干燥条件对鳗鲞风味成分的影响

采用不同的干燥方法对腌制后的鳗鱼肉进行处理,利用高效液相色谱(high performance liquid chromatography,HPLC)和固相微萃取-气质联用(solid phase microextraction-gas chromatography-mass spectrum,SPME-GC-MS)分析鳗鲞的三磷酸腺苷及其关联化合物、游离氨基酸和挥发性风味成分。冷风干燥工艺样品肌苷酸以及挥发性风味的含量比其他干燥工艺样品高,分别为10.94μmol/g和55.56%,而游离氨基酸含量则最低,可最大限度保证营养成分和风味品质。鳗鲞干燥最适条件为冷风干燥方式、温度10℃、风速1.5m/s、干燥介质为干燥空气、干燥至水分含量45%。     

基于Logarithmic方程的干燥参数对稻谷水分扩散特性影响分析

稻谷籽粒内部水分扩散的快慢决定了干燥速率。本文基于Logarithmic方程,建立稻谷水分传递动力学模型,并分析热风温度(40、50、60、70℃)和风速(0.3、0.4、0.5 m/s)对稻谷(湿基水分含量23.4%)有效水分扩散系数和扩散活化能的影响。结果表明:随着干燥温度和风速的上升,稻谷干燥速率提高,同时对应的有效水分扩散系数越大,分别为5.123×10-12~2.141×10-11m~2/s;扩散活化能从32.94 k J/mol增加至36.30 k J/mol;对比常用的5种谷物干燥模型发现,Logarithmic模型对稻谷薄层干燥的拟合度较好,R20.997,RMSE2.810×10~(-3),同时该模型模拟得出的有效水分扩散系数与实际差值均低于3.8×10~(-13)m~2/s,扩散活化能均低于2.53 k J/mol,与实际值基本吻合。     

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。     

热风干燥温度和风速对玉米种子品质的影响

为探究热风干燥温度和风速对玉米种子品质的影响,以德利农988 玉米为原料,用电热鼓风干燥箱以不同干燥温度（45、55、65、75 ℃）和干燥风速（0.4、0.6、0.8、1.0 m/s）对种子进行热风干燥,定期对水分、裂纹率、出碴率、电导率、颗粒度指数、硬度、发芽率、呼吸强度、容重、可溶性蛋白质含量进行测定,研究其对种子物性和活性的影响。结果表明,干燥温度越高、干燥风速越快,种子含水量下降越快,裂纹率、出碴率、颗粒度指数越高,电导率、硬度、发芽率、呼吸强度、容重、可溶性蛋白质含量越低。干燥温度55 ℃、干燥风速0.6 m/s 条件下种子的干燥时间较短,活性较高、呼吸强度较低,便于种子的储藏,为最佳干燥工艺。     

马铃薯片热风干燥特性及收缩动力学模型

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。     

基于BP神经网络预测红外-喷动干燥带壳鲜花生水分比

为实现带壳鲜花生红外-喷动干燥过程中水分比的预测,本实验探究了不同干燥温度（55、60、65 ℃和70 ℃）、进口风速（16、17、18 m/s和19 m/s）和助流剂质量（1.0、1.5、2.0 kg和2.5 kg）对带壳鲜花生干燥时间和干燥速率的影响,建立了输入层为干燥温度、进口风速、助流剂质量和干燥时间,隐含层节点数为11,输出层为带壳鲜花生水分比,拓扑结构为“4-11-1”的BP神经网络模型。结果表明：干燥温度和进口风速是影响带壳鲜花生水分比的主要因素,增加进口风速和提高干燥温度能有效缩短带壳鲜花生的干燥时间,提高干燥效率。采用Levenberg-Marquardt（L-M）算法为训练函数,选择tansig-purelin为网络传递函数,经过有限次训练得到的BP神经网络模型,其水分比预测值与实验值之间的决定系数R2为0.99,均方误差为0.02,水分比预测结果相较于传统经典数学模型准确且迅速。本研究建立的BP神经网络模型可为带壳鲜花生在红外-喷动干燥过程中的水分比在线预测提供理论依据和技术支持。     

