扫描电镜法分析常见可食用淀粉颗粒的超微形貌

运用扫描电镜对多种常见可食用淀粉颗粒的超微形貌进行观察,按照淀粉颗粒形貌差别,将考察的所有种类淀粉颗粒分为：块茎形、棒形、球形、扁平形、复粒结构、棱角圆滑和棱角尖锐多面体形及肾形等类别,对每一类及每一种淀粉颗粒超微形貌的特征都分别进行分析和总结,并归纳淀粉颗粒超微形貌特征规律。在本研究成果的基础上初步形成可食用淀粉颗粒超微形貌电镜照片集锦,为从淀粉颗粒超微形貌特征上加强国内淀粉产品的质量监管提供可靠参考。     

玉米抗性淀粉的制备及其性质的研究

对玉米抗性淀粉的制备工艺进行了研究,确定了最佳的制备工艺:淀粉调乳(浓度2 5 % ,pH值8 0 )→预糊化→压热处理(12 0℃,30min)→冷却→低温静置(4℃,2 4h)→提纯。按该工艺制备RS ,其产率可达10 4 7%。研究了玉米抗性淀粉的性质,包括抗酶解能力、对普通淀粉黏度特性的影响、吸水能力及微观颗粒形貌。     

玉米抗性淀粉的制备及其性质的研究

对玉米抗性淀粉的制备工艺进行了研究，确定了最佳的制备工艺：淀粉调乳(浓度25％，pn值8．0)→预糊化→压热处理(120℃，30min)→冷却→低温静置(4℃，24h)→提纯。按该工艺制备RS，其产率可达10．47％。研究了玉米抗性淀粉的性质，包括抗酶解能力、对普通淀粉黏度特性的影响、吸水能力及微观颗粒形貌。     

酸浆法和超微粉碎法生产的豌豆淀粉特性研究

本文研究了酸浆法和超微粉碎碱萃取法生产的豌豆淀粉的特性差异. 通过研究发现：两种工艺生产的淀粉在组分构成上无明显差异（P>0.1）,但是在回收率上差异显著;糊化特性差异显著（P<0.05）,超微法的峰值黏度低 5.52%、衰减值低16.70%、回生值高3.20%、最终粘度高6.66%,峰值时间长5.78%,糊化温度高2.06%;粒径的差异显著（P< 0.01）,其中酸浆法整体粒径高于超微粉碎法;电镜分析结果显示, 酸浆法的淀粉颗粒比较完整,颗粒大,表面磨损较少,超微法生产的淀粉颗粒破损较明显,颗粒小,表面磨痕明显;凝胶分析结果显示, 超微法生产的淀粉的凝胶在脆度和强度上明显高于酸浆法（P<0.01）。 通过对比两种工艺生产的淀粉的特性,为淀粉在不同领域的应用提供了理论支持。     

糯小麦淀粉提取工艺和基本特性研究

以糯质小麦粉为原料,采用水洗和离心相结合的工艺提取糯小麦淀粉。通过单因素和正交实验,确定了糯小麦淀粉提取的最佳工艺参数为和面加水量60%,面团静置时间30 min,离心时间10 min。此工艺可使糯小麦淀粉提取率达到57.23%,且淀粉颗粒保持较完整。利用偏光显微镜、扫描电镜和X射线衍射仪对糯小麦淀粉颗粒形貌和结晶性质进行了观察和分析,结果表明:糯小麦淀粉颗粒形貌和大小与普通小麦淀粉无明显差别,相对结晶度高于普通小麦淀粉。     

淀粉及变性淀粉颗粒形貌结构的研究

通过扫描电子显微镜观察了各种原淀粉及其经过不同处理方式得到的变性淀粉的颗粒形貌结构,发现运用不同的处理方式得到的淀粉与原淀粉具有不同的颗粒形貌结构并具有一定的规律性,为判断未知变性淀粉样品的处理方式提供了一定的依据。     

