磷脂酶C用于大豆油脱胶的工艺优化

用磷脂酶C对大豆毛油进行实验室模拟脱胶.研究了pH、反应温度、加水量、加酶量、反应时间、搅拌速度对大豆毛油脱胶效果的影响,采用正交试验对脱胶工艺条件进行优化.结果表明,大豆毛油脱胶最佳工艺条件为:加酶量30 mg/kg,反应温度50℃,反应时间1h,pH5.0,加水量2％,搅拌速度200 r/min.在此条件下得到的脱胶大豆油磷含量为17.8 mg/kg,为大豆油酶法脱胶开辟了新途径.     

菜籽油磷脂酶C脱胶与水化脱胶条件优化及效果对比研究

以菜籽毛油为原料,分别利用二次回归正交实验对菜籽毛油磷脂酶C(PLC)脱胶工艺和常规水化脱胶工艺进行优化,按照国标要求,对两种不同脱胶方式生产的菜籽油的磷脂含量、水分、过氧化值等基本指标进行检测,并对指标结果进行对比。确定了PLC用于菜籽毛油脱胶的最优工艺参数为p H5.4、酶添加量10μL/kg、酶解温度42℃,经PLC脱胶后菜籽油磷脂含量为7.45mg/kg;水化脱胶最优工艺参数为作用时间4.8h、操作温度86℃、加水量为毛油磷脂含量的3.2倍,经水化脱胶后菜籽油磷脂含量为76.32mg/kg。且酶法脱胶油整体上比水化脱胶油品质更好,酶法脱胶油经常规精炼后可达到国家一级油标准,该研究可为菜籽油酶法脱胶工业生产提供一定的理论参考。     

小桐子毛油酶法脱胶工艺研究及机理分析

以小桐子毛油为原料，应用复合磷脂酶通过单因素试验和正交试验开展酶法脱胶工艺研究。结果表明：在酶加量50 μg/g、pH5.5、反应温度50 ℃、转速350 r/min、反应时间2 h的条件下，脱胶后油中的磷、金属、氮等微量杂质含量明显减少，脱胶效果明显。在试验研究的基础上，并对毛油酶法脱胶机理进行分析。     

菜籽油酶法脱胶的研究

研究磷脂酶对菜籽油脱胶及品质的影响,通过单因素、正交试验并结合生产成本确定最佳工艺条件。结果表明最佳工艺参数为:酸碱比(V/V)1:4.5,加酶量88 mg/kg,反应温度50℃,反应时间4 h。在此条件下,菜籽油的磷含量可由原来的406.66 mg/kg降到3.42 mg/kg;采用棒状薄层色谱—氢火焰离子化检测器测菜籽毛油与脱胶油的甘油酯含量,脱胶油的甘油酯中甘一酯的含量变化不太明显,甘二酯的质量分数从毛油的2.50%增加到6.51%,而甘三酯的质量分数从96.08%降到90.46%。Rancimat法测定氧化稳定性后发现,脱胶油的氧化诱导时间由毛油的5.37 h增加到6.10 h,表明酶法脱胶后的菜籽油的氧化稳定性高于菜籽毛油;同时对水化脱胶磷脂与酶法脱胶磷脂中的溶血磷脂进行对比分析,其质量分数分别为10.71%和65.76%,酶法脱胶的酶解率达65.72%。     

酶法脱胶在大豆油脱胶中的应用

研究了PLA1酶法脱胶的影响因素,确定了实验室小试条件下PLA1酶法脱胶最佳工艺参数;并采用PLA1、PLC单酶脱胶以及PLC耦联PLA1双酶脱胶3种脱胶方式在不同批次大豆毛油上进行了小试验证。结果表明：PLA1酶法脱胶最佳工艺条件为酶添加量20 mg/kg、水添加量3%、搅拌速度500 r/min、反应温度55 ℃、反应时间2 h,在此条件下大豆毛油含磷量降至10 mg/kg以内;相对于水化脱胶,PLA1单酶脱胶得油率提升0.74~0.91个百分点,PLC单酶脱胶得油率提升0.70~0.84个百分点,双酶脱胶得油率提升1.34~1.89个百分点。经中试生产验证,PLA1和PLC单酶脱胶与水化脱胶相比得油率分别提升0.63个百分点和0.91个百分点。     

