Mass Transfer During Osmotic Dehydration Using Acoustic Cavitation

An experimental study on intensifying osmotic dehydration was carried out ina state of nature and with acoustic cavitation of different cavitating intensity (0.5A, 0.7A and0.9A) respectively, in which the material is apple slice of 5mm thickness. The result showed thatacoustic cavitation remarkably enhanced the osmotic dehydration, and the water loss was acceleratedwith the increase of cavitating intensity. The water diffusivity coefficients ranged from1.8x10^(-10)m^2·s^(-1) at 0.5A to 2.6x10^(-10)m^2·s^(-1) at 0.9A, and solute diffusivitycoefficients ranged from 3.5x10^(-11) m^2·s^(-1) at 0.5A to 4.6X10^(-11)m^2·s^(-1) at 0.9A. On thebasis of experiments, a mathematical model was established about mass transfer during osmoticdehydration, and the numerical simulation was carried out. The calculated results agree well withexperimental data, and represent the rule of mass transfer during osmotic dehydration intensified byacoustic cavitation.

Osmotic Dehydration of Cherry-Part I. Using General Factorial Design

Cherry is extremely perishable fruit and it needs to be dried in order to preserve the fruit for later uses. In this work, the influences of different osmotic solution concentrations on water loss （WL）, solid gain （SG） and weight reduction （WR） during osmotic dehydration of cherry halves were investigated. These were studied using general factorial design with different sucrose concentrations （40, 55, 70%, w/v） and immersion time （5 hours）. Quadratic regression equations describing the effects of processes on WL, SG and WR were developed. The results revealed that the soaking time and sucrose concentration significantly （P 〈 0.05） influenced most of the quality indices of osmotically-dehydrated cherry halves. It is suggested that the regression equation obtained in this study can be used to find optimum conditions for osmotic dehydration.

Influence of Osmotic Dehydration with High Electric Field on the Drying Kinetics and Mass Transfer of Green Apples

Traditional thermal methods of drying food have often led to loss of flavours, nutrients, vitamins, etc., which encourages non-thermal pretreatments such as osmotic dehydration （OD） and/or high electric field （HEF） application to improve the overall product quality. The aim of this study was to evaluate the effect of osmotic dehydration （50% sucrose） with high electric field strengths of 0.5 and 1.0 kV/cm as pretreatments on the drying kinetics and mass transfer of green apples during convective drying at 65 ~C and microwave drying at 1 W/g. The added value of the OD and HEF on the drying kinetics, and the effective mass transfer coefficients of the subsequent drying methods were investigated through this research. The efficacy of these pre-treatments was assessed and compared using cell disintegration index, product texture and thus bring forth new correlations between these pre-treatments and the cell disintegration index using dielectric spectroscopy and its effect on the product texture.

An Evolutionary Firefly Algorithm, Goal Programming Optimization Approach for Setting the Osmotic Dehydration Parameters of Papaya

An evolutionary nature-inspired Firefly Algorithm (FA) is employed to set the optimal osmotic dehydration parameters in a case study of papaya. In the case, the functional form of the dehydration model is established via a response surface technique with the resulting optimization formulation being a non-linear goal programming model. For optimization, a computationally efficient, FA-driven method is employed and the resulting solution is shown to be superior to those from previous approaches for determining the osmotic process parameters. The final component of this study provides a computational experimentation performed on the FA to illustrate the relative sensitivity of this evolutionary metaheuristic approach over a range of the two key parameters that most influence its running time-the number of iterations and the number of fireflies. This sensitivity analysis revealed that for intermediate-to-high values of either of these two key parameters, the FA would always determine overall optimal solutions, while lower values of either parameter would generate greater variability in solution quality. Since the running time complexity of the FA is polynomial in the number of fireflies but linear in the number of iterations, this experimentation shows that it is more computationally practical to run the FA using a “reasonably small” number of fireflies together with a relatively larger number of iterations than the converse.

