Vacuum press drying studies on two fast-growing Indian wood species

Two fast-growing Indian species, Melia composita Benth. and Eucalyptus tereticornis Sm., which have different sets of physical properties, were dried together in a vacuum press dryer(VPD) under two drying conditions,i.e., above boiling point(ABP) and below boiling point(BBP). The ABP and BBP conditions were maintained by keeping the temperature constant at 75 ℃ and maintaining two pressure levels: 300 mm of Hg(ABP) and 450 mm of Hg(BBP). In order to understand pressure conditions at the core during vacuum drying, a cylindrical brass pipe was inserted in both wood cores and attached with pressure gauges placed outside of the VPD. The results indicate that the Melia wood core attained equilibrium pressure immediately with the pressure of VPD, while Eucalyptus attained it very slowly, reaching equilibrium at later stages of drying when cracks and checks advanced to the core.The drying rate was higher for Melia than Eucalyptus under both drying conditions. The drying rate of Melia(ABP) was higher than Melia(BBP), however, the drying rate for Eucalyptus(ABP) was not significantly different from the BBP drying rate.

Effect of steam pretreatment on wood moisture content and characteristics of vacuum drying

The effects of high temperature steam pretreatment on the change in wood moisture content （MC） and characteristics of vacuum drying were investigated in this study. Poplar and manchurian walnut woods were pretreated with high temperature steam at 100~C and 140~C, prior to vacuum drying. A comparison of the characteristics of vacuum drying between steam pretreated wood and untreated wood was carried out. The results show that during steam pretreatment, the MC of wood decreased within a few hours. The reduction of MC varied with the temperature; the higher the temperature, the faster the MC dropped. During the vacuum drying stage, the rates of drying ofpretreated samples were higher than those of untreated samples when MC was below the fiber saturation point. Furthermore, the total drying time of samples treated at a steam temperature of 140~C was lower than that of untreated samples. Therefore, a vacuum procedure after steam pretreatment can effectively shorten the drying time when drying wood.

Application of Vacuum Drying to Silica Sol Ceramic Mold

Silica sol ceramic mold was made at room temperature with JN-30 silica sol, silica powder and NH4Cl. It is found that the harden time of silica sol ceramic mold is only 0.5 to 1.5 h under the amount of NH4Cl solution of 7% to 8% with 15% concentration, and less surface cracks occur by using vacuum drying. The proper vacuum drying process parameters： vacuum drying temperature is 80 to 100℃, drying time is 5 h and vacuum is 0.06 to 0.07MPa. The harden mechanics, vacuum drying mechanics and the reason of less surface cracks of silica sol ceramic mold by vacuum drying： were also analyzed in this paper.

Research on vacuum drying process and internal heat conduction of Li-ion battery core

In this research, an innovative cylindrical automatic battery core oven was designed to avoid the structural deformation that frequently occurs in traditional ovens. The oven could be automatically connected with the electrolyte injection process after baking, achieving improvement in a battery's baking consistency. This contributed to the feasibility of studying the internal heat conduction process of batch battery cores during actual baking processes. A mathematical model of a certain plate battery cell during the baking process was established. The simulation results of the temperature change inside the battery core during the baking process were consistent with the calculation results of the mathematical model. The temperature distribution at each point inside the battery core could be fitted through the thermal conductivity at different temperatures and the temperature distribution between the layers of the battery core.Finally, based on the thermodynamic balance energy conservation method, the relationship between the temperature change inside the battery core and the entire baking process was established. A feasible algorithm for studying the thermal conduction of complex material and internal structure objects in the baking process was obtained.

Factors affecting relative humidity during wood vacuum drying

Effects of pressure and temperature in the chamber during vacuum drying on the relative humidity and evaporation of wood surface were investigated by using the vacuum chamber.The setting temperature during vacuum drying included dry-bulb temperature td, the wet-bulb temperature tw and the temperature difference between the air in the vacuum chamber and the cooling water in the condenser.Results indicated that relative humidity during vacuum drying was affected by the dry-bulb temperature td, the wet-bulb temperature tw and the temperature difference between the air in the vacuum chamber and the water in the condenser.Relative humidity of wood decreased with the increase in temperature at the given temperature of the water in the condenser.The relative humidity was affected slightly by pressure in the vacuum chamber pA, and it decreased from 70% to 65% with pA increased from 50 kPa to 101 kPa.Moreover, there was nearly no evaporation under the vacuum without external heating.

