米糠油化学酯化脱酸的研究

以单甘酯和甘油混合物作酯化剂,ZnCl2为催化剂对米糠油进行化学酯化脱酸研究。分别考察了反应温度、反应时间、催化剂添加量、酯化剂添加量和单甘酯与甘油的比例对酸值的影响。由单因素和正交实验得出酯化脱酸的最佳反应条件为：反应温度200℃,反应时间6h,催化剂添加量0．4％,酯化剂添加量150％,单甘酯与甘油的比例为1：1。在此条件下酸值（KOH）由原料的43．0mg／g降到2．2mg／g。     

无溶剂体系高酸值米糠油酶法酯化脱酸工艺优化研究

研究了无溶剂体系中,两种固定化脂肪酶(Lipozyme RMIM和Lipozyme 435)对高酸值米糠油的酶法酯化脱酸效果。结果表明,脂肪酶Lipozyme 435脱酸效果较脂肪酶Lipozyme RMIM更好。在单因素实验的基础上,运用正交实验对高酸值米糠油酶法酯化脱酸工艺条件进行优化,得到最优工艺条件为:反应温度70℃,脂肪酶Lipozyme 435添加量为米糠油质量的3%,反应时间10 h,甘油添加量为理论甘油质量的250%。在最优工艺条件下,米糠油酸值(KOH)从39.81 mg/g降到2.06 mg/g,脱酸率达到94.83%,谷维素保留率为92.44%、VE保留率为77.94%、植物甾醇保留率为82.34%。     

固体超强酸催化大豆油和大豆油脂肪酸酯化与酯交换制备单甘酯的研究

采用固体超强酸催化大豆油和大豆油脂肪酸与甘油酯化和酯交换制备单甘酯,通过二级分子蒸馏纯化单甘酯。通过响应面优化得到的最佳条件为：大豆油30.0 g,大豆油脂肪酸20.0 g,反应温度200℃,固体超强酸催化剂添加量0.26%（占大豆油和大豆油脂肪酸质量）,甘油添加量12.66 g和反应时间4.81 h。在最佳条件下,反应得到的甘油酯混合物中,单甘酯含量达到69.82%。甘油酯混合物在Ⅰ级135℃分子蒸馏除去游离脂肪酸和甘油,在Ⅱ级185℃分子蒸馏蒸出单甘酯,得到产品中单甘酯含量为96.54%。     

高酸价米糠油酯化脱酸技术的研究

以甘油作酯化剂,氧化锌为催化剂对高酸价米糠油进行化学酯化脱酸研究.探讨了酯化反应过程中反应时间、反应温度、催化剂和甘油的添加量对米糠油脱酸效果的影响,最佳酯化条件为:反应时间为6h、反应温度200℃、催化剂的添加量为0.2％、甘油添加量为200％的情况下,可使高酸价(≥酸价37.0 mgKOH/g)的米糠油酸价大幅度下降,可降低到3.6 mgKOH/g油脂以下,显著提高了米糠油的精炼率和品质.     

基于响应面分析法优化高酸值米糠油化学法酯化脱酸工艺

在对催化剂的种类、反应时间、反应温度、催化剂添加量和甘油添加量5个影响因素考察的基础上,根据中心组合试验原理设计了试验,并以响应面法优化高酸值米糠油的脱酸工艺。结果表明,酯化脱酸的最佳方案为反应时间4 h、反应温度215℃、甘油添加量为理论甘油的115%、催化剂添加量为0.3%,在此条件下的理论脱酸率可达90.95%,实际脱酸率可达91.81%,其中谷维素保留率为30.23%。以上结果表明,该工艺条件可靠,具有可行性和参考价值。     

甘油钠催化大豆油甘油解制备单甘酯的研究

采用甘油钠催化大豆油甘油解制备单甘酯,对反应温度、反应时间、甘油钠添加量和底物物质的量比进行了研究,得到选定的反应条件是:反应温度175℃、甘油钠添加量(油重)为2.4％、底物物质的量比(大豆油和甘油)为1∶4和甘油解反应时间为2h,在此条件下,反应得到的甘油酯混合物中,单甘酯质量分数为53.1％.采用二级分子蒸馏纯化单甘酯产品,粗甘油酯在Ⅰ级分子蒸馏(140℃)除去游离脂肪酸和甘油;在Ⅱ级分子蒸馏(190℃)纯化单甘酯,得到纯度为93.0％的单甘酯产品,单甘酯回收率为96.8％.     

