罗非鱼片渗透处理中的水分传递特性

为了研究水产食品原料在不同的渗透处理条件下的水分传递规律,本实验选择了罗非鱼片为研究对象,采用食盐溶液作为渗透液,在改变渗透液浓度、固液比和鱼片厚度的条件下,研究了罗非鱼片的水分迁移变化特性.结果表明,鱼片在10%浓度的盐水溶液中表现为吸水增重,在20%以上的盐水中才会出现渗透脱水现象;在渗透液浓度和鱼片厚度不变的条件下,鱼片的脱水率随着固液比的增大而升高;同时厚度对鱼片脱水率的影响与渗透时间有关,渗透时间的延长会降低较薄鱼片的脱水率.     

莴笋渗透脱水传质研究及参数优化

以失水率(WLR)和固形物增加率(SGR)为实验指标,采用二次回归正交旋转设计,选取葡萄糖溶液浓度(10%～40%)、氯化钠溶液浓度(2%～5%)、温度(35～65℃)、切片厚度(3～7mm)和渗透时间(60～150min)为影响因素,研究这5因素对莴笋渗透脱水指标的影响。使用SPSS软件拟合出了指标的回归方程,并利用方差分析研究了各因素对指标的影响程度。结果表明:除氯化钠溶液浓度外,其他4因素对失水率有极显著影响,而5种因素对固形物增加率有极显著作用。由Matlab软件优化的莴笋渗透脱水回归方程各参数为:葡萄糖浓度32.5%,氯化钠浓度2%,温度35℃,厚度5mm,渗透时间139min。     

超声波预处理对胡萝卜渗透脱水技术初探

以胡萝卜为原料探讨了超声波预处理对胡萝卜糖溶液渗透脱水的协同作用。探讨了胡萝卜切片厚度、浸泡液浓度、渗透时间、超声波的功率和超声波处理时间等几种因素对胡萝卜糖溶液渗漏脱水的影响。实验结果(正交试验)显示,胡萝卜渗透脱水的最佳处理条件是:切片厚度为6mm的胡萝卜在15%的糖液中经100w超声波预处理15min,再在65%的糖液中脱水4h。     

超声波强化紫薯渗透脱水工艺

分别以蔗糖质量分数、渗透温度、渗透时间和超声波功率为单因素,研究其对紫薯超声波渗透脱水的脱水率和固形物增加率的影响。以各因素为自变量,以脱水率和固形物增加率为因变量,对紫薯渗透脱水进行响应面工艺研究,得出最优工艺参数。结果表明：影响脱水率和固形物增加率的主次顺序均为渗透时间＞渗透温度＞糖液质量分数＞超声波功率;响应面优化最优工艺参数为糖液质量分数56.29%、渗透液温度65℃、渗透时间2.46h、超声波功率142.33W。结合实际操作,响应面优化的最优工艺调整为糖液质量分数56%、渗透液温度65℃、渗透时间2.5h、超声波功率140W,经验证,此条件下脱水率为40.79%,固形物增加率为8.33%。     

响应面法优化渗透脱水板栗工艺

研究了渗透脱水板栗的最佳工艺,以浓度(45%～65%)、温度(20℃～60℃)、液固比(6.25∶1～25∶1)、时间(60 min～540 min)为自变量,失水率和固形物得率为响应值,通过可旋转中心组合试验设计,得到最大失水率和最小固形物得率的条件为:糖质量浓度52.58%、温度40℃、液固比13.72∶1、渗透时间474.17 min。在此条件下失水率23.94%、固形物得率5.41%。     

樱桃番茄真空渗透预脱水工艺优化

以苏龙一号樱桃番茄作为试材,通过比较烫漂划线、针刺、划线、超声波预处理方法,确定了烫漂划线作为真空渗透预脱水的预处理方法。在该基础上,运用单因素试验研究了真空度、糖液浓度、渗透温度、渗透时间对樱桃番茄渗透预脱水效果的影响,进而确定真空度为0.080MPa,并应用响应曲面法优化其它参数,得出樱桃番茄真空渗透预脱水的最佳工艺条件为:糖度50°Brix、温度53.37℃、时间4.88h,该条件下樱桃番茄失水率与固形物增加率比值最大,为7.24。     

