气相色谱法测定乳制品中共轭亚油酸的含量

共轭亚油酸（CLA）作为一种新型的功能性脂肪酸，其主要存在于瘤胃动物的乳和肉的脂肪中。CLA在乳制品中的含量受加工方式、贮藏等多种因素的影响。本文采用毛细管气相色谱法分析不同加工方法的各种乳制品中共轭亚油酸的含量，结果发现经发酵加工的乳制品中共轭亚油酸的含量明显高于未加工的原料乳，被测乳制品中以9c，11t结构的CLA含量为主，加工后的乳制品其反式CLA的含量都有所增加。     

牛乳中共轭亚油酸（CLA）的研究

共轭亚油酸（CLA）是亚油酸的同分异构体的混合物,主要来源于牛乳、乳制品及反刍物食品的天然成分。本文就CLA的抑癌和降血脂等多种生理功能及其作用机理,阐述了CAL作为一种新型营养物质的潜力。     

共轭亚油酸在液态乳制品中的应用研究

本文研究了在液态乳制品中添加不同含量的共轭亚油酸(Conjugated linoleic Acid，CLA)及不同的CLA产品形式(CLA，CLA乙酯,CLA甘油三酯)后对产品感官品质(可接受度)的影响，并对CLA的贮藏稳定性进行了研究。研究结果表明，当CLA的添加量超过1‰时，产品即有一种CLA特有的涩味，比较难以让人接受；当使用CLA甘油三酯时，对产品的感官品质没有影响，反而使得产品更加滑爽，脂肪香味更浓；CLA甘油三酯在贮藏过程中具有良好的稳定性。     

酸奶中共轭亚油酸的强化

比较了3种不同形式的共轭亚油酸(CLA)对酸奶的感官可接受性、pH值、滴定酸度和保水性的影响,并研究了CLA在酸奶中的稳定性.结果表明:酸奶中添加质量分数0.3%的共轭亚油酸甘油酯(CLA-TG)感官可接受性较好.添加3种不同形式的CLA对牛乳中保加利亚乳杆菌、嗜热链球菌的生长和发酵及酸奶的保水性没有影响,CLA在酸奶中稳定性良好.     

共轭亚油酸的生理功能及提高其在乳制品中含量的途径

概述共轭亚油酸(CLA)的生理功能,及提高其在乳制品中CLA的途径,如选育高产CLA的动物品种、研发新饲料、控制和改进加工条件等.     

牛奶中共轭亚油酸含量的紫外分光光度测定方法

研究了牛乳中共轭亚油酸含量的紫外分光光度测定方法。利用紫外分光光度计,先建立标准曲线与回归公式,再将牛奶样品提取、甲酯化后,进行紫外检测。结果表明,共轭亚油酸甲酯的最大吸收波长是234nm;共轭亚油酸浓度的有效测定范围是0.00856-0.0428mg/mL;吸光度与共轭亚油酸浓度间的回归公式为Y=52.602X+0.0917（R2=0.9862）;得出共轭亚油酸浓度与吸光度之间的经验公式为:共轭亚油酸浓度C（mg/mL）=0.019×吸光度（ABS）;并且推出了利用紫外分光光度法测定牛奶中共轭亚油酸含量的计算公式。同时,检验了几种市售牛奶中共轭亚油酸,其平均含量为1.64mg/g。      

牛奶中共轭亚油酸含量的紫外分光光度测定方法

研究了牛乳中共轭亚油酸含量的紫外分光光度测定方法。利用紫外分光光度计,先建立标准曲线与回归公式,再将牛奶样品提取、甲酯化后,进行紫外检测。结果表明,共轭亚油酸甲酯的最大吸收波长是234nm;共轭亚油酸浓度的有效测定范围是0.00856-0.0428mg/mL;吸光度与共轭亚油酸浓度间的回归公式为Y=52.602X 0.0917(R2=0.9862);得出共轭亚油酸浓度与吸光度之间的经验公式为:共轭亚油酸浓度C(mg/mL)=0.019×吸光度(ABS);并且推出了利用紫外分光光度法测定牛奶中共轭亚油酸含量的计算公式。同时,检验了几种市售牛奶中共轭亚油酸,其平均含量为1.64mg/g。     

