LIPASE-CATALYZED ACIDOLYSIS OF CORN OIL WITH CONJUGATED LINOLEIC ACID IN HEXANE

Lipase-mediated acidolysis of corn oil with conjugated linoleic acid (CLA) was studied in hexane. The largest extent of incorporation was obtained using a weight ratio of CLA to corn oil of 1:7 (1:2.22 mole ratio). Commercial immobilized lipases from Rhizomucor miehei and Candida antarctica effectively catalyzed interesterification. Of the total acylglycerols in the products, triacylglycerols constituted >90%. For both immobilized enzymes, CLA residues were esterified mainly at the sn-1,3 positions.     

FATTY ACID COMPOSITION IN TISSUES OF MICE FED DIETS CONTAINING CONJUGATED LINOLENIC ACID AND CONJUGATED LINOLEIC ACID

The influence of 1% alpha-eleostearic acid (α-ESA, cis9,trans11,trans 13-18:3) and 1% punicic acid (PA, cis9,trans11,cis13-18:3) on fatty acid composition in mouse tissues was compared with conjugated linoleic acid (CLA, mixture of primarily cis9,trans11- and trans10,cis12-18:2) in the present study. The content (% total fatty acids) of 18:2n-6 was significantly reduced in the heart and adipose tissues, and total polyunsaturated fatty acids (PUFAs) and n-6 PUFA were significantly reduced in adipose tissue by α-ESA, PA and CLA feeding. The content of 22:6n-3 and total n-3 PUFA were significantly increased in the liver, kidney and heart by PA feeding, but not by α-ESA. In contrast to PA, supplementation with CLA significantly decreased 22:6n-3 in the liver, kidney and heart. The content of 20:4n-6 was significantly decreased in the liver and kidney by CLA feeding, but not by α-ESA and PA. The present results indicate that α-ESA, PA and CLA have differential effects on 22:6n-3 and 20:4n-6 content in mouse tissues.

PRACTICAL APPLICATIONS

Conjugated linolenic acid (CLnA), a group of octadecatrienoic acid isomers with a conjugated triene system, has been reported to exhibit favorable physiological effects, including anticancer properties and regulation of lipid metabolism. Punicic acid and alpha-eleostearic acid, two isomers of CLnA, have been shown to convert into cis 9, trans 11-18:2 in vivo . The effect of CLnA on fatty acid composition in mouse tissues was investigated in comparison with CLA mixtures in the present study. The data obtained here could provide information for the potential application of CLnA-containing seeds as functional food ingredients, a natural source of endogenously formed cis 9, trans 11-18:2 and a dietary feeding strategy to beneficially modify the fatty acid composition of animal tissues.     

共轭亚油酸的功能性质及安全性评价

介绍了共轭亚油酸及其对健康的益处，综述了共轭亚油酸对动物和人体机体组成影响的研究进展，并讨论了共轭亚油酸添加物的安全性问题。研究认为，共轭亚油酸对健康和机体组成等均具有较好的作用，但人体服用共轭亚油酸的安全性问题有待进一步的研究。     

功能性油脂共轭亚油酸及其在食品工业中的应用

作为一种新型功能性油脂，共轭亚油酸由于具有抑癌、减肥、抗动脉硬化、提高免疫力等多种有益作用．在国际上越来越受关注。本文分别从其来源、生理功能及其在食品工业上的应用等方面进行综述。     

CONJUGATED LINOLEIC ACID CONCENTRATIONS IN COOKED BEEF CONTAINING ANTIOXIDANTS AND HYDROGEN DONORS

Conjugated linoleic acid (CLA) is a potential anticarcinogenic compound found in beef. The ability of antioxidants and hydrogen donors to influence CLA concentrations in ground beef during cooking (broiled, 80C) and storage was determined. Addition of food additives such as carnosine, cysteine, ascorbate, whey protein concentrate or beef plasma to ground beef did not result in any significant increases or decreases in CLA concentrations in freshly cooked beef. Additives which inhibited formation of thiobarbituric acid reactive substances in stored meat including 2.0% WPC, 0.5 and 2% beef plasma, ascorbate (0.5%) and carnosine (0.5%) were not any more effective at increasing or decreasing total CLA concentrations than additives which did not inhibit lipid oxidation during storage (0.5% WPC and 0.5% cysteine). Lack of changes in CLA in the presence of antioxidants suggests that these additives could be used to inhibit flavor deterioration of cooked beef products without decreasing CLA concentrations.     

天然活性物质共轭亚油酸的化学合成与生物转化

介绍了近年来在共轭亚油酸的化学合成及生物转化领域中取得的进展，并做了简要评述。     

共轭亚油酸生物合成的研究

共轭亚油酸是80年代末才被发现的一种具有多种生理功能的天然不饱和脂肪酸，具有抗癌、抗动脉粥样硬化、减肥、促进生长、缓和免疫反应副作用等许多重要生理功能，在医药、食品、保健品、化妆品等中具有广阔的应用前景。目前，工业化生产共轭亚油酸的方法是碱并构化法，但共轭亚油酸的生物合成法是未来的发展趋势。本文对近年来共轭亚油酸生物合成方面的研究进展进行了综述。     

EFFECTS OF CONJUGATED LINOLEIC ACID ISOMERS ON SERUM TUMOR NECROSIS FACTOR-A CONCENTRATION IN MICE

In previously studies, we showed that tumor necrosis factor‐α (TNF‐α), a cytokine involved in a variety of biologically important events, is partially involved in the effects of conjugated linoleic acid (CLA). In this report, we further tested the effects of individual CLA isomers on serum TNF‐α concentration along with other biological markers in mice. The animals were fed experimental diets (control, 0.5% CLA‐mixed isomer, 0.25% cis‐9,trans‐11 CLA or 0.25% trans‐10,cis‐12 CLA) for 5 days and were then challenged with endotoxin. Both cis‐9,trans‐11 and trans‐10,cis‐12 CLA isomers reduced serum TNF‐α levels compared to control. CLA had no effect on the other biological markers examined. These results suggest possible early involvement of CLA in immune and/or inflammatory responses, followed by reduction of body fat. Its effect on TNF‐α helps explain in part how CLA modulates other biological functions such as immune response, insulin responses, atherosclerosis and cancer.     

