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.

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.

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.

Effect of vacuum impregnation on the performance of Co/SiO_2 Fischer-Tropsch catalyst

Two silica-supported cobalt catalysts were prepared by incipient wetness impregnation under atmospheric and vacuum conditions.N2 ph- ysisorption,H2 chemisorption,XRD,SEM,TEM,XPS and H2-TPR were used to characterize the catalysts.The results showed that the impregnation methods had an effect on the size,dispersion and reducibility of cobalt particles.Under vacuum conditions,cobalt-containing steeping liquor could penetrate into the inner pores of silica support and more bivalent cobalt oxides were formed in the Co3O4 crystallites.Furthermore,cobalt precursors were rarely inclined to agglomerate and the smaller cobalt particles were uniform on the support,which led to the higher activity of the Co/SiO2（B）catalyst than the normal one under the reaction conditions of 483- 523 K,1 - 2 MPa,gas hourly space velocity of 500–1000 h-1 and molar ratio of H2/CO=0.5 - 2.0.

Optimization of Bioactive Fortification in Apple Snacks through Vacuum Impregnation Using Response Surface Methodology

Fortification of apple slices with t-resveratrol glucoside was obtained by vacuum impregnation (VI) of apple slices with a solution containing grape juice using response surface methodology (RSM). Three independent variables of the VI process: vacuum pressure, application time and relaxation time, were coded at five levels in a central composite design. The VI-treated and dried apple slices were analyzed for t-resveratrol glucoside concentration and textural attributes (gradient and linear distance). Multiple response optimization revealed the following optimum VI condi-tions for the bioactive enrichment and improved textural quality of dried apple slices: vacuum pressure of 6 in. of Hg, application time of 10 min, and relaxation time of 22.5 min.

Comparison of Drying Rate and Energy Consumption between Vacuum and Ambient Pressure Drying for Chinese Fir

In this work, Chinese fir samples with a size of 400 mm (L) by 50 mm (W) 30 mm (H) weretaken as specimens, and drying rate and energy consumption were compared under the conditions, inwhich the absolute pressure was 0.02 , 0.04 , 0.06 and 0.10 MPa, respectively, and the temperature was80 oC. The results showed that, when the moisture content (MC) of the samples was above fibersaturation point (FSP), the vacuum drying rate was 0.96-1.24 times as high as the ambient pressuredrying rate. However, when it was below FSP, the vacuum drying rate was 1.26-1.32 times as high as theambient pressure drying rate. At the same time, when the MC was above FSP, the energy consumptionof vacuum drying was 81.1%-95.9% of that of ambient pressure drying; when the MC was below FSP,the energy consumption of vacuum drying was 62.40%-69.40% of that of ambient pressure drying.Therefore, the vacuum drying was superior to the ambient pressure drying in terms of drying rate andenergy consumption.

Freeze and microwave vacuum combination drying technique for sea cucumber

To improve the quality and efficiency of sea cucumber drying,an orthogonal experiment of freeze and microwave vacuum combination drying technique was carried out.Factors and levels were FD time of conversion point(8 h,16 h and 24 h),initial microwave power density(1.7 W/g,2.0 W/g and 2.3 W/g)and microwave intermittent ratio(12s-on/18s-off,14s-on/16s-off and 20s-on/10s-off).Results showed that the optimal parameters of FD-MVD were 8 h FD conversion point,1.7 W/g initial microwave power density,12 s-on/18 s-off microwave intermittent ratio,and the maximum rehydration rate of 280.71%,the lowest shrinkage rate of 14.48%,the least drying time of 9.25 h and energy consumption of 77316 kJ could be obtained.

Effects of different pulsed vacuum drying strategies on drying kinetics,phenolic composition,and antioxidant capacity of chrysanthemum(Imperial chrysanthemum)

This work aimed to discuss effects of pulsed vacuum drying(PVD)at different temperatures(45°C,50°C,55°C and 60°C),vacuum durations(5 min,10 min and 15 min)and multi-stage heating on drying kinetics,colour attributes,phenolic compounds and antioxidant capacity of chrysanthemum(Imperial chrysanthemum).Results indicated that successive temperature increase reduced the drying time and enhanced the drying rate and moisture diffusivity.Lower temperature(45°C)and the multi-stage(35°C-55°C-60°C)drying presented the superiority in the protection of color,preservation of phytochemical composition(chlorogenic acid,luteolin,total phenolic and total flavonoid content)and improvement of antioxidant capacity(DPPH and FRAP)of chrysanthemum,which was attributed to the low-oxygen drying environment and reduction of thermal degradation losses.Based on the results of drying efficiency and drying quality,the multi-stage heating(35°C-55°C-60°C)has the excellent potential to produce high-quality dried chrysanthemum on a commercial scale.

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.

Microstructure changing and moisture removing of lychee during microwave vacuum drying

Micrographs of lychee pericarp and pulp during microwave vacuum drying were tested and analyzed in order to illuminate the microstructure change of lychee and effect of the change on moisture removing in lychee.The results showed that the pericarp consisted of three parts:outer layer with cuticle,inter layer and inner layer.Outer layer and inter layer cells are easily destroyed than inner layer because of small and intact inner layer cells.Furthermore,micrographs showed that the moisture content of pulp keep constant with the temperature increasing at first 40 min due to the inner layer cells prevent the moisture removing from pulp.The long tubular structure of pulp cell would become break and lost over time,because the intercellular spaces reduced and the moisture removing was slow down in pulp.Meanwhile,the microstructure of lychee dried with temperature control was better than that without temperature control.

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.

Preliminary Research on Critical Dimension of Wood under Vacuum Drying

The objective of this experiment is to explore how the thickness and the length of the specimen affect the vacuum drying rate, and to explore whether the different lengths of specimens have different vacuum drying rates. The results are as follows: in a certain range of dimension and pressure, the length of specimens has more effect on the vacuum drying rate than the thickness. When the ratio of end area to volume is less than 0.10 cm-1, the drying rate decreases exponentially with the increasing of the length.

Effects of pulsation ratio on center temperature and drying characteristics of pineapple slices with pulsed vacuum drying

This research explored the application of pulsed vacuum technology on the drying(PVD)of pineapple slices.Influences of drying temperature and pulsed vacuum ratio(PVR)on drying characteristics and pineapple quality(color,rehydration characteristics,microstructure,and texture)were analyzed.As expected,increasing the drying temperature resulted in a higher drying rate and effective moisture diffusivity.The optimal PVR of 5:5 was beneficial in accelerating the drying rate of pineapple slices and the corresponding effective moisture diffusion coefficient(8.9601×10^(-10))was higher than other PVR conditions based on material center temperature.The material temperature increased during the normal pressure period and decreased rapidly when the pressure dropped to the vacuum condition,which indirectly reflected the moisture transfer that occurred during the vacuum holding period,while moisture diffusion happened during the atmospheric pressure holding period.The optimal pulsed vacuum drying process(PVR of 5:5)could expand air and water vapor and create a looser structure so as to obtain better rehydration performance(rehydration ratio(RR)was 5.43).High drying temperature led to the decrease of L^(*)value,the increase ofΔE value,and even the formation of surface scorch at 80℃.At the same drying temperature,the color quality depended on the drying time,and the color difference increased with the extension of the drying time.The chewiness and hardness of pineapple slices dried by PVD were significantly higher than those of fresh samples,which was conducive to the chewing taste.