Experimental Study of Osmotic Dehydration of Date （Phoenix dactylifera L,）： Application for Lemsi Cultivars

The cultivar date Lemsi is well known in the coastal oasis of Tunisia for both its quality stage ＂blah＂ and its earliness. This variety is characterized by its astringent taste and has never been studied extensively. An osmotic dehydration treatment is necessary to improve the quality of the final product for maintaining its integrity. Thus, it is a preservation technique that is often used as pretreatment to obtain partially dehydrated fruit. In this experimental study, the cultivar date Lemsi were cut into cubes of 1 cm3 and were immersed in sucrose solutions of 50%, 60% and 70% at 20℃ for 0-240 min. The moisture content, the solute gain, the water loss and the ratio WL/SG are determined and discussed. The results deduced from this work have showed that sugar gain SG, water loss WL and the ratio WL/SG are increased with concentration of osmotic solution. Likewise, the osmotic dehydration treatment need to be followed of a convective drying to ensure the quality of the final product.

Optimization of Osmotic Dehydration of Medlars Slices in Sucrose Solution Using Response Surface Methodology

Response surface methodology, according to CCD （central composite design）, was used to determine the optimum processing conditions giving maximum water loss and minimum solid gain during osmotic dehydration of medlars in sucrose solution. The independent variables of osmotic dehydration were temperature （25-65 ℃）, processing time （20-240 min）, sugar concentration （45%-65% w/w） and blanching time （0-180 s）. The optimum conditions were found to be： temperature = 55 ℃, time = 180 min, concentration = 60° Brix and blanching time = 30 s. At this optimum point, water loss, weight reduction and solid gain were found to be 74.12% and 7.136%, respectively.

Optimization of Osmotic Drying Parameters for Button Mushroom (<i>Agaricus bisporus</i>)

Response surface methodology was used to investigate the effect of brine concentration (10% - 20%) solution temperature (35℃ - 55℃), and duration of osmosis (30 - 60 min) with respect to water loss (WL) and salt gain (SG). The solu- tion to sample ratio of 5/1 (w/w) was used. The Box-Behnken design of three variables and three levels including seventeen experiments formed by five central points were used for optimizing input parameters. Linear, quadratic and interaction effects of three variables were analyzed with respect to water loss and solid gain. For each response, second order polynomial models were developed using multiple regression analysis. Analysis of variance (ANOVA) was per- formed to check the adequacy and accuracy of the fitted models. The response surfaces and contour maps showing the interaction of process variables were constructed. The optimum operating conditions were: solution temperature 44.89℃, brine concentration of 16.53 per cent and duration of osmosis of 47.59 min. At this optimum point, water loss and salt gain were predicted to be 44.55 per cent and 2.98 percent respectively.

渗透脱水对真空油炸辣椒脆片品质的影响

为研究渗透脱水预处理对辣椒脆片品质的影响,以湖南大红椒为原料,将辣椒渗透处理后真空油炸,研究渗透时间、料液比、渗透液含盐率等因素对辣椒脆片感官品质、色泽、含油率和脆度的影响。结果表明,辣椒脆片最佳工艺条件为渗透液含盐率6%、料液比1∶12(g/g)、渗透时间10 h、真空油炸温度90℃、油炸时间20 min、脱油时间10 min。由此方法加工得到的辣椒脆片色泽均匀,表面完整,咸甜适中,口感清爽而不油腻,其含油率、脆度及感官评分分别为6.67%、1 119.40 g、85.60。

斑块面积对干燥-复水条件下藓类植物生理活性的影响

干扰会导致生物结皮斑块破碎并退化。为明确生物结皮斑块破碎诱发生物结皮退化机理,以黄土丘陵区土生对齿藓(Didymodon vinealis)结皮为研究对象,研究了干燥-复水条件下,单株和直径1 cm、2 cm、3 cm、4 cm、5 cm的藓结皮斑块内土生对齿藓的干燥速率、渗透调节物质、丙二醛和光合色素含量等的变化,以期揭示干扰后生物结皮退化的生物学机理。结果表明(1)除单株外,干燥速率随斑块面积减小而增加,直径1 cm斑块内藓的干燥速率是直径5 cm的2倍。(2)反复干燥-复水25天后,直径小于5 cm的斑块内藓的可溶性糖、可溶性蛋白和叶绿素含量低于直径5 cm斑块内藓的含量,丙二醛含量随斑块面积变化无明显规律。(3)干燥速率与斑块面积、可溶性糖、可溶性蛋白及叶绿素含量均呈极显著负相关。以上结果表明,藓结皮斑块面积通过影响斑块内藓类植物干燥速率进而影响其渗透调节和光合作用能力。藓结皮斑块面积减小,藓类植物干燥速率增大,生理活性降低,是藓结皮斑块破碎诱发其退化的原因。研究从藓类植物生理的角度,阐明了干扰后藓类植物衰亡的生理学原因,为生物结皮的保护和管理提供了科学依据。

