NMR-Βased Μetabolomics of the Lipid Fraction of Organic and Conventional Bovine Milk

International audienc

Nuclear magnetic resonance screening of changes in fatty acid and cholesterol content of ovine milk induced by ensiled olive cake inclusion in Chios sheep diets

© 2019 Elsevier B.V. Lipid supplementation of dairy ewe diets has been shown to introduce changes in the fatty acid (FA) profile and cholesterol content of milk. In the present study sheep were fed diets including ensiled olive cake (OC), a conserved by-product of olive oil production, and the lipid content of their milk was assessed in lyophilized samples with nuclear magnetic resonance (NMR) technique. Thirty lactating Chios ewes were allocated into three groups of ten animals fed isonitrogenous and isoenergetic diets which differed in the quantity of ensiled OC inclusion: G0, G500 and G1000 groups with 0, 500, 1000 g (on fresh weight basis) of ensiled OC inclusion per ewe, per day, respectively. Fat percentage, FA profile and cholesterol content were determined in milk samples collected after a 4-week feeding period. Results indicated that saturated FA were reduced by 7.2% and 11.3% in milk samples from the G500 and G1000 groups, respectively. Ensiled OC increased unsaturated FA content by 26.3% and 41.4% and monounsaturated FA content of milk by 30.3% and 45.6% in the G500 and G1000 groups, respectively. Furthermore, the inclusion of 1000 g ensiled OC significantly increased the content of beneficial for human health FA such as conjugated linoleic acids (CLA isomers: 9-cis, 11-trans CLA; 9-trans, 11-cis CLA and 10-trans, 12-cis CLA) by 47.2% and linoleic acid by 14.4% compared to control group. However, any rate of ensiled OC inclusion in the diets of ewes had no effect on milk cholesterol content or milk fat percentage. Overall, the present work provides novel experimental data with NMR fingerprinting of the lyophilized milk lipid fraction, and suggests the use of ensiled OC in sheep rations since it induces desirable changes in ovine milk lipids

Nuclear magnetic resonance screening of changes in fatty acid and cholesterol content of ovine milk induced by ensiled olive cake inclusion in Chios sheep diets

© 2019 Elsevier B.V. Lipid supplementation of dairy ewe diets has been shown to introduce changes in the fatty acid (FA) profile and cholesterol content of milk. In the present study sheep were fed diets including ensiled olive cake (OC), a conserved by-product of olive oil production, and the lipid content of their milk was assessed in lyophilized samples with nuclear magnetic resonance (NMR) technique. Thirty lactating Chios ewes were allocated into three groups of ten animals fed isonitrogenous and isoenergetic diets which differed in the quantity of ensiled OC inclusion: G0, G500 and G1000 groups with 0, 500, 1000 g (on fresh weight basis) of ensiled OC inclusion per ewe, per day, respectively. Fat percentage, FA profile and cholesterol content were determined in milk samples collected after a 4-week feeding period. Results indicated that saturated FA were reduced by 7.2% and 11.3% in milk samples from the G500 and G1000 groups, respectively. Ensiled OC increased unsaturated FA content by 26.3% and 41.4% and monounsaturated FA content of milk by 30.3% and 45.6% in the G500 and G1000 groups, respectively. Furthermore, the inclusion of 1000 g ensiled OC significantly increased the content of beneficial for human health FA such as conjugated linoleic acids (CLA isomers: 9-cis, 11-trans CLA; 9-trans, 11-cis CLA and 10-trans, 12-cis CLA) by 47.2% and linoleic acid by 14.4% compared to control group. However, any rate of ensiled OC inclusion in the diets of ewes had no effect on milk cholesterol content or milk fat percentage. Overall, the present work provides novel experimental data with NMR fingerprinting of the lyophilized milk lipid fraction, and suggests the use of ensiled OC in sheep rations since it induces desirable changes in ovine milk lipids

Direct nuclear magnetic resonance identification and quantification of geometric isomers of conjugated linoleic acid in milk lipid fraction without derivatization steps: Overcoming sensitivity and resolution barriers

We report the first successful direct and unequivocal identification and quantification of four minor geometric (9-cis, 11-trans) 18:2, (9-trans, 11-cis) 18:2, (9-cis, 11-cis) 18:2 and (9-trans, 11-trans) 18:2 conjugated linoleic acid (CLA) isomers in lipid fractions of lyophilized milk samples with the combined use of 1D 1H-NMR, 2D 1Hsingle bond1H TOCSY and 2D 1Hsingle bond13C HSQC NMR. The significant sensitivity barrier has been successfully overcome under selective suppression of the major resonances, with over 104 greater equilibrium magnetization of the single bond(CH2)nsingle bond1H spins compared to that of the 1H spins of the conjugated bonds of the CLA isomers. The resolution barrier has been significantly increased using reduced 13C spectral width in the 2D 1Hsingle bond13C HSQC experiment. The assignment was confirmed with spiking experiments with CLA standard compounds and the method does not require any derivatization steps for the lipid fraction. The proposed method is selective, sensitive and compares favorably with the GS-MS method of analysis

