Dietary fatty acid intervention of lactating cows simultaneously affects lipid profiles of meat and milk

BACKGROUND: The present study investigated tissue‐specific responses of muscle and mammary gland to a 10 week intervention of German Holstein cows (n = 18) with three different dietary fat supplements (saturated fat; linseed oil or sunflower oil plus docosahexaenoic acid‐rich algae) by analysing fatty acid profiles and quality parameters of meat and milk. RESULTS: Plant oil/algae intervention affected neither fat content nor quality parameters of meat but decreased fat content and saturated fatty acid amounts of milk. Linseed oil/algae intervention caused significantly higher concentrations of C18:3n‐3 (meat, 1.0 g per 100 g; milk, 1.2 g per 100 g) and C22:6n‐3 (meat, 0.3 g per 100 g; milk, 0.14 g per 100 g). Sunflower oil/algae intervention increased n‐6 fatty acid contents in milk (4.0 g per 100 g) but not in meat. Elevated amounts of C18:1trans isomers and C18:1trans‐11 were found in meat and especially in milk of plant oil/algae‐fed cows. C18:1cis‐9 amounts were found to be increased in milk but decreased in meat after plant oil/algae intervention. CONCLUSION: The present study demonstrated that dietary fatty acid manipulation substantially shifted the fatty acid profiles of milk and to a lesser extent of meat, whereas meat quality traits were not affected. Indications of tissue‐specific responses of mammary gland and muscle were identified. Copyright © 2012 Society of Chemical Industry     

Relationships between intramuscular fat content, selected carcass traits, and fatty acid profile in bulls using a F2-population

The quality and nutritional value of beef is related to the amount of intramuscular fat (IMF) as well as to its fatty acid composition. In this study the relations between the IMF content and the total fatty acid composition, the fatty acids (FA) of triacylglycerols (TG) and the FA of phospholipids (PL) in longissimus muscle of F₂ Charolais × German Holstein crossbred bulls have been analysed. Polyunsaturated fatty acids (PUFA, C18:2n-6; C18:3n-3) and stearic acid (C18:0) are strongly positively correlated to IMF in longissimus muscle at the quantitative level (mg/100 g fresh tissue), but there are negative correlation coefficients for the relative proportion of these fatty acids to IMF. The relationships between IMF and the fatty acid profile of the subfractions TG and PL are lower compared to total muscle fat. Selected carcass fat traits are positively correlated to most of the fatty acids.     

Seasonal variation in the fatty acid composition of milk available at retail in the United Kingdom and implications for dietary intake

Milk and dairy products are major sources of fat in the human diet, but there are few detailed reports on the fatty acid composition of retail milk, trans fatty acids in particular, and how these change throughout the year. Semi-skimmed milk was collected monthly for one year from five supermarkets and analysed for fatty acid composition. Relative to winter, milk sold in the summer contained lower total saturated fatty acid (SFA; 67 vs 72 g/100 g fatty acids) and higher cis-monounsaturated fatty acid (MUFA; 23 vs 21 g/100 g fatty acids) and total trans fatty acid (6.5 vs 4.5 g/100 g fatty acids) concentrations. Concentrations of most trans-18:1 and -18:2 isomers also exhibited seasonal variation. Results were applied to national dietary intakes, and indicated that monthly variation in the fatty acid composition of milk available at retail has limited influence on total dietary fatty acid consumption by UK adults.     

Amino acid and fatty acid compositions and nutritional quality of muscle in the pomfret, Pampus punctatissimus

The pomfret, Pampus punctatissimus, is an important fisheries resource in China, but little is known about its amino acid and fatty acid compositions. Pomfret muscle contained 18.6% crude protein and 4.95% crude fat. Pomfret protein has a well-balanced amino acid composition, with high amounts of glutamic acid (114 mg/g), lysine (82.8 mg/g), leucine (76.7 mg/g), and aspartic acid (76.0 mg/g). Twenty two fatty acids were found in pomfret oil and saturated fatty acids were the most abundant (48.3%). Palmitic acid (16:0) was the dominant fatty acid, followed by oleic acid (18:1), DHA (22:6n-3), myristic acid (14:0) and stearic acid (18:0), with percentages of 30.5, 26.3, 12.2, 7.37 and 6.86, respectively. The ratio of n-3/n-6 polyunsaturated fatty acids (PUFAs) was 8.04; thus, pomfret muscle is rich in n-3 PUFA.     

