蛋壳膜中透明质酸的提取及部分特性研究

分别采用胰蛋白酶和胃蛋白酶降解蛋壳膜,从中提取透明质酸。通过正交实验考察酶解温度、pH、酶用量、料液比和酶解时间对透明质酸提取量的影响,确定采用胰蛋白酶酶解的最佳条件为:温度为50℃,时间为7h,料液比为1∶40,酶用量为8000U/g,pH为8.5,提取率为13.294mg/g;采用胃蛋白酶酶解的最佳条件为:温度为37℃,时间为5h,料液比为1∶40,酶用量为11000U/g,pH为3.0,提取率为24.494mg/g。结果表明,胃蛋白酶提取透明质酸的效果好于胰蛋白酶,且壳膜中含有重要数量的透明质酸。通过红外光谱分析和测定葡萄糖醛酸、氨基葡萄糖的含量,对提取的透明质酸进行分析鉴定。      

双酶复合法提取蛋壳膜中透明质酸的研究

利用双酶复合法,以胰蛋白酶、木瓜蛋白酶复合提取蛋壳膜中透明质酸,通过响应面试验确定双酶法提取透明质酸的最佳工艺条件:料液比1∶40(m∶V),木瓜蛋白酶和胰蛋白酶的活性比1∶1,酶用量1 240U/g,温度50℃,pH值7.3,提取时间6h。该条件下,蛋壳膜中透明质酸的提取量为12.2mg/g.蛋壳膜。     

蛋壳膜中透明质酸的提取及部分特性研究

分别采用胰蛋白酶和胃蛋白酶降解蛋壳膜,从中提取透明质酸.通过正交实验考察酶解温度、pH、酶用量、料液比和酶解时间对透明质酸提取量的影响,确定采用胰蛋白酶酶解的最佳条件为:温度为50℃,时间为7h,料液比为1:40.酶用量为8000U/g,pH为8.5,提取率为13.294mg/g;采用胃蛋白酶酶解的最佳条件为:温度为37℃,时间为5h,料液比为1:40,酶用量为11000U/g,pH为3.0,提取率为24.494mg/g.结果表明,胃蛋白酶提取透明质酸的效果好于胰蛋白酶,且壳膜中含有重要数量的透明质酸.通过红外光谱分析和测定葡萄糖醛酸、氨基葡萄糖的含量,对提取的透明质酸进行分析鉴定.     

响应面法优化林蛙皮中透明质酸的提取工艺

以中国林蛙皮为原料,用透明质酸提取得率作为衡量提取工艺的指标。在单因素实验的基础上,在料液比1∶40（g/m L）的条件下,利用Box-Benhnken中心组合设计原理和响应面分析法探索了双酶（碱性蛋白酶+胰蛋白酶）水解的酶解温度、酶解时间(h_{碱性蛋白酶}=h_胰蛋白酶)、加酶量（碱性蛋白酶∶胰蛋白酶=1∶1）3个因素作为自变量及其交互作用对响应值透明质酸得率的影响,模拟得到二次多项式回归方程的预测模型,并确定最佳提取工艺条件为加酶量55000 U/g、酶解时间14 h、酶解温度50℃,在此条件下,平均透明质酸提取得率为27.6839 mg/g,葡萄糖醛酸的含量为13.8420 mg/g,转化成百分含量为42.2%。说明响应面优化双酶法提取林蛙皮透明质酸条件准确可行。      

可溶性蛋壳膜蛋白的提取工艺研究

鸡蛋壳膜中有多种有效成分,具有一定的深加工价值,研究开发可溶性蛋壳膜蛋白提取技术,可大大提高鸡蛋壳膜附加值。本试验采用乙酸-酶解联用分段提取技术对鸡蛋壳膜蛋白进行分离提取,通过单因素及正交试验得出乙酸提取中最优的工艺条件为乙酸浓度1.5 mol/L、提取温度70℃、液料比110∶1（mL/g）、提取时间4 h,蛋白提取率为17.2%;胃蛋白酶第二次提取的最优条件为酶添加量800 U/g、底物浓度6%、提取温度38℃、提取时间5 h,蛋白提取率为74.2%。综合一次和二次提取,鸡蛋壳膜蛋白的提取率高达91.4%。     

胰酶酶解猪骨素的工艺条件

利用胰酶酶解猪骨素并测定其酶解液的水解度.通过单因素试验确定胰酶水解猪骨素的酶解温度、pH值、酶用量、料液比(底物浓度)及水解时间,在此基础上用正交试验分析酶解的最佳工艺,在本试验条件下,酶解的最佳工艺为在温度45℃,pH7.5,酶用量8750U/g以及料液比1:12.5g/mL条件下酶解3h,此条件下水解度可以达到25.88%.     

正交试验优化纤维素酶法提取牛蒡根皮中绿原酸工艺

目的：研究纤维素酶法提取牛蒡根皮中绿原酸的提取工艺。方法：通过单因素试验探讨纤维素酶用量、料液比、酶解温度、酶解时间、pH值对绿原酸提取率的影响,并通过正交试验对影响绿原酸提取率的参数进行优化。结果表明牛蒡根皮中绿原酸提取的最佳工艺条件为纤维素酶用量4mL、酶解温度60℃、酶解时间1.5h、pH6.0、料液比1:20,此条件下绿原酸提取率为1.45%。     

响应面优化法酶解提取骨素工艺研究

利用响应面法对酶解提取鸡骨素工艺进行优化,分别对温度、加酶量和酶解时间进行响应面分析.确定适宜反应条件为温度63.48℃,加酶量在0.1％,反应时间1.83 h,料液比是1:1和自然pH.实际水解度为15.2％.     

酶法提取鸡蛋壳膜中透明质酸的工艺优化

以机械法分离得到鸡蛋壳膜,经预处理,以酶种类、酶用量、料液比、pH、酶解温度、酶解时间为考察因素,设计单因素实验。在此基础上设计L_9(3~4)正交实验,优化透明质酸提取的工艺条件,并对透明质酸提取物进行成分分析。结果表明,最佳提取工艺条件为复合胰蛋白酶80000 U/g、料液比1:40、p H9.0、酶解温度50℃、酶解时间7 h,透明质酸的提取量为23.694mg/g。提取物中透明质酸纯度较高,其成分为:氨基葡萄糖含量为30.2%,葡萄糖醛酸含量为32.9%。     

超声波辅助酶法提取小麦麸皮中阿魏酸的工艺研究

以小麦麸皮为原料,研究了在超声波辅助条件下利用木聚糖酶酶解小麦麸皮制备阿魏酸的最佳工艺条件.结果表明,通过正交试验确定超声波辅助酶法提取阿魏酸的最佳工艺参数为:超声功率150 W、超声时间20 min、酶解时间45 min、料液比1:10、酶解pH5.0、加酶量1.2%、酶解温度50℃,在此反应条件下的阿魏酸的提取率为94.48%.     

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.