ΝΜR in Dairy Lipid Research: Improving the fatty acid profile of sheep milk by olive cake supplementation

The aim of this study was to investigate the effect of an oil rich by-product to the fat quality of sheep milk. A mixture of skins, pulp, woody endocarp and seeds obtained after extraction of olive-oil (namely olive cake) was prepared according to a method developed earlier. Thirty lactating Chios ewes were selected at random to form three balanced groups and allocated to the following feeding regimes: (a) no inclusion of olive cake (G1 group), (b) inclusion of 500 g/day/ewe (G2 group) and (c) inclusion of 1000 g /day/ewe (G3 group), while the other ingredients of the diet were similar and according to animal requirements. Milk samples were collected from each ewe after four weeks on the diet treatment and analysed for the content of different fatty acids (FA) and cholesterol using 1D 1H-NMR spectroscopy. More specifically, the organic phase of lyophilized milk was extracted according to previously developed method [1] and the FA composition and cholesterol content identified and quantified by peak integration using appropriate calculations [2]. The effect of inclusion of olive cake was tested using one-way analysis of variance and Tuckey pairwise comparison between groups (IBM-SPSS ver. 22). Total saturated FAs were affected (P<0.001) by olive cake feeding with the supplemented animals producing less saturated milk (mean values expressed in g/100g of milk fat were 78.6, 73.0 and 69.7 for G1, G2 and G3, respectively). Mono-unsaturated FAs, were significantly (P<0.001) increased in milk from both G2 and G3 animals compared to the control group (mean values of 18.7, 24.4 and 27.3 g/100 g milk fat from G1, G2 and G3, respectively). Total unsaturated FAs were also increased when olive cake included in the diet (P<0.001), while significant was the differences between the G2 and G3 milk (mean values of 21.3, 27.0 and 30.2 g/100g fat for G1, G2 and G3, respectively for total unsaturated FA). However, no differences between treatment groups were identified for linoleic and linolenic acids or cholesterol content of sheep milk. Content of conjugated linoleic acid (CLA) isomers were affected by olive cake supplementation (Figure 1), demonstrating an increase in CLA isomers content in milk from supplemented animals. Overall, the present study using innovative NMR method showed that the inclusion of oil rich by-product in animal diets affects positively the content of milk fat in beneficial FA and the total fat unsaturation in sheep milk

ΝΜR in Dairy Lipid Research: Improving the fatty acid profile of sheep milk by olive cake supplementation

The aim of this study was to investigate the effect of an oil rich by-product to the fat quality of sheep milk. A mixture of skins, pulp, woody endocarp and seeds obtained after extraction of olive-oil (namely olive cake) was prepared according to a method developed earlier. Thirty lactating Chios ewes were selected at random to form three balanced groups and allocated to the following feeding regimes: (a) no inclusion of olive cake (G1 group), (b) inclusion of 500 g/day/ewe (G2 group) and (c) inclusion of 1000 g /day/ewe (G3 group), while the other ingredients of the diet were similar and according to animal requirements. Milk samples were collected from each ewe after four weeks on the diet treatment and analysed for the content of different fatty acids (FA) and cholesterol using 1D 1H-NMR spectroscopy. More specifically, the organic phase of lyophilized milk was extracted according to previously developed method [1] and the FA composition and cholesterol content identified and quantified by peak integration using appropriate calculations [2]. The effect of inclusion of olive cake was tested using one-way analysis of variance and Tuckey pairwise comparison between groups (IBM-SPSS ver. 22). Total saturated FAs were affected (P<0.001) by olive cake feeding with the supplemented animals producing less saturated milk (mean values expressed in g/100g of milk fat were 78.6, 73.0 and 69.7 for G1, G2 and G3, respectively). Mono-unsaturated FAs, were significantly (P<0.001) increased in milk from both G2 and G3 animals compared to the control group (mean values of 18.7, 24.4 and 27.3 g/100 g milk fat from G1, G2 and G3, respectively). Total unsaturated FAs were also increased when olive cake included in the diet (P<0.001), while significant was the differences between the G2 and G3 milk (mean values of 21.3, 27.0 and 30.2 g/100g fat for G1, G2 and G3, respectively for total unsaturated FA). However, no differences between treatment groups were identified for linoleic and linolenic acids or cholesterol content of sheep milk. Content of conjugated linoleic acid (CLA) isomers were affected by olive cake supplementation (Figure 1), demonstrating an increase in CLA isomers content in milk from supplemented animals. Overall, the present study using innovative NMR method showed that the inclusion of oil rich by-product in animal diets affects positively the content of milk fat in beneficial FA and the total fat unsaturation in sheep milk