干热条件下大豆分离蛋白-壳寡糖美拉德反应及产物表征

对不同质量比的大豆分离蛋白（SPI）与壳寡糖（COS）在干热条件下的美拉德反应及产物性质进行系统性研究,以420 nm和290 nm下的吸光值、游离氨基酸、糠氨酸和5-羟甲基糠醛等的变化来监测美拉德反应的进程,并对美拉德反应产物的Zeta-电位、溶解性、乳化性、热性能、荧光强度等进行表征。结果表明:SPI与COS之间的美拉德反应程度随体系中COS比例的增大而增大;与SPI-COS混合物相比,SPI与COS的美拉德反应产物的Zeta-电位、溶解性、热稳定性均降低,SPI:COS为8:1时Zeta-电位最低达到?33.8 mV;SPI与COS之间的美拉德反应提高了SPI的乳化能力,其中SPI:COS为8:1时乳化活力最强,较SPI-COS混合物提高了509.3%,4:1时乳化稳定性最好,较混合物提高了183.3%。因此,SPI与COS之间的美拉德反应有效的提高了SPI的乳化性能,有望作为一种新型的乳化剂在食品领域广泛应用。     

pH和阿拉伯胶对大豆分离蛋白/大豆蛋白酶解产物乳化性质的影响

研究了pH和阿拉伯胶对大豆分离蛋白(soy protein isolate,SPI)或低限度酶解改性产物的乳化性质的影响。结果表明:SPI酶解改性处理后制备的乳液颗粒粒径和液滴间絮凝程度明显降低;添加阿拉伯胶促进了SPI或大豆蛋白酶解产物(soy protein hydrolysate,SPH)在油水界面的吸附,SPH-阿拉伯胶复合物制备的乳液在pH4的条件下室温放置14 d具有较好稳定性;添加阿拉伯胶前后,SPH制备的乳液黏度均低于SPI。     

糖基化反应对大豆蛋白-乳糖复合物抗原性及结构的影响

本文将乳糖通过糖基化反应引入到大豆分离蛋白(SPI)上制备大豆分离蛋白-乳糖复合物,采用间接竞争ELISA法测定不同温度、不同质量比、不同反应时间下大豆分离蛋白-乳糖复合物中β-伴大豆球蛋白的抗原性变化,并对糖基化产物进行了结构特性的研究。结果表明,糖基化能有效降低β-伴大豆球蛋白的抗原性,其抗原性从93.79%降到37.75%。糖基化改性后,大豆蛋白中游离氨基含量降低,在反应60 h时,游离氨基含量下降最大;傅里叶红外光谱结果表明,与原大豆分离蛋白相比,大豆分离蛋白-乳糖糖基化产物的α-螺旋、β-转角、无规卷曲的含量下降,而β-折叠的含量增加;SDS-PAGE电泳及PAS染色结果表明,随着糖基化反应的程度增加,SPI谱带逐渐的减弱,说明SPI与乳糖分子发生了共价连接。     

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。     

湿法糖基化改性大豆分离蛋白在低致敏千页豆腐中的应用

为寻求高效的糖基化改性条件和良好的应用途径，本文以葡萄糖、木糖两种单糖为糖基供体，探究反应时间、反应温度、蛋白与糖比例、蛋白浓度对大豆分离蛋白湿法糖基化反应的影响，分析大豆分离蛋白-葡萄糖复合物(SPI-葡萄糖)、大豆分离蛋白-木糖复合物(SPI-木糖)致敏性的变化，并将SPI-葡萄糖、SPI-木糖应用于低致敏千页豆腐生产。结果表明，木糖相较于葡萄糖更易与大豆分离蛋白发生糖基化反应，但也更容易有类黑素产生。在蛋白浓度为25 mg/mL时，糖基化反应程度最高，并且糖基化反应程度与反应温度、反应时间、糖添加量呈正相关。SDS-PAGE和傅里叶变换红外光谱分析结果表明糖基化改性使大豆分离蛋白和糖分子发生了共价结合，SPI的自由氨基减少。糖基化反应程度越高，SPI致敏性越低，SPI-木糖接枝物致敏性降低程度最高可达50%，以其为原料经谷氨酰胺转氨酶(TG酶)交联所制作的千页豆腐有良好的弹性和咀嚼性。     

大豆分离蛋白的双酶改性改善功能性的实验

对大豆分离蛋白(SPI)进行传统改性,只可以改善一个或几个功能性,而SPI的溶解性和分子量不能兼得。利用中性蛋白酶和谷氨酰胺转胺酶(TG)对大豆分离蛋白进行复合改性,通过单因素和正交实验研究了中性蛋白酶酶解的最佳工艺条件:温度60℃、时间0.5h、pH7.0、酶用量4000U/g,SPI溶解性可达97.9%;再经过TG改性,所得的聚合物虽然有很大的分子量,还可以改善SPI的溶解性,并且乳化性、发泡性均有提高。     

双酶复合改性增强大豆分离蛋白溶解性研究

传统方法对大豆分离蛋白(SPI)进行改性,一般只可改善一个或几个功能性,而SPI溶解性和分子量不能兼得。利用中性蛋白酶和谷氨酰胺转胺酶(TG)对大豆分离蛋白进行复合改性,通过单因素和正交实验研究,中性蛋白酶酶解最佳工艺条件:温度60℃,时间0.5小时,pH7.0,酶用量4000u/g,SPI溶解性可达97.9%;再经TG改性,所得聚合物虽有很大分子量,但还可改善SPI溶解性,并且乳化性、发泡性均有提高。     

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。     

酰基转移现象对大豆蛋白-磷脂酶解物相互作用及乳化特性的影响

通过联合采用核磁共振氢谱与三维荧光光谱技术,针对酶解过程中酰基转移现象对复合体系中大豆分离蛋白-磷脂酶解物相互作用及乳状液乳化稳定性、储存稳定性的影响机理进行探究。结果显示:在大豆分离蛋白乳液、大豆分离蛋白-磷脂复合乳液、大豆分离蛋白-磷脂4 h酶解物复合乳液、大豆分离蛋白-磷脂8 h酶解物复合乳液4种样品中,大豆分离蛋白-磷脂4 h酶解物复合乳液具有最佳的乳化稳定性、储存稳定性。而磷脂经8 h酶解由于酰基转移现象的发生,溶血磷脂会部分转变成甘油磷脂酰胆碱,导致其与大豆蛋白之间相互作用减弱,稳定性有所下降。因此,适度酶解时间磷脂酶解产物的添加会促进其与大豆分离蛋白相互作用,在水油界面上形成较稳定的界面膜,从而提高乳液的乳化特性。     

高温短时干热法制备SPI-麦芽糊精糖基化产物及其乳化性的研究

采用高温(90,115和140℃)短时(2 h)干热法制备了大豆分离蛋白(SPI)-麦芽糊精(MD)糖基化产物。利用接枝度和SDS-PAGE研究了SPI与MD发生糖基化反应的程度。同时考察了SPI-MD糖基化产物稳定水包油乳液的性质,并探讨了盐离子和热处理对SPI-MD糖基化产物稳定乳液的储藏稳定性的影响。试验发现,提高反应温度能增大糖基化反应的接枝度,且pH 3.0时,与添加盐离子或经过热处理的SPI,SPI-MD糖基化产物(90℃)和SPI-MD糖基化产物(115℃)稳定乳液相比,添加盐离子或经过热处理的SPI-MD糖基化产物(140℃)的稳定的乳液具有较高的乳化稳定性和储藏稳定性。     

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