9个杂交蓖麻品种蓖麻籽中不同脂肪酸含量分析

对9个杂交蓖麻品种蓖麻籽的百粒重、出仁率、含油率及主要脂肪酸含量进行了分析,试验结果表明,不同品种蓖麻籽的百粒重、含油率及主要脂肪酸蓖麻油酸的含量差别较大。百粒重变化范围为21．1—52.1g;含油率变化范围为46．0％-57．6％,1号蓖麻籽含油率最高,高达57．6％;9种蓖麻籽中蓖麻油酸含量变化范围为81．44％-90．25％,2号品种的蓖麻油酸含量最高,高达90．25％;油酸、亚油酸含量变化范围分别为2．83％-6．03％和4．27％-7．80％,蓖麻油中还含有少量的棕榈酸、硬脂酸和极少量的二十烷酸、二十烷一烯酸,其中棕榈酸、硬脂酸含量变化范围分别为0．81％-1．74％和0．88％-1．91％,二十烷酸和二十烷一烯酸的含量均低于1％。     

鸡骨泥的酶解工艺及其酶解液中游离氨基酸和脂肪酸分析的研究

本实验以美拉德(Maillard)反应产物(MRPs) 的风味为判断依据,以水解度(DH)为动物蛋白酶解液(Maillard 反应底物之一)的特征性指标,根据MRPs的风味确定动物蛋白水解液的最佳水解度,通过木瓜蛋白酶水解鸡骨泥水解工艺的研究,得出酶解的最佳工艺参数为:温度55℃,pH6.0,时间4h,E/S 为5000U/g.通过氨基酸自动分析仪和GC-MS气相色谱质谱联用仪测定其游离氨基酸和脂肪酸,结果表明:鸡骨泥中含有丰富的钙、铁、锌、硒和一定量的蛋白质,脂肪含量较低.含有17种游离氨基酸,其中人体必需的异亮氨酸、亮氨酸、蛋氨酸、苯丙氨酸、苏氨酸、缬氨酸等8种氨基酸含量较高、比例较适合.含有的5种游离脂肪酸中人体必需的亚油酸、亚麻酸占有一定的比例.     

Distribution and fatty acid content of phospholipids from bovine milk and bovine milk fat globule membranes

The phospholipid (PL) content was determined comparatively in the milk fat globule membrane (MFGM) and whole milk including their fatty acid profiles. The possible role of milk PLs in defence against pathogens was also addressed. The MFGM and whole milk showed a similar distribution of PL species; however, the fatty acid contents of the PL species were different. Total PL from MFGM showed a decrease in C18:0 content in parallel with an increase in C18:1 and C18:2 and very long-chain fatty acid (more than C20) content. No significant differences in the fatty acid content of phosphatidylcholine and sphingomyelin from either source were found. However, the phosphatidylethanolamine from MFGM had more C18:1 and C18:2 and less C14:0 and C16:0 than that from whole milk. A similar but less pronounced result was found for phosphatidylserine/phosphatidylinositol. Enterotoxigenic Escherichia coli strains failed to bind to PL, which had been previously separated by high-performance thin-layer chromatography.     