Artificial neural network techniques to predict the moisture ratio content during hot air drying and vacuum drying of Radix isatidis extract

Background:To predict the moisture ratio of Radix isatidis extract during drying.Methods:Artificial neural networks were designed using the MATLAB neural network toolbox to produce a moisture ratio prediction model of Radix isatidis extract during hot air drying and vacuum drying,where regression values and mean squared error were used as evaluation indexes to optimize the number of hidden layer nodes and determine the topological structure of artificial neural networks model.In addition,the drying curves for the different drying parameters were analyzed.Results:The optimal topological structure of the moisture ratio prediction model for hot air drying and vacuum drying of Radix isatidis extract were“4-9-1”and“5-9-1”respectively,and the regression values between the predicted value and the experimental value is close to 1.This indicates that it has a high prediction accuracy.The moisture ratio gradually decreases with an increase in the drying time,reducing the loading,initial moisture content,increasing the temperature,and pressure can shorten the drying time and improve the drying efficiency.Conclusion:Artificial neural networks technology has the advantages of rapid and accurate prediction,and can provide a theoretical basis and technical support for online prediction during the drying process of the extract.

A valid evaluation method for UPLC fingerprint analysis and moisture ratio prediction model:application to microwave vacuum drying of Radix isatidis extract

Background:Drying is a necessary component of traditional Chinese medicine extracts.The heating principle of microwave vacuum drying is different from that of the conventional heat method.However,at present,there is paucity of information on the drying process of traditional Chinese medicine extract by microwave vacuum drying,and the results of such process are unclear.Methods:To study the dynamic changes in the chemical characteristics of microwave vacuum drying under different drying conditions,ultrahigh-performance liquid chromatography fingerprint profiles were established using Radix isatidis extract as a model drug and analyzed using similarity analysis,partial least squares-discriminant analysis,and semi-quantitative analysis.In addition,a backpropagation artificial neural network model was developed to predict the moisture ratio of the drying process.Results:Qualitative results showed that the similarity between different drying conditions was greater than 0.95,and 2 amino acid components(peaks 5 and 6)affected by process fluctuations were screened out.The quantitative results showed that the mass concentration of component 1 fluctuated after drying,while that of component 2 increased.The optimal backpropagation artificial neural network model structure used to predict the moisture ratio was 5-4-1,with regression and mean squared error values of 0.996 and 0.0003,respectively,after training,which were well fitted and had a strong approximation ability.Conclusion:Upon comparison of fingerprints and the evaluation of statistical methods,common components of Radix isatidis extract had little variation under different drying conditions,and the selected components provided a reference for the establishment of process evaluation indexes.The establishment of backpropagation artificial neural network provides a theoretical basis for the application of microwave vacuum drying technology and online monitoring of moisture ratio.

Effect of different drying methods on the taste and volatile compounds,sensory characteristics of Takifugu obscurus

Pufferfish is prone to deterioration due to abundant nutrients and high moisture content.Drying technology can extend the shelf life and enhance the flavor quality of aquatic products.The study investigated the effect of hot air drying(HAD),microwave vacuum drying(MVD)and hot air assisted radio frequency drying(HARFD)on the taste and volatile profiles of Takifugu obscurus.Different drying methods had significant influence on the color,rehydration,5’-nucleotides,free amino acids and volatile components(P<0.05).The results showed that HAD and HARFD could promote the flavor of T.obscurus by producing higher equivalent umami concentration(EUC)values,which were about two times of MVD group,and more pronounced pleasant odor according to sensory analysis.HAD is more appropriate for industrial application than HARFD and MVD considering the economic benefits.This study could provide a reference for the industrial application of drying T.obscurus.

