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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。 相似文献
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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。 相似文献
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淀粉及变性淀粉颗粒形貌结构的研究 总被引:1,自引:1,他引:1
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。 相似文献
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非晶颗粒态玉米淀粉酶解活性及工艺研究 总被引:5,自引:3,他引:2
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. 相似文献
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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%。 相似文献
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D.N. Morton C.J. Roberts M.J. Hey J.R. Mitchell J. Hipkiss J. Vercauteren 《Journal of food science》2003,68(4):1411-1415
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. 相似文献
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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. 相似文献
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Empar Llorca Isabel Hernando Isabel Pérez-Munuera Amparo Quiles Virginia Larrea M. Ángeles Lluch 《European Food Research and Technology》2007,225(5-6):807-813
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. 相似文献
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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. 相似文献
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Microstructural analysis of frying potatoes 总被引:2,自引:0,他引:2
Pedro Bouchon & José M. Aguilera 《International Journal of Food Science & Technology》2001,36(6):669-676
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. 相似文献
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Valentine N'da Kouam Stephan Handschin Matthias Derungs Georges N'guessan Amani Batrice Conde‐Petit 《Starch - St?rke》2011,63(12):747-753
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. 相似文献
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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。 相似文献
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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。 相似文献
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J. Lademann M. C. Meinke S. Schanzer H. Richter M. E. Darvin S. F. Haag J. W. Fluhr H.‐J. Weigmann W. Sterry A. Patzelt 《International journal of cosmetic science》2012,34(6):551-559
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. 相似文献