山毛豆油磷酸辅助脱胶工艺条件优化

目的：研究酸种类、酸添加量、加水量、脱胶温度、搅拌时间对山毛豆毛油脱胶率的影响。方法：在单因素试验基础上,利用响应面分析法对山毛豆毛油脱胶工艺进行优化。结果：得到山毛豆酸辅助脱胶最佳工艺条件为磷酸添加量2.47g/kg、加水量4.1%、脱胶温度62℃、搅拌时间45min。该条件下山毛豆毛油脱胶率为92.48%,与模型预测值91.5256%接近,脱胶山毛豆油中磷脂含量为0.095%。结论：磷酸辅助脱胶技术可对山毛豆毛油中的磷脂进行有效脱除。     

菜籽油磷脂酶C脱胶工艺优化及效果分析

分别研究了柠檬酸添加量、酶加入量、温度、加水量和时间5个单因素对磷脂酶C(PLC)脱胶效果的影响,在单因素基础上,采用响应面试验设计,对主要脱胶工艺参数进行优化,得到最佳条件:柠檬酸添加量5.80m L/kg,加酶量12.60 m L/kg,酶解温度42.20℃,在该条件下验证,菜籽毛油磷含量由693 mg/kg降低至7.85mg/kg。采用棒状薄层色谱-氢火焰离子化检测器(TLC-FID)对毛油与脱胶油中甘油酯含量进行检测,结果表明:脱胶油中甘一酯的含量变化不明显,甘二酯含量从约2.5%增加到约6.5%,而甘三酯的含量从约93%下降到约89%;而同样采用TLC-FID对水化脱胶磷脂与PLC脱胶磷脂中的溶血磷脂进行检测,分析得知,PLC脱胶磷脂中溶血磷脂含量比水化脱胶磷脂中的高出约50%,酶法脱胶的酶解率显著升高。研究结果表明,磷脂酶C脱胶比常规水化脱胶更有效和彻底,可为油脂精炼提供了一定理论参考。     

青豆油脱胶工艺研究

对青豆毛油水化脱胶工艺路线中所添加酸的种类进行了研究,探讨了柠檬酸、磷酸、柠檬酸与磷酸1∶1的混合液等3种酸溶液对青豆油脱胶率的影响效果,并对影响水化脱胶工艺的主要因素进行了单因素试验,以水化时间、水化温度、酸的添加量、加水量等4个因素为研究对象进行进行二次回归旋转正交试验,得出了该工艺的主要影响因素在该工艺中的最佳操作条件,添加的酸为磷酸:柠檬酸为1∶1的混合溶液、脱胶时间55 min、脱胶温度64℃、酸添加量0.4％、加水量6.9％.该条件下得到的青豆油最大脱胶率为11.08％.     

超声波处理对磷脂酶脱除菜籽油中磷脂的影响

研究酶解时间、酶添加量、含水量、pH值、酶解温度、多频超声波频率及组合,超声波功率和超声处理时间对菜籽毛油脱胶效果的影响。利用单因素试验对菜籽毛油超声辅助酶解脱胶工艺进行优化。优化的工艺条件为:磷脂酶A1用量为90μL/kg毛油,pH值为4.8,酶解反应温度为40℃,含水量为2%,超声功率为180 W,超声频率为20/50 kHz,超声时间为60 min。经多模式超声波辅助磷脂酶解脱胶后菜籽油磷脂含量为4.36 mg/kg,达到国家标准(≤10 mg/kg)的要求。该研究可为菜籽油酶法脱胶工业生产提供一定的理论参考。     

酶促大豆油脱胶的研究

探讨了大豆毛油在脱胶过程中利用LecitaseNovo磷脂酶作催化剂水解磷脂分子，在温和的条件下将毛油中水合的和非水合磷脂转变成溶血磷脂，从而能够用离心操作使其与水相一起被分离出来。通过对酶浓度、反应温度、反应时间、水分含量、pH值、搅拌速度等多项单因素的考查，得到大豆毛油的酶法脱胶工艺，该法的工艺参数为：酶浓度42μL／kg、反应温度42～44℃、反应时间2h、水分含量为1．2％左右、pH4．5、搅拌速度为120r／min，经离心分离去除胶质，可得到高质量的大豆磷酯和脱胶油．     

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.