低场核磁共振技术分析玉米干燥过程中水分的赋存状态

为了解物料在干燥过程中的水分变化,以玉米籽粒为研究对象,采用低场核磁共振技术(LF-NMR)结合干燥曲线,研究在不同的干燥温度下(50℃, 60℃, 70℃, 80℃和90℃),玉米籽粒内部的水分赋存状态及迁移规律。结果表明,玉米主要存在3种状态的水:自由水、半结合水和结合水,对应于3个明显的吸收峰。随干燥时间的延续和温度的升高,各吸收峰均向左迁移且信号幅值变小,核磁锋面积总和显著降低,自由水对应的信号幅值降幅最大,表明干燥温度越高,干燥时间越长,失水越多,而自由水散失的最多。另外,低场核磁总信号面积与干基含水率呈显著的线性关系,因此,在生产实践中,利用核磁共振无损检测可间接测得玉米在干燥过程中的水分含量。     

马铃薯燕麦复合面条热泵-热风联合干燥质热传递规律分析

本研究采用新型热泵-热风联合干燥技术对马铃薯燕麦复合面条进行干燥处理,采用低场核磁共振(low fieldnuclearmagneticresonance,LF-NMR)技术及扫描电子显微镜分析其干燥过程中的干燥特性及水分状态迁移等质热传递规律。结果表明:热泵温度越高、转换点含水率越大、热风温度越高,越有利于干燥的进行及水分的扩散;Midilli模型适宜描述复合面条热泵-热风联合干燥行为;不同干燥条件下复合面条的有效水分扩散系数在3.82×10-10～5.12×10-10 m2/s之间;LF-NMR结果表明:干燥过程中总水分含量持续下降,弱结合水峰左移且峰值降低,即弱结合水含量下降最多,且自由度降低,大部分弱结合水向自由水迁移,部分向深层结合水迁移;到达平衡含水率时结合水占比大于自由水,干基水分含量与峰面积呈极显著正相关(P0.01);核磁共振成像结果显示面条中部氢质子密度最大,随着干燥的进行,氢质子向外部迁移,复合面条微观结构越来越致密,深层结合水与大分子结合紧密,面筋网络更加完整。     

食用菌恒温干燥过程中MRI成像及水分迁移变化

利用低场核磁共振(low-field nuclear magnetic resonance,LF-NMR)技术研究了7种食用菌(茶树菇、杏鲍菇、金针菇、双孢蘑菇、蟹味菇、香菇、花菇)在恒温干燥过程中内部水分分布和迁移规律。自旋-自旋弛豫测定结果显示,食用菌中主要存在3种组成水:自由水、不易流动水和结合水,干燥主要脱除了自由水和不易流动水,结合水无明显变化。通过核磁共振成像(nuclear magnetic resonance imaging,MRI)进一步发现,7种食用菌内部水分分布都不均匀,且不同食用菌水在同一阶段水分流失速度不尽相同。LF-NMR技术成功实现了食用菌干燥过程中内部水分的在线监测,为食用菌干燥工艺提供了理论依据。     

超声预处理对杏片微波冻干过程中水分迁移的影响

为探究超声前处理对杏片微波冷冻干燥(MDF)过程干燥特性以及水分迁移扩散特性,以鲜杏为原料,采用微波冷冻干燥技术,使用低场核磁共振技术,测定不同超声前处理条件下杏片MFD干燥过程中的横向弛豫时间T2反演谱。结果表明:超声前处理对杏片MFD前期干燥速率影响较大。扫描电镜观察发现,内部结构最佳的超声处理条件为350 W,35℃,15 min,有利于水分迁移。新鲜杏中所含自由水约占总水分的83%。通过对不同超声处理条件的杏片在干燥过程中内部各状态水分的迁移规律分析发现:随着干燥的进行,部分自由水先向结合水的方向迁移,同时弱结合水逐渐向结合水迁移,结合水向弱结合水的迁移则贯穿整个干燥过程。不同超声前处理条件下杏片干燥过程中有效水分扩散系数变化范围是8.44×10~(-11)~15.00×10~(-11) m~2/s,超声处理使杏片的有效水分扩散系数提高了82.29%~223.97%。     

