小麦面筋蛋白乙酰化及琥珀酰化改性对功能性改善效果的比较及反应机理初探

本研究采用乙酸酐及琥珀酸酐对小麦面筋蛋白进行酰化改性，比较乙酰化及琥珀酰化改性对小麦面筋蛋白功能性的改善效果，对酰化反应的机理进行了初步研究。结果表明，在相同的反应条件下，琥珀酰化反应对小麦面筋蛋白功能性的改善效果强于乙酰化反应；小麦面筋蛋白的酰化是在面筋蛋白中引入酰基，改变蛋白结构，从而提高其功能性的过程。     

小麦面筋蛋白酶解特性研究

采用风味蛋白酶对小麦面筋蛋白进行深度水解,通过单因素实验,分析了底物浓度、温度、pH、酶用量、反应时间对水解度和蛋白质提取率的影响,并通过正交实验确定制备酶改性小麦面筋蛋白的最佳工艺参数为:底物浓度5%,T=50℃,pH6.5,酶用量=80LAPU/g,水解时间7h。反应最终可得水解度和蛋白质提取率均很高,且没有苦味的植物蛋白水解液,其中酶解液的水解度可达28.03%,蛋白质提取率可达52%。     

小麦面筋蛋白酶解特性研究

采用风味蛋白酶对小麦面筋蛋白进行深度水解,通过单因素实验,分析了底物浓度、温度、pH、酶用量、反应时间对水解度和蛋白质提取率的影响,并通过正交实验确定制备酶改性小麦面筋蛋白的最佳工艺参数为:底物浓度5%,T=50℃,pH6.5,酶用量=80LAPU/g,水解时间7h。反应最终可得水解度和蛋白质提取率均很高,且没有苦味的植物蛋白水解液,其中酶解液的水解度可达28.03%,蛋白质提取率可达52%。      

乙酰化马铃薯粉的变性工艺研究

研究醋酸酐用量、反应温度、反应时间和反应pH值对马铃薯粉乙酰化变性工艺的影响,采用正交实验找到马铃薯粉乙酰化改性的最佳工艺;制备乙酰化马铃薯粉的最佳条件为反应温度25℃、反应pH8.0、马铃薯与醋酸酐用量比例12∶1、反应时间1h。     

小麦面筋蛋白琥珀酰化修饰研究

采用琥珀酸酐对小麦面筋蛋白进行改性修饰，系统研究了底物浓度、改性剂用量和反应温度对反应程度、溶解性、乳化性、起泡性和泡沫稳定性等蛋白功能特性的影响。优化出小麦面筋蛋白琥珀酰化的最佳条件：琥珀酰化底物浓度10％，琥珀酸酐用量15％，反应温度45℃。应用红外光谱对最优条件下改性的面筋蛋白结构进行了表征。将琥珀酰化改性后的小麦面筋蛋白添加至小麦粉中，面团粘着性提高32％。     

复合改性对谷朊粉溶解性的影响研究

为了提高小麦面筋蛋白的溶解度,通过超声波功率、底物浓度、加酶量、温度和pH值的正交实验,研究了超声波-酶法复合改性小麦面筋蛋白的反应条件。以水解度和溶解度为评价指标,确定了在超声波作用下小麦面筋蛋白最佳的酶解条件:超声波功率210W,谷朊粉质量分数8%,加酶量质量分数0.6%,pH9.0,温度65℃,水解1h。结果表明,在该条件下小麦面筋蛋白的溶解度明显提高,溶解度达到12.16mg/ml。     

小麦面筋蛋白酶法去酰胺改性的研究

采用木瓜蛋白酶对小麦面筋蛋白进行去酰胺改性研究,实验得出最佳工艺条件为:物料浓度6%,加酶量E/S为1/200,反应pH=11.0,反应时间3h,反应温度25℃。小麦面筋蛋白经酶法去酰胺改性,溶解性及乳化性都大大提高。      

小麦面筋蛋白酶法去酰胺改性的研究

采用木瓜蛋白酶对小麦面筋蛋白进行去酰胺改性研究,实验得出最佳工艺条件为:物料浓度6%,加酶量E/S为1/200,反应pH=11.0,反应时间3h,反应温度25℃。小麦面筋蛋白经酶法去酰胺改性,溶解性及乳化性都大大提高。     

小麦面筋蛋白的性质和转谷氨酰胺酶对其成膜性能的影响

以小麦面筋蛋白为研究对象,探讨小麦面筋蛋白的性质,转谷氨酰胺酶的作用和制备条件对膜性能的影响。结果表明,酶用量为20U/g,反应时间为120min,pH为11,甘油/谷朊粉1:2.5,塑料平板作为成膜介质和乙醇体积分数均为40%～50%时,膜的抗拉强度增加51%,阻水性提高23%,透光率提高了5.48倍。扫描电镜显示膜的超微结构更加细致光滑。说明蛋白质的性质对其成膜性能的影响至关重要,酶处理有助于改善膜的机械性能和透光性,选择合理的制备条件,可得到性能优良的小麦面筋蛋白膜。     

脱酰胺作用对降解小麦面筋蛋白特性的研究

研究了在湿热条件下可食性有机酸(琥珀酸)对降解小麦面筋蛋白脱酰胺作用的特征。通过对改性小麦面筋蛋白(SDWG)的脱酰胺作用程度、氮溶指数、水解度等理化指标,以及热特性、分子量分布、蛋白质的二级结构表征湿热处理过程中SDWG分子聚集态变化特征。结果显示改性过程中小麦面筋蛋白分子的降解反应呈明显阶段性,在前10 min,当脱酰胺程度(从24.65%到64.79%),氮溶指数(从11.55%到91.31%),玻璃态转变温度(从50.70℃到61.80℃)和反应热焓[从1.73 J/(g·K)到2.35 J/(g·K)]均明显增加,但是小麦面筋蛋白水解度增加幅度仅小于1%,且SDS-PAGE和SE-HPLC检测到SDWG总体呈降解的反应趋势,然而红外光谱表示SDWG的分子柔性总体下降,特别反应第6 min,分子质量分布以及二级结构特征均呈现明显的改变。该数据表明在湿热条件下琥珀酸对小麦面筋蛋白的脱酰胺作用具有较高特异性,而小麦面筋蛋白解离特征呈现逐步降解和分阶段性。     

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.     

Announcing a new international peer-reviewed journal:Food Science and Human Wellness now accepting manuscript submission in English

<正>We are pleased to announce the launch of a new international peer-reviewed journal-Food Science and Human Wellness,ISSN 2213-4530,which is an open access journal,produced and hosted by Elsevier B.V.on behalf of Beijing Academy of Food Sciences.Food Science and Human Wellness is an international peer-reviewed English journal that provides a forum for the dissemination of the