±0.0690, 3.28±0.0660, or 10.7±0.106 μm (mean ± SD) were investigated. Hydroperoxide contents in the emulsion with a mean droplet size of 0.831 μm were significantly lower than those in the emulsion with a mean droplet size of 12.8 μm for up to 120 h of oxidation time. Residual oxygen contents in the headspace air of the vials containing an o/w emulsion with a mean droplet size of 0.831 μm were lower compared with those of the emulsion with a mean droplet size of 12.8 μm. Hexanal developed from soybean oil TAG o/w emulsions with smaller droplet size showed significantly lower residual oxygen contents than those of the larger droplet size emulsions. Consequently, oxidative stability of TAG in o/w emulsions could be controlled by the size of oil droplet even though the origins of TAG were different. Spin-spin relaxation time of protons of acyl residues on TAG in o/w emulsions measured by ¹H NMR suggested that motional frequency of some acyl residues was shorter in o/w emulsions with a smaller droplet size. The effect of the wedge associated with hydrophobic acyl residues of emulsifiers was proposed as a possible mechanism to explain differences in oxidative stability between o/w emulsions with different droplet sizes.     

Characterization and oxidative stability of enzymatically produced fish and canola oil-based structured lipids

Two-kilogram quantities of structured lipids (SL) of menhaden fish and canola oils containing caprylic acids (8∶0) were produced in a laboratory-scale packed-bed bioreactor by acidolysis catalyzed by an immobilized lipase, Lipozyme IM, from Rhizomucor miehei. SL were characterized and their oxidative stabilities investigated. The SL contained 29.5% 8∶0 for fish oil and 40.15 for canola oil. Polyunsaturated fatty acids (PUFA) of fish oil remained unchanged after the modification while PUFA of canola oil were reduced from 29.6 to 21.2%. Monoenes, especially 18∶1n−9, were completely replaced by 8∶0 in fish oil and reduced from 61.9 to 34.7% in canola oil. Downstream processing of enzymatically produced SL led to loss in natural total tocopherol contents of the fish and canola oils. The effects of antioxidants such as α-tocopherol (TOC), tert-butylhydroxyquinone (TBHQ), and combinations thereof on the oxidative stability of SL were investigated. SL were analyzed for oxidative stability index, peroxide value, conjugated diene content, free fatty acid content, iodine value, saponification number, and thiobarbituric acid value. Iodine value of unmodified fish oil (154.71) was reduced to 144.10 and that of canola oil (114.49) to 97.27 after modification. The SN increased from 183.72 to 242.63 for fish oil and from 172.50 to 227.90 for canola oil. TBHQ exhibited better antioxidant effects than TOC. A combination of TBHQ/TOC also proved to be an effective antioxidant for SL. We suggest the addition of antioxidants to enzymatically produced and purified SL.     

Dietary menhaden, seal, and corn oils differentially affect lipid and Ex vivo eicosanoid and thiobarbituric acid-reactive substances generation in the guinea pig

This investigation was carried out to characterize the effects of specific dietary marine oils on tissue and plasma fatty acids and their capacity to generate metabolites (prostanoids, lipid peroxides). Young male guinea pigs were fed nonpurified diet (NP), or NP supplemented (10%, w/w) with menhaden fish oil (MO), harp seal oil (SLO), or corn oil (CO, control diet) for 23 to 28 d. Only the plasma showed significant n−3 polyunsaturated fatty acid (PUFA)-induced reductions in triacylglycerol (TAG) or total cholesterol concentration. Proportions of total n−3 PUFA in organs and plasma were elevated significantly in both MO and SLO dietary groups (relative to CO), and in all TAG fractions levels were significantly higher in MO-than SLO-fed animals. The two marine oil groups differed in their patterns of incorporation of eicosapentaenoic acid (EPA). In guinea pigs fed MO, the highest levels of EPA were in the plasma TAG, whereas in SLO-fed animals, maximal incorporation of EPA was in the heart polar lipids (PL). In both marine oil groups, the greatest increases in both docosahexaenoic acid (22∶6n−3, DHA) and docosapentaenoic acid (22∶5n−3, DPA) relative to the CO group, were in plasma TAG, although the highest proportions of DHA and DPA were in liver PL and heart TAG, respectively. In comparing the MO and SLO groups, the greatest difference in levels of DHA was in heart TAG (MO>SLO, P<0.005), and in levels of DPA was in heart PL (SLO>MO, P<0.0001). The only significant reduction in proportions of the major n−6 PUFA, arachidonic acid (AA), was in the heart PL of the SLO group (SLO>MO=CO, P<0.005). Marine oil feeding altered ex vivo generation of several prostanoid metabolites of AA, significantly decreasing thromboxane A₂ synthesis in homogenates of hearts and livers of guinea pigs fed MO and SLO, respectively (P<0.04 for both, relative to CO). Lipid peroxides were elevated to similar levels in MO- and SLO-fed animals in plasma, liver, and adipose tissue, but not in heart preparations. This study has shown that guinea pigs respond to dietary marine oils with increased organ and plasma n−3 PUFA, and changes in potential synthesis of metabolites. They also appear to respond to n−3 PUFA-enriched diets in a manner that is different from that of rats.     

