近临界水中废油脂无催化水解研究

研究了在无外加催化剂的情况下,厨房排油烟机回收盒中的废油脂在近临界水中的水解,考察了搅拌速度、反应时间、反应压力、反应温度和水油比对水解反应的影响.通过正交试验确定了最佳水解条件:反应温度230℃,反应压力4.0 MPa,反应时间5.5h,水油比3∶1.在此条件下,废油脂水解率达97％以上.     

棉籽油亚临界水解反应及其动力学研究

以棉籽油为原料,研究了油脂在亚临界水中制备脂肪酸的水解反应及其动力学。结果表明,棉籽油亚临界水解反应最优条件为:反应温度280℃,棉籽油与水体积比1∶3,反应时间30 min;在此条件下,转化率可达98.7%。棉籽油亚临界水解反应的平均反应级数为1.149 9,活化能为108.63 k J/mol,频率因子为2.696×109,动力学模型为-dcA dt=2.696×109e108.63RTc1.149 9A。     

正交试验探讨橡胶籽油亚临界水解反应

以橡胶籽油为原料,在间歇式高温高压反应釜中进行亚临界水解反应,分别考察了反应温度、反应时间、水油体积比对水解率的影响.应用正交试验得出水解反应的较适宜条件为:反应温度290 ℃,反应时间40 min,水油体积比为4:1.在此条件下水解率可达96.8%.通过超高效液相色谱(UPLC)检测分析,橡胶籽油水解产物主要由亚油酸、油酸、亚麻酸、棕榈酸、硬脂酸5种脂肪酸组成.     

响应面优化法研究花椒籽油在近临界水中的水解

利用响应面法对花椒籽油在近临界水中水解的反应条件进行了优化.以水解转化率为考察指标,根据Box-Benhnken的中心组合试验设计原理对试验进行设计和结果分析.研究了温度、时间和水油体积比对反应的联合影响,得出最佳工艺条件为:反应温度241.1 ℃,反应时间4.94 h,水油体积比2.95∶1.在此条件下,花椒籽油水解转化率接近100%.     

亚临界水中甘油酯型鱼油水解工艺研究

研究亚临界水中鱼油水解制备游离型EPA和DHA,本试验以甘油酯型鱼油为原料,采用亚临界水作为其水解的反应介质,分别探讨了反应温度、反应时间、油水体积比和反应压力对其水解率的影响。在此基础上,采用正交试验对其水解工艺进行优化。结果表明,其较优水解工艺条件为反应温度330℃,反应时间30 min,油水体积比1∶3,反应压力15 MPa。在此条件下,甘油酯型鱼油水解率可达(91.04±0.39)%。水解产物经RP-HPLC检测分析,游离型EPA和DHA的得率分别为96.31%和83.85%。     

亚临界水中乙酯型鱼油水解工艺的响应面优化

亚临界水作介质进行乙酯型鱼油的水解试验,考察反应温度、反应时间和水油体积比对水解率的影响。在此基础上,采用Box-Benhnken设计法和响应面分析法优化其水解工艺,建立其水解二次多项数学模型与验证其可靠性。同时,探讨该3个因素交互作用和较适水解条件,并对其进行验证。结果显示,影响乙酯型鱼油水解工艺的因素主次顺序:反应温度水油体积比反应时间,其较适水解工艺参数为反应温度339℃,反应时间16 min,水油体积比3.9。在此条件下,水解率实测值为(88.42±0.17)%,与模型预测值88.44%接近。     

固体酸碱催化餐饮废油脂制备生物柴油

采用固体酸、碱催化餐饮废油脂制备生物柴油.首先用煅烧后的(NH4>)2>SO4>/Al2>O3>催化甲醇和餐饮废油脂中的游离脂肪酸进行预酯化反应,然后再用煅烧后的Na2CO3/Al2O3催化甲醇和餐饮废油脂中的甘油三酯进行酯交换反应.结果表明,经预酯化的餐饮废油脂在以正己烷为溶剂、溶剂用量为1.5 mL/g(oil)、醇油摩尔比为15:1、反应温度为50℃、反应时间为4 h和催化剂用量为8%的最佳工艺条件下进行酯交换反应.反应转酯率为96.85%.     

废弃植物油亚临界水解制取混合脂肪酸及其动力学研究

以废弃植物油为原料,用亚临界水解法制备混合脂肪酸,研究混合脂肪酸的制备条件及其反应动力学。结果表明,废弃植物油在亚临界水中的适宜反应条件为:反应温度280℃,反应时间30 min,油水体积比为1:3.5,转化率最高达98.1%。废弃植物油在亚临界水中的水解反应平均反应级数为n=1.123 89,活化能E_a=70.87 kJ/mol,频率因子A=1.770 6×10~5,动力学模型为-dc_A/dt=1.770 6×10~5e~(-70.87/RT)C_A~1.123.89。     

菜籽油脂肪酸在超临界甲醇中酯化反应工艺条件研究

以菜籽油在亚临界水解反应中制取的脂肪酸为原料,研究菜籽油脂肪酸在超临界甲醇中的酯化反应工艺条件及动力学模型。通过单因素试验考察了反应温度、醇酸体积比、反应压力、反应时间对酯化转化率的影响,并采用超高效液相色谱法分析油酸甲酯含量的变化情况。试验结果表明菜籽油脂肪酸在超临界甲醇中酯化反应的最佳工艺条件为:反应温度270℃,反应时间40 min,反应压力25 MPa,醇酸体积比2∶1。在最佳工艺条件下菜籽油脂肪酸酯化转化率超过了98%,动力学模型为-dCA/dt=62.98e-20.14/RTC1.8A。     

响应面优化法研究桐油在近临界水中的水解

在近临界水条件下水解桐油制备桐油脂肪酸,并利用响应面法对水解条件反应温度、反应时间和水油体积比进行了优化,得出最佳工艺条件为:反应温度246.16℃,反应时间4.21 h,水油体积比2.33∶1。在此条件下,桐油脂肪酸的转化率接近100%。     

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.     

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.     

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.     

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.