植物油脂中脂肪酸的分离与鉴定方法

本文介绍了油脂中脂肪酸的提取及脂肪酸甲酯的制备，应用硝酸银硅胶柱层析、反相液液分配层析和高压液相色谱等方法分离脂肪酸。采用气相色谱、氧化断链与远端化学修饰技术等手段鉴定脂肪酸结构。     

漆脂脂肪酸的工业应用

脂肪酸及其衍生物在工业方面的用途极其广泛,漆脂脂肪酸的组成主要是棕榈酸和硬脂酸,其用途也非常广阔。本文主要介绍了脂肪酸的化学反应以及脂肪酸及其衍生物在工业方面的应用情况,以促进我国漆脂深加工的研究,扩大漆脂的用途,充分利用我国漆脂这一丰富的资源。     

啤酒污染菌的鉴定及其细胞膜脂肪酸的组成分析

从纯生啤酒中富集分离得到11株啤酒污染菌。对这11株菌进行16S rRNA同源性分析和系统发育树构建。结果表明:11株菌均属于乳酸杆菌,分属于植物乳杆菌(Lactobacillus plantarum)、类布氏乳杆菌(Lactobacillus parabuchneri)和乳酸短杆菌(Lactobacillus brevis)3个种。进一步对11株菌的膜脂肪酸组成进行分析,其脂肪酸组成变化规律与16S rRNA进化分布高度一致。将BN01、BN02和BN03号菌接种到不同程度啤酒环境胁迫的培养基中,发现随着啤酒成分增加,菌的膜不饱和直链脂肪酸和链长18和20碳的脂肪酸含量增加。该研究结果不仅对啤酒污染菌进行了分类鉴定,而且阐述了基于膜脂肪酸调控的污染菌膜对啤酒环境胁迫的耐受机制。     

中国印刷及设备器材工业2009年1月～9月进出口商品情况

这里所指的印刷设备及器材包括印刷设备、印刷器材、印刷器材含印刷油墨、胶印版材、制版软片。     

主要进出口经济鱼类及其制品分子鉴定技术的研究进展

随着我国进出口贸易的不断发展,进出口鱼类品种繁多,数量巨大。但部分国内外企业受高额利润驱使,以假充真、以劣充好事件时有发生,鱼类制品更是真伪难辨,掺假状况极其普遍。通过形态学和生物学方法已经不能满足对鱼类种属鉴定。近年来,随着分子生物技术的迅猛发展,分子检测技术在鱼类品种鉴定领域得到广泛应用。本文针对不同分子鉴定技术进行阐述,包括普通聚合酶链反应(polymerase chain reaction,PCR)技术、多重PCR技术、实时定量PCR技术、DNA条形码技术、环介导等温扩增检测技术(loop-mediated isothermal amplification,LAMP)、聚合酶链反应-限制性酶切多态性技术(polymerase chain reaction-restriction fragment length polymorphism,PCR-RFLP)以及随机扩增多态性DNA检测技术(random amplified polymorphic DNA),并根据不同检测技术的特点进行分析,为进出口鱼类鉴定提供技术支撑。     

大豆及其主要制品进出口形势分析

一、大豆进出口形势分析 大豆在我国食物生产和消费系统一直扮演着非常重要的角色,一方面大豆为人民生活提供了优质的植物蛋白来源,另一方面大豆又对我国传统农业的精耕细作和可持续发展提供了良好的地力基础。 目前中国是大豆的净进口国,这种形势的转变出现在20世纪90年代的后期（表1）。中国是世界大豆主产国之一,其产量约占全球大豆总产量的10％,居世界第4位,中国曾经也是大豆出口大国,其出口量居世界首位。1929年大豆出口量达到170万t,占当时世界大豆出口量的85％-90％。改革开放以后,中国有大豆出口,1985年曾达到114万t。然而进入1992年以后,我国大豆出口量开始减少,到1996年出口量下降为 19.2万t,且大豆进出口贸易发生逆转,出现了进口量大于     

进出口脱皮花生涉税归类鉴定快速检测方法

建立脱皮花生涉税归类鉴定的快速检测方法——过氧化氢酶和过氧化物酶活性测定法。以pH 7.7的磷酸盐缓冲液提取花生中的过氧化氢酶,加入过氧化氢溶液后30℃水浴15 min,以0.1 mol/L高锰酸钾标准滴定溶液滴定剩余过氧化氢,通过高锰酸钾耗液量计算过氧化氢酶活动度;以pH 7.0的磷酸盐缓冲液提取花生中的过氧化物酶,25℃孵育30 min,加入愈创木酚和过氧化氢,在436 nm波长下,测定初始时和2 min后的吸光度值,计算两者之差ΔA,计算过氧化物酶活力。分别对鲜花生、出口生花生、干燥脱皮花生以及150℃烘烤30 min出口生花生和干燥脱皮花生进行过氧化氢酶和过氧化物酶活性测定。对数据做方差分析,结果有显著性差异。鲜花生中2种酶活性最高,经干燥后活性降低,150℃烘烤30 min后,2种酶失去活性。     

