稻米中脂肪酸值测定方法的研究

建立了稻米中脂肪酸值的滴定新方法。样品以石油醚提取后，过滤，加入50％乙醇溶液，以酚酞为指示剂，用KOH标准溶液滴定至下层溶液呈微红色。该方法回收率为96．66％-100．77％，相对标准偏差为0．29％-3．56％。本方法的选择性和精密度均优于乙醇提取法，滴定终点变化敏锐。     

邻二氮菲亚铁指示剂法测定茶叶中茶多酚的含量

本研究建立了以邻二氮菲亚铁为指示剂测定茶叶中茶多酚含量的定量分析方法。在硫酸强酸性介质中,以高锰酸钾为氧化剂、邻二氮菲亚铁为指示剂,用待测样品试液进行滴定,滴定终点颜色变化敏锐。该法的RSD在1．01％～1．40％（n=5）,平均回收率在99．9％～101．1％,方法准确、简便,可用于茶叶中茶多酚含量的测定。     

高效液相色谱法测定微胶囊中的维生素A

本方法应用罗紫-哥特里方法分离提取微胶囊中的油脂，然后用正相液相法测定油脂中的维生素A。测定方法的变异系数为2．2％；回收率为96．6～110．5％。该方法与十年前的国家标准《食物中维生素A和维生素E的测定方法》相比较，它减少了样品皂化程度，免去了苯并芘(致癌物质)添加剂，具有方法简单、无毒、快速的优点，是测定含油脂较高的微胶囊产品中VA的新方法。     

高效液相色谱法测定微胶囊中的维生素A

本方法应用罗紫－哥特里方法分离提取微胶囊中的油脂，然后用正相液相法测定油脂中的维生素A。测定方法的变异系数为2．2％；回收率为96．6－110．5％。该方法与十年前的国家标准《食物中维生素A和维生素E的测定方法》相比较，它减少了样品皂化程度，免去了苯并花（致癌物质）添加剂，具有方法简单、无毒、快速的优点，是测定含油脂较高的微胶囊产品中VA的新方法。     

双指示剂银量法测定小麦粉皮中氯化物的含量

目的：建立双指示剂银量法测定小麦粉皮中氯化物含量的方法。方法：从提取溶剂中乙醇的体积分数、提取温度、提取方式、提取时间、蛋白沉淀剂用量等方面对前处理方法进行优化,以得到最佳的样品提取方法。使用百里香酚酞和铬酸钾双指示剂银量法测定提取溶液中氯离子的含量,通过公式计算得到样品中氯化物的含量。采用智能手机RGB色彩空间取色比较双指示剂银量法和摩尔法滴定终点前后体系的颜色变化敏锐程度。结果：提取溶剂中乙醇的体积分数和提取时间对测定结果影响显著。双指示剂银量法在滴定终点前后体系的颜色变化更敏感,容易判断滴定是否到达终点。10份测试样品中,氯化物的含量在1.30%～3.78%之间,平行测定结果的精密度均小于2.57%。t检验结果证明,该方法与电位滴定法之间无显著性差异。结论：该方法准确性高、可靠性好,前处理过程简单且操作简便,适用于小麦粉皮中氯化物含量的测定。     

葡萄酒中SO2残留量电位滴定检测方法的探讨

本研究建立了葡萄酒中SO2残留量的电位滴定检测方法,该方法以自动电位滴定仪记录反应终点,以通入氦气驱除SO2后样品为空白对照,排除了干扰物质对检测结果的影响.该方法相对标准偏差范围在0.15%～0.67%之间,标准品回收率在99.1%～100.7%之间,最低检测限(LLD)为0.5mg/L.     

气相色谱-质谱法分析啤酒中游离脂肪酸

啤酒中游离脂肪酸的含量对啤酒的风味具有重要的影响。采用固相萃取法对市售啤酒中游离脂肪酸成分进行提取,气相色谱/质谱法进行定性分析并外标法定量。通过添加一定加标水平的脂肪酸(辛酸、癸酸、月桂酸、棕榈酸、油酸),结果表明各脂肪酸在不同的加标浓度下都能获得较高的回收率(78.1%~93.5%),标准偏差为2.2%~3.8%,试验精密度较高。比较不同比例提取溶剂对各种脂肪酸回收率的研究,结果表明采用正己烷-乙醚(体积比50∶50)作为提取溶剂时提取效率相对最高(辛酸82.1%、癸酸84.2%、月桂酸88.4%、棕榈酸89.8%、油酸93.5%),说明该方法能准确测定啤酒中的游离脂肪酸含量。     

蔬菜中农药多残留预处理方法的研究

目的选择一种高效可靠的农药残留提取试剂,研究合适的农药多残留预处理方法。方法选取蔬菜为试材,经打浆处理后在样品处理液中分别加入乙腈和乙酸乙酯作为提取试剂,并采用SPE固相萃取方法进行净化处理,提取液通过气质联用仪进行检测,分析提取效果并对样品中添加22种农药的回收率进行测定。结果用乙腈进行预处理,农药残留加标回收率在70%~110%范围内;用乙酸乙酯进行预处理,农药残留加标回收率在70%~120%范围内,2种前处理方法回收率差别不大。结论从节约成本、污染性小、毒性低等角度出发,采用乙酸乙酯进行农药残留提取既能保证数据的准确性,同时又能节约成本、减轻污染,可减少溶剂对实验人员的危害。     