Factors influencing variation of fatty acid content in ovine milk

Between January 2006 and December 2007, a total of 4,579 test-day observations for contents of milk fatty acids (FA) were obtained from 2,218 lactations of 1,109 ewes belonging to 14 Churra dairy flocks. The 36 analyzed FA were quantified as grams per 100 g of total FA and were grouped as 18 dependent variables: 10 FA, 6 groups of FA, and 2 FA indexes. Flock, day of testing within flock (TD), ewe age, stage of lactation, and season effects contributed significantly to variations in FA. The 2 most important variation factors were flock (3 to 30% of total variance) and TD (35 to 70% of total variance). The percentage of variance explained by the TD effect for conjugated linoleic acid (CLA, C18:2 cis-9, trans-11) and linolenic acid (C18:3 cis-9, cis-12, cis-15) was particularly high: 60.7 and 68.2%, respectively. The season effect was also a very important variation factor, closely linked to feeding. The most significant seasonal variations were observed in polyunsaturated FA, with the highest values occurring in spring and summer and the lowest in winter. More specifically, CLA and linolenic acid contents were 44 and 30% higher in spring-summer than in winter. As the age of the ewe increased, the monounsaturated and polyunsaturated FA decreased and the short- and medium-chain saturated FA increased. The CLA and the CLA/C18:1 trans-11 Δ⁹-desaturase index increased significantly throughout lactation. The correlation coefficient between rumenic acid (CLA) and vaccenic acid was high (0.47) because of the precursor-product relationship via the Δ⁹-desaturase enzyme. The correlation coefficients were high between C10:0 and C12:0 (0.79), C12:0 and C14:0 (0.73), and C14:0 and C16:0 (0.29), probably because of their similar metabolic origin. Positive correlations were also obtained among the C₁₈ FA family. All the studied factors of FA variation would be considered as fixed effects in the statistical models used for estimation of genetic and phenotypic parameters from test-day records of commercial flocks.     

Estimating fatty acid content in cow milk using mid-infrared spectrometry

Interest in the fatty acid composition of dairy products is increasing; however, the measurement of fatty acids requires using gas-liquid chromatography. Although this method is suitable, it involves a time-consuming procedure, expensive reagents, and qualified staff. By comparison, the mid-infrared (MIR) spectrometry method could be a good alternative for assessing the fatty acid profile of dairy products. The objective of this study was to explore the calibration of MIR spectrometry for estimating fatty acid concentrations in milk and milk fat. Estimated concentrations in milk fat were less reliable than those for the same fatty acids in milk. Results also showed that when the fatty acid concentrations in milk increased, the efficiency of the infrared analysis method in predicting these values simultaneously increased. Selected prediction equations must have a high cross-validation coefficient of determination, a high ratio of standard error of cross-validation to standard deviation, and good repeatability of chromatographic data. Results from this study showed that the calibration equations predicting 12:0, 14:0, 16:0, 16:1cis-9, 18:1, and saturated and monounsaturated fatty acids in milk could be used. Thus, with its potential for use in regular milk recording, this infrared analysis method offers the possibility of assessing and improving the quality of milk produced. Indeed, it enables the fatty acid composition in milk to be estimated for each cow and the estimates to be used as indicator traits to determine the genetic values of underlying fatty acid concentrations. The knowledge of these genetic values would open up opportunities for animal selection aimed at improving the nutritional quality of cow milk.     

人初乳脂肪酸组成及sn-2位脂肪酸分布的研究

选择广州市健康产妇20例,用超声法快速萃取乳中脂肪,采用DM-FFAP毛细管柱气相色谱对人初乳脂中总脂肪酸组成及sn-2位脂肪酸进行了测定,并采用SPSS13.0软件对测定数据进行统计分析。结果表明:总脂肪酸组成中饱和脂肪酸(主要为棕榈酸)含量低,为36.47%,不饱和脂肪酸含量高(主要为油酸和亚油酸),为63.9%;sn-2位脂肪酸组成中饱和脂肪酸含量为61.48%,不饱和脂肪酸含量为37.95%;棕榈酸多分布在sn-2位(72.08%),油酸和亚油酸多分布在sn-1,3位。初乳中脂肪酸的组成和分布具有独特的特点,对婴儿生长发育具有非常重要意义,本文对开发人乳脂替代品具有理论指导意义。     

The production of milk rich in protein and low in fat, the fat having a high polyunsaturated fatty acid content

In two experiments, dairy heifers were offered a basal diet of ground dried grass cubes and flaked maize. In Experiment 1, the diet contained equal amounts of these components whereas, in Experiment 2, the proportions were varied from all-grass to equal amounts of grass and flaked maize. Before and after the main part of each experiment, the animals were offered a diet containing hay, molassed sugar beet pulp and barleybased concentrates. Compared to this diet, the grass cubes-flaked maize diet reduced the fat content of the milk and increased the crude protein content. The proportions of all the milk fatty acids up to 18:0 were reduced and those of 18:1, 18:2 and 18:3 were increased. In Experiment 1, the basal diet of grass cubes and flaked maize was supplemented with 180 and 360 g day^?1 soya bean oil given as crushed, unextracted soya beans or with 180 g day^?1 soya bean oil given as a formaldehyde-treated caseinoil preparation but none of these supplements had any effect on the composition of the milk. In Experiment 2, the crude protein content of the milk increased as the proportion of flaked maize in the diet was increased. Otherwise, there were no differences between the different diets.     

