复合酶法制备多孔淀粉条件的优化

采用α-淀粉酶和糖化酶复合水解法,以玉米淀粉为原料制备具有较高吸油率的多孔淀粉,研究了复合酶的作用条件对多孔淀粉吸油率和得率的影响,通过测定多孔淀粉的吸油率及扫描电镜分析,对多孔淀粉制备条件进行了优化.试验结果表明,α-淀粉酶在50℃、pH 6.0、水解14 h后,再在pH 4.0、50℃加入糖化酶水解14 h,α-淀粉酶和糖化酶配比为1:2,总酶量为2%时,制得多孔淀粉的吸油率56.62%、得率88.79%.扫描电镜结果显示淀粉颗粒表面小孔分布均匀,孔径适中,孔较深.     

酶法制备多孔玉米淀粉及其显微结构的研究

采用α-淀粉酶和糖化酶双酶协同制备多孔玉米淀粉,研究了加酶量、反应温度、pH值、时间等因素对多孔淀粉水解率和吸油率的影响,得出制备多孔玉米淀粉的最佳条件为:加酶量1%以淀粉干基计),酶配比(α-淀粉酶:糖化酶)1:2,反应温度55℃,pH 5.0,反应时间16 h,所得多孔淀粉的水解率为53.45%,吸油率为98.48%,并借助于偏光显微镜、扫描电子显微镜(SEM)对产品的显微结构进行研究.     

超声波辅助酶解制备多孔淀粉的研究

以玉米淀粉为原料酶解制备多孔淀粉,在酶解前、中、后分别用超声波处理,以水解率和吸油率为指标,探讨了超声波频率、超声时间、淀粉乳浓度等因素对所得产品成孔情况的影响;同时,用扫描电镜对多孔淀粉颗粒的微观形态进行了分析。结果表明,在酶解中用超声波间歇处理效果最好。在超声功率50%、超声时间30 min、淀粉乳浓度70%的条件下,所得多孔淀粉的水解率和吸油率最高,成孔情况最好,其吸油率比普通多孔淀粉提高56%。电镜微观形态分析显示,多孔淀粉微孔的水解率和吸油率的变化与其孔径、孔深及数目的变化相吻合。     

2种前处理方法对多孔淀粉吸油率的影响

为了制备高吸油率的马铃薯多孔淀粉,分别采用超声波和加热预处理辅助酶法处理马铃薯淀粉,研究超声波条件与加热预处理条件对多孔淀粉吸油率的影响。研究结果表明:超声波法最佳条件为超声时间30 min、超声功率600 W、酶解温度55℃、pH 6.5、酶用量1.5%,所得多孔淀粉的吸油率为71.34%;加热预处理最佳反应条件为淀粉乳质量浓度30 g/100 mL,加热温度50℃,加热时间为15 min,过筛细度80目,酶解条件同超声波法,制备的多孔淀粉吸油率为69.05%。因此,两种前处理方法都可用于制备多孔淀粉,但超声波辅助酶法优于加热预处理辅助酶法。     

多孔淀粉制备及对速冻水饺品质的影响研究

本文研究了α-淀粉酶酶解玉米淀粉后的多孔淀粉及其应用。从酶的用量、酶解温度、酶解时间三方面研究了对多孔淀粉得率和吸油率的影响,然后又采用正交试验优化多孔淀粉制备工艺。将制得的多孔淀粉添加到饺子馅和饺子皮中,添加量为2%时产品品质得分最高。     

超声波辅助制备醋酸酯多孔淀粉

以玉米多孔淀粉为原料,研究超声辅助处理对制备醋酸酯多孔淀粉的影响,以及对醋酸酯多孔淀粉吸油率的影响。实验结果表明,超声波辅助处理对多孔淀粉的醋酸酯化反应作用明显,在超声功率为200 W,超声时间为150 min时取代度和吸油率分别能达到0.055 9和89.1%,跟未经过超声的醋酸酯化多孔淀粉相比,取代度提高了64.4%,吸油率提高了13.9%,在此超声处理条件下酯化后多孔淀粉的蜂窝状孔洞未被破坏,相对结晶度与多孔淀粉原料相比,下降16.1%。     