渗透条件对罗非鱼肉渗透-真空微波干燥的影响

为获得罗非鱼片渗透-真空微波干燥前最佳的渗透条件,研究渗透液组成、渗透时间、渗透温度和切片大小对鱼片渗透-真空微波干燥后的含水率、水分活度及品质(收缩率、复水率、色差)的影响。结果表明:鱼片在糖浓度较高的渗透液中,渗透脱水效果较好,但品质不理想;在2 h内鱼片含水率随渗透时间的延长而减少,2 h后渗透效果不明显;渗透温度升高脱水效率增加,但温度过高会破坏组织结构,不利于渗透的进行;切片越大,干燥后含水率越高但品质较差。结论:罗非鱼片渗透-真空微波干燥渗透最佳条件是渗透液组成为20%食盐+10%白砂糖,渗透时间2 h,渗透温度30℃,切片大小为500 mm2。     

莴苣真空渗透脱水的二次回归正交旋转组合试验

为获得莴苣真空渗透脱水的较优工艺参数,以莴苣为原料,通过试验研究了渗透温度、切片厚度、真空度和蔗糖浓度4个因素对莴苣真空渗透脱水过程的影响;其失水率和固形物增加率随着切片厚度和真空绝对压力的增大而减少,随着渗透温度和蔗糖浓度的增大而增大。运用二次回归正交旋转组合设计方法建立了莴苣真空渗透脱水的失水率和固形物增加率回归数学模型,模型相关系数值分别为0.912和0.904。最后利用多目标非线性优化分析法对莴苣真空渗透脱水工艺进行了综合优化;优化结果表明,在试验范围内,莴苣真空渗透脱水的较优工艺参数为:切片厚度2 mm、渗透温度28℃、蔗糖浓度47%和真空度22 kPa,此时,失水率为72.16%,固形物增加率为11.82%。     

超声渗透处理对香菇脱水复水性的影响

为了明确超声渗透在缩短香菇干制时间及提高复水性中的作用,本研究以鲜香菇为材料,研究了超声波功率、超声时间、渗透液浓度三个因子对香菇干制时间和复水性的影响,在单因素试验基础应用正交试验优化了香菇超声渗透工艺条件。结果表明:三因素对香菇干制时间,产品还原糖、氨基酸保留量、亮度(L*)、复水比均有影响。就干制时间而言,因素影响大小为超声波功率 > 渗透液浓度 > 超声处理时间。香菇超声渗透脱水的最适工艺条件:超声波功率为250 W、超声时间为15 min、渗透液浓度为15%。在该条件下,香菇干制时间为7.4 h,复水比为4.55。这表明,渗透结合超声可以提高香菇干燥效率和产品品质。     

渗透压脱水前处理对芒果冻藏中品质变化的影响

本文研究了渗透脱水前处理对芒果冷冻时间和品质的影响,渗透脱水条件是:分别采用不同浓度(30%、40%、50%(m/m))的混合溶液(蔗糖、葡萄糖、果糖质量比为3.6:1:3)作为渗透液、温度30℃,时间2 h;冻藏条件为-18℃,为期6个月。实验结果表明,与直接冷冻相比,渗透脱水联合冷冻能够缩短6.3~13.8%的芒果冷冻时间。并且,在经过6个月的冻藏后,渗透脱水联合冷冻使得芒果的总色差降低了12.5~36.8%,硬度提高了35.8~65.5%,汁液流失率减少了11.3~44.5%,维生素C含量提高了21.2~134.8%。结果显示,较高浓度的渗透脱水前处理能够较好地保持冻藏芒果的品质,而40%的渗透液浓度是芒果冷冻保藏的最优条件。同时,芒果阴面(较硬)比阳面(较软)更适合于冷冻保藏。随着冻藏时间延长,渗透脱水前处理的冻藏芒果比直接冷冻的芒果品质下降缓慢。本文表明渗透脱水联合冷冻能够提高芒果的冷冻速率和品质。     

Mathematical modeling of mass transfer in osmotic dehydration of onion slices

The study on osmotic dehydration of onion slices was carried out in order to remove the moisture prior to the further mechanical drying. Three salt concentration levels (5%, 12.5% and 20%), three temperature levels of osmotic solution (28 °C, 43 °C and 58 °C) and the observations on weight loss and solid gain were taken at an interval of 5 min up to first half an hour followed by interval of 10 min for next 1 h. The sample to solution ratio of 1:5, agitation of 100 shakes per minute, sample thickness of 4 mm and 0.2% potassium metabisulphite mixed with osmotic solution were used for the study. A two-parameter mathematical model developed by Azuara et al. was used for describing the mass transfer in osmotic dehydration of onions slices. The effect of time on mass transfer kinetics was investigated and the constants of two-parameter model and final equilibrium points for moisture loss as well as solid gain were found. The effect of solution concentration and solution temperature was also studied and it was found that equilibrium moisture loss and solid gain are related to solution concentration and solution temperature logarithmically. The optimum conditions of osmotic dehydration for further drying were found to be 20% salt concentration, 28 °C solution temperature and 1-h of osmosis.     