除膻菌株分离鉴定及其对膻味脂肪酸降解能力的研究

为了分离筛选出能作用于膻味脂肪酸的微生物,从火腿和土壤中分离出11株菌,这11株菌均能对羊油脂进行水解。通过形态学、生理生化特征鉴定及16S rRNA基因序列和ITS基因序列分子生物学鉴定,确定为6株细菌和5株霉菌。分别将11株菌接种到加入4-甲基辛酸和4-乙基辛酸的液体培养基进行发酵,发现4-甲基辛酸的减少量达到30%～70%,4-乙基辛酸减少量达到10%～70%。这11株菌对膻味脂肪酸具有不同程度的降解作用,该研究结果可为微生物羊肉除膻提供理论基础。     

我国葡萄及其制品进出口概况及改善策略

为了解我国葡萄及其制品进出口贸易现状,对2010—2020年我国葡萄及其制品的进出口情况进行调查和分析。结果表明：近十年来,我国葡萄种植面积和产量持续增长,鲜食葡萄的出口量和出口额明显增加,但在葡萄酒及其他加工品的出口贸易方面相对薄弱。究其原因,一方面是因为我国葡萄产业存在品种结构单一、物流供应链环节脆弱等问题;另一方面葡萄及其制品自身存在质量安全、品牌知名度不高等问题,也影响了出口。针对现有情况提出优化葡萄品种和品质、助推葡萄全产业链标准化、加强深加工产业发展、打造特色优势品牌、改善进出口结构、健全完善质量管理机制等提升策略,以期为中国葡萄产业的可持续发展提供思路。     

Free fatty acids quantification in dairy products

Free fatty acids (FFA) in dairy products have experienced a resurgence of interest in recent years due to their associated health benefits, flavour potential and antimicrobial activity, as a direct cause of hydrolytic rancidity, and also because of the importance of accurate determination for quality, research and legislative purposes. Gas chromatographic analysis remains the technique of choice for FFA analysis; however, little advancements in method development have occurred over the last twenty years. The purpose of this review is to provide an overview of the methodology used to quantify FFA in dairy products by gas chromatography since its inception, to highlight some of the challenges experienced, to suggest aspects that could be improved to increase accuracy and throughput and reduce labour costs and solvent usage and to widen applications.     

烟叶多元酸和高级脂肪酸分析及其对感官品质的影响

为明确湖南烟区烟叶原料多元酸和高级脂肪酸含量及其与感官品质的关系,采用非衍生化方法的气相色谱法对湖南烟区3个区县,不同部位的7种烟叶样品的多元酸和高级脂肪酸含量进行检测,发现7种烟叶原料,多元酸中丙酸含量最高,其次是3-甲基戊酸和2-甲基丁酸,高级脂肪酸中十六酸含量最高,再次是亚油酸和油酸;同时发现,这些多元酸和高级脂肪酸在上部烟叶中的含量高于中部烟叶;采用偏最小二乘回归分析(PLSR)方法对烟叶中多元酸和高级脂肪酸含量与感官品质相关性进行了分析。结果表明,多元酸含量越高,提香越明显,口腔刺激感越低且透发性越强,而高级脂肪酸仅仅可以提高烟叶抽吸劲头,但不利于其他感官指标。     

Effectiveness of fatty acids and their monoglycerides against gram-negative pathogens

The effectiveness of lauric, myristic and palmitic acids and their monoglycerides against Escherichia coli O157:H7, Yersinia enterocolitica and Salmonella sp. A total of 20 ppm of myristic and palmitic acids and their monolgycerides showed a promising bioactivity (60–80%) against E. coli O157:H7 within 10–24 h; 50 ppm of monolaurin inhibited Y. enterocolitica and E. coli O157:H7 by >90% of control for 96 h; otherwise, 40 ppm of monolaurin and 30–50 ppm of lauric acid reduced Y. enterocolitica growth by >65% of control. The effect of lauric acid and its monoglyceride against Salmonella spp. was moderate (inhibition of approximately 30%). The results of this paper suggested some interesting ideas: the same compound could exert an inhibition or a stimulation of microbial growth; moreover, the studied compounds seemed to act in a reversible manner, as the inhibition of micro-organism was quite strong within the first 10–24 h and decreased for a prolonged incubation.     

Conjugated fatty acids in food and their health benefits

Conjugated fatty acids (CFAs) are a mixture of positional and geometric isomers of polyunsaturated fatty acids with conjugated double bonds. Reports indicate that CFAs have potent beneficial effects, including antitumor, antiobese, antiatherogenic and antidiabetic activities. The molecules have also been shown to prevent the onset of hypertension. Recent reports suggest that each CFA isomer has different functions, for example the 10trans,12cis isomer of conjugated linoleic acid (CLA) has anticarcinogenic, antiobese and antidiabetic effects, whereas the 9cis,11trans-CLA isomer exerts an anticancer effect. Although it would be interesting to know the effects of CFAs on humans, there are only few reports concerning the anticancer and antiobese effects of CLA in humans. More detailed evaluations of the physiological bioactivities of CFA isomers on lifestyle-related diseases in humans and animals will be of great interest in future studies.     

