提高和稳定低度白酒品质方法的研究

利用气相色谱法测定了添加有稳定剂阿拉伯胶、β-CD和HP-β-CD的汾酒在不同贮存时间后的酯类含量.结果表明,稳定剂可抑制汾酒中含有的主要酯类化合物的水解,并且提高了低度白酒的品质.     

低度浓香型白酒品质提高方法的研究

应用气相色谱法测定了添加有稳定剂低聚果糖、阿拉伯胶、β-CD和HP-β-CD的38%vol浓香型白酒在不同贮存时间后的主要香味成分的含量.结果表明,稳定荆可抑制白酒中舍有的主要酯类化合物的水解,并可提高低度白酒的品质.     

脂肪酶在白酒酯类化合物合成中的作用研究进展

酯类化合物是白酒中最重要的一类风味物质,其含量影响白酒的品质和香型。鉴于酯类化合物对白酒风格具有重要影响,研究白酒酿造过程中酯类化合物形成的影响因素具有重要意义。经系统研究并分析白酒酿造过程可知,白酒中酯类化合物主要来源于酸-醇的酶促反应,并且确定了酯化酶中的脂肪酶对白酒酯类化合物合成具有重要的酶促催化作用。为此,本文分析了白酒酿造过程中酯类化合物形成的途径,进而简单介绍脂肪酶及其催化酯类化合物合成机制,论述脂肪酶在白酒酯类化合物形成的研究现状,并探索脂肪酶在白酒酯类化合物形成中的研究前景。     

清香型白酒快速陈酿化的初步研究

研究了以微波,超声波,紫外和陶瓷粒处理清香型白酒对其总酸、总酯和乙酸乙酯的影响,结果表明微波结合陶瓷粒的复合处理方式催陈效果最佳,其处理条件为2450MHz,5min;超声波结合陶瓷粒的复合方式次之,其最佳处理条件为20KHz,20min。研究结果可应用于清香型白酒的快速催陈。     

物理方法在白兰地和白酒催陈中的研究进展

物理方法以其作用快速,无额外添加物等特点在白兰地和白酒催陈中得到国内外的一定认可,采用物理方法对白兰地和白酒进行催陈,可以改善酒的口感和品质、缩短陈酿周期、提高企业效益。文中重点介绍了电场、超重力场、超声波、微波等物理方法在白兰地和白酒人工陈酿中的作用原理及应用优缺点等方面的研究进展;对物理方法用于白兰地和白酒催陈的作用机理作了总结,并展望了新方法的发展方向和应用前景。     

中国传统白酒风味酯合成研究进展

传统发酵食品是我国食品工业中的重要分支,而白酒则是传统发酵食品的重要组成部分。开放式的固态生态发酵方式赋予了白酒独特的风味属性,其中酯类化合物是白酒中最重要的一类香味成分,其组成和含量与酒体感官、品质密切相关。研究表明微生物合成代谢途径和酶促反应是白酒酿造过程中酯类物质积累的主要生物途径。文章系统总结了白酒酿造过程中酯类化合物的种类,在此基础上,概述了微生物和酯合成酶在风味酯合成方面的研究现状,并对未来风味酯合成的研究方向进行了展望。     

低度白酒稳定性的研究及应用

从白酒生产过程中加浆用水对低度白酒稳定性的影响入手,分别测定自来水、软化水、纯净水及其配制的低度白酒的电导率、介电常数及白酒中主要香味成分含量随贮存时间的变化规律,并探讨白酒胶体溶液胶核、胶粒和胶团的组成以及影响白酒胶体稳定性的主要因素。结果表明：加浆用水中含有适量的金属离子,可有效提高白酒胶体的稳定性、降低体系的介电常数、抑制酯类化合物的水解、提高低度白酒的稳定性。同时,通过使用酒体中富含酯对应酸的有益微量元素的羧酸盐调整金属离子浓度后的加浆用水,配制的低度清香型白酒(38°),放置一年,乙酸乙酯和乳酸乙酯含量总和比对照样提高了31.0%,低度浓香型白酒(38°)放置一年,己酸乙酯、乙酸乙酯和乳酸乙酯含量总和比对照样提高了10.2%。     