复合柱净化-超高效液相色谱-串联质谱法测定粮油中黄曲霉毒素和玉米赤霉烯酮类毒素

目的建立C_(18)-Al_2O_3复合固相萃取柱净化,同时检测粮食及植物油中黄曲霉毒素和玉米赤霉烯酮类毒素的超高效液相色谱-串联质谱方法。方法植物油样品用乙腈-水(90∶10,V∶V)提取,粮食样品先用乙腈-乙酸-水(84∶1∶16,V∶V)再用二氯甲烷-乙酸乙酯(90∶10,V∶V)进行二次提取,进一步采用C_(18)-Al_2O_3复合固相萃取柱净化,稳定同位素内标稀释,以乙腈和水为流动相,CORTECSTMC18色谱柱(2. 1 mm×100 mm,2. 7μm)进行分离,电喷雾离子化多反应监测模式检测。结果黄曲霉毒素和玉米赤霉烯酮类毒素的线性范围分别为0. 1～30. 0和1. 0～500. 0ng/ml,检出限分别为0. 03和0. 3μg/kg,定量限分别为0. 10和1. 0μg/kg。黄曲霉毒素和玉米赤霉烯酮类毒素的平均回收率分别为68. 3%～98. 6%和84. 5%～108. 0%,相对标准偏差分别为4. 6%～11. 5%和4. 2%～9. 0%(n=6)。采用本方法分析了国内外5种质控样品,测定值均在质控样品指定范围内。对大连市市售的100份粮油样品进行测定,结果表明散装花生油和玉米油中黄曲霉毒素B1和玉米赤霉烯酮检出率较高,最高含量分别为12. 80和370. 00μg/kg。结论本方法定量准确、操作简便、更环保、检测成本低,适于批量粮油样品中黄曲霉毒素和玉米赤霉烯酮类毒素的同时检测。     

高效液相色谱法对玉米中玉米赤霉烯酮的测定

研究了高效液相色谱法测定玉米中玉米赤霉烯酮的方法.样品借鉴了GB/T 19540-2004中提取玉米赤霉烯酮的方法,通过Oasis HLB净化柱对提取液净化,以agilent extent C18色谱柱为分离柱,乙腈-水(V水:V乙腈=55:45)为流动相进行荧光检测(λex=235 nm,λem=460 nm).玉米赤霉烯酮的质量浓度在12～2 400μ/kg范围内呈良好线性,相关系数为0.9994,对添加高、中、低3个浓度玉米赤霉烯酮的玉米样品进行加标回收试验,平均回收率分别为96.736%、93.839%、86.240%,变异系数在1%～10%之间,最低检测限为10μ/kg.此方法对玉米中玉米赤霉烯酮的检测是可行的,且可给谷物中玉米赤霉烯酮检测方法优化提供参考.     

反式脂肪酸危害与控制

通过对食品中反式脂肪酸含量强制标示,向广大消费者指出反式脂肪酸对人体健康危害;同时对油脂加工业而言,这也意味着一场旨在减少食品中反式脂肪酸变革开始。     

花生四烯酸分离纯化方法研究进展

花生四烯酸是人体必需不饱和脂肪酸,具有极高保健价值。该文介绍并比较花生四烯酸分离纯化方法,主要包括低温溶剂结晶法,脲包法,银离子络合法,超临界萃取法,高效液相色谱法等方法。     

Milk fatty acids as possible biomarkers to early diagnose elevated concentrations of blood plasma nonesterified fatty acids in dairy cows

Most cows encounter a state of negative energy balance during the periparturient period, which may lead to metabolic disorders and impaired fertility. The aim of this study was to assess the potential of milk fatty acids as diagnostic tools of detrimental levels of blood plasma nonesterified fatty acids (NEFA), defined as NEFA concentrations beyond 0.6 mmol/L, in a data set of 92 early lactating cows fed a glucogenic or lipogenic diet and subjected to 0-, 30-, or 60-d dry period before parturition. Milk was collected in wk 2, 3, 4, and 8 (n = 368) and blood was sampled weekly from wk 2 to 8 after parturition. Milk was analyzed for milk fatty acids and blood plasma for NEFA. Data were classified as “at risk of detrimental blood plasma NEFA” (NEFA ≥0.6 mmol/L) and “not at risk of detrimental blood plasma NEFA” (NEFA <0.6 mmol/L). Concentrations of 45 milk fatty acids and milk fat C18:1 cis-9-to-C15:0 ratio were subjected to a discriminant analysis. Milk fat C18:1 cis-9 revealed the most discriminating variable to identify detrimental blood plasma NEFA. A false positive rate of 10% allowed us to diagnose 46% of the detrimental blood plasma NEFA cases based on a milk fat C18:1 cis-9 concentration of at least 230 g/kg of milk fatty acids. Additionally, it was assessed whether the milk fat C18:1 cis-9 concentrations of wk 2 could be used as an early warning for detrimental blood plasma NEFA risk during the first 8 wk in lactation. Cows with at least 240 g/kg of C18:1 cis-9 in milk fat had about 50% chance to encounter blood plasma NEFA values of 0.6 mmol/L or more during the first 8 wk of lactation, with a false positive rate of 11.4%. Profit simulations were based on costs for cows suffering from detrimental blood plasma NEFA, and costs for preventive treatment based on daily dosing of propylene glycol for 3 wk. Given the relatively low incidence rate (8% of all observations), continuous monitoring of milk fatty acids during the first 8 wk of lactation to diagnose detrimental blood plasma NEFA does not seem cost effective. On the contrary, milk fat C18:1 cis-9 of the second lactation week could be an early warning of cows at risk of detrimental blood NEFA. In this case, selective treatment may be cost effective.     

