Optimization of Process Parameters of Continuous Microwave Drying Raspberry Puree Based on RSM and ANN-GA

To improve drying uniformity and anthocyanin content of the raspberry puree dried in a continuous microwave dryer,the effects of process parameters(microwave intensity,air velocity,and drying time)on evaluation indexes(average temperature,average moisture content,average retention rate of the total anthocyanin content,temperature contrast value,and moisture dispersion value)were investigated via the response surface method(RSM)and the artificial neural network(ANN)with genetic algorithm(GA).The results showed that the microwave intensity and drying time dominated the changes of evaluation indexes.Overall,the ANN model was superior to the RSM model with better estimation ability,and higher drying uniformity and anthocyanin retention rate were achieved for the ANN-GA model compared with RSM.The optimal parameters were microwave intensity of 5.53 W•g^(-1),air velocity of 1.22 m·s^(-1),and drying time of 5.85 min.This study might provide guidance for process optimization of microwave drying berry fruits.

Self-adaptive PID controller of microwave drying rotary device tuning on-line by genetic algorithms

The control design, based on self-adaptive PID with genetic algorithms(GA) tuning on-line was investigated, for the temperature control of industrial microwave drying rotary device with the multi-layer(IMDRDWM) and with multivariable nonlinear interaction of microwave and materials. The conventional PID control strategy incorporated with optimization GA was put forward to maintain the optimum drying temperature in order to keep the moisture content below 1%, whose adaptation ability included the cost function of optimization GA according to the output change. Simulations on five different industrial process models and practical temperature process control system for selenium-enriched slag drying intensively by using IMDRDWM were carried out systematically, indicating the reliability and effectiveness of control design. The parameters of proposed control design are all on-line implemented without iterative predictive calculations, and the closed-loop system stability is guaranteed, which makes the developed scheme simpler in its synthesis and application, providing the practical guidelines for the control implementation and the parameter design.

Mathematical Modeling and Effect of Various Hot-Air Drying on Mushroom(Lentinus edodes)

An experimental study was performed to determine the characteristics and drying process of mushroom （Lentinus edodes） by 6 different hot-air drying methods namely isothermal drying, uniform raise drying, non-uniform raise drying, uniform intermittent drying, non-uniform intermittent drying and combined drying. The chemical composition （dry matter, ash, crude protein, crude fat, total sugars, dietary fiber, and energy）, color parameters （L, a＊, b＊, c＊, and h~） and rehydration capacities were determined. Among all the experiments, non-uniform intermittent drying reached a better comprehensive results due to the higher chemical composition, better color quality associated with high bright （26.381＋5.842）, high color tone （73.670＋2.975）, low chroma （13.349a：3.456） as well as the highest rehydration （453.76% weigh of dried body）. Nine kinds of classical mathematical model were used to obtained moisture data and the Midili-kucuk model can be described by the drying process with the coefficient （R2 ranged from 0.99790 to 0.99967）, chi-square （X2 ranged from 0.00003 to 0.00019） and root mean square error （RMSE ranged from 0.000486 to 0.0012367）.

Microwave Drying of Scots Pine Lumber:Structure Changes,Its Effect on Liquid Permeability

Microwave(MW)drying method was adopted to enhance the liquid permeability of Scots pine lumber.Structure changes were characterized by stereoscope microscope,scanned electron microscope(SEM)and transmission electron microscope(TEM)examination.Pore parameters before and after MW treatment were detected by mercury intrusion porosimetry(MIP)method,and the effect of structure changes on liquid permeability were analyzed.As stereoscope microscope,SEM and TEM examination results showed,macro and micro checks mainly developed at intercellcular of tracheids,intercellular of ray parenchyma and tracheid,while these checks extend main along the radial-longitudinal plane.Pit border destruction,aspirated pits’orus translocation and micro-checks in tracheid cell wall were also observed.MIP test shown that pore volume and pore area increased as macro and micro checks generated to form new cavities.Microstructure changes would increase the quantity of pores or enlarge the pore diameter.Liquid flow pathways increased as macro and micro checks generated,aspirated pits reopened to form new pathways;liquid flow efficiency improved as porosity,pore volume and pore diameter increased which facilitated the liquid flow.