猪肉过热蒸汽加工中水分变化规律研究

以猪通脊肉为研究对象,选择过热蒸汽温度120、140、160℃和180℃,利用模型拟合计算不同加工温度猪肉的水分比与加工时间的关系,得到拟合方程,并求解相应的水分扩散率,以探究不同加工条件下猪肉样品内部的水分变化规律。结果表明,加工过程中猪肉水分比与加工时间之间呈指数型关系,水分扩散率随加工温度的升高而增大,当温度低于140℃时,升高温度对水分扩散速率的影响较大,继续升高温度,其影响减弱。在120～180℃下,猪肉水分扩散率的范围是3.98×10~(—9)～1.58×10~(—8)。低场核磁共振T21弛豫测定结果表明在加工过程中样品不易流动水大量流失,当加工温度高于140℃时,弛豫时间T21与峰面积A21显著降低。因此,140℃可视为过热蒸汽加工的关键控制温度。该研究结果为过热蒸汽技术应用于猪肉热加工提供了技术参考与依据。     

怀山药片热泵-热风联合干燥研究

以提高怀山药片干燥效率和产品品质为目标,利用热泵-热风联合干燥方法,研究了热泵温度、热泵风速、切片厚度、热风温度以及联合干燥含水率转换点对怀山药片干燥速率、L值、复水率的影响。为避免怀山药片营养成分的损失以及色泽和质地变差,在前期的低温热泵干燥阶段,采用干燥温度为40℃,热泵风速为1.5 m/s;同时为了避免怀山药片表面结壳和焦化断裂现象,采用物料厚度为5 mm。在后期的热风干燥中,为提高干燥速率和保持较好色泽,将热风温度设置为60℃。试验结果表明:热泵-热风联合干燥的最佳参数为热泵温度40℃,热泵风速1.5 m/s,切片厚度5 mm,热风温度60℃,转换点干基含水率为1.00。     

广陈皮热泵干燥工艺参数优化研究

应用热泵和传统热风干燥方法,研究了一定环境相对湿度下,温度、风速对广陈皮干燥特性、外观及营养成分(挥发油、橙皮苷)的影响。结果表明:与传统热风干燥相比,热泵干燥效率更高,产品外观和营养成分保留更好;通过方差分析可知,温度是陈皮干燥速率的主要影响因素;在环境相对湿度为70%,优化热泵干燥工艺参数为60℃,1.5 m/s;相对湿度为40%,干燥耗时2.25 h,检测产品的收缩率为35.3%,橙皮苷和挥发油含量分别为1.692 mg/100 m L和1.085 mg/100 m L。     

Drying of carrot slices using infrared radiation

Carrot slices were dried from initial moisture content of 8.52 kg water kg⁻¹ dry matter to 0.11 kg water kg⁻¹ dry matter by infrared dryer. Experiments were conducted using three levels of infrared power (300, 400 and 500 W) and at air velocities (1.0, 1.5 and 2.0 m s⁻¹). The effects of process variables on the drying kinetics of carrot, drying time, specific energy consumption and quality parameters of dried carrot (shrinkage, rehydration ratio and colour) were investigated. The drying time at infrared power of 300, 400 and 500 W was 252 and 277 min, 205 and 236 min, and 145 and 155 min at air velocities of 1.0 and 2.0 m s⁻¹, respectively. The drying rate increased with increasing infrared power. The specific energy consumption values varied between 12.22 and 14.58 MJ kg⁻¹-evaporated water for all the drying conditions. Shrinkage, rehydration ratio and colour parameters were found to be affected by process variables.     