二元/三元渗透溶液渗透脱水处理对黄桃果块特性的影响

以蔗糖、麦芽糖醇及二者复配的三元溶液为渗透溶液,探究渗透脱水处理对黄桃果块质构特性、介电特性、细胞壁多糖含量以及微观结构的变化,并利用核磁共振氢谱(1H nuclear magnetic resonance,1H NMR)技术测定了可溶性糖含量的变化,明确麦芽糖醇和蔗糖的协同作用在渗透脱水过程中对黄桃果块特性的改善作用。结果表明:相较于对照组,SM14(蔗糖、麦芽糖醇质量比1∶4的溶液)显著降低黄桃果块的硬度、咀嚼性和黏附性。渗透脱水处理导致黄桃果块的阻抗和有效电阻显著降低,同时诱导静电容量显著增加,表明渗透脱水可能作用于细胞壁多糖而使果肉细胞特性改变。1H NMR检测结果发现,与蔗糖组相比,三元渗透液处理显著降低了黄桃果块组织中蔗糖的含量,其中SM14处理组蔗糖信号强度仅为19803.9±156.00,麦芽糖醇信号强度为54934.9±1239.11。此外,相比较对照组,SM14组水溶性果胶和鳌合性果胶含量均显著增加,分别为(26.63±1.80)mg/g和(21.59±0.71)mg/g,碱溶性果胶含量显著降低,为(27.24±0.46)mg/g。微观结构观察发现,SM14处理组细胞圆润且完整度较高,塌陷程度低,细胞壁厚度明显增加,这可能是由于蔗糖与麦芽糖醇之间的交互作用有对细胞的协同保护作用。因此,蔗糖与麦芽糖醇复配的三元渗透溶液可以有效地改善二元渗透脱水导致的黄桃果块品质劣变等问题,同时拓宽了糖醇的应用场景。

糖液与钙盐组合渗透脱水处理对冻融蓝莓品质的影响

为探究钙盐作为冷冻保护剂与高浓度糖液浸渍组合在常温下进行渗透脱水处理对冷冻蓝莓融化后质地品质的影响。对比以丙酸钙、乳酸钙、氯化钙为代表的3种钙盐冷冻保护剂及质量浓度为0.5、1.5、3.0、5.0 g/mL丙酸钙处理对冻融蓝莓品质的影响。通过观测蓝莓冻融后外观,测定硬度值、弹性、咀嚼性、胶着性、内聚性和回复性品质指标及可溶性果胶、共价结合型果胶和离子结合型果胶的含量。结果表明:添加钙盐结合糖液渗透脱水处理组均可减少蓝莓冻融后皱缩和质地瘫软现象,丙酸钙结合糖液渗透脱水处理组的汁液流失率比对照组降低约25.42%,显著低于(P<0.05)其他处理组,丙酸钙处理组为较优的钙盐添加种类。对丙酸钙添加浓度进行优化筛选,发现当丙酸钙添加浓度为1.5g/mL时可显著降低(P <0.05)蓝莓果实的汁液流失和细胞膜透性,冻融后硬度为1.54 N、弹性0.75 mm,可溶性果胶、共价结合型果胶和离子结合型果胶含量分别达到1.03、0.83和0.68 mg/g,减少蓝莓果实的质地瘫软现象并保持最佳冻融品质。丙酸钙浓度为1.5 g/mL结合渗透脱水技术使冻融蓝莓具有更好的品质,有利于食用和加工。研究结果不仅为解决蓝莓加工行业出现的由于长期冷冻所造成果实质地瘫软问题提供数据基础,还为研发提升果蔬原料冷冻贮藏品质的助冻剂及改性技术提供一定的理论依据。