Milling fractions fatty acid composition of common (Fagopyrum esculentum Moench) and tartary (Fagopyrum tataricum (L.) Gaertn) buckwheat

The objective of the present study was to determine the composition of fatty acids in the whole grain, hulls, bran and the light flour of common (Fagopyrum esculentum Moench) and Tartary (Fagopyrum tataricum (L.) Gaertn) buckwheat harvested in two consecutive years. Fatty acid composition for different milling fractions was determined as methyl esters using gas chromatography. Nine fatty acids were determined: lauric (12:0), myristic (14:0), palmitic (16:0), palmitoleic (16:1), stearic (18:0), oleic (C18:1; n-9), linoleic (C18:2; n-6), α-linolenic (C18:3; n-3) and arachidic (20:0) acid. The highest relative content was determined for linoleic acid (from 35.54 to 47.57%), followed by oleic acid (from 20.96 to 40.76%) and palmitic acid (from 13.86 to 26.42%). The total fatty acid content was the highest in bran (up to 62.64 g/kg), followed by whole grains (up to 22.93 g/kg), light flour (up to 9.69 g/kg) and hulls (up to 5.87 g/kg). Saturated fatty acid content was the highest in the hulls and the lowest in the bran. Polyunsaturated fatty acid content was the highest in light flour. High positive correlations were found between saturated fatty acids with 18 carbon atoms or less.     

Effect of postharvest period on sugars,organic acids and fatty acids composition in commercially sold medlar (<Emphasis Type="Italic">Mespilus germanica</Emphasis> 'Dutch') fruit

Fructose, glucose, and sucrose as the major soluble sugars, and citric, malic, and ascorbic acids as the major organic acids were determined by HPLC, and palmitic acid (16:0) and stearic acid (18:0), oleic acid (18:1), linoleic acid (18:2n-6) and linolenic acid (18:3n-3) as the major fatty acids were determined by GC in medlar (Mespilus germanica 'Dutch') fruit. The compositional changes of these constituents were monitored during the post harvest period of commercially sold Dutch form throughout its rapid ripening (fruit softening-darkening). Sucrose was highest at 1 WAH (228.4 mg/100 g fresh wt) and then decreased, remaining very low at 4 WAH (1.4 mg/100 g fresh wt). As for the levels of fructose and glucose, their levels shifted up to 2230.8 and 845.2 mg/100 g fresh wt at 2 and 3 WAHs, then the levels lessened to their lowest concentration. The levels of the three acids were high at the beginning, except malic acid level at 2 WAH, all acids leveled off through the latter weeks of post harvest period. In the fruit studied, the levels of saturated palmitic acid (16:0) and stearic acid (18:0), and unsaturated oleic acid (18:1), linoleic acid (18:2n-6) and linolenic acid (18:3n-3) were most abundant fatty acids detected throughout medlar ripening (pulp softening and darkening). The level of palmitic and stearic acids as well as the level of linoleic and linolenic acids were the highest at 1 WAH and then suddenly decreased as the medlar soften and the pulp becomes slightly (2 WAH) and fully (3 WAH) brown through 2 and 4 WAHs. In addition to these prominent fatty acids, a remarkable decrease was also obtained in the content of some other fatty acids (C_10-15, C_16:1, C_20-24).     