俄罗斯落叶松锯材干燥过程中含水率和应力变化分析

分析了30mm厚度的俄罗斯进口落叶松(Larixgmelinii)木材干燥过程中的干缩量和干燥应力、以及含水率变化间关系。结果表明:俄罗斯产落叶松的弦、径向干缩系数和弦径向干缩比均小于国产落叶松,相同干燥条件下国产落叶松比俄罗斯产落叶松更易发生开裂和变形等缺陷;干燥过程中产生的应力与含水率梯度、干缩量和含水率、应力指标,存在一定的相关关系。     

Experimental investigation of drying behaviour and conditions of pumpkin slices via a cyclone‐type dryer

This paper describes an experimental investigation of the drying behaviour and conditions of pumpkin slices via a convective cyclone‐type dryer. Drying experiments were conducted at air inlet temperatures of 60, 70 and 80 °C and air velocities of 1 and 1.5 m s^?1. Samples of 200 g of cylindrical pumpkin slices (thickness 5 mm × diameter 35 mm) were arranged in a single layer on each of two trays. The least squares method was applied to derive the drying curve equation of samples. During the experiments the following parameters were measured: weight loss, temperature, relative moisture and velocity. From these parameters, dimensionless mass loss, moisture content, mass shrinkage and drying rate of samples were calculated and are discussed in detail. Additionally, the transport of water during dehydration was described by the diffusion mechanism, and Fick's equation was used for evaluation of the experimental data. The linear sections of drying curves were analysed by linear regression to obtain the moisture diffusivities. It was found that pumpkin slices would dry perfectly within 340–720 min under these drying conditions. The convective cyclone dryer could also be used to dry other products. Thus it is expected that this new dryer will help farmers and producers to reduce the cost of drying. Copyright © 2003 Society of Chemical Industry     

全脂米糠膳食纤维化挤压及可溶性工艺技术研究

为了探索全脂米糠粉挤压规律,以纤维素酶为催化剂,利用双螺杆挤压机做生化反应器对全脂米糠粉进行了挤压试验研究,获得了具有不同膳食纤维含量的挤出物。在单因素研究的基础上,采用了五元二次正交旋转组合设计(1/2)实施研究了机筒温度、螺杆转速、物料水分、加酶量和模孔直径对挤出物膳食纤维含量的影响规律。结果表明:5个因素对膳食纤维得率的影响大小依次为水分(X2)机筒温度(X4)pH值(X1)酶添加量(X3)螺杆转速(X5)。在pH值6.5、水分39%、加酶量3.5%、转速110r/min和机筒温度125℃条件下,所得全脂米糠粉中膳食纤维产率为33.51%。可溶性膳食纤维含量为9.9%。     

Modeling Shrinkage and Density Changes During Microwave-Vacuum Drying of Button Mushroom

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.     

空气解冻温度对猪里脊肉品质的影响

以冷冻猪里脊肉为研究对象,在4、12、20、30 ℃温度条件下对其进行空气解冻,测定猪里脊肉解冻时 间、汁液流失率、蒸煮损失率、保水性、pH值、色泽、水分分布、质构和微观结构等特性变化。结果表明：猪里 脊肉汁液流失率与解冻时间呈非线性关系;12、20 ℃空气解冻对猪里脊肉的保水性影响较小;不同空气解冻温 度对猪里脊肉pH值、亮度值和红度值无显著影响;30 ℃空气解冻对猪里脊肉中不易流动水影响最小,稳定性 最好,其次为20、4、12 ℃;与对照组鲜肉相比,不同温度空气解冻处理组猪里脊肉蒸煮后硬度存在显著差异 （P＜0.05）;12 ℃空气解冻后猪里脊肉中肌纤维间空隙变大。不同空气解冻温度对猪里脊肉品质的影响存在 差异性。     

Hot-air drying of whole fruit Chinese jujube (Zizyphus jujuba Miller): physicochemical properties of dried products

Drying characteristics of whole fruit was studied as distinct from fruit slices. Taking Chinese jujube as an example, shrinkage, density, vitamin C, colour and rehydration of whole fruit were measured in hot-air drying at 50, 60 and 70 °C. Unlike fruit slices or lumps where shrinkage volume typically equals the volume of removed water, volumetric shrinkage of Chinese jujube was much more than the volume of removed water. Change in shrinkage with moisture content was described using three linear regions. Increased drying temperature increases the retention of vitamin C and the extent of browning, while decreasing shrinkage and the density. The findings are useful for industrial drying of whole fruit of Chinese jujube but also possibly extend to drying of other drupes.     

