不同温度胁迫条件下太平洋牡蛎挥发性化合物的变化

为探究温度胁迫后太平洋牡蛎挥发性成分的变化,该研究采用感官评定、气相色谱-离子迁移谱（Gas Chromatography-Ion Mobility Spectroscopy,GC-IMS）、气相色谱-质谱联用（Gas Chromatography-Mass Spectrometer,GC-MS）结合多元统计分析的方法,对不同温度胁迫条件（12、22、32℃）的太平洋牡蛎挥发性成分进行了检测,同时测定了其存活率以及脂肪酸含量的变化。结果显示,胁迫6 d后,低温12℃组的存活率达到97.90%,n-3型多不饱和脂肪酸（Polyunsaturated Fatty Acid,PUFA）含量升高。感官评定、GC-IMS以及GC-MS结果显示辛醛等鱼腥味醛类成分含量下降,而呈紫罗兰气味的(E,Z)-2,6-壬二烯醛升至12.15%,提供了愉悦的气味。高温32℃胁迫后存活率降至26.00%,n-3 PUFA含量下降从46.07%下降至39.59%,同时饱和醛等腥味醛类含量显著上升,加重了太平洋牡蛎的腥味,导致牡蛎的品质严重下降。最后通过统计分析筛选6种关键成分：己醛、辛醛、(E,Z)-2,6-壬二...     

北部湾海区几种常见牡蛎基础营养及脂肪酸成分比较分析

目的 比较分析北部湾海区常见的熊本牡蛎、香港牡蛎和近江牡蛎鲜品的基础营养成分及脂肪酸组成。方法 以北部湾海区熊本牡蛎、香港牡蛎和近江牡蛎为实验样品, 测定其水分、粗蛋白、粗脂肪和灰分的含量, 并用气相色谱-质谱联用法(gas chromatography-mass spectrometry, GC-MS)测定脂肪酸组成及含量。 结果 香港牡蛎的水分含量(89.44 g/100 g)、近江牡蛎粗脂肪含量(1.09 g/100 g)和灰分含量(1.77 g/100 g)均显著高于另两种牡蛎(P<0.05), 香港牡蛎粗蛋白含量(4.59 g/100 g)显著低于另两种牡蛎(P>0.05)。熊本牡蛎和近江牡蛎含有33种脂肪酸, 而香港牡蛎为34种, 其中多不饱和脂肪酸(polyunsaturated fatty acid, PUFA)含量占41.02%~50.79%; 3种牡蛎中二十碳五烯酸(eicosapentaenoic acid, EPA)、二十二碳六烯酸(docosahexoenoic acid, DHA)的含量占脂肪酸总量的27.13%~38.65%, 近江牡蛎(27.13%)显著低于另两种牡蛎(P<0.05)。结论 北部湾海区熊本牡蛎、香港牡蛎和近江牡蛎脂肪酸种类丰富, 与饱和脂肪酸及单不饱和脂肪酸含量所占脂肪酸总量相比, PUFA占比最高, 且以DHA和EPA为主, 具有优良的开发潜力。     

坚果中脂肪含量及脂肪酸组成分析

目的分析16种市售坚果中脂肪含量及脂肪酸组成,比较不同品种坚果间脂肪含量、饱和脂肪酸和不饱和脂肪酸组成的差异。方法采用气相色谱分析法测定坚果中37种脂肪酸的含量,用最小显著性差异法(least-significant difference,LSD)法进行多重比较。结果坚果的平均脂肪含量为(55.6±0.86)g/100 g,变化范围为40.2~71.3 g/100 g,碧根果脂肪含量显著高于其他品种坚果脂肪含量(P0.05);坚果中的不饱和脂肪酸含量为72.77~95.47 g/100 g脂肪,平均值为(86.68±0.12)g/100 g脂肪,显著高于饱和脂肪酸4.53~22.19 g/100 g脂肪,平均值为(11.31±0.16)g/100 g脂肪(P0.05),东北榛子中单不饱和脂肪酸总含量最高,为84.34 g/100 g脂肪,而纸皮核桃中的多不饱和脂肪酸总含量最高,为74.17 g/100 g;坚果中不含短链脂肪酸和中链脂肪酸。结论坚果中不饱和脂肪酸含量较多,富含ω-6和ω-3脂肪酸,营养价值较高。     