Changes in sugars, acids and fatty acids in naturally parthenocarpic date plum persimmon (Diospyros lotus L.) fruit during maturation and ripening

The date plum persimmon fruit (Diospyros lotus L., fam: Ebenaceae) is cultivated throughout northern of Turkey for its edible fruits. Sugars and organic acids were measured during fruit maturation and ripening using HPLC. The analyses showed that fructose and glucose were the main sugars accumulated in the fruit pulp. Fructose and glucose increased up to 43,552.8 mg.100 g^–1 fw and 35,450.8 mg.100 g^–1 fw respectively during fruit ripening. Sucrose content remained relatively low and decreased during ripening. The major organic acids found in date plum fruit were citric and malic acids, which increased through the immature and midripe maturity, and then the levels decreased in the overripe fruit. Palmitic acid (16:0), palmitoleic acid (16:1), stearic acid (18:0), oleic acid (18:1) and linolenic acid (18:3) were among the major fatty acids determined by GC throughout the maturation and ripening of the fruits. The levels of these fatty acids were found to be significantly different (P=0.05) between the three maturity stages. The fruits displayed the level of linoleic acid (0.7%) in low and -linolenic acid (17.8%) in higher quantities, and the combined levels of linoleic and -linolenic acid comprised 19% (120.1 g.g^–1 dw) of the total fatty acid content in the over ripened fruit. These results show that naturally parthenocarpic date plum fruits have high levels of sugars and organic acids and moderate levels of fatty acids that significantly changed during maturation and ripening. This information can be used by nutritionalists and food technologists to improve the nutrition of local people and develop food products that would be beneficial to human health.     

Amino acid and fatty acid composition of wild sea bass (Dicentrarchus labrax): a seasonal differentiation

Seasonal variations in the amino acid and fatty acid compositions of wild sea bass (Dicentrarchus labrax) captured in the north eastern Mediterranean were investigated. In all seasons, the major amino acids in sea bass fillets were determined to be aspartic acid, glutamic acid and lysine. Methionine, tyrosine and histidine composition of the fillets were lower than those of the other amino acids in all seasons. The ratios of essential (E, g amino acid/16 g N)/nonessential (NE, g amino acid/16 g N) amino acids were observed to be 0.75 for winter, 0.76 for autumn, 0.77 for both spring and summer. Results showed that, sea bass fillets are well-balanced food source in terms of E/NE ratios in all seasons. In addition, seasonal differences in polyunsaturated fatty acid (PUFA) composition of the fillets were observed in all seasons. The major fatty acids of sea bass fillets were observed to be palmitic acid (16:0), oleic acid (18:1ω9), eicosapentaenoic acid (EPA, 20:5ω3) and docosahexaenoic acid (DHA, 22:6ω3). The amounts of EPA+DHA in autumn, winter, spring and summer were determined as 0.16, 0.12, 1.14 and 1.02 g/100 g wet weight, respectively.     

Determination of proximate composition,fatty acid content and amino acid profile of five lesser‐common sea organisms from the Mediterranean Sea

Proximate composition, fatty acid and amino acid analysis of an echinoderm (Paracentrotus lividus), a crustacean (Penaeus kerathurus), a tunicate (Microcosmus sulcatus), and two gastropod molluscs (Littorina littorea and Patella coerulea) were determined. All organisms except M. sulcatus, were found to be good protein sources. P. lividus contained on average 15.1 g/100 g, P. kerathurus 15.6 g/100 g, L. littorea 8.3 g/100 g and P. coerulea 9.2 g/100 g protein. The crustacean contained high percentages of n‐3 fatty acids (28.3 g/100 g fatty acids), the tunicate high percentages of saturated fatty acids (62.2 g/100 g fatty acids) while the gastropod molluscs and the echinoderm had a balanced content of all fatty acid families. The most abundant amino acid in P. kerathurus, M. sulcatus, L. littorea and P. coerulea was glutamic acid (11.13 ± 0.9, 1.05 ± 0.3, 5.39 ± 0.3, 5.55 ± 0.8 g/100 g freeze‐dried sample respectively), while glycine was the most abundant amino acid in P. lividus (10.34 ± 1.0 g/100g freeze‐dried sample).     

