高酸值废油萃取反应耦合脱酸、酯化工艺优势的研究

以高酸值废油和甲醇为原料,强酸性阳离子交换树脂同时作为固体酸催化剂和萃取填料,在自制的固定床反应器中进行萃取-酯化反应的耦合过程,成功降低了高酸值油脂的酸值,并合成了脂肪酸甲酯.将萃取-酯化反应耦合工艺与单纯的萃取工艺和单纯的酯化工艺相比较,结果:在脱酸效果方面,萃取-酯化反应耦合工艺的脱酸效果相当于七级错流甲醇萃取工艺的脱酸效果;在酯化效果方面,同样达到68%的酯化率,萃取-酯化反应耦合工艺的停留时间为32 min,酯化工艺则需要160 min的停留时间,反应时间缩短了5倍.而对于酯化工艺、停留时间为32 min,酯化率仅为22%.     

棉籽油脱臭馏出物中脂肪酸甲酯化工艺研究

棉籽油脱臭馏出物中含有40%-80%的游离脂肪酸,对这部分脂肪酸的甲酯化进行了研究。考察了甲醇用量、催化剂用量、酯化温度、酯化时间对脂肪酸甲酯化的影响。结果表明,脂肪酸甲酯化优化条件为甲醇/原料为2∶1(V/W),催化剂/原料为0.005∶1(V/W),酯化温度65℃,酯化时间3 h;在此条件下脂肪酸甲酯化率达到98%以上。     

皂脚制备生物柴油的研究

介绍了以皂脚为原料制备生物柴油的方法,反应以H2SO4为催化剂,通过将皂脚转化为脂肪酸,然后与甲醇进行酯化反应获得脂肪酸甲酯。分别考察了酯化反应条件如反应温度、反应时间、甲醇与脂肪酸的比例对酯化率的影响。应用正交实验方法得出酯化反应的最佳条件为:反应温度60℃,反应时间60 min,甲醇与脂肪酸的比例为1∶1(V/W)。     

酶法生产脂肪酸甲酯并提取植物甾醇

脂肪酸甲酯是一种绿色生物柴油,植物甾醇是甾体类药物生产的重要原料.探讨了用固定化脂肪酶从脱臭馏出物中生产脂肪酶甲酯并提取植物甾醇的方法.研究了酯化过程中酶用量、甲醇用量、反应温度、时间和含水量等反应条件对酯化率的影响.试验结果表明,在脂肪酶用量为10%、加水量为15%,甲醇采用分批流加方式下,30℃下反应36h,酯化率可达89.4%,植物甾醇的收率达7.3%.     

樟树籽油酯交换法制备生物柴油的研究

以浓H2SO4为催化剂,樟树籽油与甲醇预酯化生成酯化油;再以NaOH为催化剂,酯化油与甲醇进行酯交换制备生物柴油。在单因素试验的基础上,利用正交试验优化酯交换反应条件。结果表明:当甲醇与酯化油摩尔比为4.0∶1、催化剂与酯化油摩尔比为0.050∶1、反应时间为80 min、反应温度为55℃时,酯交换率最高,达94.38%。经气相色谱分析,樟树籽油生物柴油的脂肪酸甲酯组成为:癸酸甲酯53.67%,月桂酸甲酯42.92%,肉豆蔻酸甲酯0.44%,棕榈酸甲酯0.37%,油酸甲酯2.11%,亚油酸甲酯0.26%。     

地沟油制备生物柴油的预精制

以固体酸为催化剂,采用釜式反应与固定床反应相结合的方式,将地沟油预精制成为制备生物柴油的原料油。釜氏反应预酯化条件：反应温度70℃,反应时间8h,催化剂用量5%;再通过固定床反应器进一步酯化,酯化条件：反应温度70℃,油重时空速0．2h^-1,甲醇重时空速0.2～0．3h^-1。     