葵花籽油制备共轭亚油酸中共轭条件的研究

葵花籽油混合无水乙醇,通过酶催化得到亚油酸乙酯,以亚油酸乙酯为原料,采用无溶剂碱催化共轭化得到共轭亚油酸乙酯,经皂化酸化得到共轭亚油酸。通过单因素试验得到共轭化过程中最优的反应条件,即反应温度140℃,催化剂用量6%,反应时间2 h。并对共轭亚油酸的含量进行检测,在最优条件下共轭亚油酸C18:2(9c,11t和10t,12c)异构体含量达到63.03%,共轭化转化率97.82%。     

提高水牛奶中共轭亚油酸含量的菌种筛选

在水牛奶中分别添加不同的菌种进行发酵,通过溶剂法提取发酵乳中的脂肪,采用BF3/甲醇对脂肪酸进行甲酯化,使用紫外分光光度法与气相色谱法相结合进行发酵乳中共轭亚油酸的含量测定。结果显示,经单一菌种发酵的水牛奶其共轭亚油酸(CLA)的含量均有一定的提高,其中德式乳杆菌保加利亚亚种的转换能力相对最高。     

瘤胃内共轭亚油酸(CLA)的形成

对瘤胃内共轭亚油酸（CLA）的形成机制、参与氢化的微生物及影响氢化的因素进行了综述，并对如何提高牛乳中CLA含量进行简要概述。     

π-Complex formation of conjugated linoleic acid with iron

Conjugated linoleic acid (CLA) is known to have several beneficial biological effects in animal models, including anticarcinogenic and antiatherosclerotic effects, antiobesity, and antioxidant activity. However, reports of its antioxidant activities have been inconsistent. In this study, we investigated the possible occurrence of π-bonding between CLA and iron. CLA methyl ester was reacted with triiron dodecacarbonyl and confirmed to form π-complexes with iron tricarbonyl. This study may suggest the possible involvement of CLA in oxidation by way of interacting with iron.     

Effects of conjugated linoleic acid on color and lipid oxidation of beef patties during cold storage

The effects of conjugated linoleic acid (CLA) on color and lipid oxidation of beef patties were investigated. Ground beef was divided into three batches. The control patties were prepared with 90% lean meat and 10% tallow. The second treatment consisted of 90% lean meat with 9.5% tallow+0.5% CLA sources. The third treatment consisted of 90% lean meat with 8% tallow+2% CLA sources. The patties were wrap-packaged and then stored at 4° for 14 days. The CLA concentration significantly increased (P<0.05) by substituting CLA sources for fat. Storage of the patties did not alter the CLA concentration in beef patties. The treatment substituted with CLA sources had significantly lower TBARS (2-thiobarbituric acid-reactive substances) values (P<0.05) than the control. For oxymyoglobin contents and a* value, substituted CLA sources treatments had significantly higher values than the control. However, L* value significantly increased by substituting CLA sources for fat.     

Volatile oxidation compounds in a conjugated linoleic acid-rich oil

In this study, volatile oxidation compounds formed in a commercial conjugated linoleic acid (CLA)-rich oil were quantified and results compared to those found in safflower oil (rich in linoleic acid, LA). Intact oil samples and pure triacylglycerols obtained following elimination of tocopherols and minor compounds were oxidised at 60 °C, and volatile oxidation compounds were analysed by solid phase microextraction-gas chromatography with flame ionisation detector and mass spectrometer. Results showed that while, as expected, hexanal was the major volatile oxidation compound found in oil and triacylglycerols rich in LA, both hexanal and heptanal equally were the most abundant compounds in oil and triacylglycerols rich in CLA. Besides, samples rich in CLA also showed significantly high quantities of trans-2-octenal and trans-2-nonenal and the latter, along with heptanal, were absent in samples rich in LA. Results for CLA samples were not easy to interpret since major volatiles found are not expected from theoretically stable hydroperoxides formed in CLA and could in part derive from dioxetanes coming from 1,2-cycloadditions of CLA with oxygen. Overall, results obtained support evidence that oxidation mechanisms of CLA may differ than those of LA. Also, it was concluded that heptanal determination could serve as a useful marker of oxidation progress in CLA-rich oils.     

