超声协同接枝反应改性大豆蛋白及其冻融稳定性

采用超声波技术促进大豆蛋白-葡聚糖(SPI-D)接枝反应,提高改性产物的冻融稳定性,研究SPI质量分数、SPI∶D质量比、超声反应条件(温度、功率、时间)对接枝产物的接枝度、褐变程度和冻融循环后乳析指数的影响。结果表明:SPI质量分数4%、SPI∶D质量比2∶3、超声反应温度80℃、超声反应功率500 W、超声反应时间40 min条件下,接枝度为32.43%,褐变程度为0.322。改性产物与对照相比,经1,2,3次冻融循环后乳析指数分别降低了57.76%,75.33%,96.20%,显著提高了改性产物的冻融稳定性。由Pearson相关系数和Lorentz函数拟合得知接枝度与冻融稳定性高度相关。红外光谱分析表明发生美拉德反应。紫外光谱分析表明超声SPI-D的分子结构较SPI疏松,其结构朝向有利于提高冻融稳定性方向转变。     

辐照辅助接枝反应提高大豆蛋白乳液冻融性质

采用辐照技术辅助大豆分离蛋白(soybean protein isolate,SPI)与麦芽糖(maltose,M)发生接枝反应,进而改善SPI乳液的冻融性质,研究SPI质量分数、m(SPI)∶m(M)、辐照剂量对改性产物的接枝度、褐变程度和乳析指数的影响。结果表明,在SPI质量分数4%、m(SPI)∶m(M)为4∶1和辐照剂量7.5 kGy的条件下,经历1、2、3次冻融循环后,与SPI相比,改性SPI乳析指数分别降低了23.58%、29.9%和31.2%。十二烷基硫酸钠-聚丙烯酰胺凝胶电泳结果证实SPI与麦芽糖发生接枝反应。改性SPI乳液经过冻融循环的出油率与SPI相比得到明显改善。光学显微镜观察结果也证实优化后的SPI微观结构更稳定。研究表明辐照能够辅助接枝反应,提高大豆蛋白乳液冻融性质,为综合改性技术提供新思路。     

大豆分离蛋白与单糖、双糖、多糖共价复合物的冻融特性及结构表征

研究糖种类对大豆分离蛋白(soybean protein isolate,SPI)-糖共价复合物冻融特性的影响,以改性产物的乳化性质和乳析指数为指标,研究SPI与葡萄糖(glucose,G)、麦芽糖(maltose,M)和葡聚糖(dextran,D)共价复合产物冻融特性的变化,并分析改性产物的出油率、接枝度、傅里叶变换红外光谱、荧光光谱变化情况。结果表明,在反应温度80℃、反应时间3 h、蛋白质量分数4%、SPI与M质量比4∶1的条件下,SPI-麦芽糖共价复合物(SPI-M)的乳化活性和乳化稳定性分别是对照样品的1.41倍和1.29倍,经过3次冻融循环后,乳析指数分别降低了29.68%、28.3%、29.57%,出油率分别降低了4.8%、16.8%、22.6%,SPI-M的冻融稳定性显著提高,且SPI-M的乳化性和冻融稳定性均好于SPI-葡萄糖共价复合物(SPI-G)和SPI-葡聚糖共价复合物(SPI-D)。接枝度分析表明SPI-M的接枝度明显高于SPI-G和SPI-D的接枝度;傅里叶变换红外光谱分析表明糖分子以共价键的形式接入到SPI分子中;荧光分析表明蛋白结构发生改变。     

超声糖基化大豆分离蛋白冻融稳定性的研究

本文采用超声波技术促进美拉德反应改性大豆蛋白提高其冻融稳定性。比较研究了由大豆分离蛋白(SPI)、大豆分离蛋白+葡聚糖(SPI+D)混合物以及超声SPI-D接枝物作为乳化剂的乳液的冻融稳定性,分析了乳析指数、出油率、絮凝程度、聚结程度、粒径、zeta电位、显微结构等性质,与SPI相比,经过3次冻融循环后超声SPI-D制备的乳液仍保持较好的稳定性,其乳析指数和出油率分别降低了96.20%、80.53%,粒径维持在50~60μm范围内,呈窄单峰分布,絮凝程度和聚结程度分别降低了187.8%、235.3%。zeta电位和显微结构可以看出其乳液仍处于相对稳定的状态。扫描电镜研究得知改性后蛋白颗粒状态更加疏松,大小均匀,分子间聚集程度显著降低。超声SPI-D乳化体系具有较好的冻融稳定性,为生产出冷冻产品专用大豆分离蛋白提供理论依据。     

冻融循环对酶切糖基化大豆蛋白稳定性的影响

为研究酶切糖基化大豆蛋白的实际应用效果,采用限制性酶切大豆分离蛋白(SPI)-葡聚糖糖基化产物,以表面吸附量、乳析指数、平均粒度、显微结构为评价指标,比较了分别由SPI、SPI与葡聚糖的糖基化产物(SPID)、酶切糖基化大豆蛋白产物作为乳化剂的乳化体系的冻融稳定性。结果表明,经3次冻融循环后,酶切糖基化大豆蛋白产物乳化体系仍保持较好的稳定性,显著高于SPI、SPI-D对照组。限制性酶切糖基化大豆蛋白可用于改善食品乳化体系的冻融稳定性,为生产冷冻产品专用大豆蛋白提供理论依据。     