Increasing omega fatty acid content in cow's milk through diet manipulation: Effect on milk flavor

Milk with an increased content of eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and conjugated linoleic acid (CLA) was obtained by incorporating fish oil into the feed of cows. The 4 feed treatments used were a control diet of 57% forage and 43% concentrate mix with EnerGII fat supplement at 1.65% of dietary DM, or EnerGII in the basal diet was partially replaced with 1) 0.21% partially ruminally inert calcium salts of 71% fish oil given at 0.41% of DM; 2) 0.41% inert calcium salts of 71% fish oil given at 0.83% of DM; or 3) 0.83% inert calcium salts of 43% fish oil given at 0.83% of DM. The cows were milked after 5 and 8 wk and the EPA, DHA, and CLA contents in the pasteurized whole milk were determined. The presence of off-flavors in the milk was investigated after 3 and 10 d of storage. Twelve judges were trained to evaluate the presence of grassy, fishy, oily, oxidized, and rancid off-flavors. Although levels of EPA, DHA, vaccenic acid, and CLA increased for all 4 treatments, a trained sensory panel detected no difference in milk flavor between treatments and the control, with little or no intensity of off-flavors. Results suggest that feeding fish oil and EnerGII at varying levels enhanced CLA, EPA, DHA, and total n-3 fatty acids in milk over the length of the experiment without negatively affecting milk flavor. This creates the potential for a more marketable and healthful product.     

Comparison of fatty acid content of milk from Jersey and Holstein cows consuming pasture or a total mixed ration.

Holstein (n = 19) and Jersey (n = 18) cows were used to study effects of two feeding systems on fatty acid composition of milk. Confinement cows were fed a total mixed ration with corn silage and alfalfa silage and pastured cows grazed a crabgrass (90%) and clover (10%) pasture and were allowed 5.5 kg of grain per head daily. Two milk samples were collected from each cow at morning and afternoon milkings 1 d each week for four consecutive weeks in June and July 1998. One set of milk samples was analyzed to determine fatty acid composition, and the second set was used for crude protein and total fat analyses. Data were analyzed by the general linear models procedure of SAS, using a split-plot model with breed, treatment, and breed x treatment as main effects and time of sampling and week as subplot effects along with appropriate interactions. Milk from pastured cows was higher than milk from confinement cows for the cis-9, trans-11 octadecadienoic acid isomer of conjugated linoleic acid (CLA). Also, milk from Holsteins was higher than milk from Jerseys for C16:1, C18:1, and CLA and lower than Jerseys for C6:0, C8:0, C10:0, C12:0, and C14:0. Several treatment x week interactions existed, but main effects were still important; for example, proportions of CLA in milk of grazed cows were relatively constant across weeks (0.66, 0.64, 0.64, and 0.69% +/- 0.02%, respectively), but the CLA in milk of confinement cows increased in wk 4 (0.35, 0.31, 0.31, and 0.48% +/- 0.02% for wk 1 to 4, respectively). There are potentially important differences in fatty acid composition of milk from cows consuming a warm season pasture species compared with milk from cows consuming a total mixed ration, as well as differences between Holstein and Jersey breeds.     