不同载体剂对冻干生姜粉末品质的影响

为探究麦芽糊精、海藻糖、阿拉伯胶对冻干生姜粉品质的影响,对添加载体剂后冷冻干燥的生姜粉的得率、物理特性、活性成分、粒径进行测定,用差示扫描量热法分析生姜粉在升温过程中的热流变化,并用傅里叶红外光谱法对特征基团进行分析,结果显示:与直接冻干的生姜粉相比,添加载体剂制备的样品的得率、物理特性及活性成分含量均有所提高,阿拉伯胶组得率最高;麦芽糊精组色差、吸湿性最小,生姜蛋白酶活力最高(65.84 U/g),姜辣素含量最高(24.4 mg/g);海藻糖组溶解度最高。DSC曲线显示:添加载体剂的生姜粉玻璃态转化温度均有所提高,其中阿拉伯胶组最高,性质更稳定。通过红外光谱分析,3种生姜粉的主要基团无明显变化。综合考虑,麦芽糊精是冷冻干燥生姜粉生产中保留生化活性和保持功能特性的最佳载体剂。

不同切分处理草莓的冻干效果比较

为明确适宜冻干加工的草莓切分方式,以整颗草莓为对照,将对半纵切、四半纵切、纵切片、横切片等4种不同切分方式的草莓进行冻干处理,分别考查了预冻速率、冻干速率等工艺参数指标,脱水率、复水率、维C含量、可溶性固形物含量、可滴定酸含量等营养理化指标,以及草莓冻干前后的色泽变化和感官评分。结果表明,横切片处理最佳,纵切片与对半纵切次之,四半纵切最差。其中,横切片冻干速率最快(0.50/h),横切片次之(0.48/h),冻干后草莓的维C含量以纵切片最高(保留率97.57%)、可溶性固形物含量以对半纵切最高(保留率97.12%)、可滴定酸含量以整颗处理最高(保留率96.19%),感官评分以横切片最高(89.6分),2种切片处理冻干后表皮及切面的亮度、红色程度均显著增加。可提高草莓附加值、减少损耗、降低生产耗能,为北京及周边地区草莓冻干加工的工业化生产提供有益参考和借鉴。

Effects of different drying methods on quality,bacterial viability and storage stability of probiotic enriched apple snacks

Effects of four different drying methods on the colour, texture, sensory quality, microstructure, bacterial viability and storage stability of probiotic-enriched apple snacks were assessed. The drying methods were air drying （AD）, freeze drying （FD）, freeze drying followed by microwave vacuum drying （FD＋MVD） and air drying followed by explosion puffing drying （AD＋EPD）. Overall, FD＋MVD can be used as a suitable drying method for the development of probiotic enriched apple snacks in consideration of colour, texture, sensory quality, bacterial viability and storage stability. Probiotic bacteria in FD＋MVD-dried samples remained above 1×106 CFU g 1 for 120 days at 25℃C. Interestingly, bacterial viability in FD＋MVD-dried samples turned out to be significantly higher than FD-dried samples during storage for 120 days.

Improvement of silty clay by vacuum preloading incorporated with electroosmotic method

A laboratory test was performed to assess the effectiveness of vacuum preloading incorporated with electroosmotic (EOM) treatment on silty clay (combined method) for reclamation projects like new disposal ponds, where the horizontal electrode configurations beneath the soil layer were possible and the drainage pipes and the prefabricated vertical drains (PVDs) system could be easily installed in advance before the sludge dragged from sea bed or river bed was filled into the site. Three groups of tests were conducted on the silty clay from Qinhuai River in Nanjing, China. The model is able to apply vacuum pressure at the bottom of the soil layer and a direct current electric field simultaneously. It is also possible to measure the pore pressures at different depths of soil column, and the changes in settlement and volume with the elapsed time. In this study, the vacuum preloading method, vacuum preloading applied at the bottom (VAB method), was applied and the cathodes were installed beneath the soil layer. The results obtained indicate substantial reduction in water content, and increases in dry density and undrained shear strength in comparison with those obtained by the vacuum preloading only, particularly at the positions close to the anode. The combined method utilizes the vertical drainage flow created by the electroosmosis integrating the horizontal drainage flow created mostly by the vacuum pressure. The total drainage flow can be calculated as a result of the vertical drainage flow by electroosmosis only and the horizontal drainage flow by the vacuum preloading only. The way of placement of the cathode and the anode in the combined method also overcomes the disadvantage of EOM method itself, i.e. the appearance of cracks between the anode and the surrounding soil. Moreover, it is observed that the vacuum preloading plays a primary role in earlier stage in deduction of free pore water; meanwhile, the electroosmotic method is more efficient in later stage for absorbing water in the diffused double layers of soil.

