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Volume and area shrinkages occur during food dehydration. The food behaviour must be characterized not only for using in process and equipment simulation models but also to evaluate the final quality of the product. No literature reports were found on the rose hip behaviour. After removing the peduncles, whole fruits were dehydrated in heated air at temperatures of 50, 55, 60, 65, and 75°C, air velocities of 1, 2, 3, 5 m/s, and air relative humidities of 5 and 50%. Volume changes were evaluated by picnometric techniques and with geometric measurements by micrometer and superficial area from geometric measurements. In agreement with previous reports on other foods, volume and area changes do not depend on dehydration operating variables. A linear relationship was found between the dimensionless volume change and the moisture content of the partially dehydrated fruits. The area depended on moisture according to a third-grade polynomial. 相似文献
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探讨果蔬深加工技术及新型果蔬干燥技术发展趋势。比较论述了真空冷冻干燥、微波干燥、真空油炸干燥技术特性,最后重点介绍了变温压差膨化干燥技术特点及国内外发展趋势,期望对果蔬干燥技术的研究与开发提供一定的参考性。 相似文献
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Kinetics of shrinkage of mushroom tissue and whole mushrooms was investigated. Shrinkage of tissue was found to be described by three apparent first order reactions, consisting of an initial slow phase, a second rapid phase, and a third slow phase. The duration of each phase depended on temperature. The major part of the shrinkage took place during the rapid shrinkage period. Activation energies during this phase were 18.25 Kcal mole?1 and 16.80 Kcal mole?1 for mass and volume shrinkage, respectively. Results for whole mushrooms were consistent with those for tissue. 相似文献
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Fei Pei Ying Shi Alfred Mugambi Mariga Wen-jian Yang Xiao-zhi Tang Li-yan Zhao Xin-xin An Qiu-hui Hu 《Food and Bioprocess Technology》2014,7(6):1629-1639
Button mushroom slices were dried using freeze-drying (FD) and freeze-drying combined with microwave vacuum drying (FD?+?MVD) methods. Drying parameters including drying temperatures (20, 30, and 40 °C), chamber pressures (70, 100, and 130 Pa) and material layer thicknesses (single, double, and triple) during FD process, and microwave power densities (20, 40, and 60 W/g) and material layer thicknesses (single, double and triple) during MVD period of FD?+?MVD process, were investigated for their drying characteristics. The FD and FD?+?MVD products were then rehydrated at two temperatures (20 and 70 °C). Different mathematical models were tested with the drying and rehydration behaviors of button mushroom slices, and the effective diffusivities (D eff) in the FD and FD?+?MVD processes were also calculated. The results indicated that based on the statistical tests, the Page model and logarithmic model provided the best fit for FD (in both FD and FD?+?MVD processes) and MVD (in FD?+?MVD process) curves, respectively. The regression equations obtained from selected models can accurately predict the relationships between moisture ratio (MR) and time (t). Furthermore, the D eff values of the MVD period in FD?+?MVD process (2.318–5.565?×?10?5 m2/s) were about ten times greater than those in FD process (1.291–3.389?×?10?6 m2/s). In addition, the Peleg model gave a better fit for rehydration conditions applied in both FD and FD?+?MVD products. The values of equilibrium moisture content (W e) of FD?+?MVD products were almost similar to those of FD products, which indicated that the rehydration capacities of the two dehydrated products were comparable. 相似文献
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目前,针对果蔬干制加工中存在的能耗高、时间长、营养成分损失严重等问题,主要通过干燥技术的创新以及干燥设备的研发予以不断改善,而干燥前处理技术在国内发展相对缓慢。干燥前处理技术是指通过物理、化学、生物等技术手段对物料进行处理,从而起到加快物料干燥速率、提高产品外观及营养品质、延长货架期的作用。目前常用的果蔬干燥前处理技术有:热烫、冻融、渗透、化学试剂、超声、超高压、高压脉冲电场、二氧化碳浸渍处理等。本研究针对上述几种前处理技术的原理、特点进行综述,对比不同前处理技术的作用机制及适用果蔬的种类,并展望了不同前处理技术的发展前景与趋势,以期为果蔬干燥新技术的研究与开发提供指导意见。 相似文献
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银杏果微波间歇干燥工艺的优化 总被引:1,自引:0,他引:1
为探究银杏果微波间歇干燥最佳工艺,选取微波功率、加热时间和间歇时间为试验因素,以干燥过程平均 干燥能耗、质量干燥速率以及干燥后的感官品质评分为评价指标,采用二次正交回归试验优化银杏果微波间歇干燥 工艺,运用BackWard分析法建立二次回归数学模型,并对回归模型进行响应面分析。结果表明:所选试验因素对 干燥进程有显著影响,其强弱顺序为:加热时间>微波功率>间歇时间。试验因素之间存在交互作用。采用响应面 寻优法得到银杏果干燥的最佳工艺参数为:微波功率4.5 W/g、加热6.5 s、间歇80 s,在此条件下,质量干燥速率为 0.157 kg/(h·kg),平均干燥能耗为65.54 kJ/g,感官品质评分为8.5。实验结果对改进干燥设备和银杏果微波干燥 有一定的参考价值。 相似文献
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Two-Stage Intermittent Microwave Coupled with Hot-Air Drying of Carrot Slices: Drying Kinetics and Physical Quality 总被引:1,自引:0,他引:1
Dandan Zhao Kejing An Shenghua Ding Lijun Liu Zhiqiang Xu Zhengfu Wang 《Food and Bioprocess Technology》2014,7(8):2308-2318