Investigating the day-to-day variations of potential marker fatty acids for organic milk in milk from conventionally and organically raised cows

Milk samples from organic and conventionally raised cows differ in the content of specific fatty acids due to the different feed used. Several marker fatty acids (phytanic acid, α-linolenic acid (18:3n-3), eicosapentaenoic acid (20:5n-3)) have been proposed to distinguish both types of dairy agriculture. Owing to the higher amount of grass in the feed of organic cows, the concentrations of these fatty acids are usually higher than in conventional milk. In this study, we were interested to determine the day-to-day fluctuation of these and further fatty acids in milk of cows. For this purpose, milk samples from an organic and a conventionally raised cow taken on subsequent days were analyzed for potential marker fatty acids for the authentication of organic milk. An organic cow was milked daily in the morning over a period of 30 days while milk of a conventional cow was collected for 15 days in the morning and evening. Based on milk lipids, no differences were found between morning and evening milk. However, the concentrations of phytanic acid, α-linolenic acid (18:3n-3), eicosapentaenoic acid (20:5n-3) were ~twofold higher in organic milk fat than in conventional samples. The day-to-day fluctuations were small, and the lowest value in organic milk was generally higher than the highest value in conventional milk. Phytanic acid is interesting as it will not be influenced by supplementation of n-3 fatty acids in the fodder of conventional cows. Pristanic acid was also ~40% higher in organic milk fat, but five conventional samples reached the lowest value in organic milk. Significantly higher concentrations in organic milk fat were also observed for 12-methyltridecanoic acid (i14:0) and 16-methylheptadecanoic acid (i18:0) as well as for vaccenic acid (18:1n-7tr).     

Dietary manipulation of the yield and composition of milk: Effects of dietary inclusions of barley and oats in untreated or formaldehyde-treated forms on milk fatty acid composition

Eight 1st-lactation cows were given four dietary treatments in a duplicated 4×4 Latin square experiment. Diets consisted of hay and soya bean meal together with barley, formaldehyde-treated barley, oats or formaldehydetreated oats (approximately 34:12:54 on a dry matter basis). Barley diets supplied 211 g fatty acids d^?1, oats diets supplied 537 g d^?1. The fatty acid composition (g kg^?1 total fatty acids) for barley diets was: 300 (16:0); 20 (18:0); 150 (18:1); 470 (18:2); 60 (18:3). Corresponding values for oats diets were 180, 20, 390, 380 and 30 g kg^?1. Formaldehyde treatment of the cereals tended to increase milk yield and reduce milk fat content (P<0·01 for barley) but did not affect milk fatty acid composition. Feeding oats in replacement for barley significantly (P<0·05) increased milk yield and lactose yield and reduced milk fat content (P<0·05 for the untreated cereals) and protein contents (P<0·01) without significant effects on milk fat or protein yields. Oats diets led to significant (P<0·001) reductions in the content of 8:0–16:0 fatty acids in milk fat with associated increases (P<0·001) in the content of 18:0 and 18:1. Changes in milk fat content of 18:2 and 18:3 acids were small. The results show the inclusion of oats in the cow's diet to be a means of reducing the saturated fatty acid content of milk fat thereby improving the nutritional value of milk and milk products and their appeal to the health-conscious consumer.     

Chemometric analysis of mass spectra of cis and trans fatty acid picolinyl esters