非晶颗粒态玉米淀粉酶解活性及工艺研究

本文采用扫描电子显微镜、光学显微镜等分析测试方法,以原淀粉为参照,对非晶颗粒态玉米淀粉的颗粒形貌及酶降解过程进行了观察和研究,结果发现,在非晶化处理过程中发生了从内向外爆裂式膨胀而形成大小、深度、位置不同的爆裂孔,以此爆裂孔为突破口,在酶作用下非晶颗粒态淀粉逐渐降解,直至淀粉颗粒的完全消失,而原淀粉具有致密的结晶结构,在相同条件下酶降解活性远远低于非晶颗粒态淀粉.并在此基础上对常温下非晶颗粒态淀粉的酶解工艺进行了研究,探讨了酶量、温度、时间等因素对DE值的影响.     

超微粉碎锥栗淀粉的理化性质变化

研究了超微粉碎对锥栗淀粉理化性质的影响。实验结果表明,随着超微粉碎时间的延长,锥栗淀粉颗粒的粒径、结晶度、膨胀度、糊化温度范围、糊化焓减小,溶解度与酶解率增加;当超微粉碎达到60 min后,淀粉颗粒粉碎达到极限,其结晶结构全部被破坏成为无定形结构,从35℃左右开始糊化,至62℃左右时已完全糊化,溶解度将近60%,α-淀粉酶的酶解率超过70%。当超微粉碎达到75 min时,更多的细微粒子发生团聚,粒径为0~5μm的细微颗粒明显减少,而粒径大于25μm的大颗粒增加。超微粉碎既破坏了淀粉颗粒的表观结构,也破坏了其结晶结构,使之变成了无定型态,大大改善了其糖化、酒精发酵特性;锥栗淀粉经60 min超微粉碎处理后,其免蒸煮的液化-糖化发酵工艺发酵96 h的酒精产量达到13.64%,而直接糖化发酵工艺发酵108 h后酒精产量也可达12.32%。     

米发糕蒸煮工艺对大米淀粉颗粒特性的影响研究

探讨蒸煮工艺对大米淀粉颗粒特性的影响,为米发糕的工业化生产提供科学依据。应用扫描电子显微镜(SEM)、X- 射线衍射和差示扫描量热仪(DSC)对米发糕进行了分析测试。随着压热的不断增大,淀粉的颗粒形貌逐渐崩溃,特征衍射峰逐渐变弱并消失,结晶度也逐渐降低,吸热焓变小。当压力达到0.2MPa 时,其结晶区域完全消失。蒸煮工艺对大米淀粉颗粒形貌影响较大,压热处理会破化大米淀粉的结构。     

淀粉颗粒形貌表征研究进展

淀粉是一种非常重要的营养物质,同时也是重要的工业原料。在淀粉应用研究中,淀粉的加工及改性一直是研究的热点。近些年,人们对淀粉改性后结构及性能进行了深入的研究,发现淀粉改性对其颗粒形貌有明显影响,导致其性能有一定程度改变。因此,对淀粉改性前后颗粒形貌的表征尤为关键。本文概述了目前淀粉颗粒形貌的表征方法,并对其进行了比较,有助于大家正确选择合适的表征方法。     

Surface Characterization of Caramel at the Micrometer Scale

ABSTRACT: The surface of caramel has been imaged using pulsed force atomic force microscopy (AFM) and scanning thermal microscopy, revealing shallow depressions in the surface of 1 to 10μm in dia that have a higher adhesion to the silicon AFM probe and a lower stiffness and different thermal character than the surrounding sample. This is consistent with the view of caramel as fat droplets within a matrix of sugars. As confirmation, the depressed regions were identified by infrared microscopy as consisting mainly of fat in a matrix of sugar. AFM also reveals that regions surrounding the depressions are decorated with thin (about 6nm) plate-like features that display a higher stiffness than the rest of the matrix. We propose that these are of crystalline origin and most probably consist of fat.     