抗冻融大豆蛋白的制备

采用湿法美拉德反应对大豆蛋白进行糖基化改性,研究了糖基化接枝产物的冻融稳定性。结果表明,湿法糖基化大豆蛋白能有效提高接枝产物的冻融稳定性,在SPI(大豆分离蛋白)浓度40 mg/m L、蛋白与糖质量比1∶3、反应时间4 h、p H 8.0、反应温度95℃条件下的接枝物冻融前后的EAI(乳化活性)分别是未改性蛋白的1.69倍和1.76倍,ESI(乳化稳定性)是未改性蛋白的1.37倍和1.27倍。傅里叶红外光谱分析表明,SPI-D接枝物在1 000 cm-1附近有较强的吸收,在3 700~3 200 cm-1处有一个更宽的振动伸缩吸收,葡聚糖以共价键的形式接入到SPI上。SPI-D接枝物在激发波长为347 nm,发射波长在435 nm处有最大的荧光强度,符合美拉德反应产物的荧光特性,进一步证明SPI与葡聚糖发生了美拉德反应。     

转谷氨酰胺酶对大豆分离蛋白乳状液冻融稳定性的影响

采用转谷氨酰胺酶（transglutaminase,TGase）改性提高大豆分离蛋白（soybean protein isolate,SPI）乳状液冻融稳定性。以出油率和分层系数为稳定性指标,研究TGase交联时间、添加量、冻融循环次数对SPI乳状液冻融稳定性的影响。通过显微结构、热特性分析比较研究由SPI、TGase改性SPI作为乳化剂乳状液的冻融稳定性,利用十二烷基硫酸钠-聚丙烯酰氨凝胶电泳分析酶改性对SPI组成的影响,进而分析与乳状液稳定性的关系。结果表明：经过3 次冻融循环后改性SPI制备的乳化剂仍保持较好的冻融稳定性,TGase交联时间3 h、添加量1.5%时稳定性较好,微观结构可看出改性SPI乳状液处于相对稳定状态。乳状液冻融过程中热特性的差异,反映出改性蛋白在冻融过程中乳状液结晶及融化的热行为得到了改变。十二烷基硫酸钠-聚丙烯酰氨凝胶电泳结果表明酶改性使蛋白组成发生改变,从而影响大豆蛋白的冻融稳定性。TGase改性大豆蛋白具有较好的冻融稳定性,为其在冷冻食品中应用提供理论依据。     

葡聚糖接枝对大豆蛋白功能特性及结构的影响

采用干热糖基化对大豆分离蛋白进行改性,研究其功能特质及结构特性。以葡聚糖和大豆分离蛋白(soy protein isolate,SPI)为原料,考察底物质量比和反应时间两个因素。结果表明:蛋白质与糖质量比2∶1,反应温度60℃时,产物接枝比较高,褐变程度中等;与SPI相比,糖基化之后大豆蛋白的溶解度提高了72.72%,乳化活性(emulsifying activity,EAI)和乳化稳定性(emulsion stability,ESI)分别提高了117.53%和134.20%。十二烷基硫酸钠聚丙烯酰胺凝胶电泳(sodium dodecyl sulfate-polyacrylamide gel electrophoresis,SDS-PAGE)表明SPI与葡聚糖发生了糖基化反应;傅里叶红外光谱(Fourier transform infrared spectroscopy,FT-IR)和荧光光谱分析表明,糖链的引入导致了大豆蛋白空间结构的变化;模拟体外消化特性结果表明,葡聚糖糖基化修饰对SPI体外消化性的改善效果不明显。     

微波辅助糖基化对大豆分离蛋白乳化性的影响

该文采用微波辅助糖基化改性大豆分离蛋白以提高大豆分离蛋白(soybean protein isolate,SPI)的乳化性。通过单因素实验研究微波时间、大豆分离蛋白与葫芦巴胶质量比、糖基化反应时间、反应温度对改性大豆分离蛋白乳化性的影响,并运用响应面法优化微波辅助糖基化改性大豆分离蛋白的最佳工艺条件,研究结果显示,在微波时间3 min、SPI与葫芦巴胶质量比1∶3、反应时间41 min、反应温度58℃时,改性大豆分离蛋白乳化性达到最高,糖基化程度达到最佳的水平,与只进行微波改性的大豆分离蛋白相比,乳化活性提高了51.33%,乳化稳定性提高了294.14%;与未改性的大豆分离蛋白相比,乳化活性提高了88.67%,乳化稳定性提高了788.84%。利用红外光谱和紫外光谱表征改性产物,结果表明大豆分离蛋白与葫芦巴胶发生了糖基化反应。     

氮气对改性大豆分离蛋白功能性的影响

利用氮气对大豆分离蛋白 (SPI)进行改性 ,研究结果表明充氮气、反应温度、反应时间、充氮量四因素对SPI改性均有影响。通过正交试验确定了经氮气改性的SPI凝胶性、保水性、乳化性和乳化稳定性的 4组最佳处理组合。试验表明改性后SPI的凝胶性、保水性、乳化性和乳化稳定性分别比对照样提高了 10 0 %、 2 10 %、 7%和 91%。     

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