苹果片太阳能低温吸附干燥工艺优化与模型研究

以新鲜苹果片为研究对象,采用本单位研制的太阳能低温吸附干燥(LSAD)系统为实验设施,探讨干燥温度、相对湿度、干燥介质流速、载样量、切片厚度对苹果片太阳能低温吸附干燥特性的影响。结果表明,苹果片太阳能低温吸附干燥过程可以分为三个阶段:即调整、恒速、降速干燥阶段;其中干燥温度对苹果片干燥的速率影响最显著,如50℃比10℃节时达65.9%,各因素对苹果片干燥的影响的主次顺序为干燥温度相对湿度干燥介质流速切片厚度载样量,苹果片太阳能低温吸附干燥优化的工艺条件为:干燥温度50℃、相对湿度20%、干燥介质流速0.9 m/s、载样量7.5 kg/m~2、切片厚度3 mm;采用数学软件选用3种模型对实验数据进行计算拟合,苹果片干燥数学模型与Page模型拟合程度最高,苹果片太阳能低温吸附干燥数学表达式为MR=exp(-0.00557*t^1.76669);此模型的建立为应用太阳能低温吸附干燥生产脱水苹果片提供理论支撑。     

红肉苹果片穿流式热风薄层干燥特性及数学模型

以新疆红肉苹果为试材,研究不同切片厚度、热风温度及热风速率下苹果切片的干燥特性,通过Origin8.0软件对试验数据进行数学模型拟合,得到红肉苹果片的热风薄层干燥模型。结果表明,热风温度、切片厚度和热风风速对红肉苹果片的干燥特性均有一定影响,热风温度对其影响程度最为显著。热风温度越高,切片厚度越小,风速越大,红肉苹果片的干燥速率越大。综合而言,在热风温度80℃、切片厚度2 mm、热风速度1.5m/s时,红肉苹果片干燥速率最大。所选6个数学模型均可以较好地阐述红肉苹果片在热风薄层干燥过程中的水分变化规律,其中Page模型具有最高的R~2值、最低均方根误差RMSE及卡方值χ~2,更适于评估红肉苹果片干燥过程中的水分脱除规律。     

正交试验优化苹果片低氧热泵干燥工艺

以红富士苹果作为实验材料,以氮气为干燥介质置换空气降低设备中氧体积分数,研究了温度、切片厚度、氧体积分数和风速对苹果片热泵干燥速率、L值、VC和总酚含量等指标的影响,正交试验结果表明：最佳干燥工艺参数为干燥温度55 ℃、切片厚度5 mm、氧体积分数5%,干燥后苹果片水分含量为5.83%,L值为83.01,VC含量为3.68 mg/100 g,总酚含量为68.26 mg/100 g。     

大球盖菇粉的热风干燥工艺研究

以大球盖菇为原料,对热风干燥制作大球盖菇粉的加工工艺和护色剂的护色效果进行研究。结果表明,热风干燥前,对大球盖菇进行护色处理可提高干制菇片的色泽,复合护色液的最佳配方为亚硫酸钠0.1%、50℃、柠檬酸0.3%。干燥温度、蘑菇切片厚度和装载量对大球盖菇粉的色泽有显著影响,其中干燥温度对色度影响最为显著。大球盖菇粉制备的最佳工艺条件为:干燥温度50℃、切片厚度4 mm、装载量2 kg/m^2、干燥时间8 h,按此工艺生产的大球盖菇粉的色泽接近冷冻干燥粉,且具有较好的功能特性。     

熟化紫薯片微波干燥特性及数学模型

以熟化紫薯片为研究对象,利用可调微波干燥机干燥熟化紫薯片,探讨不同微波功率、装载量和切片厚度对熟化紫薯片的干燥特性、水分有效扩散系数及色泽的影响,通过SPSS软件对试验数据进行数学模型拟合,得到熟化紫薯片微波干燥模型。结果表明,熟化紫薯片的微波干燥过程表现为恒速干燥;微波功率、装载量和切片厚度对熟化紫薯的微波干燥特性均有一定影响,微波功率和装载量对其影响最为显著;微波功率越大、装载量越小、切片厚度越小,物料的干燥速率越大。熟化紫薯片微波干燥过程中的水分有效扩散系数随着微波功率与切片厚度的增大、加载量的减小而增大,其最大值为1. 135 4×10^-8m²/s,其平均活化能为4. 893 8 W/g;当微波功率较大、装载量较小时得到的干燥熟化紫薯片品质较差,而切片厚度对其影响不显著。所选用的6个模型中,Modified Page模型具有最大的确定系数R²(0. 999 7),最低的RMSE(0. 006 1)和最小的χ² (0. 000 5),是熟化紫薯片微波干燥的最佳模型,可有效描述熟化紫薯片微波干燥...     