利用LF-NMR研究牛肉粒微波干燥过程中水分迁移和分布变化

水分是食品体系特别是干制品中重要的组成部分。干制品中水分的含量、分布和存在状态的差异会对其风味、质地、稳定性及货架期产生显著影响。所以研究食品干燥过程中水分的分布和迁移变化规律具有重要意义。利用低场核磁共振(Lowfield-nuclear magnetic resonance,LF-NMR)技术研究一种牛肉粒在高火、中高火、中火和中低火微波干燥过程中水分的分布和迁移变化规律。T2弛豫测试结果显示,牛肉粒中的水分可以分为结合水、不易流动水和自由水3个组分,在不同功率干燥的过程中,不易流动水能够部分转化为结合水,转化而来的结合水弛豫时间较原组织结合水增加;核磁共振成像(Magnetic Resonance Imaging,MRI)结果直观地显示出,微波干燥是一个均匀的干燥过程,牛肉粒内部和外部同时失水,且微波干燥功率越高,失水速率越快。中高火微波干燥时,水分含量高(20.87%)而水分活度低(0.676),故为牛肉粒最佳干燥功率。     

利用低场核磁共振分析烘烤过程烟叶水分迁移干燥特性

为探究烘烤过程烟叶水分状态及迁移变化规律,以上部叶为试验材料,利用低场核磁共振技术分别对烘烤过程烟叶叶片和主脉进行弛豫特性及质子密度成像分析。结果表明:(1)叶片含有自由水、半结合水和结合水3种状态水分,主脉含有自由水、半结合水2种状态水分,烘烤过程烟叶主脉各对应状态水分流动性大于叶片;(2)42~48℃和54~60℃分别为叶片和主脉水分状态迁移变化的关键时期;烘烤过程烟叶叶片和主脉中自由水最先被干燥去除,而半结合水和结合水需要转化为自由水才能散失,其中少量结合水难以通过干燥脱除。(3)烘烤过程主脉水分由"主脉—侧脉—叶片"通道迁移效率较高,由主脉直接向叶片转移效率较低;另外,叶片厚度收缩率和主脉直径收缩率分别与其自由水散失规律密切相关。研究揭示了烘烤过程烟叶的干燥特性,可以为其烘烤工艺优化提供理论依据。     

基于低场核磁技术的不同花期金银花红外干燥过程中的水分变化

本文研究了不同花期金银花(三青期、大白期和全花期)红外干燥过程中的水分分布及状态变化。不同花期金银花在45℃条件下进行远红外干燥,应用低场核磁共振技术(LF-NMR)分析金银花中水分随时间的迁移变化情况。结果表明,不同花期的金银花中均含有三种状态的水:结合水、半结合水和自由水,其含量为:半结合水结合水自由水;三青期金银花的结合水和自由水含量高于大白期和开花期,半结合水含量相对低于大白期和开花期;金银花干燥过程中,不同状态的水也呈现出不同的变化规律,半结合水含量逐渐减小,结合水含量先减少后增加,干燥过程改变了金银花内部水分分布状态和水分含量,不同状态的水分之间会发生一定的相互转化,三青期金银花中部分结合水在干燥初期流动性变大,后期流动性变小,大白期金银花结合水流动性持续变小。干燥过程中金银花水分含量与半结合水的峰面积、总峰面积均有较高的相关性(R20.9),LF-NMR技术为金银花中水分分布及变化规律提供了直观的参考依据。     

双孢菇远红外干燥过程中内部水分的变化规律

利用低场核磁共振技术分析远红外干燥双孢菇内部水分分布及变化规律,研究在50、60、70 ℃条件下,切片厚度为3、5、7 mm双孢菇切片干燥过程中内部水分变化。结果表明：双孢菇中主要存在自由水、弱结合水和结合水3 种状态水,其中切片厚度为3、5、7 mm双孢菇片自由水含量（M23值）分别为9 048.26、12 038.71、17 532.27,在3 种状态水中所占比例最大。在相同干燥温度条件下,切片厚度为3 mm的双孢菇自由水和弱结合水去除所需的时间最短;随着干燥温度的升高,3、5、7 mm双孢菇片中自由水和弱结合水含量逐渐降低。3 种切片厚度的双孢菇在不同温度干燥过程中结合水含量无明显下降趋势,说明干燥过程中脱去的主要是自由水和部分弱结合水,结合水基本不会去除,因此结合水含量对双孢菇远红外干燥效果无明显影响。     

远红外辐射温度对猕猴桃干燥水分迁移的影响

利用低场核磁共振技术研究不同远红外辐射温度对猕猴桃内部水分状态与迁移的影响规律。结果表明:随着辐射温度的升高,猕猴桃所需干燥时间缩短,在120,160,200,240,280℃的辐射温度下平均干燥速率之比为1.001.301.542.002.50;远红外辐射干燥猕猴桃的有效水分扩散系数为2.85×10-10～7.03×10-10 m2/s,提高辐射温度有利于增大扩散系数值;猕猴桃中存在自由水、不易流动水和结合水3种状态水分;随着干燥的进行,自由水的相对比例逐渐减少,辐射温度由120℃升至280℃时,自由水去除所需时间可缩短75%;在干燥前期会有部分水分由高自由度向低自由度转变;干燥结束时,样品中残余水分以结合水为主;提高辐射温度可以促进各种水分状态之间的转变以及水分的去除。     

