响应曲面法优化茶叶籽油超声辅助LVK脂肪酶酶解工艺

对茶叶籽油的超声波辅助LVK脂肪酶酶解工艺进行优化。在单因素实验基础上,选取LVK脂肪酶浓度、初始p H、酶解温度和时间为考察因子,茶叶籽油水解率为响应值,运用中心组合实验设计对其酶解工艺进行优化,并建立数学回归模型。结果表明,优化工艺条件为:超声功率220 W,搅拌转速800 r/min,油水比1∶1.75(w/v),氯化钙浓度0.25%,LVK脂肪酶浓度5.5%,酶解温度49.5℃,初始p H9.4,酶解时间4 h。在此条件下,水解率实测值为83.15%,模型预测值为82.06%,水解效率高。     

超声波辅助脂肪酶水解茶叶籽油条件的优化与动力学研究

研究无溶剂体系中超声波辅助脂肪酶水解茶叶籽油,通过单因素试验和正交试验获得最佳酶解条件为:油水比2∶3(g∶m L),加酶量为茶叶籽油质量的4.5%,缓冲液初始p H 8.5,超声波处理温度50℃,搅拌转速300 r/min,反应时间19.5 h。在此条件下,茶籽油的水解率达到72.25%。对其进行了表观动力学研究,测得超声波辅助脂肪酶水解茶叶籽油的米氏常数Km为0.053 m L/g,表观活化能Ea为14.05 k J/mol,比无超声波辅助酶解的Km=4.556 m L/g和Ea=30.73 k J/mol均降低,说明超声波能促进茶叶籽油的酶解。     

响应面优化超声波辅助水酶法提取茶叶籽油工艺

利用响应面法(RSM)优化超声波辅助水酶法提取茶叶籽油工艺条件,在单因素试验基础上,选取复合酶用量、酶解pH、酶解温度、酶解时间为影响因子,茶叶籽油得率为响应值,应用Box-behnken中心组合试验设计建立数学模型,进行响应面分析。结果表明,超声波辅助水酶法提取茶叶籽油工艺优化条件为:高压蒸煮20min,超声处理20min,超声温度60℃,料液比1:5、复合酶用量1.75%,酶解pH4.6,酶解温度44℃,酶解时间6.9h。茶叶籽油得率为29.88%。     

猪胰脂肪酶水解花椒籽油动力学及条件优化

为开发花椒籽油中的α - 亚麻酸,对猪胰脂肪酶水解花椒籽油的酶解特性和水解条件进行研究。结果表明：油水界面面积(αt)与温度(t)、搅拌速率(ω)、底物浓度(S)的关系为αt=0.04ω 0.577t1.242S(1+0.02S)。水解反应速率随温度的变化服从Arrhenius 方程,反应活化能为21.891kJ/mol。以米氏方程为理论基础,考虑αt 对水解反应速率的影响,建立猪胰脂肪酶对花椒籽油的水解动力学模型。猪胰脂肪酶水解花椒籽油的适宜条件为：温度50℃、油质量分数30%、酶质量浓度72.9g/L,在此条件下反应4h 后水解率达57.13%。     

超声波辅助酶法提取茶叶籽油及其脂肪酸组成分析

以湖南怀化地区茶叶籽为原料,在单因素试验的基础上,通过正交试验优化超声波辅助酶法提取茶叶籽油的工艺条件,并采用气相色谱-质谱联用分析茶叶籽油的脂肪酸组成。结果表明:超声波辅助酶法提取茶叶籽油最佳工艺条件为料液比1∶5、植物提取复合酶添加量0.6%、p H 5.8、超声酶解温度55℃、超声酶解时间90 min、超声功率300 W,在此条件下,茶叶籽出油率为(52.61±0.11)%;茶叶籽油中共鉴定出17种脂肪酸,主要含油酸(47.67%)、亚油酸(24.32%)、亚麻酸(4.26%)等不饱和脂肪酸。     

超声波辅助脂肪酶水解红花籽油条件优化与动力学

本文通过单因素实验,分别考察超声时间、超声温度、pH、酶添加量对脂肪酸水解率的影响,结合响应面实验优化超声波辅助脂肪酶水解红花籽油的工艺条件,并比较超声波辅助酶解和水浴酶解中米氏常数及表观动力学的变化。结果表明:最佳酶解条件为:超声时间10 h,超声温度28℃,pH7.0,米曲霉脂肪酶添加量为280 U/g,水油比1.6:1(v/v),此时红花籽油的水解率达到94.47%。对其进行表观动力学研究,测得超声波辅助脂肪酶水解红花籽油的米氏常数Km=4.63 mL/g,表观活化能Ea=2.05 kJ/mol,比水浴酶解条件下米氏常数Km=14.93 mL/g和表观活化能Ea=2.40 kJ/mol均降低,证明超声波辅助脂肪酶能促进红花籽油的水解。     

水酶法提取茶叶籽油工艺条件研究

采用水酶法提取茶叶籽油,通过单因素实验和正交实验优化提取工艺条件。结果表明,水酶法提取茶叶籽油优化工艺条件为:纤维素酶用量1.1%、果胶酶用量2.0%、蛋白酶用量0.2%,料液比1:6,酶解温度45℃、酶解pH值5.0、酶解时间8h,茶叶籽油得率28.64%。     

水解鸡脂肪制备香料

通过对解脂假丝酵母脂肪酶对鸡脂肪水解条件的控制,得到风味增强的鸡肉味调味剂.确定解脂假丝酵母脂肪酶水解鸡脂肪的工艺条件;分析水解前后主要挥发性物质的变化.在单因素试验基础上,通过正交试验对解脂假丝酵母脂肪酶水解鸡脂肪的工艺条件进行优化,得出最佳工艺条件为:加酶量300U/g鸡脂肪,pH7.25,底物浓度50%;反应温度40℃;摇床转速180 r/min.     

超声波辅助α-淀粉酶制备蜡质玉米微孔淀粉的工艺和性质

为优化超声波辅助∝-淀粉酶水解蜡质玉米淀粉制备微孔淀粉的工艺,通过单因素及正交试验,以吸油率为指标,确定了制备微孔淀粉的最佳工艺。同时采用偏光显微镜和差示扫描量热分析仪研究所得微孔淀粉的显微结构及热力学特性。结果表明,在超声功率600 W,超声时间30 min,淀粉乳浓度30%的辅助条件下,酶添加量100 U/g、酶解温度50℃、酶解pH值6.0、酶解时间20 h制得的蜡质玉米微孔淀粉吸油率最高,为175.41%。经超声波辅助酶解制备的蜡质玉米微孔淀粉,淀粉颗粒结构保持完整,均一性提高,糊化温度升高。与普通酶解工艺相比,超声辅助酶解工艺制备的微孔淀粉吸油率提高了19.79%。     

浓香茶叶籽油的制备及其条件优化

该实验研究了利用美拉德生香源反应原理制备浓香茶叶籽油,综合利用茶叶籽资源,并对浓香茶叶籽油制备工艺进行了优化,确定最佳工艺条件为酶解温度50℃,酶解p H 8.5,酶解过程加酶量20 000 U,酶解过程料液比1∶10,浓香成分提取时间30 min,酶解时间为4 h,提香过程油料比为1∶9,提香温度为130℃,并建立了浓香茶叶籽油的感官评价方法,最佳条件下制备的产品品质良好。     

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.     

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.     

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.     

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.