两步法催化潲水油制备生物柴油的研究

采用两步法催化高酸值潲水油制备生物柴油,第一步先用硫酸铁催化潲水油中游离脂肪酸和甲醇酯化生成脂肪酸甲酯(生物柴油),然后再用氢氧化钾催化潲水油中的甘油三酯和甲醇进行酯交换。结果表明,硫酸铁对酯化反应具有很强的催化活性,而且可以回收利用。通过正交试验得到最佳酯化反应参数:硫酸铁用量2%,反应温度95℃,醇油摩尔比10∶1,反应时间4 h,该条件下游离脂肪酸酯化率达97.22%。酯交换条件为:KOH用量1%,反应温度65℃,反应时间1 h,醇油摩尔比6∶1。经过两步催化,产品中总的脂肪酸甲酯(生物柴油)含量达97.02%。该两步催化法具有不产生酸化废水,不需要耐强酸设备,反应时间短,转化率高,同时硫酸铁可以回收重复利用等优点。     

两步法利用高酸值潲水油制备生物柴油研究

以潲水油为原料,采用两步催化法制备生物柴油。先用聚合硫酸铁催化潲水油中游离脂肪酸和甲醇酯转化为脂肪酸甲酯,然后再通过碱催化剩余的甘油三酯进行酯交换反应。通过响应面试验设计优化酯化反应,结果表明,在反应时间6.0 h、甲醇用量108.7%(质量比,按油质量)、催化剂用量5.87%(质量比,按油质量)、反应温度80℃下,酸值可达到2.20 mgKOH/g,即酯化率为97.71%。在110℃下对经两步催化得到的生物柴油进行分子蒸馏,得率为98.20%,测定了生物柴油的脂肪酸甲酯组成,按照国标检测了纯化的生物柴油的物化性质。     

乳酸甲醇酯化床催化研究

为研究乳酸甲醇酯化反应过程,采用强酸性阳离子交换树脂床催化乳酸甲醇酯化反应,研究反应物进料流速、反应温度、醇酸物质的量比对酯化率的影响。结果表明：随进料速度的降低,酯化率先上升后趋于稳定;随反应温度升高,反应速率变大,平衡酯化率基本不变;随醇酸比增加,平衡转化率升高,但增加幅度变小。建立乳酸甲醇床催化拟均相模型,反应活化能为33805.56J/mol,指前因子为4856.63mol-1·L·min-1。实验测得平衡常数为1.1151,且在所考察的温度范围内基本不变。实验值与模型估计值平均相对偏差为2.74%。     

利用地沟油制备生物柴油

以废弃地沟油为原料,经预处理后采用两步酯化工艺将其转化为生物柴油.第一步为酸催化预酯化反应,主要是将地沟油中的游离脂肪酸转化为脂肪酸甲酯;第二步为酸催化转酯化反应.主要是进一步将地沟油中的甘三酯转化为甲酯和甘油.通过正交实验得到预酯化反应的最佳条件为:醇油摩尔比10:1、催化剂用量1.0%、反应温度70℃、反应时间4 h;转酯化反应的最佳条件为:醇油摩尔比20:1、催化剂用量6%、反应温度70℃、反应时间4 h.在最佳反应条件下,甘三酯的酯化率可达到86.89%.     

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.     

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.     

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.     

Detection of adulteration of locust bean gum with guar gum by capillary electrophoresis and polarized light microscopy

Capillary electrophoresis (CE) and polarized light microscopy (PLM) were utilized in the detection of the adulteration of locust bean gum with guar gum. For CE analyses, standards of locust bean and guar gums were extracted with 30% CH₃CN, removing the residual proteins from the gum matrix. A 8.75 mM NaH₂PO₄-20.6 mM Na₂B₄O₇ buffer, pH 9, was used to separate these proteins and to identify marker proteins that were present in the guar gum. These markers did not co-migrate with components in the extracts of mechanically processed locust bean gum, and are used as indicators of adulteration. Using PLM with toluidine blue and iodine staining techniques, unadulterated locust bean gum samples were distinguished from mixed samples through the differential staining of components in locust bean versus guar and tara gums. These experiments in the use of CE and PLM provide orthogonal and complementary methods for the verification of 'true' positives and the elimination of 'false' positives.