低聚木糖分离纯化的研究

利用Freundlich吸附等温方程对活性炭和阴离子交换树脂的色素吸附效能进行了评价,选择活性炭Ly-T-ac和离子交换树脂D-301作为低聚木糖液中色素的吸附剂。通过单因素实验确定了低聚木糖液的活性炭脱色条件为:温度80℃,pH5.0,活性炭用量4%,脱色时间1.5h,活性炭对糖液的脱色率为81.40%。阴离子交换树脂D-301在9%用量,温度40℃脱色2.5h下对糖液的脱色率为40.50%。低聚木糖糖液经过阴阳离子交换树脂脱盐处理后,脱盐率为65.65%。     

营养性双糖——麦芽糖脱色工艺优化

麦芽糖是一种营养性双糖,采用粉末活性炭为脱色剂,以麦芽糖液的脱色率为考察指标,对其脱色工艺进行了研究,通过单因素实验和正交实验对麦芽糖脱色条件进行了优化,确定最佳的脱色工艺条件是活性炭用量2.5%(m/m)、脱色温度80℃、脱色时间20 min、pH值3.6,此时活性炭对麦芽糖液的脱色率为85.98%.     

活性炭-新磷酸钙对玉米芯低聚木糖脱色工艺优化

采用活性炭-新磷酸钙体系对高温蒸煮玉米芯酶法制备的低聚木糖进行脱色工艺研究。经过单因素试验和响应面分析,得出玉米芯低聚木糖脱色最佳工艺条件为:活性炭添加量2.00 g/L、氢氧化钙添加量3.00 g/L,脱色温度49℃,脱色时间31 min,初始pH 4.6。此时,低聚木糖脱色率可达到90.88%,还原糖损失率为5.16%。     

籼米淀粉酶法制备低聚异麦芽糖糖化转苷工艺研究

为提高碎米的综合利用程度和低聚异麦芽糖中异麦芽糖、潘糖和异麦芽三糖的含量,采用碎籼米淀粉酶法制备低聚异麦芽糖。以低聚异麦芽糖中异麦芽糖、潘糖和异麦芽三糖含量为考察指标,采用单因素实验和正交实验对糖化转苷工艺进行优化,确定最佳工艺参数为籼米淀粉液化液DE值为12,α-葡萄糖转苷酶用量为1.0U/(g淀粉),糖化转苷p H5.0、糖化转苷温度55℃、糖化转苷时间36h,在此条件下,低聚异麦芽糖中异麦芽糖、潘糖和异麦芽三糖的含量为(37.86±0.31)%,达到了中国发酵工业协会拟定的低聚异麦芽糖质量标准。     

低聚乳果糖的初步提纯

采用粉末状活性炭对低聚乳果糖酶反应液进行脱色，研究了活性炭用量、脱色温度和脱色时间对低聚乳果糖反应液脱色的情况，实验结果表明：当活性炭用量为3％，温度60℃，吸附时间45min，低聚乳果糖反应液的脱色效果明显，低聚乳果糖的损失率仅为3．33％。     

响应面法优化低聚果糖液脱色工艺

以粉末活性炭对酶法生产的低聚果糖溶液进行吸附脱色,研究活性炭的用量、脱色温度及脱色时间对脱色效果的影响。在单因素试验的基础上,利用响应曲面法对低聚果糖溶液脱色进行优化。得到最佳工艺条件为活性炭的用量22g/L、脱色温度60℃、脱色时间30min,在此条件下低聚果糖溶液的脱色率达79.16%。     

猪血粉酶解液脱色工艺研究

利用活性炭对猪血粉酶解液进行脱色,研究了活性炭用量、pH值、脱色温度和吸附时间对猪血粉酶解液脱色效果的影响。试验结果表明:活性炭对猪血粉酶解液具有理想的脱色效果,最佳脱色工艺参数为活性炭用量2.5%,pH 4.0,脱色温度60℃,吸附时间1.0h,在此最佳脱色工艺条件下脱色率达92.20%,同时氮损失率为10.42%。     

L-亮氨酸脱色工艺研究

采用活性炭对L-亮氨酸洗脱液的粗结晶溶液进行了脱色研究,考察了活性炭用量、pH值、脱色温度、料液浓度、脱色时间等工艺条件对脱色效果的影响,确立了最佳的工艺条件为活性炭加入量2％,脱色温度60℃,发酵液pH值为4．5,脱色时间为20min。     

雪莲果低聚果糖粗提液的活性炭脱色研究

以雪莲果低聚果糖粗提液为研究对象,用5种不同材质(核壳、煤质、椰壳、核桃壳、竹质)的活性炭对其进行脱色,以脱色率和低聚果糖保留率为指标,采用静态吸附法确定最佳脱色材料,在单因素试验的基础上,通过响应面法对脱色工艺进行优化。结果表明,椰壳活性炭的脱色效果最好,其最佳脱色条件为:溶液pH4、脱色温度40℃、脱色时间28.5 min、活性炭用量1.5 g/m L,此条件下低聚果糖粗提液的平均脱色率和低聚果糖保留率分别为88.5%和58.6%,实际总评"归一值"(OD值)与模型预测值相近。     

响应面优化活性炭对麦芽糖浆脱色的条件

本实验以麦芽糖浆为处理对象,以活性炭为脱色剂,研究使用活性炭为麦芽糖浆脱色的最佳条件。利用单因素实验和响应面分析法对麦芽糖浆的脱色工艺进行优化。结果表明:脱色的最佳工艺条件为活性炭用量1.4%、pH4.3、脱色时间32min、脱色温度51℃。此条件下麦芽糖浆的投射率达到99.07%。     

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