高温加热对玉米淀粉糊化特性的影响

针对高温加热对玉米淀粉的影响进行分析。采用"120℃加热1~10 h"和"120℃~200℃加热1 h"两种方案对原淀粉进行处理,并使用偏光显微镜和Brabender黏度仪测试淀粉的颗粒形貌、偏光十字和糊化曲线。结果表明:淀粉的颗粒形貌无明显变化,只是在120℃下加热10 h或200℃加热1 h后,淀粉颗粒的棱角受到一定程度的破坏,变得比较圆滑;在120℃下加热8~10 h或在180℃~200℃下加热1 h后,淀粉颗粒的偏光十字逐渐模糊,少数淀粉颗粒发生了非晶化现象;随着加热时间的延长或温度的提高,糊化温度先增加后降低,而峰值黏度、热糊黏度和最终黏度都显著降低。     

高温处理对玉米淀粉应用性质变化的影响

探讨在100℃以上的高温处理后,玉米淀粉应用性质的变化,本实验对玉米淀粉进行蒸煮、焙烤、油炸的高温处理,并对高温处理后的淀粉颗粒形态、淀粉糊黏度、糊化温度及淀粉糊性质等进行检测和对比分析。结果说明,玉米淀粉经过蒸煮、焙烤和油炸处理后,淀粉颗粒形态发生很大变化;蒸煮和焙烤的玉米淀粉的溶解度和膨胀度都低于原淀粉,随温度升高而增加的趋势变缓;峰值粘度降低,粘度稳定性增加,冻融稳定性变化不大,淀粉糊透明度好于原淀粉。玉米淀粉油炸处理后,淀粉粒结构变化程度大,应用性质不及蒸煮、焙烤淀粉和原淀粉。     

干燥条件对玉米淀粉颗粒形态、色泽和糊化特性的影响

为了能对干燥后玉米的品质进行合理的评价,分别在自然干燥、热风干燥和真空干燥等干燥方式下处理玉米样品并测定了干燥玉米淀粉的颗粒结构、色泽及热学特性。结果表明:自然晾晒玉米、45℃低温干燥玉米淀粉颗粒有明显脐心和偏光十字;90℃高温干燥玉米的淀粉颗粒的脐点和偏光十字出现偏移和模糊。随着干燥温度的升高,玉米淀粉亮度、白度、峰值黏度、崩解黏度下降,最终黏度升高,糊化温度几乎没有明显变化。     

水分、温度、时间和pH对板栗淀粉颗粒形态的影响

以安徽大红袍板栗为原料,采用光学显微镜分析其在不同水分、温度、时间和pH条件下表观形态的变化.结果表明:随着淀粉体系中水分含量的升高,板栗淀粉颗粒越易膨胀破裂,水分含量达到70%后,大部分淀粉颗粒膨胀:加热温度和加热时间都能促进板栗淀粉颗粒膨大破裂,而加热温度对颗粒形态变化的影响较加热时间大;常温下中性和酸性条件对板栗淀粉颗粒膨胀的影响不大,而强碱性条件对板栗淀粉糊化有明显的作用,当pH达到13时,淀粉颗粒明显膨胀.     

湿热处理对不同淀粉理化特性的影响

以普通玉米淀粉、高直链玉米淀粉、马铃薯淀粉和绿豆淀粉为试验材料,研究湿热处理对不同淀粉颗粒形貌、颗粒大小、糊化特性以及抗消化特性的影响。结果表明,在淀粉乳水分含量为30%,在120℃处理湿热处理10h,不同来源的淀粉,其颗粒形貌变化不同,其中普通玉米淀粉和高直链玉米淀粉的部分颗粒间发生粘结,少许淀粉颗粒中出现了较小的颗粒,淀粉表面有较大的凹坑;马铃薯淀粉和绿豆淀粉部分颗粒形态发生变化,颗粒的脐点处出现凹坑、部分淀粉颗粒有破碎;但湿热处理前后淀粉的偏光十字没有明显变化。与原淀粉相比,不同来源淀粉经过湿热处理后淀粉糊的溶解度、膨胀度和透明度均降低,降低幅度因淀粉种类的不同而有差异。湿热处理能够提高抗性淀粉含量。湿热处理后淀粉的糊化特性发生变化,糊化温度升高,峰值黏度、低谷黏度和破损值降低。普通玉米淀粉和绿豆淀粉的最终黏度和回生值下降,马铃薯淀粉的最终黏度和回生值增大。     

聚焦光束反射分析仪测定淀粉糊化过程中糊化度的变化

利用聚焦光束反射分析仪(FBRM)分析了玉米淀粉、马铃薯淀粉和木薯淀粉在糊化过程中颗粒总数的变化,实现了淀粉颗粒变化的"动态"监测,并提出用颗粒总数的变化量/颗粒的初始总数来表示糊化度,简化了以往测量糊化度的方法。结果表明:FBRM测得的玉米淀粉颗粒总数呈先增加后减小的趋势,在70℃时下降幅度最大;马铃薯淀粉颗粒总数一直减小,在70℃时下降幅度最大;木薯淀粉颗粒总数也一直减小,但在65℃时下降幅度最大。FBRM测得玉米淀粉在70℃糊化度达到最大值60.05%,马铃薯淀粉在70℃糊化度达到最大值38.83%,木薯淀粉在65℃糊化度达到最大值54.66%;当温度达到75℃时,玉米淀粉,马铃薯淀粉和木薯淀粉总的糊化度分别为93.55%、90.19%和85.85%,它们都没有达到100%。     