东北不同杂豆油脂含量及脂肪酸组成分析

为开发与利用东北杂豆资源,本文以东北特有杂豆为原料,采用气质分析方法对杂豆脂肪含量及脂肪酸组成进行初步分析。结果表明：杂豆中含有丰富的不饱和脂肪酸,且在测定所有杂豆中均是高活性的n:3、n:2类不饱和脂肪酸含量高,而活性相对的n:1类不饱和脂肪酸含量低。芸豆类杂豆的脂肪酸中不饱和脂肪酸含量均大于80%;且高活性的n:3类不饱和脂肪酸含量较多,紫花芸豆的n:3类不饱和脂肪酸含量达到了48.99%,具有进一步开发应用的价值。本研究为东北杂豆的综合利用提供了理论参考与依据     

α-亚麻酸研究进展

α-亚麻酸属于n-3系列多不饱和脂肪酸,分子结构为△9,12,15-18:3,主要来源于陆地植物, 如杜仲、藿香、亚麻、紫苏等。在体内代谢过程中,它主要作为EPA和DHA前体物质,并具有降低胆固醇、血脂,预防心血管疾病、保护视力和抑制过敏反应等功能。该文主要介绍α-亚麻酸的来源、分离提取方法进展及生理功能,并对α-亚麻酸发展前景进行展望。     

膳食中的脂肪酸平衡

本文综述了膳食中三类脂肪酸（饱和脂肪酸、单不饱和脂肪酸及多不饱和脂肪酸）的营养学功能，并就有关膳食脂肪酸的平衡及n-6与n-3的合适比例作了总结。     

Effect of ruminal pulse dose of polyunsaturated fatty acids on ruminal microbial populations and duodenal flow and milk profiles of fatty acids

The objective of this study was to examine the effect of ruminal pulse dose of free linoleic acid (LA) and free docosahexaenoic acid (DHA) on microbial populations in the rumen, duodenal fatty acid (FA) flow, milk composition, and milk FA profiles of Chinese Holstein dairy cows. Four rumen- and duodenal-fistulated Chinese Holstein cows in mid lactation (138.5 ± 10 d in milk) were randomly assigned to 3 treatment groups and 1 control group in a 4 × 4 Latin square design over 4 periods (3 wk per period). Diets contained either no LA or 2.7% LA and either no DHA or 0.5% DHA in a 2 × 2 factorial arrangement of treatments. Ruminal pulse dose with DHA increased counts of Megasphaera elsdenii, decreased Fibrobacter succinogenes, but did not affect Butyrivibrio fibrisolvens or Ruminococcus flavefaciens. The pulse dose of LA at 2.7% dry matter had no effect on the population sizes of the 3 major cellulolytic bacterial species or M. elsdenii, and no interaction was observed between LA and DHA. The pulse dose of LA or DHA, either alone or in combination, increased the duodenal flow of vaccenic acid (VA). The milk VA and cis-9,trans-11 conjugated linoleic acid (CLA) contents also increased in response to the fatty acid pulse dose, and the pulse dose of both LA and DHA together had the most profound stimulatory effect. This study indicated that ruminal pulse dose of LA or DHA could be used to increase duodenal flow of VA and the milk contents of potentially health-promoting FA, such as VA and cis-9,trans-11 CLA. These results might be useful in formulating dietary interventions to improve milk cis-9,trans-11 CLA contents.     

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。     

A survey of lipid composition of Khoa samples in relation to possible adulteration

The fatty acid composition of Khoa a heat‐desiccated milk product was determined and compared with those obtained with cow milk, buffalo milk and toned milk. Fatty acid methyl esters were analysed by capillary gas chromatography (GC). Among the Khoa samples analysed, 57% showed fatty acid composition characteristic of milk fat. The ratio of major saturated fatty acids to unsaturated fatty acids (S/U) including 18:1 transfatty acids was calculated for all the fats. The GC profiles of 43% Khoa samples showed the composition of fatty acids not conforming to milk fats. The Khoa samples adulterated with nonmilk fats were further confirmed by cholesterol and triglyceride estimation.