乳酸菌降胆固醇作用及其机理的研究进展

乳酸菌是一类广泛存在于人和动物体内的微生物,具有调节胃肠道健康、消除人体自由基、降低食物及人体血清中胆固醇含量等作用。文章从降胆固醇乳酸菌的筛选、乳酸菌降解胆固醇的体外研究、乳酸菌降解胆固醇在动物和人体内的研究、乳酸菌降胆固醇机理的研究和降胆固醇乳酸菌高密度培养等方面进行了论述,提出目前在研究中存在的一些问题,以期对乳酸菌的进一步开发和利用提供帮助。     

色氨酸及其代谢产物5-HT对肠道功能的作用综述

色氨酸是人和动物机体自身无法合成、需要从食物中摄取的必需氨基酸之一,也是代谢为5-羟色胺、褪黑激素、犬尿氨酸和烟酸等的重要前体物质。色氨酸虽然在人和动物体内含量较少,但是可以通过其多元的代谢途径及其代谢产物发挥着各种重要作用。色氨酸在体内主要有两条分解代谢途径:一是沿5-羟色胺的代谢途径;二是沿犬尿氨酸的代谢途径。通过膳食摄入体内的色氨酸不仅能参与调节蛋白质的合成,还能在控制动物食欲、免疫调节以及改善情绪认知等方面发挥重要作用。近年来,随着对色氨酸及其代谢产物研究的不断深入,其应用领域也越来越广泛,目前已被广泛应用于食品、饲料和医药等领域。本文就色氨酸及其代谢产物5-羟色胺对动物肠道免疫、肠道蠕动以及肠易激综合征三方面的作用做一综述。     

植物角鲨烯提取研究进展

角鲨烯是一种重要的脂质不皂化物,广泛应用于食品、药品及化妆品等行业。对植物角鲨烯的来源、提取、检测及应用等方面进行了综述,并提出了一些新视角。第一,脱臭馏出物是提取植物角鲨烯的理想原料;第二,不能用液相色谱测定的角鲨烯含量来度量脱臭馏出物中角鲨烯的含量;第三,脱臭馏出物提取角鲨烯的过程中,需要与天然VE、植物甾醇等营养素一起提取,以提高资源的综合利用率,降低生产成本。本研究对于植物角鲨烯的进一步深入和拓展,具有一定的参考。     

应用生物信息学定向筛选产角鲨烯的微生物研究分析

角鲨烯作为一种具有生物活性的萜烯化合物被广泛应用于医药、食品等行业,而微生物发酵为解决角鲨烯资源匮乏开辟了一条新途径。为提高产角鲨烯微生物的分离筛选效率,充分利用生物信息数据库,对比分析了角鲨烯合成途径的关键酶基因和茅台酒酿造过程中优势酵母的全基因组注释结果,定向筛选获得1株具有产角鲨烯潜力的粟酒裂殖酵母。经发酵验证,该菌株在常规培养基中不产角鲨烯,但根据其全基因组解析的代谢通路特征添加一定量的乙酸后,角鲨烯的产量可达14.72μg/g干菌体。这表明应用生物信息数据资源能够实现产角鲨烯微生物的高效分离筛选,以及沉默基因的有效激活,该方法对其他微生物代谢产物的挖掘也具有重要的借鉴意义。     

食物防癌的机理

近年来,食物防癌已受到国内外专家的广泛关注,经过多年研究,陆续揭开了食物防癌之理。1 硒能防癌 硒可减少致癌物所引起的氧化损害,阻止致癌物在体内的代谢,减弱其致突变特性并可迅速分化细胞的选择性毒性作用,激活机体免疫防卫功能等。因此,经常吃些含硒丰富的食物有防癌作用。据医学研究确定,植物和动物体中的硒量与土壤、饲料中硒含量及其化合态有关。动物肝、肾、海产品、大蒜等是硒的良好补充源。     