超高压改性淀粉凝胶特性研究

以马铃薯淀粉及玉米淀粉为原料,在确定适宜淀粉乳浓度基础上,研究了超高压改性淀粉糊化特性、凝胶质构及冻融稳定性。结果显示,马铃薯淀粉较玉米淀粉更能耐受超高压,500 MPa处理会导致玉米淀粉部分糊化,而马铃薯淀粉颗粒形貌变化不大。适宜条件超高压改性有利于马铃薯淀粉及玉米淀粉形成更强的凝胶,所制备的凝胶硬度、黏性、咀嚼性较原淀粉明显增加。与玉米淀粉凝胶相比,马铃薯淀粉凝胶具有更好的冻融稳定性,超高压处理进一步增强了淀粉冻融稳定性,尤其是马铃薯淀粉经过一次冻融循环时,冻融稳定性较高。然而,淀粉部分糊化不利于形成高强度淀粉凝胶,且冻融稳定性亦变差。     

湿热处理对不同晶型淀粉理化性质及消化性的影响

采用三种不同晶型淀粉即玉米淀粉(A型)、马铃薯淀粉(B型)、豌豆淀粉(C型)为原料,在水分含量为25%、温度120℃条件下湿热处理13 h,研究湿热处理对不同晶型淀粉的理化性质及消化性的影响。研究表明,与原淀粉相比,经湿热处理的三种淀粉的结晶结构均发生了改变,玉米淀粉由A型变为了A+V型,马铃薯淀粉和豌豆淀粉分别由B型和C型变为了A型;三种淀粉颗粒表面均出现了不同程度的破损;三种淀粉的部分颗粒的偏光十字的中心强度有所减弱;三种淀粉样品的糊化温度均升高,但A型和B型淀粉的焓值降低,而C型淀粉的焓值升高;三种淀粉的抗性组分含量均有所升高,抗消化性显著增强,其中C型淀粉变化最明显。     

淀粉与转谷氨酰胺酶复配引起肌肉蛋白功能特性的变化

在60、70?℃加热条件下,利用添加马铃薯淀粉（0%、1%、2%、3%、4%）和外源转谷氨酰胺酶（transglutaminase,TG）（0%、0.10%、0.30%、0.50%和0.70%）的鲤鱼肌原纤维蛋白进行热诱导凝胶的制备,通过分析添加物对肌原纤维蛋白功能特性（凝胶性和乳化性）和十二烷基硫酸钠-聚丙烯酰胺凝胶电泳（sodium dodecyl sulfate-polyacrylamide gel electrophoresis,SDS-PAGE）图谱的变化,研究淀粉和TG复配对鲤鱼肌原纤维蛋白功能特性的作用。结果表明：在同一温度条件下,马铃薯淀粉和TG的添加对肌原纤维蛋白凝胶特性具有影响,凝胶的硬度和弹性随着添加量的增加而增大,且差异性显著（P＜0.05）。不同温度条件下凝胶的白度值差异不明显（P＞0.05）,70?℃与60?℃相比凝胶保水性有所增加。马铃薯淀粉和TG的添加对肌原纤维蛋白的乳化活性并没有明显的作用,但是对乳化稳定性有较大影响,随添加量的增加其变化趋势表现为先增大后减小,当马铃薯淀粉、TG添加量分别为2%和0.5%时乳化稳定性达到最大值94.5%。对SDS-PAGE图谱分析可知：马铃薯淀粉及TG添加使肌原纤维蛋白的主要蛋白质如肌球蛋白重链、肌动蛋白带等条带强度减弱。因此,蛋白质的结构和功能特性明显受到了淀粉和TG添加量的影响。     

油炸对马铃薯淀粉特性的影响

本文采用直接油炸淀粉的方法,研究不同油炸温度对马铃薯淀粉结构和性能的影响。采用电子扫描显微镜(SEM)、偏光显微镜、X-射线衍射仪(XRD)、Brabender 粘度仪等对油炸处理后淀粉的颗粒形态、结晶结构、糊化性质、透明度及冻融稳定性等进行测定分析。结果表明,随着油炸温度的升高,马铃薯淀粉的颗粒表面结构发生了明显的变化,淀粉颗粒表面出现凹陷、膨胀和破裂,样品的偏光十字双折射强度减弱,甚至消失;油炸破坏了淀粉的结晶结构,180℃油炸淀粉结构变化最显著,最适于淀粉的消化吸收;随着油炸温度的升高,样品粘度逐渐降低,且峰值粘度小于原淀粉;油炸淀粉的透光率较低,冻融稳定性较差,且均低于原淀粉,油炸淀粉类食品不适于冷冻。     

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