Occurrence of 3-MCPD fatty acid esters in human breast milk

A series of twelve breast milk samples were analysed by gas chromatography-mass spectrometry (GC/MS) operated in selected ion monitoring mode for 3-chloropropane-1,2-diol (3-MCPD). Whilst none of the samples contained 3-MCPD above the limit of detection of 3 microg kg(-1) milk, all contained high amounts of 3-MCPD esterified with higher fatty acids. The levels of 3-MCPD released by hydrolysis of these esters (bound 3-MCPD) ranged from the limit of detection (300 microg kg(-1), expressed on a fat basis) to 2195 microg kg(-1); with a mean level of bound 3-MCPD of 1014 microg kg(-1), which corresponded to 35.5 microg kg(-1) milk. The presence of bound 3-MCPD was confirmed using orthogonal gas chromatography coupled with high-speed time-of-flight mass spectrometry analysis for four randomly selected breast milk samples. Six breast milks collected from one of the nursing mothers 14-76 days after childbirth contained bound 3-MCPD within the range of 328-2078 microg kg(-1) fat (mean 930 microg kg(-1) fat). The calculated bound 3-MCPD content of these samples was within the range of 6 and 19 microg kg(-1) milk (mean of 12 microg kg(-1) milk). The major types of 3-MCPD esters were the symmetric diesters with lauric, palmitic, and oleic acids, and asymmetric diesters with palmitic acid/oleic acid among which 3-chloro-1,2-propanediol 1,2-dioleate prevailed.     

Occurrence of 3-MCPD fatty acid esters in human breast milk

A series of twelve breast milk samples were analysed by gas chromatography-mass spectrometry (GC/MS) operated in selected ion monitoring mode for 3-chloropropane-1,2-diol (3-MCPD). Whilst none of the samples contained 3-MCPD above the limit of detection of 3 μg kg^?1 milk, all contained high amounts of 3-MCPD esterified with higher fatty acids. The levels of 3-MCPD released by hydrolysis of these esters (bound 3-MCPD) ranged from the limit of detection (300 μg kg^?1, expressed on a fat basis) to 2195 μg kg^?1; with a mean level of bound 3-MCPD of 1014 μg kg^?1, which corresponded to 35.5 μg kg^?1 milk. The presence of bound 3-MCPD was confirmed using orthogonal gas chromatography coupled with high-speed time-of-flight mass spectrometry analysis for four randomly selected breast milk samples. Six breast milks collected from one of the nursing mothers 14–76 days after childbirth contained bound 3-MCPD within the range of 328–2078 μg kg^?1 fat (mean 930 μg kg^?1 fat). The calculated bound 3-MCPD content of these samples was within the range of 6 and 19 μg kg^?1 milk (mean of 12 μg kg^?1 milk). The major types of 3-MCPD esters were the symmetric diesters with lauric, palmitic, and oleic acids, and asymmetric diesters with palmitic acid/oleic acid among which 3-chloro-1,2-propanediol 1,2-dioleate prevailed.     

Genetic parameters of saturated and monounsaturated fatty acid content and the ratio of saturated to unsaturated fatty acids in bovine milk

Fatty acid composition influences the nutritional quality of milk and the technological properties of butter. Using a prediction of fatty acid (FA) contents by mid-infrared (MIR) spectrometry, a large amount of data concerning the FA profile in bovine milk was collected. The large number of records permitted consideration of more complex models than those used in previous studies. The aim of the current study was to estimate the effects of season and stage of lactation as well as genetic parameters of saturated (SAT) and monounsaturated (MONO) fatty acid contents in bovine milk and milk fat, and the ratio of SAT to unsaturated fatty acids (UNSAT) that reflect the hardness of butter (SAT:UNSAT), using 7 multiple-trait, random-regression test-day models. The relationship between these FA traits with common production traits was also studied. The data set contained 100,841 test-day records of 11,626 Holstein primiparous cows. The seasonal effect was studied based on unadjusted means. These results confirmed that milk fat produced during spring and summer had greater UNSAT content compared with winter (63.13 vs. 68.94% of SAT in fat, on average). The effect of stage of lactation on FA profile was studied using the same methodology. Holstein cows in early first lactation produced a lower content of SAT in their milk fat. Variance components were estimated using a Bayesian method via Gibbs sampling. Heritability of SAT in milk (0.42) was greater than heritability of SAT in milk fat (0.24). Estimates of heritability for MONO were also different in milk and fat (0.14 vs. 0.27). Heritability of SAT:UNSAT was moderate (0.27). For all of these traits, the heritability estimates and the genetic and phenotypic correlations varied through the lactation.