白酒微波催陈及其工艺优化

以浓香型白酒为研究对象,考察了微波醇化温度、微波处理时间、微波功率等因素对白酒陈化的影响,研究了不同因素组合对微波催陈白酒的影响效果。试验结果表明:醇化温度50℃、微波功率70 W、处理时间10min为最佳催陈工艺条件,该条件下白酒的总酸含量为1.46g/L,总酯含量为2.98g/L,与新酒的总酸、总酯含量差异显著(P0.05)。经微波处理后,白酒中酯类物质含量有增加的趋势,发生红移,基团有更加不稳定的趋势;白酒中主要微量成分的浓度及配比与自然陈化最为接近,如乙酸乙酯、己酸乙酯、乳酸乙酯、乙酸、己酸等;此外白酒中还产生了丙酸、戊酸、己酸己酯、癸酸乙酯等呈香呈味物质。     

桑黄子实体多糖超声波微波协同辅助提取及活性研究

桑黄因具有独特的抗癌等功能,已经成为国内外功能性食品研究的热点,是目前国际所公认的生物抗癌领域中效率最高的真菌。该研究应用超声波微波复合法辅助提取桑黄多糖,试验在不同提取时间、液料比、超声波功率和微波功率等条件下多糖的提取率,选出最佳超声波-微波协同辅助提取工艺。对热水法和超声波微波法辅助提取的多糖进行抗氧化与抗肿瘤活性测定,桑黄多糖表现出很强的抗氧化性,超声波微波法辅助提取的多糖抗氧化活性更强;多糖对人肝癌细胞和人宫颈癌细胞有较强的细胞毒活性,超声波微波辅助提取的桑黄多糖其抗肿瘤活性更强。试验结果表明超声波微波辅助提取法不但效率高,而且未减弱多糖的活性。     

超声波、微波对鲑鱼肽结构及抗氧化性的影响

研究了微波、超声波及超声波-微波共同作用对鲑鱼肽超氧阴离子自由基清除能力的影响.通过紫外、红外光谱扫描及氨基酸组成分析对鲑鱼肽结构的变化进行了探讨.结果表明:在一定的条件下,蛋白酶解液经超声波、微波处理后其超氧阴离子自由基清除能力均有一定程度的提高.经微波、超声波-微波红外吸收光谱在1669cm-1处的C=0伸缩峰,及1544cm-1处的N-H弯曲峰均发生偏移,且峰形变得更为尖锐,可以推测鲑鱼肽的二级结构经过超声波、微波处理后均发生了变化.通过分析鲑鱼肽的氨基酸组成发现:经过微波、超声波及超声波-微波共同处理后,鲑鱼肽游离氨基酸中与抗氧化相关的氨基酸总量变化不显著,证实了其活性物质为小分子肽类物质.     

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.     

An internet compendium of analytical methods and spectroscopic information for monomers and additives used in food packaging plastics

An internet website (http://cpf.jrc.it/smt/) has been produced as a means of dissemination of methods of analysis and supporting spectroscopic information on monomers and additives used for food contact materials (principally packaging). The site which is aimed primarily at assisting food control laboratories in the European Union contains analytical information on monomers, starting substances and additives used in the manufacture of plastics materials. A searchable index is provided giving PM and CAS numbers for each of 255 substances. For each substance a data sheet gives regulatory information, chemical structures, physico-chemical information and background information on the use of the substance in particular plastics, and the food packaging applications. For monomers and starting substances (155 compounds) the infra-red and mass spectra are provided, and for additives (100 compounds); additionally proton NMR are available for about 50% of the entries. Where analytical methods have been developed for determining these substances as residual amounts in plastics or as trace amounts in food simulants these methods are also on the website. All information is provided in portable document file (PDF) format which means that high quality copies can be readily printed, using freely available Adobe Acrobat Reader software. The website will in future be maintained and up-dated by the European Commission's Joint Research Centre (JRC) as new substances are authorized for use by the European Commission (DG-ENTR formerly DGIII). Where analytical laboratories (food control or other) require reference substances these can be obtained free-ofcharge from a reference collection housed at the JRC and maintained in conjunction with this website compendium.     

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.