Capillary GC of fatty acid methyl esters with MS detection only yields information about the molecular weight of the compound. However, if picolinyl esters of fatty acids are analysed in this way it is possible to obtain more information about their structure, perhaps even the cis or trans configuration. Picolinyl esters of fatty acids are prepared by adding carbonyl-diimidazole, 3-hydroxymethylpyridine and 4-pyrrolidin-o-pyridine to a solution of free fatty acids in dichloromethane. The picolinyl esters dissolved in heptane are then separated by capillary GC on a CP Sil 88 column equipped with a quadropole MS-detector. The mass spectra clearly show the molecular weight and the position of double bonds in the fatty acids, but whether the configuration is cis or trans is impossible to discern visually. However, with the use of principal component analysis, it is possible to distinguish between cis and trans fatty acids of C16:1, C18:1,n-9, C18:1,n-12, C18:2 and C22:1 in two- and three-dimensional score plots. With Soft Independent Modelling of Class Analogy (SIMCA), it is possible to calculate models that can predict from the mass spectra of unknown fatty acids whether they are of the cis or trans configuration, which is demonstrated for C18:1 trans from hardened margarine and butter.     

Lipids classes, fatty acids and carotenes of the leaves of six edible wild plants

 α-Linolenic acid and unusual fatty acids of the ω3 and ω6 series play an important role in the modulation of human metabolism. The presence of these acids in the leaves of several edible wild plants has recently been reported. In this study, six edible wild species were selected in order to establish the fatty acid compositions in their leaf lipids. Thus, young leaves from Amaranthus viridis L.(blet), Chenopodium album L. (goosefoot), Crithmum maritimum L. (rock samphire), Plantago major L. (plantain), Portulaca oleracea L. (purslane) and Verbena officinalis L. (vervain) yielded 1.50, 2.20, 3.02, 1.46, 3.81, and 2.28 g of lipids per 100 g dry plant material. Silica gel chromatography yielded 0.64 g (Plantago major) to 2.19 g (Crithmum maritimum) neutral lipids, 0.37 g (Plantago major) to 1.60 g (Portulaca oleracea) glycolipids, and 0.26 g (Crithmum maritimum) to 0.57 g (Verbena officinalis) phospholipids per 100 g (dry weight). Gas chromatography (GC) showed the major fatty acids to be 18 : 3ω3, 18 : 2ω6 and 16 : 0 in all fractions, with high concentrations of 18 : 3ω3 in the glycolipid fraction. GC-mass spectrometric analyses did not reveal the presence of unusual fatty acids. Carotenes were found in high concentrations, ranging from 30.5 mg/100 g (Chenopodium album) to 89.2 mg/100 g (Portulaca oleracea). The analyzed plants are rich sources of essential fatty acids (18 : 2ω6 and 18 : 3ω3) and also of carotenes. Received: 29 October 1998     

Nitrogen concentration and nitrate/ammonium ratio affect yield and change the oxalic acid concentration and fatty acid profile of purslane (Portulaca oleracea L.) grown in a soilless culture system

Purslane is an excellent source of omega‐3 fatty acids, amino acids and vitamins. The aim of this research was to study the effect of different nitrogen levels and NO₃⁻‐N/NH₄⁺‐N ratios in the nutrient solution on the yield and on the oxalic acid content and fatty acid profile in purslane grown in a soilless culture system. Two experiments were carried out to test different levels of nitrogen: (1) 8–12–16 mmol L⁻¹ and (2) 0–12–24–36 mmol L⁻¹. A third experiment was carried out maintaining the N level fixed (12 mmol L⁻¹) but varying the NO₃⁻‐N/NH₄⁺‐N ratio: 60:40, 40:60, 0:100. The results indicated that plants grew with increasing nitrogen level up to 36 mmol L⁻¹. Nitrogen supplied in both NO₃⁻ and NH₄⁺ forms produced bigger plants than N supplied in NH₄⁺ form only. Nitrogen did not significantly influence the polyunsaturated fatty acid content in the canopy. Significant trends were found for α‐linolenic acid (LNA; 18:3 n‐3) and linoleic acid (LA; 18:2 n‐6), indicating a favorable accumulation of omega‐3 fatty acids with increasing N; palmitic acid decreased by increasing N and by switching the NO₃⁻/NH₄⁺ ratio towards the NH₄⁺ level in the nutrient solution, but using 0:100 NO₃⁻/NH₄⁺, decreased plant quality. Increasing N lowered oxalic acid production and palmitic acid content, enhancing purslane nutritional quality. Keeping a high N level in the nutrient solution with a 40:60 NO₃⁻/NH₄⁺ ratio would give the best results in terms of yield, oxalic acid concentration and fatty acid profile. Copyright © 2006 Society of Chemical Industry     

