澄清胡萝卜汁的流变特性及其粘度的数学模型

本文利用１～９０流变仪对澄清胡萝卜汁流变特性及其粘度变化规律进行了测定和研究。结果表明了澄清胡萝卜汁为牛顿流体。通过非线性回归分析方法，建立了在不同温度下汁液的粘度与浓度和在不同浓度下温度与粘度关系的数学模型；最后通过逐渐逼近法求得了浓度、温度对粘度综合影响的数学模型。从而为预测在一定条件下的胡萝卜汁的粘度和有关食品工程设计提供理论依据。     

澄清胡萝卜汁流变特性及其粘度的数学模型

本文利用１－９０流变仪对澄清明萝卜汁流变特性及其粘度变化规律进行了测定的研究。结果表明了澄清胡萝卜汁为牛顿流体。通过非线性回归分析方法，建立了在不同温度下汁液的粘度与浓度和在不同浓度下温度与粘度关系的数学模型；最后通过逐渐逼近法求得了浓度、温度对粘度综合影响的数学模型。从而为预测在一定条件下的胡萝卜汁的粘度和有关食品工程设计提供理论依据。     

澄清水蜜桃汁的流变学特性研究

对澄清水蜜桃汁和脱果胶水蜜桃汁的流变学特性进行了研究。实验发现无果胶和悬浮果肉的水蜜桃汁表现为牛顿型流体。实验研究了不同温度对不同浓度水蜜桃汁粘度的影响,最后给出了描述温度和浓度对水蜜桃汁粘度影响的综合性方程。     

高透光率青梅汁浓缩过程中流变特性的研究

目的:系统研究高透光率青梅汁流变特性及其粘度变化规律。方法:用N DJ-1型旋转粘度计对不同温度和不同浓度下高透光率青梅汁的粘度进行了测定。结果:高透光率青梅汁为牛顿流体。阿累尼乌斯方程和数学模型K=A exp(BC)能分别较好地反映温度对粘度和溶解性固形物含量对粘度的影响。数学模型η=K1exp(Ea/R T+K2C+K3C2)能反映温度、溶解性固形物含量对粘度的综合影响。结论:利用回归方程,可以预测实际生产中不同温度和不同浓度下高透光率青梅汁的粘度。     

温度、浓度对澄清芹菜汁粘度的影响

粘度是流变特性中较重要的指标之一,本文试图对芹菜汁粘度与温度及浓度关系的研究,为我国的蔬菜汁加工以及有关设备的设计提供理论参考。1. 材料与方法 试验用的芹菜是1992年4月在市场购得的。其澄清汁的制备工艺如下。原料选择→洗涤→破碎→榨汁→粗滤→澄清→精滤→浓缩→冷藏 采用真空浓缩装置,温度为60～65℃,真空度为0.097MPa。 NDJ-79型旋转粘度计(余略)     

慈姑浓缩汁流变学特性研究

以慈姑酶解汁为原料,采用减压浓缩技术,研究了不同温度和时间对慈姑浓缩汁可溶性固形物含量、褐变度和浊度的影响。在此基础上,考察在不同温度和浓度条件下,慈姑浓缩汁的流变学性质。结果显示,浓缩慈姑汁在一定的温度和浓度范围内属于假塑性流体,具有触变性。温度对粘度的影响符合阿累尼乌斯(Arrhenius)方程,浓度对粘度的影响可用指数方程准确表示,并由此推导出慈姑浓缩汁粘度中温度和浓度综合影响的方程式,通过该方程能很好描述浓缩汁粘度的变化。     

温度、浓度对證清莴苣汁粘度的影响

近年来,国内杂志相继报道了有关食品如果汁、蜂蜜、乳制品等物料的流变特性的研究,但有关蔬菜汁流变特性的研究报道还很少。粘度是流变特性中较重要的指标之一,本文试图对莴苣汁粘度与温度及浓度关系的研究,为我国的蔬菜汁加工以及有关设备的设计提供理论依据。     

响应面法优化皂土澄清黄秋葵汁工艺条件研究

在不同皂土浓度、温度、时间和p H下,研究皂土对黄秋葵汁的澄清效果。在单因素试验基础上,应用响应面分析优化皂土对黄秋葵汁的澄清条件。结果表明,皂土对黄秋葵汁的最佳澄清条件为皂土添加量0.31 mg/m L、作用时间84 min、温度75℃、p H 2.10,此条件下得到秋葵汁透光率为97.6%。     

壳聚糖对玛咖汁澄清作用的影响

玛咖汁在贮存过程中易产生沉淀,需进行澄清处理,为此,采用壳聚糖澄清法,以达到快捷、经济的效果.本文在单因素的基础上,采用响应面分析法建立壳聚糖浓度、处理温度和澄清时间对玛咖汁澄清度影响的多元回归数学模型.结果表明:壳聚糖浓度0.22g/L、处理温度39℃、澄清时间32min,玛咖汁的澄清度为98.36％.玛咖汁澄清前后,其易引起果汁混浊的物质果胶、水溶性蛋白质、总酚的损失率依次为58.90％、42.93％、2.16％,玛咖汁中主要活性成分芥子油苷、水溶性生物碱、VC和总糖的损失率分别为0.56％、0.33％、0.34％和0.89％,表明在响应曲面法(Response surface methodology,RSM)优化条件下,壳聚糖澄清能较好的保留玛咖汁中的的主要活性成分.     