Morphological transitions of Bacillus subtilis in the presence of food-grade lipidic nanoemulsions

The present study aims to study the antibacterial activity of food-grade lipidic nanoemulsion (noncationized/cationized) against Bacillus subtilis (BS). Bactericidal activity was ascertained by studying the morphological transitions on BS using transmission electron microscopy (TEM), atomic force microscopy (AFM), and scanning electron microscopy (SEM). Morphological changes were witnessed by cell wall breakage, oozing out of cellular contents, loss of cell turgidity and contour. Furthermore, aggregation of cationic nanoemulsion (CaNM) was preferentially observed at apical side of BS construing comparatively more electrostatic attraction between electronegative apical side and CaNM. Resistance response of BS exhibited by apical cell-wall thickening was not able to protect the bacteria due to leakage of cellular content. AFM corroborated its importance in bacteriology, wherein the fragmented cell wall can be “piece-by-piece” identified and sutured back to its appropriate vacant places, thereby, completing the cell wall contour of the ghost cell. Such postmortem analysis of bacterial cell using AFM studies can throw light toward mechanism of cell fragmentation of bacterial cells. SEM study also demonstrated the deformed, fragmented, and amorphous nature of BS construing the bactericidal effect of prepared nanoemulsion.     

Protein breakdown during the preparation of frozen batter-coated squid rings

The objective of this paper was to study the main chemical and microstructural changes in squid proteins during processing as a frozen batter-coated product using different coatings. Protein bands of the squid and of the batters used for coating were studied using SDS-PAGE. It is concluded that it is not only the proteins of the layer of batter, which are directly exposed both to the frying oil and to freezing temperatures, that deteriorate during the preparation process, the protein fraction of the squid substrate, mainly the myofibrillar proteins, is also degraded. At a microstructural level, big voids are generated during freezing as a consequence of the packing of the fibres, although the size of these voids decreases after final frying. After this step of the process, the central sarcoplasm is still visible but has been altered by coagulation of the sarcoplasmic proteins and the sarcolemma is observed to be separate from the myofibrillar package.     

The microstructure of almond (Prunus dulcis (Mill.) D.A.Webb cv. ‘Nonpareil’) cotyledon

Microstructure of almond (Prunus dulcis (Mill.) D.A. Webb cv. ‘Nonpareil’) cotyledon was observed with light, scanning and transmission electron microscopy. The objective of this study was to characterise almond cotyledon surfaces as well as to describe internal and subcellular organisation. The testa has an outer epidermis, which consists of relatively large thin-walled cells, which range from 100 to 300 μm in width. The major portion of the testa consists of approximately 14-20 layers of flattened parenchymal cells with the total thickness of the layers ranging from 80 to 120 μm. The remainder of the testa was comprised of a small amount of vascular tissue. The embryo consisted primarily of parenchymal tissue with relatively thin cell walls (1-3 μm in thickness) and a small amount of provascular tissue. Protein bodies up to 12 μm in width and spaces once occupied by lipid bodies up to 3 μm in width were present in all cells of the embryo.     

Microstructural analysis of frying potatoes

Frying induces major structural changes in the surface of foods influencing oil uptake. This work discusses the use of several different methods of microscopy as well as techniques of image analysis to study frying at the microstructural level. Hot-stage video microscopy was instrumental in assessing geometrical changes in cells of potato tissue and in starch in real time. The swelling of starches inside cells appeared to be retarded compared with that in starch suspensions. Confocal laser scanning microscopy (CLSM) permitted 'optical' sectioning of the crust, revealing that oil was located in the interior in pockets or surrounding intact cells. The manipulation of microscopy data by image processing is also presented.     