Glass transition phenomenon on shrinkage of papaya during convective drying

A differential scanning calorimeter was used to determine the T_g of papaya pieces equilibrated with several water activities. Thermograms revealed the existence of two T_g. The first, which presented lower value, is due to the matrix formed by sugar and water. The second one, less visible and less plasticized by water, probably corresponds to macromolecules. The data of T_g were satisfactory correlated by the Gordon-Taylor model. A convective tray dryer was used for the drying experiments, which were carried out at air temperatures of 40 °C and 70 °C and air velocity of 1.0 m/s. The shrinkage behavior was accomplished by total area and apparent volume alterations along drying. Samples were photographed during process, and their length and lateral areas were measured using the ImageJ® software. As result, the effect of air temperature on shrinkage was significant and the highest temperature (70 °C) induced higher extent of shrinkage values. At this condition, papaya sample was in a rubbery state, characterized by great matrix mobility, and remained so until the end of process, since product temperature (T_p) was above the T_g along the process. At lower temperature (40 °C), shrinkage stopped at a critical value of moisture content (0.21 g/g, wet basis), which coincided with the point in which the T_g was close to T_p.     

浅发酵香肠仿天然风干工艺研究

针对浅发酵香肠仿天然风干工艺,研究了风干温度、气流速度及湿度对香肠风干时间、均匀度以及感官品质的影响。在单因素实验基础上,采用Box-Behnken响应面优化设计优化恒温风干法工艺,并进一步对比研究了梯度风干法下,不同温度梯度对香肠的风干特性和产品品质的影响。结果表明,恒温风干法的工艺条件为:温度9.0 ℃、气流速度1.0 m/s、湿度64%。适宜的温度梯度有利于提高风干效率和提升产品品质。梯度风干法的最佳工艺条件为:温度梯度7~13℃（每12 h交替一次）,气流速度1.0 m/s、湿度64%。此条件下,将浅发酵香肠风干至理想水分含量时的时间为66 h,产品各项品质指标分别为:均匀度为0.987、水分含量37.693%、a_w为0.875、pH为5.54、TBA为0.735 mg/kg。此梯度风干工艺能够在兼顾风干效率的同时,获得理想的产品品质。     

冷鲜与真空冷冻干燥猪里脊肉中脂肪酸气相色谱-质谱分析

目的:建立猪肉脂肪酸气相色谱-质谱(gas chromatograph-mass spectrometer,GC-MS)检测方法,并对冷鲜和真空冷冻干燥猪肉中脂肪进行分析,研究不同处理猪肉脂肪酸的差异。方法:猪肉进行真空冷冻,脂肪酸利用GC-MS测定。结果:在冷鲜猪肉和真空冷冻干燥猪肉样品中脂肪酸分别确定了11种和8种;猪肉脂肪酸中油酸含量最高,其他含量由高到低依次为硬脂酸、棕榈酸、反亚油酸、棕榈油酸、肉豆蔻酸、顺-11-二十碳烯酸、花生四烯酸、顺-11,14-二十碳二烯酸、花生酸、癸酸;真空冷冻干燥猪肉粉未检出癸酸、花生四烯酸和顺-11,14-二十碳二烯酸;冷鲜猪肉中脂肪酸成分及相对含量与真空冷冻干燥样品无显著差异。结论:GC-MS法能有效对脂肪酸进行分析;真空冷冻干燥是一种可行的干燥方法,能有效保持猪肉中脂肪酸成分及结构。