乳酸菌源共轭亚麻酸的分离制备

乳酸菌发酵产生的共轭亚麻酸(CLNA)在慢性疾病中有重要的生理功能,CLNA由多种异构体组成,各种异构体的生理功能存在差异。建立了分离制备乳酸菌发酵液中游离态CLNA异构体的方法,成功获得了结构单一的CLNA异构体。结果表明:在现有条件下乳酸菌源CLNA单一异构体无法通过薄层色谱法分离;高效液相色谱法可实现乳酸菌源CLNA单一异构体的分离,最优分离制备条件为高效液相色谱柱Ultimate(5XB-C30,4. 6 mm×250 mm)、流动相甲醇-水-甲酸(体积比70∶30∶0. 01)、流速1 m L/min、检测紫外波长205 nm和233 nm。在最优分离制备条件下,保留时间和峰面积的相对标准偏差分别为0. 05%～0. 38%、1. 88%～4. 65%,制备得到的CLNA1纯度为97. 48%,CLNA2的纯度为100%,CLNA3的纯度为65. 30%。该方法重复性好,分离度高,适合分离乳酸菌发酵液中游离形式CLNA。     

生物转化共轭亚麻酸植物乳杆菌的筛选及特性研究

共轭亚麻酸(conjugated linolenic acid,CLNA)是一类具有抗癌、降脂减肥、抗炎等生理功能的活性物质,为了得到高产或具有生物转化CLNA性能的生物合成体系,采用GC-MS分析方法检测了31株不同来源的植物乳杆菌的脂肪酸组成,筛选得到8种可以高效转化亚麻酸至共轭亚麻酸的菌株。基于GC-MS分析结果,对其中1株高产共轭亚麻酸的植物乳杆菌CCFM261的转化特性进行了研究。结果表明,植物乳杆菌CCFM261对亚麻酸的转化率高于50%,所得产物存在3种异构体(CLNA1,CLNA2,CLNA3),大部分以游离脂肪酸的形式存在于发酵液中,总含量可达到0.186 0 mg/m L。菌体中也积累了一定量的结合状态的CLNA。产物以CLNA1和CLNA2为主,比例约为2∶1,占总共轭亚麻酸含量的90%以上。经质谱数据分析,确定CLNA1和CLNA2分别为生物活性较高的c9,t11,c15-CLNA和t9,t11,c15-CLNA。     

泡菜中生物转化共轭脂肪酸的植物乳杆菌

共轭脂肪酸是指一类含共轭双键的多不饱和脂肪酸的总称,包括共轭亚油酸(conjugated linoleic acid,CLA),共轭亚麻酸(conjugated linolenic acid,CLNA)和共轭十八碳四烯酸(conjugated stearidonic acid,CSA)。CLA和CLNA分别是由亚油酸和亚麻酸衍生所得的多种位置与几何异构体的总称,具有多种生理功能,如抗癌、抗动脉粥样硬化、提高机体免疫力和减肥等,已成为功能性脂质的研究热点。采用GC-MS(gas chromatographymass spectrometry)法分析了筛选自泡菜的22株植物乳杆菌转化共轭脂肪酸的能力。结果显示,CCFM47和CCFM232两株菌具有极高的共轭亚油酸和共轭亚麻酸转化能力,其中亚油酸的转化率均超过30%,发酵液中CLA总浓度分别达到0.166 4 mg/ L和0.151 4 mg/mL,而对α-亚麻酸的转化率高达60%,发酵液中CLNA总浓度分别达到0.196 4 mg/mL和0.172 1 mg/mL。     

生物转化法生产共轭亚油酸及其研究进展

共轭亚油酸（CLA）是一种具有多种重要生理功能的天然脂肪酸，具有抗癌、抗动脉粥样硬化、抗糖尿病、调节免疫等多种功能。论述了利用生物转化法合成共轭亚油酸的生产菌株、培养条件和培养模式以及利用基因工程等菌株改良手段以提高生产效率的国内外研究进展；并简述了生物法工业化生产共轭亚油酸的前景。     

葱属植物生物活性物质的研究进展

葱属植物含有含硫化合物、甾体皂苷、黄酮类化合物和多糖等活性物质,具有多种生理功能,如抑菌消炎、抗血小板聚集、抗氧化、降低胆固醇、抗肿瘤和缓解糖尿病等作用。本文综述了葱属植物中的生物活性物质及其生理功能的研究进展。     

蛋黄不饱和脂肪酸的生理功能的研究进展

蛋黄因其独特而丰富的营养特性而备受关注,不饱和脂肪酸又由于具有预防糖尿病、抗炎症、抗氧化性等生理功能而受到各国研究者的重视,蛋黄中的不饱和脂肪酸已经成为食品领域的研究热点。该文就蛋黄中单不饱和脂肪酸(MUFAs)和多不饱和脂肪酸(PUFAs)的生理功能进行综述,阐述蛋黄不饱和脂肪酸具有提高视力和保护精子质量等生理功能,以期使蛋黄不饱和脂肪酸在医疗、保健和食品中得到更广泛的应用,并为相关领域研究者提供参考。     