基于综合加权法优化金桔片热风干燥工艺

为得到综合质量高的金桔热风干燥产品,对热风干燥工艺进行优化。以新鲜成熟的金桔为原料,研究金桔片的厚度、热风干燥温度和干燥风速对金桔片干燥过程和最终品质的影响。在进行正交试验后,基于综合加权法确定金桔热风干燥的最佳工艺参数。结果表明,干燥温度是影响金桔片Vc质量分数的重要因素,金桔片的切片厚度和热风干燥温度对干燥速率、复水比和单位耗能均有显著影响,最终得到金桔片热风干燥最佳工艺为切片厚度2 mm、温度为70℃、风速为0.8km/h。     

响应面法优化哈密瓜太阳能干燥工艺研究

为提高哈密瓜制干品质、降低干燥能耗,以哈密瓜为原料,在选取太阳能干燥温度、干燥风速及切片厚度进行单因素试验和基于模糊数学法构建哈密瓜干综合评分体系基础上,进行Box-Benhnken中心组合试验和响应面分析法对哈密瓜太阳能干燥工艺进行优化。结果表明:综合评分体系评价哈密瓜干品质的主要指标为口感、滋味、能耗、色泽、气味,对应权重分别为0.3、0.2、0.2、0.15、0.15;响应面分析表明干燥温度、干燥风速和切片厚度对综合评分的影响极显著(P0.01),各因素对综合评分影响强弱的顺序为切片厚度干燥风速干燥温度;制干的最佳工艺为干燥温度47.5℃、风速2.8 m/s、切片厚度3.8 mm,在此条件下,太阳能干燥哈密瓜干的综合评分为80.12。研究结果为太阳能技术工业化干燥哈密瓜提供技术依据。     

雪莲果热泵干燥特性及品质研究

研究雪莲果样品厚度、装料量、干燥温度、风速和旁通比对雪莲果热泵干燥特性及质量变化的影响。结果表明：雪莲果干燥速率随着样品厚度和装料量的增加而降低,随着干燥温度和风速的升高而增加。雪莲果热泵干燥过程绝大部分以降速干燥为主伴随相对较短时间的恒速干燥,而有些干燥速率曲线只存在降速干燥阶段。综合考虑单位能耗除湿率、色泽差异、收缩率、复水比,雪莲果热泵干燥最适参数范围：样品厚度2～4 mm、装料量1～2 kg/m2、干燥温度25～35 ℃、风速1.5～2.0 m/s。而旁通比对雪莲果热泵干燥进程影响不显著。     

雪莲果热泵干燥特性及品质研究(英文)

研究雪莲果样品厚度、装料量、干燥温度、风速和旁通比对雪莲果热泵干燥特性及质量变化的影响。结果表明:雪莲果干燥速率随着样品厚度和装料量的增加而降低,随着干燥温度和风速的升高而增加。雪莲果热泵干燥过程绝大部分以降速干燥为主伴随相对较短时间的恒速干燥,而有些干燥速率曲线只存在降速干燥阶段。综合考虑单位能耗除湿率、色泽差异、收缩率、复水比,雪莲果热泵干燥最适参数范围:样品厚度2~4 mm、装料量1~2 kg/m2、干燥温度25~35℃、风速1.5~2.0 m/s。而旁通比对雪莲果热泵干燥进程影响不显著。     

菠萝皮渣热风对流干燥工艺研究

菠萝皮渣占整个水果的45-55%,营养成分含量与其果肉相当,潜在的利用价值巨大。为了实现菠萝皮渣规模化热风干燥,需研制一种干燥速率快、提升干燥品的品质和减少干燥能耗与成本的方案。本文研究了风速、温度、装载量三个因素对菠萝皮渣的干燥影响,通过正交试验极差和方差分析确定了风速、温度、装载量三个因素对干燥速率的影响强弱。实验结果表明,70℃干燥温度能够兼顾干燥速率和干燥品质,3.9 m/s风速时对干燥前中期影响明显,0.6 kg装载量干燥产量能耗比值较好;正交试验极差和方差分析得出温度对干燥速率的影响最大,装载量次之,风速影响最小。     