Cassava slices drying by using a combined hot-air single-plane microwave dryer

Characteristics of cassava drying were investigated by using a microwave hot-air drying system. Two waveguides were installed on a single plane of the microwave cavity. The drying experiments were carried out at two levels of sample surface temperature set-points, 70℃ and 80℃respectively. Cassava (Rayong-9) with 2.5 kg weight and 61% moisture content on wet basis was dried in the dryer for about 300 - 340 minutes until the final values of moisture content of about 20% db were achieved. It was found that the drying time decreased with an increase in sample-surface temperature set point. Approximately 87% of the moisture was removed during the drying period. It was found that there was a rapid decrease in moisture ratio values followed by the gradual decline period in all experiments. With regard to drying kinetics, 5 commonly used mathematical models were examined with the experimental data. It was found that Page’s and diffusion models provided a good agreement between the experimental and predicted moisture ratio values for all temperature set-points. The regression results indicated that highest values of coefficient of determination and adjusted coefficient of determination as well as lowest value of standard error of estimation were reported for the case of Page’s model at 80℃?temperature set-point.

Modeling microwave drying kinetics and moisture diffusivity of Mabonde banana variety

This study investigates the microwave drying kinetics of thin layer Mabonde banana variety(MBV)at power levels between 100 and 300 W.Six mathematical drying models:Wang and Singh,Verma,Two-term,Page,Two term exponential,and Logarithmic models were fitted to experimental drying data obtained from the study.The statistical consistency of the models was determined using statistical parameters including coefficient of determination,mean bias error,root mean square error,and reduced Chi square.Moisture migration from banana slices was described using the Fick’s diffusion model.The effective diffusivity was calculated.The results indicated that drying took place largely in the falling rate period.The time required to reduce the moisture of banana to a certain level was dependent on the microwave output,being the longest at 100 W and shortest at 300 W.The effective moisture diffusivity increased with increasing microwave power with values at 4.89×10^(-10),1.09×10^(-9) and 1.69×10^(-9) m^(2)/s at 100,200,and 300 W,respectively.The Wang and Singh model gave the best results for the description of thin layer drying of MBV.

Structural and functional properties of hydrolyzed/glycosylated ovalbumin under spray drying and microwave freeze drying

Ovalbumin(OVA),the main protein in egg white,affects most of the functional properties of egg white protein in food processing.The aim of this study was to investigate the effects of spray drying(SD)and microwave freeze drying(MFD)on the preparation of hydrolyzed/glycosylated ovalbumin(HGOVA)and provide useful information on the applications of egg protein powders in the food industry.Results demonstrated that the structure of HGOVA was considerably changed,and its functional properties were improved compared with those of native OVA.SD and MFD processing did not lead to dissociation of HGOVA subunits.SD-HGOVA exhibited higher protein solubility,emulsifying activity,foaming capacities,and gel hardness than MFD-HGOVA.However,MFD-HGOVA was better than the SD-HGOVA in terms of color,emulsion stability,foam stability,water/oil absorption capacity,and thermal stability.Selection of an appropriate drying method could enhance the potential applications of HGOVA in the food industry.

Process Parameter Study on Microwave-assisted Foam-mat Drying Properties of Corn Soaking Water

In order to study the microwave-assisted foam-mat drying properties of corn soaking water and optimize process parameters, a quadratic regression orthogonal rotary method was used to analyze the influence of microwave power, material weight, material thickness and drying time on moisture content（dry basis）, color value and protein content. Results showed that the primary and secondary sequence of parameters with regard to moisture content（d. b.） was drying time, microwave power, material weight and material thickness; the primary and secondary sequence of parameters with regard to color value was material weight, drying time, microwave power and material thickness; the primary and secondary sequence of parameters with regard to protein content was drying time, material weight, microwave power and material thickness. Optimum conditions were obtained as microwave power of 560 W, material weight of 46.88 g, material thickness of 6.20 mm and drying time of 8.01 min. The results might provide the theoretical basis and technical support for the microwave-assisted foam-mat drying of corn soaking water to produce yeast protein power.

In flue nee of microwave drying and con venti onal drying methods on the mechanical properties of naproxen sodium drug tablets

Tablets are one of the most comm only used solid dosage forms taken by patients.The preparati on of high-quality tablets requires an understanding of the preparation process and elucidation of how the physical and mechanical properties change as a function of the preparation process.This work aims to investigate the impact of microwave irradiation drying and conventional drying methods(including freeze,convective and vacuum drying)on the hardness,tensile strength and friability of tablets made from a multi-component formulation containing naproxen sodium,microcrystalline cellulose,and polyvinylpyrrolidone.The results show that tablets subjected to microwave drying had the secondhighest tensile strength and hardness of 1.296 MPa and 67 N,respectively.The tablets subjected to vacuum drying had the lowest tensile strength and hardness of 1.21 MPa and 64 N,respectively.The friability index values for the tablets derived from the microwave and freeze-drying methods were<1%,while those for the tablets subjected to convective drying and vacuum drying methods were>l%.Microwave drying was observed to be an efficient method to produce naproxen sodium-containing tablets with satisfactory mechanical properties.These findings confirm that the drying method plays an essential role in the improvement or degradation of the mechanical properties of tablets.