Autoxidation of synthetic isomers of triacylglycerol containing eicosapentaenoic acid

Several triacylglycerols (TAG) that contained eicosapentaenoic acid (EPA) were chemically synthesized and stored at 25°C to assess the influence of TAG structure on oxidative stability and formation of oxidation products. Oxidative stability was evaluated by oxygen consumption during storage of the TAG. Autoxidation products of TAG were analyzed by high-performance liquid chromatography (HPLC) and liquid chromatography-mass spectrometry (LC-MS). Results showed that a 2:1 (mole/mole) mixture of trieicosapentaenoylglycerol (EEE) and tripalmitoylglycerol (PPP) was most susceptible to autoxidation. The oxidative stability of TAG that contained EPA and palmitic acid was negatively correlated with the moles of EPA in a single TAG molecule. When TAG with one EPA and two other fatty acids were oxidized, chainlength of constituent fatty acids hardly affected the oxidative stability of EPA-containing TAG molecules, except for stearic acid. HPLC and LC-MS analyses showed that monohydroperoxides were major oxidation products regardless of type of TAG. Bis- and tris-hydroperoxides were formed during autoxidation of EEE and dieicos-apentaenoylpalmitoylglycerol. Monohydroperoxy epidioxides were found in all autoxidized TAG. These observations suggested that TAG structure affected the oxidation of TAG with highly unsaturated fatty acids.     

玉米油W1/O/W2型多重乳状液稳定性的研究

高脂食品严重危害着人类健康,这引起人们对低脂食品的的不断追求,因此脂肪替代品的开发越来越受到人们重视。本试验以玉米油和生物高聚物为主要原料通过两步乳化法制备W1/O/W2多重乳状液作为脂肪替代品(FS),以离心稳定性为衡量标准,用显微镜直接观察,探讨了初复乳乳化工艺、各相相对体积比对玉米油W1/O/W2型多重乳状液体系稳定性的影响。结果表明:1.影响玉米油多重乳状液稳定性的主要因素有:复乳的乳化工艺,内水相与油相体积之比等。2.两步乳化工艺中第二步乳化工艺对复乳稳定性影响较大,其规律是随着乳化强度的提高,粒径减小,稳定性呈上升趋势,适宜的乳化条件为7200 r.min.1,13 min,而第一步乳化工艺对复乳稳定性几乎没有影响。3.内水相与油相、初乳与外水相均是影响复乳稳定性的主要因素,前者主要是依靠改变初乳黏度来影响复乳稳定性,后者主要是乳滴间范德华力与电排斥力共同作用的结果,适宜的体积比分别为1:4和1:1。     

Hypolipidemic Effects of Phospholipids (PL) Containing n-3 Polyunsaturated Fatty Acids (PUFA) Are Not Dependent on Esterification of n-3 PUFA to PL

Phospholipids (PL) containing n‐3 polyunsaturated fatty acids (PUFA) have beneficial effects of maintaining and promoting health compared with triacylglycerols (TAG) containing n‐3 PUFA or general PL. This study evaluated the effects of dietary PL containing n‐3 PUFA and elucidated the effects of the glycerophosphate structure and n‐3 PUFA on fatty acid (FA) metabolism in rats. Rats were fed a basal diet containing soybean oil alone, TAG containing n‐3 PUFA (1.8 %), soybean PL (2.7 %), PL containing n‐3 PUFA (2.7 %), or TAG containing n‐3 PUFA (1.8 %) + soybean PL (2.7 %). The present n‐3 PUFA‐supplemented diets had similar FA compositions, and the PL diets had similar PL compositions. TAG containing n‐3 PUFA reduced serum TAG contents, but did not affect serum cholesterol contents compared with soybean oil alone. PL diets containing n‐3 PUFA and the combination of TAG containing n‐3 PUFA and soybean PL resulted in decreased serum and liver TAG contents compared with the diet containing soybean oil alone, reflecting enhanced liver FA β‐oxidation. The results of this study show that TAG containing n‐3 PUFA with added soybean PL affects serum and liver TAG and cholesterol contents to a similar degree as PL containing n‐3 PUFA. TAG containing n‐3 PUFA and soybean PL are widely used as functional food ingredients and pharmaceutical constituents and are inexpensive compared with PL containing n‐3 PUFA. Therefore, the combination of TAG containing n‐3 PUFA and soybean PL has potential as a useful and inexpensive component of functional foods.     