发酵肉制品中生物胺及其产生菌株研究进展

生物胺是一类具有生物活性的含氨基小分子有机化合物,其广泛存在于蛋白丰富的食品中。生物体内适量生物胺具有增强代谢、促进生长等功能,但当含量达到临界值时,会产生诸多不良影响。存在大量微生物的食品中,生物胺的含量较高,同类发酵肉制品中生物胺的种类和含量也有很大不同,如发酵时间、贮藏时间和包装材料等都会对此产生影响。本文主要介绍生物胺的常见种类、生理作用,发酵肉制品中产生物胺的微生物种类、形成途径、菌株筛选方法及检测方法,旨在为今后发酵肉制品中生物胺的进一步研究提供帮助,以期为发酵肉制品的质量保障提供参考。     

β-半乳糖苷酶催化合成低聚半乳糖的研究

<正>β-半乳糖苷酶的研究进展β-半乳糖苷酶来源及作用机理。β-半乳糖苷酶(β-galactosidase)普遍存在于动物(幼小动物的肠中)、植物(杏、苹果等)及微生物(细菌、霉菌等)中,能够将乳糖水解为葡萄糖及半乳糖供生物体代谢使用。在生物体体内,β-半乳糖苷酶是由Lac Z基因编码翻译而成的蛋白质酶类,通过提取动物、植物及微生物中的乳糖酶蛋白,发现来自于不同物种体内     

微生物脂肪酶的生产及应用

脂肪酶广泛分布在动物胰液、血液、脂肪组织、肝脏等内，与生物体内的脂质代谢有密切的关系、植物种子如麻子、小麦胚芽、米糠等中也有脂酶。本文叙述微生物脂肪酶的生产及应用。     

“天然产物综合利用与检测”专题征稿函

天然产物是指由动物、植物或昆虫、海洋生物和微生物体内分离出来的生物二次代谢产物及生物体内源性生理活性化合物。近年来随着养生理念逐渐深入人心,天然产物对健康促进作用的相关研究也获得了越来越多的关注。此外,茶多酚、香辛料、壳聚糖、细菌素等天然产物在食品的护色保鲜领域也起着重要的作用。我国是天然资源大国,也是应用天然产物历史最悠久的国家之一。如何充分发挥我国的资源优势,从而更好地利用我国丰富的自然资源,是亟待解决问题。     

“天然产物综合利用与检测”专题征稿函

天然产物是指由动物、植物或昆虫、海洋生物和微生物体内分离出来的生物二次代谢产物及生物体内源性生理活性化合物。近年来随着养生理念逐渐深入人心,天然产物对健康促进作用的相关研究也获得了越来越多的关注。此外,茶多酚、香辛料、壳聚糖、细菌素等天然产物在食品的护色保鲜领域也起着重要的作用。我国是天然资源大国,也是应用天然产物历史最悠久的国家之一。如何充分发挥我国的资源优势,从而更好地利用我国丰富的自然资源,是亟待解决问题。     

Reliable identification of grapevine rootstock varieties using RAPD PCR on woody samples

Since grapevine ( Vitis spp .) rootstock material is being traded increasingly as disbudded woody material a lack of distinctive morphological features on such material necessitates an alternative and reliable means of identification. Methods described here were developed for rapid and efficient extraction of DNA from woody samples rich in phenolic compounds and polysaccharides, and for subsequent identification of varieties by RAPD PCR. Using these methods, and with the application of only one selected RAPD primer, we were able to differentiate sixteen rootstock varieties, including the seven varieties most commonly used in Germany. Problems commonly encountered with reproducibility of RAPD patterns were avoided by choosing primers with a dinucleotide sequence and a high G/C content that allowed a rather high annealing temperature of 45°C. Methods described here should also be useful for other horticultural crops, especially those with woody tissues rich in phenolic compounds and polysaccharides.     