莴笋渗透脱水有效扩散系数研究

以葡萄糖溶液浓度(10%～40%)和温度(35～65℃)为影响因素,研究了莴笋渗透脱水的动力学过程。分别使用Azuara模型和Fick第二扩散定律计算出了平衡时刻的失水率、固形物增加率以及相应的水分和固形物有效扩散系数。设计了均匀实验,通过曲面拟合的方法得到了水分、固形物有效扩散系数与因素的回归方程。结果表明:失水率随着葡萄糖溶液浓度增加而增大,但随着温度的升高而降低;固形物增加率随着溶液浓度和温度的增加而增加。Azuara模型可用来预测失水率和固形物增加率,通过曲面拟合得到的有效扩散系数回归方程拟合性较高。有效扩散系数反映了失水率和固形物增加率达到平衡时刻的快慢程度。     

Mass Transfer Modeling During Osmotic Dehydration of Hexahedral Pineapple Slices in Limited Volume Solutions

The study of mass transfer during osmotic dehydration process in limited volume solutions was carried out to evaluate the diffusion coefficients of sucrose and water in the osmotic treatment of hexahedral pineapple slices. The experimental osmotic dehydration kinetics for pineapple slices of two different sizes were conducted at 25 °C using a 1:1 solution to fruit weight ratio. The analytical solution of a 3D mass transfer model considering a limited volume of osmotic solution (i.e., an osmotic media of variable solute concentration) was used for describing the mass transfer in osmotic dehydration of pineapple slices. This model was fitted to the experimental kinetics by means of nonlinear regression to obtain the diffusion coefficients. Additionally, the diffusion coefficients were evaluated considering an infinite volume of osmotic solution (i.e., an osmotic media of constant solute concentration). Results showed that the proposed model may be fitted accurately to the experimental osmotic dehydration kinetics and allows the estimation of diffusion coefficients when solute concentration in the osmotic media varies along the process.     

不同浓度盐水对鸭肉湿腌时传质动力的影响

研究采用盐水鸭生产时使用的过饱和盐水——老卤和其他三种不同浓度的盐水(5%、15%和25%NaCl,w/w)对鸭腿肉按照盐水鸭的生产过程进行腌制,通过对腌制过程中鸭腿肉的食盐、水分和总重变化进行测定,以期获得不同盐水浓度下鸭肉的传质动力学数据,并获得腌制最适盐水浓度。结果表明,盐水浓度显著影响鸭腿肉在腌制过程中的传质变化。鸭腿肉的重量变化、水分获得都是随着盐水溶液浓度的降低而增加,盐分变化则相反。中等浓度的盐水溶液(15%NaCl,w/w)腌制的鸭肉产量较高,有较高的扩散速率——De值,对人体的损害较小。因此,较为适于用来腌制鸭肉。另外,腌制的预测模型和扩散公式计算得到的数据都有良好的线性关系,可以很好地适用于鸭腿肉的腌制实验研究。     

ANALYSIS OF MASS TRANSFER IN OSMOTIC DEHYDRATION BASED ON PROFILES OF CONCENTRATION, SHRINKAGE, TRANSMEMBRANE FLUX AND BULK FLOW VELOCITY IN THE DOMAIN OF TIME AND SPACE

An analysis of mass transfer mechanisms in osmotic dehydration was carried out by examining the profiles of concentration, shrinkage, transmembrane flux and bulk flow velocity in the domain of time and space. The profiles were obtained through simulations using a computer simulation model that described mass transfer in osmotic dehydration based on cellular structure. It was shown that bulk flow was the main resistance for solute penetration, and the magnitude of bulk flow was affected not only by the transmembrane flux, but by internal cellular structure changes. Since bulk flow often played an important role in mass transfer during osmotic dehydration, precautions should be taken when interpreting mass transfer in osmotic dehydration using a simple pure diffusion theory.     