新型功能性天然色素-茶色素

茶色素是茶叶中提取得到的一种天然色素,具有清除自由基和抗氧化作用,防癌抗癌、防紫外线照射、抗动脉粥样硬化、抗龋护齿等多种药理功能。本文综述了茶色素的生理功能、制备及应用方面的研究进展。     

功能性配料——共轭亚油酸的研究进展

共轭亚油酸(CLA)作为一种新资源食品,因具有抗癌、减肥、抗动脉粥样硬化等众多生理功能,已成为近几年的研究热点。对共轭亚油酸(CLA)的来源、生理功能、制备及分析检测方法进行综述,并对其研究中存在的问题和应用进行探讨和展望。     

共轭亚油酸的生理功能（Ⅱ）

共轭亚油酸是亚油酸的立体和位置异构体的混合物。动物实验表明,共轭亚油酸是一种很强的抗癌物质,具有抗动脉粥样化形成、抗糖尿病、抗过敏、调节免疫、促进生长、降低身体脂肪并增加瘦肉量及影响骨骼形成等生理功能。     

苦荞麦中的抗营养因子及生理功能

以往在营养学领域主要的研究课题都是如何防止营养缺乏。然而,随着生活条件的提高,营养缺乏逐渐减少,反而出现由于营养过剩引起的诸多疾病如肥胖、糖尿病等,因此不得不使营养学领域对营养进行重新评价。抗营养学领域又兴起一股抗营养因子的研究热潮,而苦荞麦中的抗消化淀粉和抗消化蛋白所具有的生理功能也引起了人们越来越多的关注。     

Bacterial Production of Conjugated Linoleic and Linolenic Acid in Foods: A Technological Challenge

Conjugated linoleic acid (CLA) and conjugated linolenic acid (CLNA) isomers are present in foods derived from ruminants as a result of the respective linoleic acid (LA) and α-linolenic acid (LNA) metabolism by ruminal microorganisms and in animals’ tissues. CLA and CLNA have isomer-specific, health-promoting properties, including anticarcinogenic, antiatherogenic, anti-inflammatory, and antidiabetic activity, as well as the ability to reduce body fat. Besides ruminal microorganisms, such as Butyrivibrio fibrisolvens, many food-grade bacteria, such as bifidobacteria, lactic acid bacteria (LAB), and propionibacteria, are able to convert LA and LNA to CLA and CLNA, respectively. Linoleate isomerase activity, responsible for this conversion, is strain-dependent and probably related to the ability of the producer strain to tolerate the toxic effects of LA and LNA. Since natural concentrations of CLA and CLNA in ruminal food products are relatively low to exert their health benefits, food-grade bacteria with linoleate isomerase activity could be used as starter or adjunct cultures to develop functional fermented dairy and meat products with increased levels of CLA and CLNA or included in fermented products as probiotic cultures. However, results obtained so far are below expectations due to technological bottlenecks. More research is needed to assess if bacterial production kinetics can be increased and can match food processing requirements.     

Evidences and perspectives in the utilization of CLNA isomers as bioactive compounds in foods

Conjugated alpha linolenic acid (CLNA) isomers are promising lipids owing to their similarities with conjugated linoleic acid (CLA) but exerting their bioactivity at lower doses; some isomers also belong to omega 3 family. This review aims to summarize the state of the art about the utilization of CLNA as a functional ingredient. Indeed, in vitro and in vivo studies reported that CLNA exerted anticancer, anti-inflammatory, anti-obese, and antioxidant activities. However, CLNA has not been tested in humans. These compounds are naturally present in meat and milk fat from ruminants but the highest concentrations are found in vegetable oils. Their incorporation in foodstuffs is one of the most effective strategies to elaborate CLNA-enriched products together with the microbiological production. Lactobacilli, propionibacteria, and bifidobacteria strains have been assayed to produce CLNA isomers but at the current moment there are not high CLNA concentration products elaborated using these strains. Furthermore, it is known that CLNA isomers are highly prone to oxidation when compared with linoleic acid and CLA, but the possible effects of elaboration and storage on high CLNA productsare unknown.The utilization of CLNA as a functional compound still remains a challenge and requires more research to address all of its technological and bioactivity aspects.     

A NEW METHOD FOR ELLAGIC ACID PRODUCTION FROM POMEGRANATE HUSK

Pomegranate ( Punica granatum L.) husk, a by-product of the pomegranate juice industry, is an inexpensive and abundant source of ellagic acid. Ellagic acid is widely used as functional food for its physiological functions. It is the breakdown product of ellagitannins. To date, the preparation of ellagic acid from pomegranate husk has not been reported. This article reports a new process for ellagic acid production from pomegranate husk by extraction of tannins followed by acid hydrolysis and purification by extraction and recrystallization. Several tests were conducted to obtain optimum conditions including extraction of tannins by varying solvents, acid concentration and reaction time for acid hydrolysis and the volume of methanol used for purification. Ellagic acid (3.5 g) with 90% purity from 100 g pomegranate husk was obtained. This new method is easy to scale up. All equipment used in this production process is widely used in food processing industry. The cost of production is low. It is suitable for industrial applications.