Chlorohydrins of bisphenol A diglycidyl ether (BADGE) and of bisphenol F diglycidyl ether (BFDGE) in canned foods and ready-to-drink coffees from the Japanese market

BADGE.2HCl and BFDGE.2HCl were determined in 28 samples of ready-to-drink canned coffee and 18 samples of canned vegetables (10 corn, 5 tomatoes and 3 others), all from the Japanese market. HPLC was used as the principal analytical method and GCMS for confirmation of relevant LC fractions. BADGE.2HCl was found to be present in one canned coffee and five samples of corn, BFDGE.2HCl in four samples of canned tomatoes and in one canned corn. No sample was found which exceeded the 1mg/kg limit of the EU for the BADGE chlorohydrins. However the highest concentration was found for the sum of BFDGE.2HCl and BFDGE.HCl.H₂O at a level of 1.5mg/kg. A Beilstein test confirmed that all cans containing foods contaminated with BADGE.2HCl or BFDGE.2HCl had at lest one part coated with a PVC organosol.     

European priorities for research to support legislation in the area of food contact materials and articles

A strong science base is required to underpin the planning and decision-making process involved in determining future European community legislation on materials and articles in contact with food. Significant progress has been made in the past 5 years in European funded work in this area, with many developments contributing to a much better understanding of the migration process, and better and simpler approaches to food control. In this paper this progress is reviewed against previously identified work-areas (identified in 1994) and conclusions are reached about future requirements for R&D to support legislation on food contact materials and articles over the next 5 or so years.     

Aroma characterization of various apricot varieties using headspace–solid phase microextraction combined with gas chromatography–mass spectrometry and gas chromatography–olfactometry

The characterization of the aromatic profile of several apricot cultivars with molecular tracers in order to obtain objective data concerning the aromatic quality of this fruit was undertaken using headspace–solid phase microextraction (HS–SPME). Six apricot cultivars were selected according to their organoleptic characteristics: Iranien, Orangered, Goldrich, Hargrand, Rouge du Roussillon and A4025. The aromatic intensity of these varieties measured by HS–SPME–Olfactometry were defined and classified according to the presence and the intensity of grassy, fruity and apricot like notes. In the six varieties, 23 common volatile compounds were identified by HS–SPME–GC–MS. Finally, 10 compounds, ethyl acetate, hexyl acetate, limonene, β-cyclocitral, γ-decalactone, 6-methyl-5-hepten-2-one, linalool, β-ionone, menthone and (E)-hexen-2-al were recognized by HS–SPME–GC–O as responsible of the aromatic notes involved in apricot aroma and considered as molecular tracers of apricot aromatic quality which could be utilized to discriminate apricot varieties.     

Textural Properties of Cold-set Gels Induced from Heat-denatured Whey Protein Isolates

A 9% whey protein (WP) isolate solution at pH 7.0 was heat-denatured at 80°C for 30 min. Size-exclusion HPLC showed that native WP formed soluble aggregates after heat-treatment. Additions of CaCl2 (10–40 mM), NaCl (50–400 mM) or glucono-delta-lactone (GDL, 0.4–2.0%, w/v) or hydrolysis by a protease from Bacillus licheniformis caused gelation of the denatured solution at 45°C. Textural parameters, hardness, adhesiveness, and cohesiveness of the gels so formed changed markedly with concentration of added salts or pH by added GDL. Maximum gel hardness occurred at 200 mM NaCl or pH 4.7. Increasing CaCl2 concentration continuously increased gel hardness. Generally, GDL-induced gels were harder than salt-induced gels, and much harder than the protease-induced gel.     