3种多孔淀粉载体性质及吸附精油缓释性研究

以玉米淀粉为原料,分别制备酶解、三偏磷酸钠(STMP)交联酶解和辛烯基琥珀酸(OSA)改性多孔淀粉载体,通过吸水率和吸油率评价吸附性,扫描电镜(SEM)观察形貌特征,激光共聚焦显微镜(CLSM)观察精油分布,并测定淀粉载体对精油的缓释效果。结果显示3种多孔淀粉的吸油率较原淀粉都有显著性提高(P0.05),OSA多孔淀粉吸油率最高。SEM观察到STMP多孔淀粉有较大空腔,CLSM观察到精油充分吸附在了多孔内部;OSA多孔淀粉对精油保留率最佳,其缓释曲线符合动力学一级和二级方程。     

硬脂酸多孔玉米淀粉酯的性质与结构研究

对以多孔玉米淀粉为原料经干法酯化制备的硬脂酸多孔玉米淀粉酯进行性质测定。与多孔玉米淀粉进行比较,考察了吸油率和比表面积,并对产品做了结构分析。结果显示:酯化后的淀粉无论在吸油率还是比表面积上都比未经酯化处理的多孔淀粉都有所增大。     

新型交联活性玉米多孔淀粉的制备及工艺优化

以玉米淀粉为原料,经过三偏磷酸钠交联及高温溶胀活化处理制备交联活性玉米,再采用酶水解法制备新型交联活性玉米多孔淀粉。通过粒径及BET分析,发现淀粉颗粒明显膨胀,比表面积增大。以吸水、吸油率的大小为指标衡量多孔淀粉的吸附性能,通过单因素及正交试验,考察了淀粉乳浓度、加酶量、酶解温度、酶解pH、酶解时间对吸附性能的影响,并对酶解工艺进行优化。结果表明,最佳的酶解工艺为淀粉乳浓度15%,加酶量2.0%,酶解温度45℃,酶解pH 4.4。此时所得交联活性多孔淀粉的吸水率为172.8%,吸油率为144.8%。     

脉冲电场协同酶解提高多孔淀粉制备效率及吸油率

以蜡质玉米淀粉为原料,采用脉冲电场(PEF)协同酶解制备多孔淀粉,探究其对多孔淀粉制备效率及吸油率的影响。结果表明:通过PEF改性后,淀粉水解率达到24.28%时所需的酶解时间缩短一半;在相同加酶量的条件下,通过PEF改性后,淀粉水解率为23.11%,较原淀粉显著提高,表明通过PEF改性可降低加酶量;在酶解6 h和加酶量为0.8×10~(-2) mL/g淀粉干基的条件下,经PEF改性协同酶解制备的多孔淀粉水解率为23.11%、吸油率为145.11%、比表面积为1.25 m~2/g,总孔容为4.31 cm~2/g×10~(-3),原淀粉酶解制备的多孔淀粉上述指标分别为18.38%、119.47%、1.16 m~2/g,4.15 cm~2/g×10~(-3),表明通过PEF改性提高酶解淀粉的水解率、吸油率、比表面积和总孔容。扫描电镜结果显示,PEF改性可使淀粉表面产生凹槽状结构;激光共聚焦显微镜观察显示,PEF改性提高了淀粉颗粒对淀粉酶的敏感性;热力学性质测试结果显示,PEF改性多孔淀粉的焓值低于原淀粉,表明PEF改性破坏了淀粉颗粒内部分致密的结晶区。本项研究揭示了PEF改性对淀粉颗粒及其酶解制备多孔淀粉的构效关系,为高效制备多孔淀粉提供了一个新思路,并拓展了PEF可应用的领域。     

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.     

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     

Chinese CTP Market

According to Printing and Printing Equipment Industries Association of China（PEIAC）＇s statistics to the plate manufucturer in China, in 2013, the actual offset plate production has reached 346 million square meters in China. Among them, the CTP production volume was 245 million square meters, up by 11% than that of last year; the total sales of the CTP plate was 239 million square meters, up by 13%.     

Preparatory Work of Print China 2015 is Going Smoothly

正Held at Guangdong Modern International Exhibition Center,Print China 2015 will cover 7exhibition halls,besides the original Hall No.3,4,5,6,7,the newly built F zone of Hall 3 will be used too.The total area will be140,000 square meters.Hall 3:Offset and large printing equipment,package printing equipment,post press