香蕉茎的化学成分及其微观形态分析

分析了香蕉茎的主要化学成分;与其他非木材纤维原料相比,香蕉茎的纤维素和综纤维素含量较高,木素含量低。此外,对其微观结构进行了光学显微镜（LM）和扫描电子显微镜（SEM）观察,结果显示,香蕉茎的纤维细长,并具有独特的纤维盘旋结构和薄膜结构。     

Thermal properties of new varieties of yam starches

Starches isolated from yam varieties of Dioscorea alata and Dioscorea cayenensis‐rotundata species were prepared at different time–temperature conditions and characterised by DSC, amperometric iodine titration, light microscopy and rheology and compared to native and chemical modified tapioca starches. The observation by light microscopy showed different morphologies of the granules when heated above 100°C and the tendency for disintegration decreased in the order native tapioca starch > yam starch > modified tapioca starch. Differences between yam and tapioca starches were also revealed by DSC. Yam starch enthalpy is higher than tapioca starch, but the peak temperature is low. However, the significant differences between yam and the other tested starches were found in terms of their rheological behaviour. The viscosity of yam starch was very stable at high temperatures on the viscograph. With this property, yam starch can be used as thickening and gelling agent in food.     

扫描电镜中半导体制冷冷台使用条件优化及在高含水量样品中的应用

目的：有效解决高含水量样品电子显微结构观察的难点。方法：通过常规扫描电子显微镜搭配半导体制冷冷台的新仪器组合模式，对一系列高含水量样品进行显微结构观察。结果：高含水量样品在以导电胶带为基质，电压5 kV，电子束斑值为 50/60，冷台温度为4 ℃的条件下，无需对样品进行固定和脱水处理，可以在扫描电子显微镜下直接成像观察其显微结构，样品微观结构没有皱缩、拉伸、扭曲等变形现象，能够更真实地反映样品的原貌。结论：常规扫描电子显微镜搭配半导体制冷冷台的仪器自由组合模式是解决高含水量样品显微结构观察的有效手段。     

冷鲜牛肉贮藏过程中线粒体变化与肌红蛋白氧化状态的相关性

为探索冷鲜牛肉贮藏过程中线粒体功能结构的变化,采用透射电子显微镜与原子力显微镜对线粒体内、外部超微结构的检测来确定贮藏时间对肌细胞线粒体变化的影响。结果发现：在4 ℃贮藏过程中（0～21 d）,Flameng线粒体评分从0.986 8升高到2.533 8,表明线粒体结构完整性逐渐降低;线粒体膜电位与线粒体呼吸控制率、ATP含量均呈极显著正相关,相关系数分别达到0.936、0.926（P＜0.01）,说明线粒体结构与功能之间关系密切;线粒体呼吸控制率与氧合肌红蛋白相对含量呈极显著正相关（r＝0.885）（P＜0.01）,线粒体膜电位与高铁肌红蛋白相对含量呈极显著负相关（r＝－0.902）（P＜0.01）,表明线粒体结构、功能变化与肉色稳定性有密切的关系。     

In vivo methods for the analysis of the penetration of topically applied substances in and through the skin barrier

The efficacy of a drug is characterized by its action mechanism and its ability to pass the skin barrier. In this article, different methods are discussed, which permit this penetration process to be analysed non‐invasively. Providing qualitative and quantitative information, tape stripping is one of the oldest procedures for penetration studies. Although single cell layers of corneocytes are removed from the skin surface, this procedure is considered as non‐invasive and is applicable exclusively to the stratum corneum. Recently, optical and spectroscopic methods have been used to investigate the penetration process. Fluorescence‐labelled drugs can be easily detected in the skin by laser scanning microscopy. This method has the disadvantage that the dye labelling changes the molecular structures of the drug and consequently might influence the penetration properties. The penetration process of non‐fluorescent substances can be analysed by Raman spectroscopy, electron paramagnetic resonance, CARS and multiphoton microscopic measurements. Using these methods, the concentration of the topically applied formulations in different depths of the stratum corneum can be detected by moving the laser focus from the skin surface deeper into the stratum corneum. The advantages and disadvantages of these methods will be discussed in this article.