Drying Characteristics of Microwave-assisted Foam Drying of Corn Soaking Water

To improve the industrial utilization of corn soaking water, the yeast protein powder was produced by microwave-assisted foam drying. Firstly, preparation experiments were carded out, which included the foaming characteristic experiments of fermentation broth and that about the effects of carbon and nitrogen ratio on solid content in the fermentation broth. Secondly, the drying characteristics experiment of corn soaking water was studied, which selected the microwave power, material amount and thickness as the influencing factors for the single experiment. The results showed that the final moisture content （d.b.） and drying rate were significantly affected by those factors.

Mathematical modeling of microwave drying of crashed cotton stalks for man-made composite material

Drying characteristics,energy consumption and drying kinetics modeling of crashed cotton stalks dried in a microwave dryer were investigated in this research.A microwave dryer with an output power of 1000 W and 2450 MHz was employed,and the effects of material load ranging from 50 g to 250 g on drying time,drying rate,drying efficiency and specific energy consumption were evaluated.The results showed that drying rate decreased with drying duration.A rising rate period was followed by a falling rate period and the overall drying process occurred in the falling rate period.Six mathematical models were used to fit the drying rates data of crashed cotton stalks,and Midilli et al.model was found the best prediction model by comparing R2,RMSE andχ^(2)values between experimental and predicted moisture ratios.With decrease in material load from 250 g to 50 g,effective moisture diffusivity increased from 2.8668×10^(-8)m^(2)/s to 7.9817×10^(-8)m^(2)/s.Results also indicated that drying efficiency and specific energy consumption significantly increased with the increase of the material load.Average drying efficiency and specific energy consumption varied in the range of 7.52%-19.78%and 12.49-35.90 MJ/kg water,respectively.There were a lowest energy consumption of 10.99 MJ/kg water and a highest drying efficiency of 17.13%at the material load level of 250 g.

Microwave Sintering of W-15Cu Ultrafine Composite Powder Prepared by Spray Drying & Calcining-continuous Reduction Technology

The effects of microwave sintering and conventional H2 sintering on the microstructure and properties of W-15Cu alloy using ultrafine W-15Cu composite powder fabricated by spray drying ＆ calcining-continuous reduction technology were investigated. In comparison to the conventional HE sintering processing, microwave sintering to W-15Cu can be achieved at lower sintering temperature and shorter sintering time. Furthermore, higher performances in microwave sintered compacts were obtained, but high microwave sintering temperature or long microwave sintering time could result in coarser microstructures.

Microwave Dried Carrot Pomace as a Source of Fiber and Carotenoids

Carrot pomace is a major by-product obtained during the industrial juice extraction process, which is discarded contributing to environmental pollution. This residue is rich in fiber, and contains high amounts of carotenoids and phenolic compounds that could contribute to its application as functional ingredient, improving the quality of foods and helping to reduce the environmental problem. In this study, carrot pomace powders obtained by microwave or hot air drying were incorporated into cookies in order to improve their phytochemical content. Cookies were prepared using a traditional cookie recipe substituting 30% of the wheat flour for either of the carrot pomace powders. Fiber, carotenoids and phenolic compounds were determined;image analysis and acceptability of the cookies were also conducted. The substitution of 30% of wheat flour for carrot pomace powders increased 3.7 fold the total dietary fiber of cookies, from 7.13 g/100gto26.44 g/100g;accounting the 7.4% of fiber daily intake with the consumption of one cookie (7 g). A similar pattern was found in the content of carotenoids and phenolic compounds. Carrot pomace dried with microwaves had the highest amount of these bioactive compounds. β-carotene, epicatechin, gallic and ferulic acids were identified in cookies with microwave carrot pomace powder. The cookies incorporated with carrot pomace powders exhibited improved antioxidant properties because of the increase in the phytochemical content. Acceptable cookies with appealing orange color were obtained. The results indicated that the replacement of wheat flour for carrot pomace powders yielded dietary fiber enriched cookies with improved carotenoid content.

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.