鸭蛋粉离心喷雾干燥工艺研究

主要研究在离心喷雾干燥鸭蛋液过程中,进料液浓度、发酵时间、进料速度、干燥室的进出口温度、进料液温度对产品感官质量的影响.通过分析产品的颗粒状态、色泽、溶解性等感官指标,得到喷雾干燥生产鸭蛋全蛋粉的最佳生产工艺参数:鸭蛋液浓度为25%,发酵时间为72 h,蠕动泵的转速为50 r/min,干燥室进出口温度为210～100℃,进料液温度在30～45℃.所得产品为粉末状或极易松散之块状,均匀淡黄色,具有鸭全蛋粉的正常气味,无异味和杂质.同时还研究了鸭蛋粉的复原性、冲调性等问题.     

Mass transfer modelling of the osmotic dehydration of some fruits

An empirical model was developed to predict the water loss and solid gain during osmotic dehydration of apple, banana and kiwi fruit. The model is based on a first-order kinetic equation, in which the rate constant is a function of the main process variables (speed of agitation, solute concentration, size of fruit and process temperature). This model was applied to a wide range of experimental data on the osmotic dehydration of apple, banana and kiwi fruit, and its parameters were estimated using non-linear regression analysis. The results showed that all of the above process variables have a significant effect on the mass transfer phenomena during osmotic dehydration.     

Design of Continuous Flow Osmotic Dehydration and its Performance on Mass Transfer Exchange During Osmotic Dehydration of Broccoli Stalk Slices

A continuous flow solution unit was designed and built with a sole purpose of achieving better hydrodynamic control during the osmotic dehydration pre-treatment process. The initial study was set up to calibrate the flow meter at different sucrose solutions at different concentrations and temperatures to obtain a flow velocity range between 1.5 to 3.5 mm/s. In this study, broccoli stalk slices were used to investigate the effect of the flow velocity on mass transfer kinetics and compared with static condition. Further, the optimization of this equipment system was performed to achieve higher water loss with minimal solute gain as pre-drying condition. Comparative studies between static and dynamic conditions show that flow velocity helps in faster rate of water removal with lower solute gain during the osmotic dehydration process of broccoli stalk slices. The optimum condition was found to be at a temperature of 30 °C with concentration of 54 °Brix for 120 min of immersion time at flow velocity of 3.5 mm/s.     

Evaluation of Mass Transfer Mechanisms During Osmotic Treatment of Plant Materials

ABSTRACT: The proportion of intact, damaged, and ruptured (non-intact) cells (Zp) due to osmotic stress during osmotic treatment of potato was monitored using electrophysical measurement based on electrical impedance analysis. Osmotic stress on potato cell culture made cell membranes shrink thereby damaging the cells. The proportion of the ruptured and shrunk cells within the samples increased with the increase in concentration of solute in the osmotic solution. The osmotic removal of water from thin potato slices started at a critical osmotic pressure. Once the critical osmotic pressure was exceeded, mass transfer was rapid and the cells lost substantial amounts of water due to rupture of cell membranes.     

鸭腿减盐滚揉腌制过程中的传质动力学

用减盐（30% KCl＋70% NaCl）和氯化钠食盐（即普通食盐,NaCl质量分数≥99.1%）分别腌制肉鸭鸭腿,测定滚揉腌制过程中鸭腿肉总质量、水分质量分数、食盐质量分数变化情况,获得鸭腿肉在不同食盐腌制时的传质动力学数据,并进行十二烷基硫酸钠-聚丙烯酰胺凝胶电泳实验,研究不同食盐滚揉腌制过程对鸭腿肉蛋白质的影响。结果显示：氯化钠腌制和减盐腌制中鸭腿肉的总质量变化量（ΔMt0）、水分质量分数变化量（ΔMtw）以及盐分含量变化量（ΔMts）均与腌制时间的平方根（t0.5）呈现出较好的相关性,而且前4 h ΔMt0、ΔMtw以及ΔMts增长较快;氯化钠腌制和减盐腌制的有效扩散系数De分别为4.432×10－8 m2/s和4.462×10－8 m2/s,相差较小;十二烷基硫酸钠-聚丙烯酰胺凝胶电泳图谱显示两种腌制方法肌原纤维蛋白都在不断降解。综上,减盐腌制和氯化钠腌制相比,对传质速率并无明显影响。