酶法催化制备富含甘油二酯米糠油的研究

以高酸值米糠油为原料,采用无溶剂体系酶法催化制备富含甘油二酯的米糠油.考察了脂肪酶种类及添加量,酯化剂种类,底物质量比,反应时间,反应温度对甘油二酯含量和游离脂肪酸残余量的影响.通过单因素试验和响应面试验,确定酶法催化酯化的最佳工艺条件为:固定化脂肪酶Lipozyme RM IM作为催化剂,油酸甘油一酯作为酯化剂,底物质量比0.25:1,反应温度56℃,反应时间5.75 h,脂肪酶添加量4.77%.在此条件下,产物中甘油二酯含量和游离脂肪酸残余量分别为27.61%和0.25%.     

酿造酱油回收油脂的酶法脱酸工艺研究

全大豆酿造酱油经过压榨工序抽取酱油时,可回收部分大豆油脂,但由于油脂氧化和酸败形成的大量游离脂肪酸（FFAs）,导致回收油脂的酸价高达64.68（KOH） mg/g,降低了回收油脂的利用价值。通过单因素及正交试验研究酿造酱油回收油脂的酶法脱酸工艺。结果表明,最佳的酶法脱酸条件为：反应时间12 h,反应温度50 ℃,甘油添加量6.6%,脂肪酶添加量为3%。在该优化工艺条件下,酿造酱油回收油脂的脱酸率高达93.75%,油脂的酸价可降低至2.86（KOH） mg/g,低于GB 2716—2018《食品安全国家标准 植物油》中食用植物油关于酸价的最高指标要求（≤3 mg/g）。进一步研究表明,在该脱酸反应体系中,固定化脂肪酶Novezym 435具有良好的脱酸稳定性。     

K2CO3/Al2O3催化大豆油甘油解制备单甘酯的研究

利用K2CO3/Al2O3固体碱催化大豆油甘油解制备单甘酯.在单因素试验的基础上,利用正交试验对单甘酯制备条件进行优化,得到最优条件为:反应温度210℃,反应时间1.5h,催化剂添加量0.8％(占大豆油质量),大豆油与甘油物质的量比1∶3.在最优条件下,单甘酯含量达到58.26％.经过两级分子蒸馏,单甘酯含量高达95.69％,回收率为90.8％.     

不同精炼脱酸方法对葡萄籽油中反式脂肪酸的影响研究

本文以酸价为15.12±0.016 mg KOH/g的葡萄籽毛油为原料,分别采用化学法、物理法和酶法精炼方法脱酸,重点研究了不同的精炼脱酸方法对葡萄籽油中反式脂肪酸的种类以及含量的影响,探讨了不同的精炼脱酸工艺中葡萄籽油的酸价以及反式脂肪酸含量的变化规律。采用化学法精炼脱酸,葡萄籽油的酸价降至0.10±0.022 mg KOH/g以下,反式脂肪酸含量增加了0.31±0.0011%。采用物理法精炼脱酸:在240℃条件下脱酸8 h,酸价为0.13±0.018 mg KOH/g,反式脂肪酸含量为1.86%。酶法酯化脱酸:在反应温度80℃、甘油添加量300%、加酶量3%、时间8 h的条件下,葡萄籽油的酸价降到2.36±0.026 mg KOH/g,反式脂肪酸含量由0.034±0.001%升至0.035±0.001%~0.041±0.0016%。不同的精炼脱酸方法对葡萄籽油中反式脂肪酸含量影响的规律为:酶法化学法物理法。采用酶促酯化脱酸方法对反式脂肪酸含量的影响很小。     

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.