Evaluating nutritional quality of pacific fish species from fatty acid signatures

Eight fish species common to the Pacific Northwest coastal waters were categorised according to total lipids in a ranking from lean fish (e.g. walleye pollock) to oily fish (e.g. herring) species. Comprehensive fatty acid signatures were compared on both the relative proportion of total fatty acids and the proportion of total carcass lipid content. Generally, fish species from the Pacific coast had a relatively high proportion of n-3 highly polyunsaturated fatty acids (n-3 HUFAs), of which more than 80% was accounted for by C20:5n-3 (EPA) and C22:6n-3 (DHA), with species-specific and lower proportions of oleic acid (C18:1n-9) and palmitic acid (C16:0) also dominating. The MUFA contents of fish were lower (P < 0.05) in the lipids of lean and low-fat fish compared to those of fattier species. In contrast, higher (P < 0.05) proportions of polyunsaturated fatty acids (PUFAs) existed in the low-fat species with DHA contents ranging from 18% to 29% in the low-fat fish and from 8% to 10% in the fattier fish, such as herring and capelin. Expressing the same fatty acid content data in terms of absolute amount of fatty acids (e.g. gFA/100 g wet tissue) showed that both EPA and DHA contents in the flesh of pollock and hake were indeed many fold lower than those found in fatty fish, such as herring. The findings confirm that it is important that both the total lipid content and the fatty acid composition of these Pacific fish food sources be considered when making evaluations on the nutritional quality.     

Conjugated linoleic acid (CLA) concentration,fatty acid composition and cholesterol content of some Turkish dairy products

Conjugated linoleic acid (CLA) concentrations, fatty acid composition and cholesterol content of some Turkish dairy products (butter, processed cheese, Kaymak and cream) were determined by capillary gas chromatography. The CLA and cholesterol content of some Turkish dairy products ranged from 1.50–5.60 mg/g fat and 148.30–369.04 mg/g fat, respectively. The most abundant saturated fatty acids in the dairy products investigated were palmitic acid (C16:0), stearic acid (C18:0) and myristic acid (C14:0). In all dairy products, C18:1 cis-9, 12 unsaturated fatty acid content (23.12–32.78 g/100 g) was considerably higher than others. In all samples studied, there was no correlation between CLA content of products and the linoleic acid content, or any other unsaturated fatty acid. A positive correlation between cholesterol and fat content of dairy products was observed.     

Effects of differences in diet and seasonal changes on the fatty acid composition in fillets from farmed and wild sea bream (Sparus aurata L.) and sea bass (Dicentrarchus labrax L.)

The effects of dietary fatty acids and seasonal variation on the fatty acid profiles of farmed and wild sea bream (Sparus aurata) and sea bass (Dicentrarchus labrax) were determined by analysis of their fillets. Farmed sea bream and sea bass were fed on the same commercial feeds all year. Fatty acid profiles in the fillets reflected the fatty acid profiles of the commercial feeds. The predominant fatty acids in the trial feeds, fillets of farmed and wild sea bream and sea bass were 16:0, 18:1n‐9, 18:2n‐6, 20:5n‐3 and 22:6n‐3. The fatty acid profiles in the fillets of farmed sea bream and sea bass did not differ (P > 0.05) except in the winter season compared with those of their wild counterparts. However, the content of eicosapentaenoic acid (20:5n‐3), docosahexaenoic acid (22:6n‐3) in the fillets of the farmed and wild sea bass were significantly (P < 0.05) higher than the farmed and wild sea bream. The wild sea bream had significantly (P < 0.05) higher total saturated fatty acid and monounsaturated fatty acid (MUFA) levels, and lower total n‐6 and n‐3 polyunsaturated fatty acid (PUFA) levels in winter than in the summer and spring seasons. Similarly, in the fillets of wild sea bass, total n‐3 PUFA levels were significantly (P < 0.05) lower, and the MUFA levels were higher in winter than in the other seasons. These results indicate that the farmed fish fillets were good sources of n‐3 PUFA in each of the three seasons. However, wild fish were good sources of n‐3 PUFA in the spring and summer.     

