水油混相协同微波提取辣椒碱工艺优化及应用研究

目的：优化干辣椒中辣椒碱的提取工艺并探究其加工特性。方法：采用高压水油混相浸提技术预处理干辣椒,再协同微波辅助溶剂法提取辣椒碱,并应用于食品加工中。结果：水油混相预处理工艺条件为干辣椒粗粉加湿量20%、浸提温度150 ℃、搅拌机转速300 r/min;微波辅助提取工艺条件为预处理的辣椒粉在600 W微波功率下处理120 s,然后按料液比（m_辣椒粉∶V_乙醇）1∶20 （g/mL） 添加65%的乙醇,在30 ℃恒温水浴锅中浸提2.5 h,辣椒碱最佳提取量为4.12 g/kg干辣椒,初次提取率达82.4%,3次理论得率可达99.45%。结论：高压水油混相浸提技术预处理后的干辣椒辣椒碱提取率显著优于传统浸提工艺,且加工性能稳定。     

精炼对牛油主要理化指标及挥发性成分的影响

为研究精炼对牛油过程中理化指标及挥发性成分的影响,对熔油、脱酸、脱色后牛油酸价、过氧化值、碘值、脂肪酸和挥发性成分变化进行测定。结果表明,在整个精炼过程中,酸价呈先降后升的趋势,过氧化值呈递增趋势,碘值呈递减趋势。精炼后牛油的酸价为0.37mg/g,过氧化值为0.057 5g/100g,碘值为12.47g/100g。精炼各阶段的牛油中含有16种脂肪酸,最主要的是油酸、棕榈酸、硬脂酸。应用气相—离子迁移谱研究发现醇类挥发性物质在精炼过程中逐渐减少;脱酸后牛油中醛类挥发性物质达到了最高值。脱色后的牛油成品中醛类挥发性物质有所降低;酯类挥发性物质则在精炼过程中逐渐增多。     

固定波长UV-VIS光对大豆油色泽的影响

通过设定不同温度、光强度、光波长、时间对大豆油进行脱色实验,对大豆油的过氧化值、酸价及色泽进行了测定,研究分析了大豆油过氧化值、酸价及色泽随温度、光强度、光波长及照射时间变化的基本规律。通过单因素及正交试验,VIS-450光照脱色的最优工艺条件：电流强度21A,温度35_oC,时间3h,脱色率为53.2%。UV-365光照脱色的最优工艺条件：电流强度21A,温度35℃,时间2h,脱色率为42.4%。结果表明：UV-365比VIS-450对大豆油品质劣变影响较大;VIS-450比UV-365对大豆油脱色率影响较大。     

奇亚籽油储藏稳定性研究及货架期预测

为研究奇亚籽油贮藏稳定性,以液压法制备的奇亚籽油为原料,探讨贮藏温度、氧气和光照条件对奇亚籽油过氧化值、酸价、K₂₃₂、K₂₆₈和TBA的影响,并应用一级动力学模型结合Arrhenius方程建立过氧化值、酸价两个氧化指标随贮藏温度、贮藏时间变化的货架期预测模型,预测奇亚籽油的货架期。结果表明：奇亚籽油的氧化稳定性受光照、氧气和温度的影响,在避光、密封、低温的贮藏条件下能有效降低过氧化值、酸价等的增长速率,延长贮藏时间;通过模型推算可得出密封、避光条件下奇亚籽油在25℃条件下的货架期为94 d。     

广式月饼储存过程中氧化问题的研究

为研究广式月饼在储存过程中的氧化问题,采用以酸价和过氧化值为指标的滴定法及感官评价的方法,分析储存时间和储存温度对广式月饼质量的影响及脂肪氧化酸败引起的风味变化情况.研究结果表明,储存时间和储存温度与广式月饼酸价及过氧化值的变化规律有一定的相关性.并且,存放时间越长,储存温度越高,广式月饼的酸价及其过氧化值升高越快.另外,酸价超标的样品,其品质经感官评价发现并无发生不良变化.因此,酸价在评价广式月饼的脂肪氧化程度上并不全面.     

三种加热方式对大豆油品质影响的比较

采用电磁炉、微波炉、常规加热对大豆油进行处理,以酸价和过氧化值为指标,比较了三种加热方式对大豆油品质的影响。结果表明,电磁炉加热对大豆油品质的影响最大,微波炉加热对大豆油品质的影响次之,常规加热的影响最小;大豆油的酸价、过氧化值与加热的温度及时间有良好的线性关系。间歇加热、加新油加热有利于油脂品质的保护。     

广式腊味氧化问题的研究

文章主要研究广式腊味酸价、过氧化值、TBA值三者之间的相互关系和储藏温度对三者的影响,以及广式腊味的风味变化情况.研究结果表明,广式腊味酸价的变化规律与过氧化值、TBA值的变化规律的相关性不显著.保藏温度越高,广式腊味酸价、过氧化值和TBA值在储藏过程中升高速率越大.储藏时间是影响TBA值更为重要的因素.酸价超标的样品其感官品质也未发生不良变化.所以,酸价和过氧化值在评价广式腊味脂肪氧化程度上并不一致,都不能作为其合适的指标;TBA值是反映广式腊味脂肪氧化程度的最合适指标.     