嗜酸乳杆菌发酵生产共轭亚油酸工艺研究

共轭亚油酸是一种具有多种生理活性的天然脂肪酸。以盐生植物紫花苜蓿的种籽油为底物，用嗜酸乳酸杆菌（Lactobacillus acidophilus）1．1854催化紫花苜蓿籽油中的亚油酸转化为共轭亚油酸。通过单因孝实验分析了发酵过程中pH、温度、预培养和苜蓿籽油的浓度对生产共轭亚油酸的影响。     

FATTY ACID COMPOSITION AND CONJUGATED LINOLEIC ACID CONTENT OF COW AND GOAT CHEESES FROM NORTHWEST ARGENTINA

ABSTRACT

In this study, we evaluated chemical characteristics, fatty acid composition and conjugated linoleic acid (CLA) content of cow and goat cheeses from Northwest Argentina. Similar chemical and fatty acid composition were determined in milk and cheese of both species. Palmitic, oleic and myristic acids were the most abundant fatty acids in dairy products. CLA level averaged 0.85 and 0.96 in milk and 0.76 and 1.04 g/100 g of fatty acids in cheese of cow and goat, respectively. Cis‐9,trans‐11 was the major isomer present in both species. Significant differences in CLA desaturase activity were observed, showing a value of 0.068 and 0.064 in milk, and 0.077 and 0.071 in cheese of cow and goats, respectively. Good nutritional properties were determined for cheeses of both species, which are fed on natural pasture during spring and summer seasons. Goat's cheese represents a higher source of CLA for human consumers than cow's cheese, offering from 156.6 to 222.6 mg/ 100 g of sample.

PRACTICAL APPLICATIONS

The present work shows the fatty acid composition and chemical characteristics of two fresh cheeses manufactured with cow and goat milk. Animals were fed on natural pasture during summer and spring seasons. It is known that pasture increases conjugated linoleic acid (CLA) concentration in milk fat, and the content in cheese is directly related to it. The CLA content of dairy products for the human consumers was analyzed, showing goat cheese with high polyunsaturated fatty acid content, including CLA. Cow and goat fresh cheese offer CLA as many ripening products of different countries, as cheddar or hard cheeses. Lipid composition of food is related to many illnesses, but some compounds are beneficial to human health. The main sources of CLA are milk and cheeses, and in Northwest of Argentina, no data are reported about it, where artisanal cheeses are consumed by the population. Therefore, the atherogenicity index was determined as well.     

气相色谱-质谱联用法分析苏尼特羔羊肉中共轭亚油酸含量

共轭亚油酸是亚油酸的一组几何和位置异构体，具有多种生理功能。作为瘤胃微生物的产物，反刍动物肉制品是共轭亚油酸异构体较丰富的天然来源，本研究利用气相色谱-质谱联用法分离测定了5月龄苏尼特羔羊肌肉和腹部脂肪中共轭亚油酸总含量，研究结果表明，背最长肌间脂肪中CLA相对百分含量平均为0．83％，腹部脂肪中CLA相对百分含量平均为0．99％。     

秋刀鱼蛋白酶解物的制备及氨基酸评价

采用正交实验法优化制备秋刀鱼蛋白酶解物的最适工艺条件，探讨了影响秋刀鱼蛋白酶水解的主要因素。实验表明，最适的酶解条件为：复合酶与风味酶之比为1：3，复合酶量为0．100g／25g鱼肉，酶解温度为50℃，酶解时间为7h。在此条件下，秋刀鱼蛋白水解度为45．5％，总游离氨基酸含量为1800．53mg／100mL。经高效液相色谱分析，在水解产物中约50％的氨基酸为具有较高营养价值的抗氧化活性氨基酸和支链氨基酸。     

VARIATION IN THE CONJUGATED LINOLEIC ACID CONTENT OF THREE TRADITIONAL GREEK CHEESES DURING A 1-YEAR PERIOD

The fat and fatty acid content of three traditional Greek cheeses were determined monthly for a period of 1 year. The analyzed cheeses, feta, graviera and manouri, are traditional Greek dairy products made exclusively or primarily from sheep milk. In all cheeses, the content of the fatty acids varies during several months, especially the conjugated linoleic acid (CLA) content of feta, graviera and manouri ranged between 0.5 and 0.9, 0.5 and 1.0 and 0.4 and 0.8 g/100 g total fatty acids, respectively. The average content of CLA in graviera and feta was similar (0.75 and 0.72 g/100 g fatty acids, respectively). On the other hand, the CLA content of manouri (0.54 g/100 g fatty acids) was less than that of the other two cheeses. In every case, the analyzed cheeses can be characterized as good or very good CLA sources.

PRACTICAL APPLICATIONS

No data exist about the variation in the fatty acid composition of standardized cheeses during the various months of the year. Several investigations were carried out in order to determine the fatty acid composition and especially the conjugated linoleic acid (CLA) content of various kinds of cheese. However, cheeses were produced from milk and it is suggested that the milk composition is affected by seasonal factors. In the present investigation, we tried to find out if the beneficial fatty acid content of cheeses, which were previously found as rich CLA sources, is season dependent. The results of this research are a potential tool for food technologist in order to provide CLA-enriched diets.