Comparing the fatty acid composition of organic and conventional milk

During a 12-mo longitudinal study, bulk-tank milk was collected each month from organic (n = 17) and conventional (n = 19) dairy farms in the United Kingdom. All milk samples were analyzed for fatty acid (FA) content, with the farming system type, herd production level, and nutritional factors affecting the FA composition investigated by use of mixed model analyses. Models were constructed for saturated fatty acids, the ratio of polyunsaturated fatty acids (PUFA) to monounsaturated fatty acids, total n-3 FA, total n-6 FA, conjugated linoleic acid, and vaccenic acid. The ratio of n-6:n-3 FA in both organic and conventional milk was also compared. Organic milk had a higher proportion of PUFA to monounsaturated fatty acids and of n-3 FA than conventional milk, and contained a consistently lower n-6:n-3 FA ratio (which is considered beneficial) compared with conventional milk. There was no difference between organic and conventional milk with respect to the proportion of conjugated linoleic acid or vaccenic acid. A number of factors other than farming system were identified which affected milk FA content including month of year, herd average milk yield, breed type, use of a total mixed ration, and access to fresh grazing. Thus, organic dairy farms in the United Kingdom produce milk with a higher PUFA content, particularly n-3 FA, throughout the year. However, knowledge of the effects of season, access to fresh grazing, or use of specific silage types could be used by producers to enhance the content of beneficial FA in milk.     

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.     

风干牦牛肉氨基酸与脂肪酸组成分析评价

通过对风干牦牛肉原料及成品中氨基酸与脂肪酸的含量进行测定,分析其组成变化,并对风干牦牛肉的营养价值进行评价。结果显示:原料肉和风干牦牛肉均含有十八种氨基酸和十四种脂肪酸,且风干牦牛肉的氨基酸和脂肪酸总量分别高于原料肉1.34g/100g干物质和0.62%（p<0.05）。风干牦牛肉的氨基酸总量为81.14g/100g干物质,EAA/TAA为39.45%,EAA/NEAA为65.15%。脂肪酸总量为97.97%,P:S为0.32,接近理想模式,n-6:n-3为1.4,处于理想范围。因此可以判断风干牦牛肉是一种具有独特风味的优质蛋白质来源,也是具有均衡脂肪酸的高营养价值的肉制品。      

苎麻籽油脂肪酸组成及其粕氨基酸组成分析

用气相色谱法对苎麻籽油脂肪酸组成进行了分析,同时用氨基酸全自动分析仪对苎麻粕进行分析,为苎麻籽的开发利用提供基础数据。结果表明,苎麻籽油中不饱和脂肪酸含量90%以上,多不饱和脂肪酸含量79%以上,亚油酸含量尤为丰富,达77.40%~78.84%;苎麻粕含17种氨基酸,总含量为209.02~278.46 mg/g,其中7种必需氨基酸占总氨基酸的32.06%~33.17%。     

米糠发酵过程中脂肪酸组分及含量变化的研究

以新鲜米糠为原料,以料水比1:9(w:v)配成培养基,接入红曲(Monascus anka)M180和木耳(Auricularia auricular)A900,在30℃、200r/min摇床培养,培养时间分别为4d和7d。利用气相色谱法,对米糠发酵过程中脂肪酸组分及含量的变化进行分析。结果显示,米糠中主要脂肪酸为C16:0、C18:1、C18:2,占总脂肪酸的95.05%,C16:1、C18:1、C18:2等不饱和脂肪酸占总脂肪酸的80.09%,在红曲和木耳发酵过程中,脂肪酸含量一直呈下降趋势,总脂肪酸含量由最初的200.75mg/g分别下降至68.35mg/g和79.95mg/g,红曲M180比木耳A900利用脂肪酸速度快。发酵结束后,红曲发酵米糠和木耳发酵米糠中不饱和脂肪酸占总脂肪酸的比例分别为83.76%和80.84%,与发酵前相比,没有得到明显提高。利用红曲和木耳发酵米糠不能达到富集不饱和脂肪酸的目的,但可作为除去米糠中脂肪,抑制酸败的潜在途径。     

山羊油理化特性及脂肪酸组成

以新鲜山羊的羊板油和肾脏油为原料,熬制得到山羊油,测定其主要的理化特性、脂肪酸组成.结果表明:板油的皂化值(KOH)、碘值(I)和折光指数(65 ℃)分别为196.8 mg/g、47.9 g/100 g和1.452 4;肾脏油的皂化值(KOH)、碘值(I)和折光指数(65 ℃)分别为194.7 mg/g、37.8 g/100 g和1.452 0.板油全样脂肪酸中棕榈酸、硬脂酸和油酸的含量分别为18.09%、20.85%和45.54%;肾脏油全样脂肪酸中棕榈酸、硬脂酸和油酸的含量分别为17.06%、34.57%和38.28%.板油Sn-2位脂肪酸中油酸、硬脂酸和棕榈酸的含量分别为64.60%、11.52%和9.84%;肾脏油Sn-2位脂肪酸中油酸、硬脂酸和棕榈酸的含量分别为55.62%、20.70%和12.65%.山羊油中还含有一定量的C17:0和C16:2.     

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.