PRACTICAL APPLICATIONS

The production of ellagic acid is easier and the yield and purity of ellagic acid produced this way are higher than before. This method can be used not only for experiment in laboratory but also for industrial applications. The material – pomegranate husk – is a by-product of the pomegranate juice industry, so it is very cheap and easy to get. High-purity ellagic acid produced this way is sold to many companies back home and abroad. It is used as food additive and cosmetic material because of its antioxidant activity and whiteningfunction. The toxicity of pomegranate husk is lower than that of gallnut, which has been the main material of ellagic acid production in the past. Reagents are common and inexpensive; some of them are reusable.     

类黑精研究进展

该文叙述类黑精的特性、制备、提取,重点阐述类黑精抗氧化、抗肿瘤、抗菌、类似食物纤维等生理活性。     

Omega-3脂肪酸磷脂制备方法综述

Omega-3脂肪酸磷脂生理功能明确,生物利用度高,在医药、保健品领域具有巨大的市场潜力,其制备方法是全球磷脂研究开发的新动向。综述了目前Omega-3脂肪酸磷脂的制备方法,包括天然提取法、酶促转化法、化学合成法及微生物发酵法。天然提取法是最早获得Omega-3脂肪酸磷脂产品的方法,主要包括溶剂萃取法、膜分离法、柱层析法和盐沉淀法;酶促转化法主要包括酶促酯交换法和酶促酯化法,是目前Omega-3脂肪酸磷脂合成效率最高、最常用的方法;化学合成法及微生物发酵法处于初步研究阶段,为Omega-3脂肪酸磷脂的制备提供了新的思路。     

超声辅助提取紫薯花青素的研究进展

花青素作为紫薯的主要生物活性物质, 具有抗氧化、预防癌症、预防心血管疾病、保护肝脏、保护大脑、降血糖血脂和阻止脂肪积累以及消除炎症等生理功能, 对于改善记忆力和抑菌也有很好的功效。我国是紫薯的生产大国、资源丰富, 从紫薯中提取花青素降低了花青素的提取成本。超声是一种非热加工的提取技术, 具有节能、省时、高效等诸多优点, 在提取植物花青素的领域越来越受欢迎。本文综述了超声辅助提取紫薯花青素的几种方法及其最新研究进展, 包括超声辅助溶剂法、超声辅助酶法、超声-微波协同法、超声辅助冻结-融解法、超声辅助双水相法, 以期为超声辅助提取紫薯花青素领域的科研工作提供理论参考。     

气相色谱法在农药残留分析中的应用

固相萃取是目前常用的一种样品预处理方法, 它具有高效、快速、方便和高选择性等特点.气相色谱是农药和药物残留分析中应用最多的分析检测方法,固相萃取和气相色谱的联用实现了样品前处理及分离分析的优化组合.综述了固相萃取和气相色谱联用技术在农药残留分析中的应用.     

米糠油制取及掺伪鉴别技术的研究现状

作为一种新型食用油,米糠油营养价值高、口感好,受到消费者的青睐。介绍了米糠油的组成和功能性成分,综述了米糠油的物理压榨法、化学溶剂浸出法、超临界流体萃取法和水酶法等提取方法以及脱胶、脱酸和脱色关键精炼方法,归纳了目前植物油掺伪鉴别的主要技术和米糠油掺伪鉴别的研究现状,旨在为米糠油的提取、精炼工艺和掺伪鉴别提供参考。     

Evaluation of a simple and promising method for extraction of antioxidants from sea buckthorn (Hippophaë rhamnoides L.) berries: Pressurised solvent-free microwave assisted extraction

The pressurised solvent-free microwave assisted extraction (PSFME) technique has been developed and optimised for extraction of antioxidants from Hippophaë rhamnoides L. berries using a two-level full factorial design. The effects of factors (extraction time, irradiation power, number of cycles) and their first order interactions were evaluated from antioxidant activity of extracts using the 2,2′-diphenyl-1-picrylhydrazil (DPPH) free radical scavenging method, the ferric reducing ability of plasma (FRAP) assay, and the estimation of total phenolic content using the Folin–Ciocalteu method. The best extraction conditions were obtained, in a laboratory scale extractor of 50 mL filled with 4 g fresh berries, using a 1000 W microwave power applied during 50 s and repeated five cycles. PSFME was then compared to other common extraction techniques such as pressing, maceration and pressurised liquid extraction. It is appeared that PSFME leads to the most active and richest extract in phenolic content including molecules such as quercetin and isorhamnetin not extracted with other techniques. Furthermore PSFME respect green chemistry, it is rapid, cheap and does not need sample preparation and/or evaporation step.