To display the advantages of two-stage intermittent microwave coupled with hot-air (60 °C) drying (IM&AD), different drying methods were compared. The activation power density of samples dried by IM&AD increased slightly and then rapidly as moisture content decreased. Drying kinetics, specific energy consumption and dried product quality, such as colour, rehydration ratio and α- and β-carotene contents, of carrot dried by IM&AD under the optimum conditions were assessed and compared with those of carrot dried by hot-air (60 °C) drying, hot-air (60 °C) drying followed by low-power microwave (145 W) drying, high-power microwave (175 W) drying followed by hot-air (60 °C) drying and high-power microwave (175 W) drying followed by low-power microwave (145 W) drying. The effective diffusivity increased gradually and then rapidly as moisture content decreased in all five drying processes. The IM&AD is a promising way for industrial application because it showed the lowest drying time with relatively low energy consumption and provided the best quality of final products with the best colour appearance, highest rehydration ratio and highest α- and β-carotene contents. 相似文献
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Md Mahiuddin Md. Imran H. Khan C. Kumar M. M. Rahman M. A. Karim 《Comprehensive Reviews in Food Science and Food Safety》2018,17(5):1113-1126
The structural heterogeneities of fruits and vegetables intensify the complexity to comprehend the interrelated physicochemical changes that occur during drying. Shrinkage of food materials during drying is a common physical phenomenon which affects the textural quality and taste of the dried product. The shrinkage of food material depends on many factors including material characteristics, microstructure, mechanical properties, and process conditions. Understanding the effect of these influencing factors on deformation of fruits and vegetables during drying is crucial to obtain better‐quality product. The majority of the previous studies regarding shrinkage are either experimental or empirical; however, such studies cannot provide a realistic understanding of the physical phenomena behind the material shrinkage. In contrast, theoretical modeling can provide better insights into the shrinkage that accompanies simultaneous heat and mass transfer during drying. However, limited studies have been conducted on the theoretical modeling of shrinkage of fruits and vegetables. Therefore, the main aim of this paper is to critically review the existing theoretical shrinkage models and present a framework for a theoretical model for the shrinkage mechanism. This paper also describes the effect of different drying conditions on material shrinkage. Discussions on how the diverse characteristics of fruits and vegetables affect shrinkage propagation is presented. Moreover, a comprehensive review of formulation techniques of shrinking models and their results are also presented. Finally, the challenges in developing a physics‐based shrinkage model are discussed. 相似文献
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Shrinkage characteristics and apparent density of whole button mushrooms were determined at various moisture content levels (ranging from 5 to 92% wet basis) during microwave-vacuum drying at two different power (150 and 250 W) and pressure (10 and 20 kPa) levels. The above properties during convective hot air drying at 60°C were also measured for comparison. In both microwave-vacuum and air-drying methods, the shrinkage (volumetric and diametric) of mushroom showed a linear behavior with moisture content. Experimental data showed that the effect of the system pressure on shrinkage and density was more significant than the power level during microwave-vacuum drying. Moisture content and method of drying also affected shrinkage statistically. Microwave vacuum drying produced less shrinkage than air drying. Simple mathematical models were used to correlate the above properties with the material moisture content. The models were fitted to experimental data satisfactorily, and the parameters were estimated. 相似文献
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为提高马铃薯片的热风干燥效率及品质,控制其干燥过程中的收缩变形,本文研究了不同热风温度(45、55、65、75 ℃)和切片厚度(3、5、7、9 mm)对马铃薯片热风干燥特性曲线、有效水分扩散系数及活化能等指标的影响。结果表明,干燥室内热风温度越高、马铃薯切片厚度越小时,干燥速率越快。在研究范围内,马铃薯片的有效水分扩散系数在5.02×10?10~11.53×10?10 m2/s范围内,其值随热风温度升高或切片厚度减小而增大。此外,研究发现Weibull分布函数能够很好地描述马铃薯片的降速干燥过程和收缩动力学模型。通过Arrhenius方程计算得到马铃薯片的干燥活化能和收缩活化能分别为27.35和46.44 kJ/mol,马铃薯片干燥比收缩消耗活化能少。本研究为马铃薯片在热风干燥加工中水分迁移和体积收缩变化的预测提供了理论依据和技术支撑。 相似文献
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以盐渍仿刺参为研究对象,以感官评分和脱水速率加权后的综合评分作为评价指标,采用单因素试验及响应面法对冷风干制(cold-air drying,CAD)工艺条件进行优化,并对CAD、真空冷冻干制(vacuum freeze drying,VFD)、热风干制(hot-air drying,HAD)和真空微波干制(vacuum microwave drying,VMD)工艺处理的仿刺参进行品质比较分析。结果表明:CAD最佳干制工艺条件为真空脱盐时间4.2 h、冷风温度19℃、冷风风速1.70 m/s,仿刺参的综合评分为0.77。在营养保持方面,VFD和CAD比HAD和VMD效果更好;在热收缩率方面,HADVMDCADVFD,其中CAD和VFD差异不大;在复水倍数方面,CADVFDHADVMD;在质构特性上,CAD和VFD质构指标明显优于HAD和VMD。对比结果说明CAD在工业生产中具有更高的实用性。 相似文献
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A proposed mathematical model, based on physical and transport properties and mass and energy balances, was developed for unsteady transport of momentum, heat and mass in granular beds of agricultural products (fruits and vegetables) under convective drying conditions. The model utilized water sorption isotherm equations and the change in solid density due to shrinkage. The unsteady-state differential equations for temperature and moisture profiles within the product were numerically solved using a central finite difference scheme. Experimental data on drying conditions and product drying rates agreed with the calculated results. A design and operation parameters optimization scheme, tested for grapes, resulted in minimized drying time and high quality dried product. 相似文献