Effect of degumming reagents on the composition and emulsifying properties of canola,soybean and sunflower acetone insolubles

Acetone insolubles (AI) extracted from crude canola, soybean and sunflower oils using six degumming reagents (water, citric, phosphoric and oxalic acids plus acetic and maleic anhydride) were separated into phospholipid (PL) components by HPTLC. The separated PL were quantified by phosphorus determination. Statistical analysis of the PL composition data indicated that the chemical degumming reagents did not dramatically alter the PL profiles although some significant differences were observed. Acetone insolubles recovered by water degumming produced the most stable oil-in-water emulsions. Those AI isolated by citric acid, acetic anhydride and maleic anhydride treatments produced slightly less stable emulsions but showed good potential as emulsifying agents. Phosphoric and oxalic acid treatments produced AI with very poor emulsifying properties.     

Determination and Structural Elucidation of Triacylglycerols in Krill Oil by Chromatographic Techniques

The content of triacylglycerols (TAG) in krill oil is generally omitted from the labels of commercial supplements and unacknowledged in studies aimed at proving its health benefits. The present study demonstrates that TAG compounds, in addition to phospholipids and lysophospholipids, are an important lipid class in pure krill oil. The fatty acid composition of TAG molecules from krill oil and their distribution on the backbone of TAG structures were determined by gas chromatography and liquid chromatography tandem mass spectrometric, respectively. The content of omega 3 polyunsaturated fatty acids (n-3 PUFA) was similar to those reported in the literature for fish oil. It was estimated that 21 % of n-3 PUFA were at the sn-2 position of TAG structures. To our knowledge, this is the first determination and structural characterization of TAG in pure krill oil supplements.     

Triacylglycerols and Polar Lipids in Cow and Goat Milk are Differentially Affected by Various Lipid Supplemented Diets

This study characterizes milk triacylglycerol (TAG) and polar lipid (PL) fractions from cows and goats fed various lipid supplements modulating milk fat content. Twelve Holstein cows and 12 Alpine goats, at 86 ± 24.9 and 61 ± 1.8 days in milk, respectively, are allocated to one of 4 groups to receive diets supplemented with either corn oil [5% dry matter intake (DMI)] plus wheat starch (COS), marine algae powder (MAP; 1.5% DMI) or hydrogenated palm oil (HPO; 3% DMI), or a no-added-lipid control diet (CTL), according to a 4 × 4 Latin square design with 28 d experimental periods. Milk TAG and PL contents are determined by liquid chromatography-mass spectrometry (LC-MS). Multivariate analysis and ANOVA demonstrate major between-species differences in diet effects. In cows, COS specifically increases TAG 54:3 and 54:4 associated with milk fat depression (MFD), and increases the sum of phosphatidylcholines (PC) and phosphatidylinositols (PI). In addition to causing a MFD, MAP diet increases long-chain polyunsaturated TAG in both species, with higher magnitude in cows than in goats, and decreases the sum of PI in goats. HPO increases TAG 52:1 and the sum of PI in cows, but not in goats. Practical applications: Feed strategies can quickly and efficiently modulate the ruminant milk fat production and composition to improve nutritional quality for consumers. Certain starch-rich diets supplemented with polyunsaturated fatty acids (PUFA)-rich vegetable oils and diets supplemented with marine products (long-chain PUFA) reduce milk fat secretion and modify the milk fatty acid (FA) profile in cows, but not—or less so—in goats. Advanced analysis of both the TAG and PL fractions of milk fat is required to unravel these differences in lipid metabolism between cows and goats fed various lipid-supplemented diets. This study brings new insight on using nutritional strategies to control milk lipid composition according to ruminant species.