Antioxidant Activity of Anthocyanins Extracted from Iraqi <i>Iresine herbstii</i>L. Flowers after Drying and Freezing

Any processing method that maintains the level of compounds known for their health benefits will be of interest to the food industries. Therefore, the effects of vacuum drying, storage and freezing on the anthocyanin content and their antioxidant properties of Iresine herbstii L. flowers were investigated. The results showed that fresh samples (AEFF) had the highest amount of total anthosyanin content (8.31 ± 0.23 mg/g dry matter, expressed as cyaniding 3-glucoside equivalents), followed by 7.17 ± 0.12 mg/g solid content, 13.72% loss of vacuum dried samples (AEDF). In comparison with fresh samples, total anthocyanins in stored samples for two weeks at 5°C (AESF) and frozen samples during 1 (AEZF1) and 3 months (AEZF3) of storage were significantly (P < 0.01) reduced to 6.43 ± 0.24 mg/g solid content, 22.63% loss, 5.65 ± 0.33 mg/g solid content, 32.01% loss and 4.71 ± 0.51 mg/g solid content, 43.33% loss, respectively. Anthocyanins from I. herbstii L. flowers exhibited a dose-dependent (AEFF > AEDF > AESF > AEZF1 > AEZF3, respectively) antioxidant activity against lipid peroxidation in a linoleic acid model system as well as strong reducing power and ferrous ion chelating abilities. Moreover, the anthocyanins extracted were found to show remarkable scavenging activity on superoxide anion radicals, hydroxyl radicals, hydrogen peroxide, nitric oxide radicals and deoxyribose degradation. Based on the results obtained, we can concluded that the Iresine herbstii L. flowers may be valuable natural antioxidant sources and are potentially applicable in both pharmacy and food

Study of the Solar Energy Drying Device and Its Application in Traditional Chinese Medicine in Drying

Background: We referred to nearly 40 years of development and application progress of solar dryer in China literature, especially its application in the field of Chinese herbal medicine drying. Objective: We explored the development direction of China’s development and application of solar dryers, especially focusing on its development and application in traditional Chinese medicine drying. Method: Five types of solar dryers including the greenhouse type solar dryer, the collector type solar dryer, the collector-greenhouse type hybrid solar dryer, the integrated solar dryer and the focusing type solar dryer accounted for the development and application of solar dryers up to 95% in China. The first three types of solar dryers are low temperature dryer (less than or equal to 70°C), while the latter two kinds of solar dryers are high temperature dryer (more than 70°C). In this paper, we respectively introduced and compared the structure, working principle, applications, advantages and disadvantages, and the research status of these five dryer. Results: The integrated solar dryer and the focusing type solar dryer belong to the high temperature dryer types are the future direction of development. Among them, the integrated solar dryer is relatively simple structure and has more promotion prospects. These two kinds of key drying device used in the dryer is the development direction of high efficient vacuum tube. On the other hand, because of their low cost, simple structure and the dry material requirements etc., the three types of low temperature dryers at low temperature for drying materials are also indispensable in the practical application. In contrast, the collector-greenhouse type hybrid solar dryer has more advantages, is the development direction of low temperature drying category. Conclusion: The collector tube which is the key element of the dryer was the core technology of solar dryer. Our country develops more successful of the all-glass vacuum solar thermal collectors and heat pipe-glass vacuum tube. Efficient vacuum tube collector technology is the future developed direction and is equally important to improve the quality of traditional Chinese medicine and dried.