不同生物源助冻剂结合渗透脱水处理对蓝莓冻融品质的影响

为探究植物乳杆菌PC11(Lactobacillus plantarum PC11)发酵代谢物、葡聚糖和冬小麦蛋白组合糖液浸渍处理对蓝莓冻融品质的影响。该研究以冷冻和糖液浸渍(65 g/mL)冷冻为对照组,以PC11发酵菌代谢物(10 g/mL)、葡聚糖(1 g/mL)和冬小麦蛋白(0.1 g/mL)结合糖液浸渍预处理后冷冻为试验组,比较分析蓝莓的抗氧化能力、活性物质含量、质构特性、冷冻特性、汁液流失率、色差和细胞膜透性等指标。结果表明:单一糖液浸渍处理不如添加助冻剂结合糖液浸渍的效果理想,其中添加PC11发酵菌代谢物(10 g/mL)的处理组可以有效维持蓝莓冻融后的各项指标,此处理组胶着性、硬度、咀嚼性和弹性分别为0.89 N、1.22 N、0.56 N和0.65 mm,总花色苷和原花青素含量与其他组相比具有显著差异(P<0.05),含量分别为2.59和0.54 mg/g,总花色苷的保留率比糖液浸渍组提高了1.78倍。该研究提出的冷冻预处理办法为针对蓝莓原料不同加工方式的冷冻贮藏技术的发展提供了新思路。

响应面优化复合糖液配方对非热渗糖工艺处理杏脯的影响

该实验以新疆特色林果李光杏为原料,为解决杏脯加工步骤繁多问题,采用配比复合渗糖溶液,将硬化、护色、渗糖、防腐简化为复合渗糖溶液,同时进行非热渗糖处理,旨在研究鲜杏果果脯最佳非热渗糖配方。研究利用单因素试验结合模糊数学感官模型,以感官品质、理化性质、营养成分为指标测定复合溶液结合冷渗处理对果脯品质的影响。设计响应面法优化试验、进行数据的处理和分析。结果表明:复合溶液渗糖配方为:1.0%CaCl_(2)+0.8%护色剂(0.20%L-半胱氨酸+0.20%抗坏血酸+0.60%柠檬酸)、糖稀液(白糖烯:砂糖=2:8)(以上比例均按质量分数计算)。该配方进行低温冷渗处理后杏脯的模糊感官得分为84.10,硬度3636.50 g,总糖含量为39.20%,可滴定酸含量为1.52%,维生素C含量为6.60 mg/100 g,色差值为38.41,POD酶活性为1.72 U/g、PPO酶活的相对活性是1.21 U/g。综上所述,该条件处理的杏脯相较传统工艺能提高营养物质保留率,提升感官特性,具有良好鲜杏风味,品质最佳。该研究为果脯非热加工处理提供理论依据。

超声渗透脱水-热风干燥梨的研究

超声波的空化效应及机械效应可有效增强脱水过程中物料内外的质量传递速率,因此超声波技术可用于果蔬渗透脱水的强化,而超声渗透脱水又常作为其他干燥方式的预处理以提高脱水速率。本研究以砀山梨梨片为实验材料,进行超声波渗透脱水预处理联合热风干燥研究。结果表明：提高超声功率及渗透液糖度可显著增加失重率;与直接热风干燥相比,单一的渗透脱水预处理延长总脱水时间约30~60 min;而超声渗透脱水预处理可缩短热风干燥的干燥时间40~120 min,并提高有效水分扩散系数11%~56%。因此,在热风干燥前进行超声渗透脱水预处理,可有效缩短总工艺时间,提高干燥效率。