Seasonal variation in the fatty acid composition of three Mediterranean fish – sardine (Sardina pilchardus), anchovy (Engraulis encrasicholus) and picarel (Spicara smaris)

The total fat contents and the fatty acid compositions of three common Mediterranean fish, namely sardine (Sardina pilchardus), anchovy (Engraulis encrasicholus) and picarel (Spicara smaris) were determined at bimonthly intervals for a one-year period. The purpose of this work was to study the seasonal variation of the fatty acids in the three fish that are some of the best sources of n − 3 fatty acids. The fat and fatty acid content of the investigated fish species show a significant seasonal dependency. Two of the fish (anchovy and picarel) have the highest fat content during the late winter – spring period. On the other hand, sardine shows the highest fat concentrations during the spring-early summer period. The fish that showed the highest variation in fatty acid composition was the anchovy. The sardine was found to be the best source of n − 3 fatty acids during the one-year period (35.35 g/100 g fatty acids). Finally the picarel had the highest oleic acid content (on average, 13.89/100 g fatty acids).     

An improved gas chromatography-based approach for characterisation of fatty acids in fresh basil seed oil

An improved gas chromatography-based analytical method for the simultaneous separation of seventy-two fatty acids was developed. Twenty-six types of trans fatty acids and conjugated linoleic acids were separated and identified with this method, especially trans C18 isomers. This method was confirmed to be high throughput and have high sensitivity and a low detection limit. It was successfully applied to separate and identify fatty acids in fresh basil seed oil. The linolenic acid content (51.67 g/100 g) was highest in basil seed oil, followed by linoleic acid (20.16 g/100 g) and oleic acid (12.70 g/100 g). These unsaturated fatty acids in fresh basil seed oil were transformed into trans fatty acids, conjugated linoleic acids and saturated fatty acids after heating to a certain temperature for an adequate duration, and the formation mechanisms were characterised.     

Efficacy of a novel whey protein gel complex to increase the unsaturated fatty acid composition of bovine milk fat

A novel whey protein emulsion gel (WPEG) complex was developed to protect dietary unsaturated fatty acids from rumen biohydrogenation with the goal of modifying the fatty acid composition of milk fat. Three experiments were conducted with WPEG complexes made from either whey protein concentrate containing 80% crude protein, whey protein isolate, or whey protein concentrate high-gel capacity. Each experiment lasted 3 wk. All cows received a basal total mixed ration (TMR). During wk 1 and 3, all cows received only the TMR. During wk 2, 3 control cows received 330 g/d of soybean oil added to the TMR, and the other 3 cows received 330 g/d of soybean oil in one of the WPEG complexes. During wk 2, C18:2 increased from 3.29 to 5.88 g/100 g of fat in Experiment 1, 2.91 to 7.42 g/100 g of fat in Experiment 2, and 3.57 to 6.56 g/100 g of fat in Experiment 3 for WPEG cows. Fatty acid C18:3 increased from 0.51 to 0.84, 0.52 to 1.15, and 0.51 to 0.97 g/100 g of fat for Experiments 1, 2, and 3, respectively, for WPEG cows. Higher proportions of C18:1 trans-9 in milk fat of control cows compared with WPEG cows were seen in all experiments. The proportion of C18:1 trans-11 was also higher in control cows in Experiments 1 and 2, but not in Experiment 3. The WPEG complexes successfully protected unsaturated fatty acids from rumen biohydrogenation and resulted in an increase in the unsaturated fatty acid composition of milk fat produced by Holstein cows without increasing the trans 18-carbon monoenes.