螺旋藻产品脂肪酸GC指纹图谱分析方法的研究

该实验选取了10个不同品牌的螺旋藻产品,采用气相色谱法对螺旋藻产品脂肪酸指纹图谱进行了研究。结果表明,通过对螺旋藻产品脂肪的提取并进行甲酯化反应,添加内标后采用气相色谱法测定其脂肪酸组成,可用于绘制螺旋藻产品脂肪酸指纹图谱。指纹图谱可以从量的角度比较多个品牌产品脂肪酸特征组分的差异,其中生物活性物质γ-亚麻酸含量在12.3%～23.0%,相对差值高达61%。所建立的螺旋藻产品脂肪酸指纹图谱具有重复性和稳定性,可用于评价螺旋藻相关产品的质量。     

Trans fatty acids content and fatty acid profiles in the selected food products from Korea between 2005 and 2008

Since a high intake of trans fatty acids (TFA) has been associated with the increased risk of developing cardiovascular disease, food regulation worldwide has been amended with respect to nutrition labeling and health claims on TFA. In the present study, the TFA levels of Korean food products were investigated to assess the regulation effect of TFA labeling. Same Korean food products within 7 different categories were purchased in years 2005 and 2008, and the contents of TFA and lipid and fatty acid composition were investigated. Lipid and TFA contents decreased in all food products manufactured in 2008. TFA levels were 0.01 to 6.88 g/100 g food in 2005, but the levels remarkably decreased to nondetectable level or up to 0.5 g TFA/100 g food in 2008. The foods from 2005 contained a various level of TFA ranging 0.6% to 44.6% of total fatty acids; however, the TFA level significantly decreased in most foods up to 3.8% from year 2008. For TFAs, trans C18:1 levels were greater than trans isomers of C18:2, and the levels in 2005 were significantly reduced in 2008 (P < 0.05). TFA levels at the sn-2 position were up to 48.3% of total fatty acids in 2005, but the level considerably decreased up to 5.4% in 2008. The considerably decreased content of TFA in 2008 suggested that food manufacturers recognized the adverse effect of TFA on human health and followed the compulsory trans fat labeling rule by Korean Food and Drug Administration (KFDA), which started December 2007.     

支链脂肪酸及其抗炎作用研究进展

支链脂肪酸主要是饱和脂肪酸,在其碳骨架上有1个或多个支链,支链以甲基最为常见。特殊的支链结构和饱和状态使支链脂肪酸具有独特的理化性质。支链脂肪酸与炎症关系密切,目前我国对于支链脂肪酸的研究大多还集中于牛羊类反刍动物的乳汁、肉制品上,对于与人类相关支链脂肪酸的研究还很少。综述了支链脂肪酸的结构及其分布特征,总结了支链脂肪酸的主要生理功能与机制,探究了人乳、喂养方式、新生儿坏死性小肠结肠炎与支链脂肪酸的关系。提出开发支链脂肪酸作为孕妇的膳食补充剂,或以支链脂肪酸为原料发展新型抗癌药是未来的研究方向。     

不饱和脂肪酸自动氧化形成反式脂肪酸机理研究进展

食用油热加工过程中由其不饱和脂肪酸异构化产生的反式脂肪酸 (TFAs) 对人体健康存在风险,有效控制TFAs的形成,对提升食品安全水平具有重要意义。以前研究者们重点关注的是油脂不完全氢化形成TFAs机理研究,而无需催化剂条件下油脂中不饱和脂肪酸热致异构化机理和氢化机理完全不同。而近年来油脂热处理过程中关注最多的顺反异构主要集中在C=C上的异构现象,因此,本文将着重总结不饱和脂肪酸自动氧化形成反式脂肪酸机理,旨在为为高脂食品中反式脂肪酸形成抑制作用研究提供理论基础和科学依据。     

常见食用植物油中特征性脂肪酸的检测及鉴别

目的分析常见市售植物油中特征性脂肪酸构成及含量范围,并探讨在此基础上如何综合利用上述指标对常见植物油进行定性鉴别。方法从6个城市采集9个品种125份样品,每种两个批次。按照GB/T 22223—2008方法测定46种脂肪酸,分析植物油中的特征脂肪酸及其构成。结果菜籽油中的特征脂肪酸为芥酸;花生油中为C20∶0、C24∶0和C22∶0脂肪酸;茶油中的油酸含量高达75.45 g/100 g,是其特征脂肪酸;亚麻籽油的特征脂肪酸为α-亚麻酸;葵花籽油的特征脂肪酸为亚油酸;稻米油中棕榈酸含量范围为15.13～16.37 g/100 g,可以此作为其特征进行鉴别;大豆油中n6/n3比值最接近中国营养学会推荐比值;芝麻油中油酸和亚油酸的总含量及棕榈酸和硬脂酸含量的组成特征比较稳定,可以此作为芝麻油的鉴别依据;玉米油中脂肪酸特征不明显。结论结合单体特征脂肪酸、脂肪酸构成以及n6/n3比值分析可达到常见植物油定性检测的目的。