不同聚合度糖渗透对苹果片干燥特性及品质的影响

渗透作为果蔬干燥预处理方式,能减少干燥时间、提高产品质量。为探究不同聚合度糖渗透对苹果片热风-压差闪蒸联合干燥特性及产品品质的影响,采用单糖(果糖、葡萄糖)、二糖(蔗糖、麦芽糖)、三糖(棉子糖)、四糖(水苏糖)对苹果片进行渗透和热风-压差闪蒸联合干燥实验。对渗透苹果片热风干燥特性曲线进行干燥动力学模型拟合,选择热风干燥至水分比为0.1的样品进行压差闪蒸处理,并对所得苹果脆片质构和色泽进行分析。结果表明:除麦芽糖外,随着渗透所用糖的聚合度增加,渗透效率降低;Page模型能准确地(R^2>0.998)描述渗透后苹果片的热风干燥规律;与未渗透处理的对照组样品相比,实验所选不同聚合度糖能显著提高苹果脆片的硬度,其中棉子糖和水苏糖对脆度提高作用最显著;此外,渗透可以保护苹果片色泽,但不同糖液渗透后苹果片的ΔE差异并不显著。本研究可为果蔬干燥渗透预处理的糖种类的选择提供理论依据。

超声场强化渗透脱水传质机理模型研究

研究超声场强化芋头渗透脱水,探讨芋头失水速率和干物质增加率随溶液质量浓度、温度、超声功率、材料厚度以及超声场下处理时间段的变化规律。分析超声空化泡在相间的传质过程,由此建立超声空化气泡强化相间传质数学模型Km≈DABπtm～(1/2)RδAfφ(BI-Cf2)(A为经验常数(10-8～10-15m2);B、C为超声波作用液体的有关常数,数量值分别在1014、106左右;f为声波频率/s-1;DAB为扩散系数/(m2/s);tm为时间/s;R为半径/m;δ为边界层厚度/m;φ为半径为R的气泡数占生成空化气泡总数百分比;I为声强/(W/cm2)),与实验结果相吻合,能较好地描述超声空化泡在液体中的传质行为。该关系式为超声波强化传质过程提供了理论依据。

预处理方式对胡萝卜变温压差膨化干燥品质的影响

探讨麦芽糖浆浓度、冷冻处理和水分含量3种胡萝卜预处理方式对胡萝卜变温压差膨化产品品质的影响。结果表明:用40%麦芽糖浆液煮沸处理20 min,在-18℃下冷冻处理24 h,胡萝卜的水分含量控制为40%,在膨化工艺为膨化温度110℃,停止时间5 min,干燥温度80℃,干燥时间150 min的条件下制备的膨化产品品质色泽亮丽、口感酥脆。

常压、真空和脉冲真空渗透脱水加工芒果脯

在24℃下,以60%蔗糖水溶液作为渗透溶液,在常压、真空和脉冲真空(压力为510mmHg)条件下对芒果进行渗透脱水,然后置于热风干燥箱中70℃干燥制成芒果脯,测定芒果脯的硬度、颜色、含水量、复水率。通过感官评定及统计分析得出,真空和脉冲真空渗透脱水制成的芒果脯品质明显优于常压渗透脱水制成的芒果脯。

超声场强化龙眼渗透脱水研究

对超声场强化龙眼果肉渗透脱水进行研究,探讨渗透脱水时间、超声处理时间、超声场强对物料脱水率、失重率、固形物得率、细胞膜透性等的影响;建立超声场强化龙眼渗透脱水的经验动力学方程.结果表明:超声场能够强化龙眼渗透脱水过程,提高脱水率.所建立的经验方程计算值与试验值有较好的一致性,试验值与计算值差的均方根小于5%.

渗透脱水前处理对芒果冻结速率和品质的影响

为了提高冷冻芒果的品质,采用了渗透脱水前处理和冻结联合加工芒果。通过研究芒果渗透脱水的质量传递,确定了芒果进行渗透脱水的条件(质量分数50%葡萄糖溶液为渗透液,渗透温度30℃,渗透时间60 min)。实验结果证明,渗透脱水-冻结与传统冻结相比,冷冻时间减少、熔点下降、冷冻速率加快。渗透脱水-冻结在色泽、硬度、汁液流失率、维生素C含量和其他生理指标都优于未处理和漂烫组。渗透脱水-冻结可使新鲜芒果的PPO活性下降,POD活性升高。