苹果热风干燥工艺优化和特性分析

为提高苹果片的热风干燥品质,采用超声波和护色剂（0.1%的NaCl、1.0%的蔗糖和0.8%的海藻糖）的预处理方法,并以热风温度、切片厚度和预处理作为试验因素,对苹果片进行热风干燥的正交实验研究并建立了苹果片热风干燥特性的数学模型。结果表明:干燥速率随切片厚度的减少、热风温度的升高而增加,超声波和护色剂都能促进干燥过程;苹果片最佳热风干燥工艺参数为热风温度为60℃,厚度为1.5 mm以及预处理方式为护色剂浸泡预处理;Weibull是模拟苹果片热风干燥特性的最优模型,干燥过程苹果片的有效扩散系数为1.1278×10-8~5.2940×10-8 m2·s-1。此次研究为实际苹果热风干燥提供依据。     

MODELING and EXPERIMENTAL STUDY ON DRYING of APPLE SLICES IN A CONVECTIVE CYCLONE DRYER

The main objective pursued in this paper is to experimentally investigate the single layer drying behavior of apple slices in a convective type cyclone dryer and also to perform the mathematical modeling by using single layer drying models in literature. the experiments were conducted at drying air temperatures of 60, 70 and 80C in drying air velocities of 1 and 1.5 m/s. It was concluded that apple slices with the thickness of 12.5 mm would perfectly dry in the ranges of 280–540 mm while those with the thickness of 8 mm would dry in the ranges of 180–320 min in these drying conditions by using convective type cyclone dryer. Additionally, the mathematical model describing the single layer drying curves was determined by nonlinear regression analysis, and the logarithmic model was selected as the most suitable model to obtain the drying curve equation of apple slices. Considering the parameters such as drying time, drying rate, moisture transfer, velocity and drying air temperature it is suggested that the apple slices be dried at the above optimum processing conditions.     

苹果片气调热泵干燥特性及数学模型

研究苹果片充氮低氧热泵干燥的干燥特性,结果表明：温度、切片厚度对其干燥速率影响较大,风速和氧体积分数对干燥速率影响较小。通过干燥曲线的对数转换及线性拟合,确定苹果片的薄层干燥模型为Page方程。利用逐步回归法,确定由干燥温度、物料厚度、风速及氧体积分数表示的干燥常数k、n的表达式。通过实验值与计算值的比较,可知该模型具有较高的预测精度,能很好地描述苹果片充氮低氧热泵干燥过程。     

不同干燥方法对苹果中毒死蜱残留的影响

目的 了解苹果干燥加工过程中毒死蜱残留的降解规律,为苹果干燥产品中农药残留风险的评估提供科学的依据。方法 以红富士苹果为研究对象,采用热风干燥、微波干燥、阳光干燥对苹果片进行了处理,毒死蜱的残留量使用高效液相质谱检测。同时,利用加工因子(PF)建立了毒死蜱的变化模型,分析了干燥过程中水分的扩散系数和苹果片的复水率。结果 毒死蜱在苹果干燥过程中的变化是动态的,它的变化复合动力学模型,微波干燥和阳光干燥对毒死蜱的去除率高于热风干燥。毒死蜱的残留量与干燥条件以及农药的理化性质相关。结论 在苹果的工业生产中,推荐采用微波和阳光干燥来处理苹果,以降低毒死蜱残留带来的食品安全风险。     