LF-NMR结合MRI分析热泵干燥过程中黑木耳水分迁移

采用低场核磁共振（low-field nuclear magnetic resonance,LF-NMR）和核磁共振成像（magnetic resonance imaging,MRI）技术，探讨黑木耳在不同热泵干燥温度脱水过程中的水分状态和分布变化。结果表明：黑木耳的热泵干燥过程加速和恒速干燥阶段持续时间较短，降速干燥阶段较长；黑木耳中的自由水首先被脱除，然后是结合水，且有部分自由水向结合水转移；黑木耳含水率与总峰面积呈较强的线性相关性（R2=0.984 7）；黑木耳边缘和表面的水分首先被脱除，根部的水分逐渐向边缘和表面转移；低场核磁共振技术可以作为一种快速、无损监测黑木耳热泵干燥过程水分迁移的有效方法。     

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.     

Review of techniques to manufacture micro-hydrogel particles for the food industry and their applications

Microgels are ‘soft’ microscopic cross-linked polymeric particles that are being increasingly exploited in a variety of industries for rheology control, encapsulation and targeted delivery. They are valued because of the ability to tune their functionality to address specific applications in oil recovery, coatings, drug delivery, cosmetics, personal care and foods. Food microgels are typically biopolymer hydrogels in the form of microspheres, nanospheres (also called nanogels), spheroids and fibres. The utilisation of engineered microgels in foods has so far been limited, despite their great potential to address several needs in the food industry, including: satiety control, encapsulation of phytonutrients and prebiotics, texture control for healthier food formulations (e.g. reduced fat products), and targeting delivery to specific areas in the digestive tract. We review the scientific and patent literature on the utilisation and manufacturing methods for producing microgels with an emphasis on micro-hydrogels for food applications.     

12—A CRITIQUE OF SOME HYPOTHESES RELATING TO THE HETEROGENEITY OF THE HIGH-SULPHUR PROTEINS OF WOOL

Joubert and Burns prepared a large number of fractions from the high-sulphur proteins of wool and estimated their molecular weights and amino-acid compositions. Their data have been re-examined in order to look for statistically significant interrelations between amino acids and between the proportion of various amino acids and molecular weight. Statistical analysis of the data is also used to examine the credibility of some hypotheses concerning the mechanism of keratin biosynthesis and to provide further evidence for the existence of families of proteins within the high-sulphur fractions of wool.     

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 Latest Data about Development of Chinese Printing Industry in 2013

In the 2014 China（Shanghai）International Printing Week,Director Wang Yanbin released the latest data about development of Chinese printing industry in 2013.According to statistics,in 2013,the total output value of Chinese printing industry exceeded 1trillion Yuan for the first time,reaching 1.03985 trillion Yuan.There were 105,000 printing enterprises in China,employees were 3.415 million.The total asset was 1.06247 trillion Yuan;     

The State Council Issued "Directory of Government Approved Investment Projects(2013 Edition)"

正On December 2nd,2013,the State Council issued the notification of"Directory of Government Approved Investment Projects(2013 Edition)"(hereafter referred to as"notification").It is pointed out in the"notification"that in order to further deepen reforms in investment systems and administrative examination and approval systems,simplify administrative procedures and delegate powers to lower levels,earnestly     

Top Ten News of China's Paper Industry 2013

On December 24th, 2013, the meeting on the selection of top 10 news of China＇s paper industry 2013 sponsored by 〈China Paper Newsletters〉 was held in Beijing. The yearly selection of the top l0 news, which began in 2000, has become a brand activity widely recognized in the industry thanks to the support from the authorities at all levels and public participation.     

National Development and Reform Commission Issued Announcement for Selection of Major Preliminary Research Projects for the "13~(th) Five-Year Plan"

In Apri Commi major p Plan＂ （h 2014, the National Development and Reform ssion issued an announcement for selection of reliminary research projects for the ＂13th Five-Year ereafter referred to as ＂The Announcement＂）     

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 latest scientific     

China textile machinery: taking off in progress

正Among the 1600 exhibitors who take apart in the ITMA ASIA+CITME2014 2/3 are Chinese manufactures.If the numerous figures failed to attract your attention,the increase of quality should draw your focus.To adopt the demand of developing textile machine market,domestic textile machinery enterprises now follow the slogan of"technology drives development"to enhance product competitiveness.Our domestic sellers will showcase product ranging from spinning,weaving,dyeing and printing,