Chemical characteristics,fatty acid composition and conjugated linoleic acid (CLA) content of traditional Greek yogurts

Many studies with conjugated linoleic acid (CLA) indicate that it has a protective effect against mammary cancer. Because dairy products are the most important dietary sources of CLA, we have investigated the CLA concentrations and additionally the fatty acid profiles and chemical composition of several commercial, traditional, Greek yogurts from different geographical origin. The fat content of yogurts was in the order of goat < cow < sheep. Cow, sheep and goat milk yogurts contain respectively 0.128–1.501, 0.405–1.250 and 0.433–0.976 g CLA/100 g fat. Low-fat milk yogurts showed lower values of c-9, t-11 CLA content on lipid basis compared to full-fat yogurts. Samples from mountain areas showed average c-9, t-11 CLA content higher than those from prairie districts. The highest amounts of saturated fatty acids (SFA) were found in low-fat yogurts, of monounsaturated fatty acids (MUFA) in sheep milk yogurts and of polyunsaturated fatty acid (PUFA) in low-fat cow milk yogurts.     

Production of bioactive substances by intestinal bacteria as a basis for explaining probiotic mechanisms: bacteriocins and conjugated linoleic acid

The mechanisms by which intestinal bacteria achieve their associated health benefits can be complex and multifaceted. In this respect, the diverse microbial composition of the human gastrointestinal tract (GIT) provides an almost unlimited potential source of bioactive substances (pharmabiotics) which can directly or indirectly affect human health. Bacteriocins and fatty acids are just two examples of pharmabiotic substances which may contribute to probiotic functionality within the mammalian GIT. Bacteriocin production is believed to confer producing strains with a competitive advantage within complex microbial environments as a consequence of their associated antimicrobial activity. This has the potential to enable the establishment and prevalence of producing strains as well as directly inhibiting pathogens within the GIT. Consequently, these antimicrobial peptides and the associated intestinal producing strains may be exploited to beneficially influence microbial populations. Intestinal bacteria are also known to produce a diverse array of health-promoting fatty acids. Indeed, certain strains of intestinal bifidobacteria have been shown to produce conjugated linoleic acid (CLA), a fatty acid which has been associated with a variety of systemic health-promoting effects. Recently, the ability to modulate the fatty acid composition of the liver and adipose tissue of the host upon oral administration of CLA-producing bifidobacteria and lactobacilli was demonstrated in a murine model. Importantly, this implies a potential therapeutic role for probiotics in the treatment of certain metabolic and immunoinflammatory disorders. Such examples serve to highlight the potential contribution of pharmabiotic production to probiotic functionality in relation to human health maintenance.     

蓖麻酸(酯)合成共轭亚油酸研究进展

蓖麻酸(酯)是蓖麻油的最主要成分,其结构决定了它很容易转变成共轭亚油酸(CLA).综述了由蓖麻酸(酯)合成CLA的研究进展,并对CLA的合成发展进行了展望,以期为CLA的高效合成提供参考.     

共轭亚油酸的分析鉴定方法

共轭亚油酸因其在实验动物身上表现出一系列令人振奋的特性，则引起了药品和食品等领域的广泛关注。近年来，在其生理特性、合成转化以及分析鉴定等领域都取得了一定的进展。文章介绍了应用于共轭亚油酸的几种分析鉴定方法。     

Systematic evaluation on the effectiveness of conjugated linoleic acid in human health

The term CLA (conjugated linoleic acid) corresponds to a mixture of positional and geometric isomers of linoleic acid. Two of these isomers (9c, 11t and 10t, 12c) have biological activity. The milk and dairy products are the most abundant source of conjugated linoleic acid, which refers to a group of positional and geometric isomers of CLA (CLA 18:2 cis-9, cis-12). The following research aims to approach aspects regarding the CLA, as well as its relationship with diseases. Conjugated linoleic acids have been studied for their beneficial effects in the prevention and treatment of many diseases, including obesity, cancer, diabetes, and cardiovascular diseases. Scientific information put together the physiological properties of CLA, which serves as inputs to claim their potential as functional ingredients to be used in the prevention and control of several chronic metabolic disorders.     

Conjugated linoleic acid in meat and meat products: A review

Conjugated linoleic acid (CLA) consists of a group of geometric and positional isomers of linoleic acid to which anticancerogenic, antidiabetic, and antiatherogenic effects, as well as effects on immune system, bone metabolism, and body composition are attributed. CLA is found predominantly in milk and meat of ruminants due to the importance of rumen micro-organism in the formation of CLA and its precursors. This review attempts to give an overview of the available data on intramuscular CLA concentrations in meat and meat products originating from different animal species. The factors influencing these concentrations are discussed and the estimated human daily intakes as well as the percentage provided by meat are reported.