A Study of Quality Improvement of Natural Rubber Products by Drying Methods

This experimental study was carried out to verify the quality enhancement of Natural Rubber Products by drying methods and ascertain to what extent the different methods of drying affected the properties exhibited. During this study, samples of natural rubber coagulum were obtained and a sample each was subjected to one of these three methods of drying: air, smoke and oven. The qualities of the dried rubber samples from the three methods of drying were then investigated. The criterion adopted for quality in this study was Plasticity Retention Index (PRI), which gave insight of the oxidative resistance of natural rubber, a measure of quality. The plasticity retention index was tested by using the Wallace plastimeter. The PRI values were calculated for the samples. Results obtained from this study showed that the qualities of natural rubber samples were actually influenced to different measurable extents depending on drying methods, as exhibited in the PRI levels. The results further gave basis for our conclusions that the smoke dried rubber samples had the poorest qualities, having the lowest values of PRI;followed by the oven and air dried samples respectively in terms of their PRI presented the best qualities, the highest PRI values.

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.

Drying characteristics and mathematical model of ultrasound assisted hot-air drying of carrots

In order to improve the heat and mass transfer process in hot-air drying,power ultrasound was coupled directly to hot-air drying of fresh carrot slices.The effects of ultrasonic power,radiation distance,hot air velocity and temperature on drying characteristics were studied.In addition,the Page equation was used to fit the ultrasound assisted hot-air drying process of the carrot slices.The results showed that the drying rate of carrot slices increased with the increase of ultrasound power and the decrease of radiation distance.Power ultrasound had a greater enhancement on hot-air drying at lower air velocity(0.5 m/s)and temperature(40ºC),especially at the middle and later periods(controlled by internal diffusion).The drying time of carrot slices using ultrasound assisted hot-air drying was shortened by 37.5%compared to that using hot-air drying at the condition with power of 150 W,radiation distance of 15 cm,air velocity of 1.0 m/s and temperature of 40ºC.All test indicators of the model meet the accuracy requirements,which show that the model can better fit the experimental values.

Lid scrubbing with a gel combining natural extracts for dry eye treatment

AIM:To evaluate the effect of lid scrubbing using a gel combining different natural extracts on ocular signs and symptoms of dry eye patients.METHODS:A retrospective study was performed on 19 dry eye patients(51.1±16.0y).Non-invasive tear break-up time,tear meniscus height,meibomian gland loss,lipid layer thickness,conjunctival redness,corneal staining,ocular surface disease index(OSDI),and ocular pain intensity were measured before(baseline),1wk,and 2mo after lid scrubbing with a gel containing different natural extracts(okra extract,aloe vera leaf juice,hydrolysed soy protein,caffeine,citrus unshiu peel extract,and raspberry seed oil).RESULTS:Compared with the baseline,there was a statistically significant improvement in both first(P=0.048)and average(P=0.026)non-invasive tear break-up time 2mo after treatment,as well as in corneal staining(P=0.043,0.012),OSDI(P<0.001),and ocular pain intensity(P<0.001)after 1wk and 2mo.In addition,there was no correlation between ocular signs and symptoms.CONCLUSION:The lid scrubbing with a gel combining different natural extracts show beneficial effects on tear film stability,corneal damage,and ocular symptoms,which is the reason why this therapeutic procedure is proposed as an alternative for dry eye management.However,it is not possible to attribute this beneficial effect solely to the presence of the natural extracts in the gel,primarily due to the absence of a negative control group.

A 3D analysis of the occurrence of fractures in hot dry rock reservoirs based on the spatial distribution of natural fractures

Hot dry rock(HDR)geothermal energy is a kind of widely distributed clean energy with huge reserves.However,its commercial development has been constrained by reservoir stimulation.In the early stage of HDR geothermal energy development,properly determining spatial distribution patterns of natural fractures in HDR reservoirs can effectively guide reservoir stimulation.This study analyzes the spatial distribution of natural fractures by using FracMan software based on the actual geological data and log data of well M-2 in the Matouying Uplift area,Hebei Province.The fracture parameters are counted and Monte Carlo simulation technique is introduced to optimize the parameters,which makes the natural fracture model more accurate and reliable.Furthermore,this study simulates hydraulic fracturing using the model combined with the actual in-situ stress parameters and the construction scheme.As verified by fitting the changes in simulated wellhead pressure during hydraulic fracturing with the actual wellhead pressure data detected during construction,the methods for natural fracture modeling used in this study are scientific and reasonable.The preliminary prediction results show that the displacement design scheme with a pump displacement of 2.0-3.0 m^(3)/min,4.0-5.5 m^(3)/min and 6-7 m^(3)/min in the early,middle and late stages,respectively,has good fracturing effect.The results of this study can be utilized as a reference for preparing development schemes for HDR reservoirs.

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.