不同方式提取调和油的热稳定性研究

为研究不同方式提取调和油的烹饪稳定性,分别测定水酶法调和油、溶剂浸提调和油在150、200℃温度条件下加热不同时间的理化性质。结果表明:加热前后,水酶法调和油的色泽较浅,且其酸价、过氧化值、p-茴香胺值始终低于溶剂法调和油,水酶法调和油的氧化稳定性优于溶剂法调和油。随着加热温度的升高,加热时间的延长,两种调和油的裂变程度均增加,酸价及p-茴香胺值升高,色泽加深,过氧化值出现先上升后下降的波动趋势,单不饱和脂肪酸(C18∶1)、多不饱和脂肪酸(C18∶2)呈下降趋势,饱和脂肪酸(C16∶0)含量升高,但在加热1h前,各项指标变化不大。     

山核桃基于温度变化的贮藏寿命预测

研究不同温度(2、12、22、32℃)贮藏过程中山核桃过氧化值、酸价及感官品质随贮存时间的变化规律及其动力学特性,在Arrhenius 动力学方程基础上,建立过氧化值和酸价与贮藏时间、贮藏温度之间的动力学模型,以预测和控制贮藏过程中山核桃的品质变化。结果表明,新鲜山核桃的过氧化值和酸价随着贮藏时间的延 长而增加,且随着贮藏温度的升高而增加迅速,其感官品质指标随着贮藏时间的延长而下降,且随着贮藏温度的升高而迅速下降。一级化学反应模型和Arrhenius 方程对过氧化值和酸价变化具有很高的拟合精度,建立的山核桃货架期预测值准确率达到± 10% 以内,可根据过氧化值、酸价在2～32℃范围内,对山核桃的氧化货架寿命进行预测。     

超声辅助双相浸提制备香椿风味油工艺优化及其贮藏品质研究

香椿含硫风味组分的制备及稳定性一直是食品风味研究领域亟待解决的难点和热点。该研究采用超声波辅助水-玉米油双相浸提制备香椿风味油,通过单因素试验考察超声温度、超声时间、超声功率对香椿风味油含硫类挥发性成分相对含量的影响,并利用正交试验对制备工艺进行优化,最后对香椿风味油的酸价、过氧化值及挥发性成分等贮藏品质进行研究。结果表明,超声辅助处理能显著提高香椿风味油含硫类挥发性成分的相对含量,最佳提取工艺为超声温度50℃、超声时间50 min、超声功率240 W,香椿风味油中含硫类挥发性成分的相对含量为(78.05±0.12)%。经56 d贮藏后,香椿风味油的酸价和过氧化值均逐渐升高,且温度越高,上升趋势越明显。含硫类物质作为香椿风味油的主要挥发性成分,对香椿风味油的风味品质起关键性作用。随着贮藏温度升高,含硫类物质相对含量显著下降,醛类物质相对含量显著上升。该研究结果为香椿风味油的制备和应用提供了理论依据和技术支撑。     

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.     

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.     

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.     

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.     

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.     

Analysis of benzo[a]pyrene in spiked fatty foods by second derivative synchronous spectrofluorimetry after microwave-assisted treatment of samples

A simple, rapid and inexpensive method has been developed for the determination of benzo[a     

The development of reference materials for paralytic shellfish poisoning toxins in lyophilized mussel. II: Certification study

This paper describes the second part of a project undertaken to develop certified mussel reference materials for paralytic shellfish poisoning toxins. In the first part two interlaboratory studies were undertaken to investigate the performance of the analytical methodology for several PSP toxins, in particular saxitoxin and decarbamoyl-saxitoxin in lyophilized mussels, and to set criteria for the acceptance of results to be applied during the certification exercise. Fifteen laboratories participated in this certification study and were asked to measure saxitoxin and decarbamoyl-saxitoxin in rehydrated lyophilized mussel material and in a saxitoxin-enriched mussel material. The participants were allowed to use a method of their choice but with an extraction procedure to be strictly followed. The study included extra experiments to verify the detection limits for both saxitoxin and decarbamoyl-saxitoxin. Most participants (13 of 15) were able to meet all the criteria set for the certification study. Results for saxitoxin.2HCl yielded a certified mass fraction of <0.07 mg/kg in the rehydrated lyophilized mussels. Results obtained for decarbamoyl-saxitoxin.2HCl yielded a certified mass fraction of 1.59+/-0.20 mg/kg. The results for saxitoxin.2HCl in enriched blank mussel yielded a certified mass fraction of 0.48 +/- 0.06 mg/kg. These certified reference materials for paralytic shellfish poisoning toxins in lyophilized mussel material are the first available for laboratories to test their method for accuracy and performance.     

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.