Tests of potential functional barriers for laminated multilayer food packages. Part I: Low molecular weight permeants

The advent of the functional barrier concept in food packaging has brought with it a requirement for fast tests of permeation through potential barrier materials. In such tests it would be convenient for both foodstuffs and materials below the functional barrier (sub-barrier materials) to be represented by standard simulants. By means of inverse gas chromatography, liquid paraffin spiked with appropriate permeants was considered as a potential simulant of sub-barrier materials based on polypropylene (PP) or similar polyolefins. Experiments were performed to characterize the kinetics of the permeation of low molecular weight model permeants (octene, toluene and isopropanol) from liquid paraffin, through a surrogate potential functional barrier (25 μm-thick oriented PP) into the food simulants olive oil and 3% (w/v) acetic acid. These permeation results were interpreted in terms of three permeation kinetic models regarding the solubility of a particular model permeant in the post-barrier medium (i.e. the food simulant). The results obtained justify the development and evaluation of liquid sub-barrier simulants that would allow flexible yet rigorous testing of new laminated multilayer packaging materials.     

Occurrence of bisphenol-F-diglycidyl ether (BFDGE) in fish canned in oil

The levels of bisphenol-F-diglycidyl ether (BFDGE) were quantified as part of a European survey on the migration of residues of epoxy resins into oil from canned fish. The contents of BFDGE in cans, lids and fish collected from all 15 Member States of the European Union and Switzerland were analysed in 382 samples. Cans and lids were separately extracted with acetonitrile. The extraction from fish was carried out with hexane followed by re-extraction with acetonitrile. The analysis was performed by reverse phase HPL C with fluorescence detection. BFDGE could be detected in 12% of the fish, 24% of the cans and 18% of the lids. Only 3% of the fish contained BFDGE in concentrations considerably above 1mg/kg. In addition to the presented data, a comparison was made with the levels of BADGE (bisphenol-A-diglycidyl ether)analysed in the same products in the context of a previous study.     

Contribution of European research to risk analysis

The European Commission's, Quality of Life Research Programme, Key Action 1—Health, Food & Nutrition is mission-oriented and aims, amongst other things, at providing a healthy, safe and high-quality food supply leading to reinforced consumer confidence in the safety of European food. Its objectives also include the enhancing of the competitiveness of the European food supply. Key Action 1 is currently supporting a number of different types of European collaborative projects in the area of risk analysis. The objectives of these projects range from the development and validation of prevention strategies including the reduction of consumers risks; development and validation of new modelling approaches; harmonization of risk assessment principles, methodologies, and terminology; standardization of methods and systems used for the safety evaluation of transgenic food; providing of tools for the evaluation of human viral contamination of shellfish and quality control; new methodologies for assessing the potential of unintended effects of genetically modified (genetically modified) foods; development of a risk assessment model for Cryptosporidium parvum related to the food and water industries; to the development of a communication platform for genetically modified organism, producers, retailers, regulatory authorities and consumer groups to improve safety assessment procedures, risk management strategies and risk communication; development and validation of new methods for safety testing of transgenic food; evaluation of the safety and efficacy of iron supplementation in pregnant women; evaluation of the potential cancer-preventing activity of pro- and pre-biotic ('synbiotic') combinations in human volunteers. An overview of these projects is presented here.     

Influence des ions sur le pouvoir hydratant de l'ure e: e tude sur peau de porc ex vivo

This study deals with the influence of ions (NaCl and MgSO4) in a W/O emulsion containing 10% urea. Moisturization kinetics are assessed by corneometry on pig skin ex vivo. The formula's influence on urea penetration is measured by infrared spectrometry with an ATR device and the stripping method. Corneometry and spectroscopy were chosen to record simultaneously the hydratation levels and urea localization into superficial cell layers. Urea crystallization after evaporation of emulsions and aqueous solutions is described. Results show that urea does not hydrate nor penetrate when applied to the skin through an aqueous gel. In a W/O emulsion, sodium chloride increases the ability of urea to moisturize without improving penetration. In vitro urea crystallization is disturbed by sodium chloride or magnesium sulphate for solutions and emulsions. This stabilization by ions is correlated with good moisturization values. The stabilization of urea in the solute state provided by ions increases its water epidermal binding capacity without enhancing penetration.