膳食纤维粉体流动性与其颗粒结构的关系

对不同来源（食用菌、粮谷和果蔬）膳食纤维粉的颗粒结构（粒径分布、孔隙结构）和粉体流动性进行比较研究,并对他们之间的相关性进行探讨。结果发现,40?种膳食纤维粉的粒径（D10,130.3～9.0?μm）、比表面积（2.06～0.18?m2/g）、孔体积（13.15～0.37?cm3/g）、孔径（61.46～4.45?nm）、休止角（32.01°～56.85°）和滑动角（21.90°～54.94°）差异很大,且无明显来源依赖性。就平均孔径而言,除甘蔗膳食纤维粉,其他均为介孔材料。相关分析发现膳食纤维粉粒径与比表面积和径距呈显著负相关,孔体积与比表面积以及孔径呈显著正相关;膳食纤维粉的流动性与其粒径、比表面积以及孔体积有显著相关性,而与径距和孔径相关性不显著。     

用原子力显微镜观测涂布纸涂层孔隙结构

该文介绍了用AFM观测颜料涂布纸涂层Z向结构的方法。颜料主要是粒径大小和分布范围不同的PCC和kaolin。对于kaolin颜料,粒径大小与涂层孔隙的大小一致。粒径分布范围与孔隙体积成反比。PCC颜料可以在涂层中产生更多的细小孔隙。     

The influence of sodium caseinate on the physical properties of spray‐dried honey

The aim of this work was to spray dry honey (rape and buckwheat varieties) with Arabic gum (AG) as a carrier alone or in combination with sodium caseinate (1% and 2% w/w NaCas) as a drying aid. Powder recovery ranged from 66.2 ± 0.7% to 75.8 ± 4.9%, and the values were significantly higher for samples containing NaCas. Powders were characterised by good flowability, the addition of NaCas had positive impact on this factor. However, the hygroscopicity of protein‐containing powders was higher, especially at 2% w/w of NaCas. Powders hygroscopicity was related to particle size: AG powder of the smallest particle size was the most hygroscopic, while the particle size did not affected flowability, which was strongly related to the feed solution composition. Based on the obtained results, it was concluded that the addition of 1% w/w of NaCas as a drying aid during buckwheat and rape honey spray drying with Arabic gum as a carrier is favourable, while the further increase of protein content does not give additional benefits.     

Flow Properties Of Encapsulated Milkfat Powders as Affected by Flow Agent

Food powders containing softer cores of fatty or flavor components present handling problems, as such powders are generally of very low density and mostly non free-flowing. Three classes of flow conditioners [silica, silicate and stearate], at three levels of concentration, were evaluated to determine effects on bulk and flow properties of sucrose, lactose and modified corn starch as well as butter oil powders encapsulated with the same materials. Silica and silicate were generally effective in improving bulk properties but only silica was effective in improving flow-ability of unencapsulated powders as well as lactose-encapsulated butteroil powder. Washing with isopropanol was effective in improving flow only with the lactose-encapsulated butteroil powder. Butteroil encapsulated in lactose had flow characteristics similar to lactose.     

Sedimentation behaviour and turbidity of carrot juices in relation to the characteristics of their cloud particles

The cloud stability of carrot juices was investigated using physical methods. In contrast to cloudy juices from fruits or other vegetables described so far, complete clarification of juice samples could not be achieved even after ultracentrifugation. Since the density of one particle fraction was almost equal to that of the continuous phase, this fraction was resistant to sedimentation by centrifugal forces up to 60 600 × g in an 8° Brix carrot juice. Cloud stability problems of carrot juices, therefore, are usually associated with bottom sediment formation, but not with visible loss of turbidity. Particle size and density were shown to be decisive for suspension stability, whilst both particle charge and serum viscosity did not show any effect on cloud stability. The reasons for the exceptional stability of the suspended particles are discussed. Based on three particle fractions, a new physical concept could be deduced according to particle size and density explaining the extraordinary suspension stability of carrot juices. Copyright © 2003 Society of Chemical Industry     

不同粒径绿茶粉粉体表征与物理性质的研究

主要对行星式球磨机制备的不同粒径茶粉的粉体表征和物理性质展开研究。结果表明,随着粉体粒径从564.24μm减小到20.84μm,粉体分布逐渐均匀,茶粉的休止角、膨胀力、溶解性增加,堆积密度、持水力减小,持油力呈先增后降的趋势,色度值得以改善。综合考虑以球磨粉碎7 h(D50=20.84μm)的绿茶粉物理性质较优,有效提高了其商品应用价值,具有较大的开发潜力。      

FeCuCoY超细合金粉的物理性能研究

采用共沉淀还原扩散法制备了不同Y含量的FeCuCoY超细合金粉,并对其物理性能进行研究,重点分析了Y含量对FeCuCoY粉末物相、粒度、形貌的影响。实验结果表明：Y元素的加入会引起粉末的衍射特征峰发生微小的偏移,使Co3Fe7相与FeCo4相的晶包参数发生了微小的改变。适量添加Y元素可明显降低FeCuCoY超细合金粉末的粒度和松装密度。FeCuCoY超细合金粉末的形貌均为表面疏松的海棉状,粉末的一次颗粒尺寸随着Y元素含量的增大而变小。通过分析,推测Y元素在FeCuCoY超细合金粉中的最佳添加量为0.5wt.%。     