超滤技术在芹菜汁澄清工艺中的应用研究

选用芹菜(犹他改良5270品种)为原料,研究了国产超滤膜聚砜(PS)、磺化聚砜(CMPS)、聚丙烯腈(PAN)对芹菜澄清汁的质量影响,获得了超滤芹菜汁的工艺参数。结果表明,国产PAN-1万平板超滤膜对芹菜汁的澄清效果明显,在0.15MPa压力下,透光率由18.7%.上升至98.8%,除果胶和蛋白质被截留外,超滤前后芹菜汁中可溶性固形物、总糖、还原糖、pH、矿质元素的含量变化不大,表明超滤可较大程度地保存芹菜汁中的营养物质。     

Effect of Temperature and Soluble Solids Content on the Viscosity of Beetroot (Beta vulgaris) Juice Concentrate

The study investigates the viscosity of clarified beetroot juice as dependent on temperature and soluble solids content. Rheological research was carried out using a rotational rheometer with a system of coaxial cylinders. Flow curves were obtained in the temperature range from 10 to 60°C and at the soluble solids content of 50° to 67.1°Bx. The concentrate under study showed a Newtonian behaviour. Dynamic viscosity ranged from 5.2 to 320 mPa·s and depended on soluble solids content and temperature of measurement. The effect of temperature was described using an Arrhenius equation. Activation energy values were between 24.68 and 39.96 kJ/mol. The effect of soluble solids content was described employing a power-law function and an exponential function. In addition, two equations were proposed to describe the combined effect of temperature and soluble solids content on the viscosity of beetroot juice concentrate.     

Effect of Temperature and Concentration on the Density of Clarified Pineapple Juice

The effect of temperature and soluble solids concentration on density of clear pineapple juices was studied. The density was determined with soluble solids content from 10 to 64.1°Brix, and temperatures between 10 to 70°C with 10°C increments. The aim of this work was to develop suitable mathematical models for the use in concentration process by evaporation. The density of pineapple juice was strongly affected by soluble solids concentration, while it was relatively less affected by temperature. Different models were developed as a function of soluble solids content and temperature.     

RHEOLOGICAL BEHAVIOUR OF CLARIFIED MANGO JUICE CONCENTRATES

The rheological behaviour of clarified mango juice was measured at temperatures 15–85C and concentrations 15–66 °Brix, using a rotoviscometer. Mango juice free of pectin and pulp behaves as a Newtonian fluid. The effect of temperature can be described by an Arrhenius-type equation. The activation energy for viscous flow was in the range of 1.64–8.44 kcal/g-mol, depending on the concentration. The effect of concentration was modelled better by an exponential relationship than a power-law relationship. Simple equations are proposed for describing the combined effect of temperature and soluble solids content on the juice viscosity.     

Heating Rates of Peach Juice in an Agitated Jacketed Vessel

Heat transfer characteristics were studied on clarified depectinized peach juices heated in an agitated jacketed vessel. Four types of agitators and several agitation rates were analyzed. Two equations were derived for the density and rheological behavior of peach juice based on the combined effects of temperature and soluble solids content. Overall and internal heat transfer coefficients were also determined. For each agitator, Nusselt number was statistically correlated as a function of the Reynolds and Prandtl numbers, and as the ratio of the fluid viscosity at the bulk temperature to the fluid viscosity at the wall temperature. The power number also correlated with the Reynolds, Froude, and time numbers.     

啤特果果汁流变学特性研究

为掌握啤特果果汁的流变学特性,试验对啤特果果汁的流体类型、模量以及温度和可溶性固形物对黏度的影响进行了研究。结果表明,在25、35、45、55、65℃条件下,啤特果果汁的流变曲线方程拟合参数n值<1,属于假塑性流体,其储能模量G′大于损耗模量G″;Arrhenius方程η=Ke-E a/R T对温度与黏度的拟合参数R 2>0.99,在25~65℃黏度由0.0013 Pa·s降低至0.0006 Pa·s,其中在30.7℃时黏度最大,在65℃时黏度最小;可溶性固形物含量对黏度的影响符合指数方程η=Kexp(A C),可溶性固形物含量增加黏度随之增加,其中25℃、可溶性固形物含量为32°Brix时,黏度最大。研究结果为啤特果果汁的加工利用提供了依据。     

芹菜汁绿茶复合饮料的研制

以芹菜、绿茶为主要原料,研究了复合饮料的加工工艺。通过正交试验和感官评定,确定了复合饮料的最佳配方。综合比较了澄清型和混浊型复合饮料的感官及理化指标,如透光率、pH值、可溶性固形物含量、总黄酮含量和茶多酚含量等,结果表明澄清型复合饮料色泽鲜亮,口感清爽,且功能性成分含量较丰富。     

Variation with temperature and soluble solids concentration of the density of a depectinised and clarified pear juice

A study of the variation with temperature and concentration of soluble solids of the density of a depectinised and clarified pear juice is reported. Different models have been applied and equations were derived which describe the combined effect of these two variables over the range of temperatures and concentrations studied. All equations described are statistically significant at a probability level of at least 95%.     

RHEOLOGICAL BEHAVIOR OF POMEGRANATE (PUNICA GRANATUM L.) JUICE AND CONCENTRATE

The rheological behavior of pomegranate juice (Punica granatum L.), prepared from fresh pomegranates, was studied as a function of solids concentration in the range 17.5–75°Brix at 10–55C, using a controlled stress rheometer. Concentration methods did not influence flow behavior. There were no significant differences (P > 0.05) between viscosity and activation energy values for the pomegranate juices concentrated by different methods. The juices exhibited Newtonian behavior regardless of the concentration method. The effect of temperature was described by an Arrhenius‐type equation with an activation energy in the range 5.34–32.2 kJ/mol depending on concentration. An exponential model described better the effect of the soluble solids on the viscosity and E_avalues. A simple equation was proposed for describing the combined effect of temperature and soluble solids content on the juice viscosity.