不同乳酸菌发酵对玉米淀粉中直链淀粉含量的影响

以普通玉米淀粉为原料,研究了三种乳酸菌发酵对玉米淀粉中直链淀粉含量的影响。结果表明:三种乳酸菌发酵处理后,玉米粉中直链淀粉的含量都有不同程度的增加,并且随着发酵时间的增加,直链淀粉含量逐渐增大,达到最大值后,逐渐降低,其中嗜酸乳杆菌发酵5d处理的样品中直链淀粉含量最大,为32·69%。     

不同乳酸菌发酵对玉米淀粉中直链淀粉含量的影响

以普通玉米淀粉为原料，研究了三种乳酸菌发酵对玉米淀粉中直链淀粉含量的影响。结果表明：三种乳酸菌发酵处理后，玉米粉中直链淀粉的含量都有不同程度的增加，并且随着发酵时间的增加，直链淀粉含量遥渐增大，达到最大值后，逐渐降低，其中嗜酸乳杆菌发酵5d处理的样品中直链淀粉含量最大，为32．69％。     

荧光光谱法测定淀粉中的直链淀粉

为了建立一种荧光光谱法测定淀粉中直链淀粉含量的方法,采用荧光光谱法测定了直链淀粉的激发光谱和发射光谱以及直链淀粉与支链淀粉的浓度比对荧光强度的影响。结果表明:直链淀粉的激发波长为370 nm、发射波长为422 nm;在0.10~0.70 μg/mL浓度范围内,直链淀粉荧光强度与其浓度呈良好线性关系,相关系数r=0.9996,检出限为0.026 μg/mL。用该方法测定玉米淀粉和土豆淀粉中直链淀粉的含量,加标回收率为94.5%~121.7%,相对标准偏差(RSD)为2.42%~3.24%。该方法不需加任何生化试剂,不受时间、温度、共存支链淀粉的影响,快速简便,绿色环保,检出限低,结果准确。     

非晶颗粒态玉米淀粉制备羧甲基淀粉

以非晶颗粒态玉米淀粉、氯乙酸为主要原料,用乙醇溶剂法制备羧甲基淀粉。研究了反应温度、时间、氯乙酸、淀粉乳浓度、水分含量对样品取代度(DS)的影响。结果表明:在淀粉乳浓度20%,n(氯乙酸):n(淀粉) =1:4,n(NaOH):n(淀粉)=1:2,乙醇溶剂含水30%条件下,55℃反应4h得到较高取代度的羧甲基淀粉。     

直链淀粉含量对玉米淀粉/瓜尔胶复配体系糊化和流变特性的影响

为考察直链淀粉含量对淀粉/瓜尔胶复配体系性质的影响,以不同直链淀粉含量的玉米淀粉(蜡质玉米淀粉、普通玉米淀粉和高直链玉米淀粉)为原料,加入瓜尔胶,研究复配体系的糊化、流变及凝胶特性。结果表明:瓜尔胶与直链淀粉之间的相互作用是引起淀粉复配体系黏度和稠度系数增加、成糊温度和流体指数降低的主要原因。动态流变实验结果表明淀粉中直链淀粉含量不同对复配体系的动态模量的影响也不同。在糊化过程中,随着直链淀粉含量增加,直链淀粉分子与瓜尔胶间的相互作用增强,阻碍了直链淀粉分子间的聚集重排,使得复配体系硬度值减小,3种玉米淀粉形成了质地更为柔软的凝胶。     

直链淀粉含量对玉米淀粉/瓜尔胶复配体系糊化和流变特性的影响

为考察直链淀粉含量对淀粉/瓜尔胶复配体系性质的影响,以不同直链淀粉含量的玉米淀粉(蜡质玉米淀粉、普通玉米淀粉和高直链玉米淀粉)为原料,加入瓜尔胶,研究复配体系的糊化、流变及凝胶特性。结果表明:瓜尔胶与直链淀粉之间的相互作用是引起淀粉复配体系黏度和稠度系数增加、成糊温度和流体指数降低的主要原因。动态流变实验结果表明淀粉中直链淀粉含量不同对复配体系的动态模量的影响也不同。在糊化过程中,随着直链淀粉含量增加,直链淀粉分子与瓜尔胶间的相互作用增强,阻碍了直链淀粉分子间的聚集重排,使得复配体系硬度值减小,3种玉米淀粉形成了质地更为柔软的凝胶。     

直链淀粉含量对玉米淀粉/PVA混溶性及成膜性能的影响

以不同直链淀粉含量的玉米淀粉与聚乙烯醇(PVA)为原料制备共混液及薄膜,以初显分离时间和沉降率为量化指标,研究了直链淀粉含量对玉米淀粉与PVA浆液混溶性的影响;对不同直链淀粉含量的共混膜进行力学性能测定、SEM形貌表征及生物降解性试验。结果表明:随着直链淀粉含量增大,共混液的初始相分离速度和分离程度都显著减小,提高了浆液稳定性;随着共混膜中直链淀粉含量的增加,提高了玉米淀粉和PVA之间的相容性,从而表现出更好的力学性能;随着直链淀粉含量的增加,共混膜的降解速率增大。该研究结果为探讨玉米淀粉/PVA共混体系相稳定性及浆液成膜性能的研究,提供了理论依据和应用价值。     

葛根淀粉提取及直链、支链淀粉的双波长测定

以淀粉提取率为指标,采用正交实验研究了葛根淀粉的加工工艺,并确定了最佳工艺参数为:料水比为2:17,浸泡液的pH为8.5,浸泡时间为1h;同时采用双波长分光光度法对葛根中直链淀粉和支链淀粉的显色反应和光度测定的最佳条件进行了详细的考察,根据吸收光谱,确定直链淀粉的测定波长为617nm和476nm,支链淀粉的测定波长为415nm和532nm,建立回归方程并求得葛根淀粉中直链淀粉的含量为18.29%,支链淀粉的含量为77.24%.     

花生淀粉的提取及性质研究

从脱脂花生蛋白粉制取花生分离蛋白后的副产物中提取纯化花生淀粉,并对其性质进行了研究.结果表明,花生淀粉提取的最佳工艺条件为:将制取花生分离蛋白后的副产物添加到浓度为4g/L的氢氧化钠溶液中,液固比为3:1,温度为25℃,浸提4 h,3 000 r/min离心20 min,得到淀粉的纯度为95.72%,提取率为55.37%.测定了花生淀粉中直链淀粉含量、透明度、凝沉性、溶解度与膨胀度、糊化温度、黏度等性质.结果表明,花生淀粉中直链淀粉含量为22.98%,透明度为29.5%,介于玉米淀粉和马铃薯淀粉之间;凝沉性很低;溶解度与膨胀度不同于玉米淀粉,在75℃膨胀较快;糊化温度为60～66℃,不易糊化;花生淀粉在75℃时出现黏度峰值为542 mPa·s.     

生姜淀粉的基本性质

研究生姜淀粉糊的相关性质。结果表明:生姜淀粉中直链淀粉含量为27.47%,糊化温度为84.98℃;随着淀粉乳质量分数、淀粉乳pH值的增加,淀粉糊黏度增大;随着剪切速率的增加,存在剪切稀化的现象;淀粉糊溶解度、膨胀度均较小,且都随着温度的增加而增加;透明度为8.20%;具有触变性;凝沉体积为73%;冻融稳定性不强,蔗糖添加量较大时能增强生姜淀粉糊的冻融稳定性。     

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.     

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