Design of ZigBee-WiFi Gateway for Vacuum Oven

In the process of power battery production, it is necessary to put battery into vacuum oven for drying, the temperature, the vacuum degree and other factors directly influence the quality of the power battery. In order to remotely control the temperature and vacuum degree of vacuum oven in the process of power battery manufacturing, the wireless communication system based on the ZigBee-WiFi gateway for the power battery production is presented. The system uses wireless module CC2530 as the core chip, to complete the machine networking in workshop, and use of WiFi wireless module ESP8266 to complete data interconnection ZigBee and WiFi network, implement the data information exchange and sharing between the vacuum oven and the Internet. This wireless communication system has the characteristics with easy networking, low power consumption and low cost. So, this communication system can meet the requirement of data transmission and sharing in power battery manufacturing and other production activities.

软枣猕猴桃速溶果粉开发研究

该文研究软枣猕猴桃真空冷冻干燥果粉的加工工艺,主要明确果实预处理技术、果粉冷冻干燥主要工艺参数及冻干粉碎技术。从外在品质和内在品质2个方面对真空冷冻干燥果粉的品质进行评定。该文归纳软枣猕猴桃真空冷冻干燥果粉研究中应注意的问题,对今后的研究重点与方向进行展望。

响应面优化香菇真空远红外干燥工艺研究

为探究香菇真空远红外干燥的最佳工艺参数,在单因素试验的基础上,采用Box-Behnken响应面法优化参数。试验以干燥温度、辐照高度和功率为因素,总色差值、复水比和平均干燥速率为评价指标,探讨了各因素对香菇真空远红外干燥的试验指标的影响,并建立各指标的二次回归方程。结果表明,建立的回归模型显著;香菇真空远红外干燥的较优工艺参数组合为:干燥温度60℃、辐照高度300 mm、功率600 W,在此条件下干制品的总色差值为13.45、复水比为1.9360、平均干燥速率为0.0103%·min-1。研究可为香菇的生产加工提供理论参考。

Drying characteristics,kinetics model and effective moisture diffusivity of vacuum far-infrared dried Rehmanniae

Vacuum far-infrared radiation(VFIR)drying has recently received many attentions because of its effective and successful applications in drying some agricultural products.The VFIR drying of Radix Rehmanniae was conducted and Weibull distribution function was applied to fit the drying kinetics in this study.The results showed that the increase of radiation heater temperature and the decrease of chamber pressure could reduce drying time obviously.Compared with single diffusion equation,Weibull distribution function had higher precision to fit the drying curves of VFIR drying of Rehmanniae.The effective moisture diffusivity(Deff)increased with the increase of heater temperature and the decrease of pressure.Scanning electron telescope(SEM)analysis showed that more porous surface could be observed after VFIR drying,which is beneficial to enhance moisture diffusivity and drying rate as well.

白萝卜智能远红外真空干燥设备的参数优化试验(英文)

To optimize the technology of on-line detection technology and automatic control system,the fresh turnip harvested in this year as test material,by analyzing the results of single factor experiment,heating temperature(60-80℃),vacuum in the warehouse(3 000-4 000 Pa),and material thickness(4-10 mm)were used as main test factors.Taking dehydration rate,rehydration rate,and VC mass ratio of dried product as test indexes,and using the quadratic general rotary unitized design approach,the influence and change law of far-infrared vacuum drying on drying turnip was studied.Analysis of interaction effects between the factors and the regression model,the regression equation was established,and the objective function optimization,the integrated balance method were adopted to identify the optimal conditions:the vacuum was 3000 Pa,the heating temperature was 70℃,and the material thickness was 7 mm.Under these conditions,the dehydration rate of dried turnip products was 25.23 g/(m2·h),VC mass ratio was2.05 mg/g,and the optimal value of rehydration ratio was 3.95.Finally,the turnip dry products were observed by SESM and the results were analyzed.The result showed that the cell wall breakage rate,cell deformation rate,and low profile shrinkage rate of turnip dried by infrared vacuum were lower;the surface smoothness preservation rate was higher;the cell tissue preservation rate was more than 80%,and the cell breakage and distortion was less.And the microscopic morphology of cell was kept well.Under these conditions,the original organization and structure of the sample were truly reflected,the better drying effect was achieved,the sensory quality of dried products was guaranteed.This study provide a technical basis for the intelligent far-infrared vacuum drying technology applying for fast drying of high moisture materials and a reference for improving the quality of the far-infrared vacuum drying of turnip.