纤维素酶催化大豆异黄酮的水解

为充分发挥大豆异黄酮生物价值,采用纤维素酶催化糖苷型大豆异黄酮水解制备游离苷元型大豆异黄酮。通过考察10种纤维素酶对糖苷型大豆异黄酮总水解率和苷元型大豆异黄酮总转化率的影响,筛选得到一种成本较低且水解效果较好的纤维素酶,用于催化水解糖苷型大豆异黄酮,优化了该纤维素酶在水解工艺中底物质量浓度、酶添加量、反应体系pH、酶解温度、酶解时间等参数。结果表明：选择来源于Trichoderma viride的纤维素酶作为大豆异黄酮水解用酶;底物质量浓度0.8～2.0 mg/mL、酶添加量7%～11%、反应体系pH 5.0、酶解温度55℃、酶解时间5～6 h是较经济有效的水解工艺参数,实验优化过程中,大豆异黄酮总水解率超过90%,总转化率接近60%。因此,采用纤维素酶催化水解大豆异黄酮可显著增加游离苷元含量,提高大豆异黄酮利用价值。     

两步水解酶法制备大豆异黄酮苷元初探

利用二步水解法制备大豆异黄酮苷元。经弱碱水解丙二酰基大豆异黄酮为糖苷型大豆异黄酮,再经果胶酶进一步水解获得富含苷元的大豆异黄酮。采用单因素试验和正交试验,得到果胶酶制备大豆异黄酮苷元的较优工艺条件:果胶酶水解时间20 min,水解温度47.5℃,水解pH值4.2,酶-底物质量比为0.80%。苷元水解得率为87.37%。     

酶解制备苷元型大豆异黄酮

以大豆异黄酮糖苷为原料,酶解制备苷元型大豆异黄酮。以水解率和苷元得率为指标对几种来源的β-葡萄糖苷酶、β-半乳糖苷酶、纤维素酶进行筛选,确定最适酶解用酶。通过单因素实验对酶添加量、底物质量浓度、酶解温度、pH、酶解时间进行优化。结果表明,最佳酶解工艺条件为：采用β-葡萄糖苷酶（300 U/g）,酶添加量7%,底物质量浓度1.6 mg/mL,酶解温度56 ℃,pH 4.8,酶解时间6 h。在最佳工艺条件下,大豆异黄酮糖苷的水解率及苷元得率分别达到96.84%和99.74%。     

酶水解对大豆异黄酮粗提物中苷元含量的影响

采用β-葡萄糖苷酶水解的方法将大豆异黄酮糖苷转化为苷元,以染料木素和大豆苷元含量为指标,通过单因素试验对水解过程中的不同影响因素进行了考察。以染料木素含量为指标,运用正交试验优化了β-葡萄糖苷酶水解大豆异黄酮的工艺条件为反应温度40℃、水解时间1.5h、水解介质pH4.5、水解底物浓度10mg/mL,在此条件下,水解得到的大豆异黄酮苷元中染料木素的含量可达到22.91%。     

β-葡萄糖苷酶水解、分离纯化大豆异黄酮甙元工艺研究

研究以低纯度的商品大豆异黄酮为原料,采用β-葡萄糖苷酶水解技术制备高纯度的大豆异黄酮甙元产品.比较系统地研究酶的用量、反应时间、反应温度、反应体系pH值、底物浓度等因素对酶水解效果的影响,最终得到酶水解制备工艺的最佳工艺参数.实验结果表明,采用该分离纯化工艺制备大豆异黄酮甙元产品,其产品得率、异黄酮回收率和产品纯度分别为12.12%、77.16%和92.78%,分离纯化效果比较理想.     

糖化酶水解大豆异黄酮

研究了糖化酶水解大豆异黄酮的技术工艺,利用糖化酶水解大豆异黄酮粉得到大豆异黄酮苷元。通过单因素试验对水解过程中的不同影响因素进行考察,运用正交试验优化了糖化酶水解大豆异黄酮的反应条件,优化结果为:水解温度55℃,pH值4.8,时间7 h,水解率可达98.18%。     

大豆异黄酮糖苷酶法水解工艺研究

通过正交试验及方差分析,得到大豆异黄酮糖苷酶法水解为大豆异黄酮苷元最佳工艺条件:在pH 6.0缓冲液体系中,酶解温度为38℃,酶解时间为90 min,加酶量为4.0 mg(4%),酶法水解率为82.55%。     

乳酸菌β-葡萄糖苷酶水解大豆异黄酮的研究

利用乳酸菌液态发酵得到一种高活性的大豆异黄酮水解酶--乳酸菌β-葡萄糖苷酶,通过单因素试验及正交试验优化了乳酸菌β-葡萄糖苷酶水解大豆异黄酮的条件.正交试验结果显示,当加酶量为25 μg/mL,水解温度50℃,水解时间2.0 h,pH 6.0时,黄豆苷水解率可达96.51%;在加酶量为25 μg/mL,水解温度40℃,水解时间2.0 h,pH 5.5时,染料木苷水解率为92.36%.     

响应面法优化酶法水解大豆异黄酮的条件

在单因素试验基础上,利用响应面分析(response surface analysis,RSA)法中Plackett-Burman和Box-Behnken进行设计,得出β-葡萄糖苷酶水解大豆异黄酮物质的最佳条件为:水解时间55 min,水解温度57℃,pH3.5.在最佳条件下,用β-葡萄糖苷酶水解大豆异黄酮得到大豆苷元,其得率达到39.05%.     

大豆异黄酮糖苷水解工艺的研究

通过正交试验得到了大豆异黄酮糖苷水解为大豆异黄酮苷元的最佳工艺条件。最佳酸法水解工艺条件为:盐酸浓度3 mol/L,水解温度80℃,水解时间180 min,酸法水解率为81.31%;最佳酶法水解工艺条件为:pH 6.0,酶解温度38℃,酶解时间90 min,加酶量为0.9 mg(50 mg糖苷型大豆异黄酮提取物),酶法水解率为82.54%。酶法水解的效果优于酸法水解的效果。     

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