灵芝超微粉理化特性研究

采用超微粉碎技术,得到了灵芝超微粉。对超微粉与常规粉(过60目筛得到)、超细粉(粒径≤30μm,相当于550目)的表征,显微镜观察和粗多糖溶出特性检测结果表明,灵芝超微粉粉体粒度分布在2.92~6.03μm(相当于5 654目),体积平均粒径为3.18μm,100%的粉体颗粒粒径(D100)小于9.96μm,呈对称的单峰分布,均匀性好;其比表面积为3.63μm/g,分别是常规和超细粉的15倍和2倍。同时超微粉细胞破壁完全,主要功效成分灵芝多糖在20 min时的浸出率与超细粉2 h时的浸出率相当,显示生物利用度得到有效提高。     

不同粒径黑果枸杞粉体的理化性质分析

试验研究分析不同粒径和粉碎时间的黑果枸杞粉体的物化特性以及多糖、总酚和花色苷含量的变化,并结合粒度和扫描电子显微镜分析进行直观说明.使用高速粉碎机将干黑果枸杞粉碎,通过标准筛得到不同粒径的黑果枸杞粉体进行物化性质研究.结果 表明,黑果枸杞经过粉碎处理后,色度、粉体流动性、复水比、持水性和松密度随粒径减小而降低;复水比和...     

奶粉流动性测试方法

目的测试粉体流动性,对比测试手段,分析各参数对安全生产和质量控制的实际指导意义。方法采用卡尔(Carr)指数法和Jenike法对市售奶粉进行粉体流动性测试。结果 Carr指数法从粉体的休止角(自然坡度角)、压缩度、板勺角(平板角)和凝集度对奶粉的流动性进行表征,Jenike法从粉体流动函数、壁面摩擦、松装密度、时间固结、拱架、鼠孔、料斗半角等方面对奶粉的流动性进行表征。结论 Carr指数法测试手段比较简单,但具有一定的经验性,只能用以表示和比较粉体物料的相对流动性,其数据的重复性和可靠性低于Jnike方法。Jenike法虽然涉及的参数多,计算量大,但其对安全生产和质量控制的实际指导意义优于Carr指数法。     

研磨方式对小麦粉粉体特性的影响

以扬麦20、新麦26籽粒为原料制备胚乳颗粒粉,再用撞击磨、锤式磨、高速粉碎机进行不同程度的粉碎得到不同粒度的小麦粉,测定水分、灰分等基本理化指标,经激光粒度仪和粉体综合特性测试仪测定粉体的流动性相关指标,并用Carr指数法对小麦粉流动性进行综合评价分析.结果表明:3种研磨方式中,经撞击磨研磨所得小麦粉流动性最好,而经锤...     

不同谷物粉的粉体特性及血糖生成指数体外评价

对糙米粉、苦荞麦粉、薏米粉、白芸豆粉、燕麦粉5种市售谷物粉进行了粉体特性评价和体外模拟消化评价试验,通过测定各样品的粒径、润湿性、休止角、平板角、松装密度、振实密度等粉体特性指标,结合流动性指数表进行了评分;又经过体外模拟消化试验,测定这些原料的体外模拟血糖生成指数（Estimated Glycemic Index,e GI）。研究发现糙米粉的粒径分布最均匀,其次为白芸豆粉和苦荞麦粉;5种谷物粉的冲调性存在显著性差异,其中苦荞麦粉润湿时间最长,燕麦粉润湿时间最短但冲调易结块;粉体流动性最好的是糙米粉,其次为苦荞麦粉和白芸豆粉,生产传输比较方便;体外模拟消化试验结果显示：白芸豆粉的水解率曲线上升趋势最平缓且最终水解率最低,计算得出白芸豆粉的e GI=60.62,对餐后血糖的影响较小。因此白芸豆粉是一种粉体特性较好,且e GI较低的谷物粉,比较适合糖尿病患者食用,该结果可为新款代餐粉的研制提供思路。     

Devices for measuring electrostatic generation and dissipation on the surfaces of polymeric materials

Dynamic electrostatic generation and dissipation on polymer surfaces are of great importance for materials such as yarns and films. To support fundamental research in this area, innovative devices and experimental techniques that can lead to a better understanding of these phenomena are of obvious academic and industrial interest. This paper reports the development of devices for testing the electrostatic generation/dissipation properties of polymer surfaces. These devices include a tester for assessing moving yarns, a high-resistance system to measure the yarn's linear resistance, a tester for evaluating stationary fabrics or films while rubbing against a moving surface and a contact charge tester for investigating charge generated by contacting of two surfaces. These devices enable the study of the influences of relative moving speed, yarn tension, electrostatic charge properties of yarns, as well as contact pressure, rubbing speed, number of rubbings or contacts on the static charge properties of films.     

真空冷冻干燥绿豆粉工艺优化

以绿豆为原料,采用浸泡、预煮、预冻、升华等工艺得到冻干绿豆粉,并对其粒度及粒度分布与速溶性的关系进行研究。试验结果表明,冷冻干燥最佳工艺条件为装料量10 kg/m~2,加热温度95-75-45℃,真空度100-80-60 Pa;绿豆粉过140目~160目筛,其速溶性最佳。