三种干燥方式下苹果脆片干燥特性及品质的比较

探究不同干燥技术对苹果脆片干燥特性和品质的影响。分别使用热风干燥、中短波红外干燥、脉动压差闪蒸干燥的方法对苹果脆片进行干燥,并对各种干燥技术对苹果脆片内部温度、体积、水分活度进行检测,对各种干燥技术苹果脆片色泽参数、品质的影响进行检测对比。结果显示:热风干燥技术的L*值为85.69、要低于中短波红外干燥技术的93.58、高于脉动压差闪蒸的81.45(p<0.05);热风干燥、中短波红外干燥、脉动压差闪蒸干燥的色差综合评分分别为20.35、4.52、17.53,三者相比(p<0.05);中短波红外干燥的Vc含量、复水比、脆度值分别为2.98、44.31、9.05,要高于热风干燥的2.71、4.05、8.64,低于脉动压差闪蒸干燥的3.26、4.98、10.59(p<0.05)。对比三种干燥方式发现,对苹果脆片品质影响最大的是脉动压差闪蒸方式,对苹果脆片色泽影响最大的为中短红外干燥方式,对苹果脆片干燥特性影响最大的为中短波红外干燥方式。     

Dehydration of apple slices by sequential drying pretreatments and airborne ultrasound-assisted air drying: Study on mass transfer,profiles of phenolics and organic acids and PPO activity

Pretreatments of either water blanching or NaCl immersion and airborne ultrasound-assisted air drying were combined to dehydrate apple slices. The drying time was found to be reduced by 1.6–69.0% compared with air drying without any pretreatment and sonication. Meanwhile, it was found that sequential water blanching coupled with air drying with sonication gave the shortest drying time. A modified diffusional model incorporating temperature-dependent moisture diffusivity (D_eff) could simulate the apple drying process well. Water blanching pretreatment and airborne sonication were found to lower the activation energy required for the enhancement of moisture diffusive ability, and intensify water exchange on apple surface to speed up the drying process. Both water blanching and NaCl immersion significantly increased the amounts of procyanidin B2 in dehydrated apple slices. However, airborne sonication promoted the loss of procyanidin B2 in apple slices with pretreatments during air drying. In addition, sonication had no obvious influences on apple PPO activity and individual organic acids throughout drying. Overall, the sequential NaCl immersion pretreatment (or water blanching pretreatment) and drying with airborne sonication are effective to improve the quality of dried apple slices.     

Mathematical modelling of hot air drying of sweet potato slices

The effect of air dry bulb temperature, air relative humidity, air velocity and sample thickness on the thin-layer air drying of sweet potato slices was investigated. The drying rate curves consisted of two approximately linear falling rate periods and contained no constant rate period. Several mathematical models were fitted to the drying rates of sweet potato slices under a range of drying conditions. It was found that the modified Page equation best described the thin-layer air drying of sweet potato slices down to a moisture content of 10% dry basis. Correlations were also determined for the slope and intercept of the modified Page equation in terms of the experimental variables.     

Influence of process variables on the drying of potato slices

Investigation of the effects of varying air velocity, slice thickness, and pre-treatment with sodium chloride solutions and surface active agents on drying potato slices indicated that the drying occurred entirely in the falling rate period and was controlled by the mechanism of liquid diffusion. The rate of drying, and therefore the diffusion coefficients, increased with the addition of sodium chloride and surface active agents. Diffusion coefficients were also influenced by air velocity and slice thickness, suggesting that the rate of drying of potato slices is controlled by a combination of internal and external resistances.     

Evaluation of drying models of apple (var. McIntosh) dried in a convective dryer

Drying behaviour of apple particles was investigated in a laboratory type dryer. The effect of drying air temperature, airflow velocity, initial height of layer, particles shape and size on the dehydration characteristics of apples was investigated. Increase in drying air temperature and increase in the airflow velocity caused a decrease in the drying time and an increase in drying rate. Increase in initial height of layer and increase in the sample thickness caused an increase in the drying time and decrease in drying rate. Drying time of the cubes was shorter and their drying rate was higher than for slices. The experimental dehydration data of apple particles obtained were fitted to the semi‐theoretical, empirical and theoretical models. The accuracies of the models were measured using the correlation coefficient (R), mean bias error (MBE), root mean square error (RMSE), reduced chi‐square (χ²), and t‐statistic method. All models described the drying characteristics of apple particles satisfactorily (R > 0.9792). The Logarythmic model can be considered as the most appropriate (R > 0.9976, MBE = ?10^?11?4.5 × 10^?6, RMSE = 0.00287–0.01746, χ² = 8.5 × 10^?6?3.1 × 10^?4, t‐stat = 7.3 × 10^?9?1.2 × 10^?3). The effect of drying air temperature, airflow velocity, characteristic dimension of the particle and initial height of layer on the drying models parameters were also determined.