Assessment of new in-bin drying and storage technology for soybean seed

On-farm, in-bin drying and storage of soybean in environments with unconditioned air often result in repeated drying and rewetting of the grains which may have adverse effects on quality metrics; if done using natural air, as recommended for soybean destined to the seed market, the in-bin drying and storage method require operation at well-defined local weather-dependent strategies to maintain the seed quality. This study simulated in-bin drying and storage of soybeans. Different fan control options and drying strategies were used to assess performance in terms of drying duration to target final moisture content (MC), percent over drying, energy expenditure, and drying cost. Fan operation included running the fan continuously, only at night, only during the day, at a set window of equilibrium MC (EMC) of natural air, and set EMC window with supplemental heating of ambient air as an option (EMC-H). Drying and storage performance were tested for soybean at initial moisture content (IMC) (16–22%, wet basis), air flow rate (1.04–5.0?m³?min^?1 [air] t^?1 [soybean]), and harvesting start dates (August 15 to November 15). Simulation model was validated using a bench-scale pressure drop system filled with soybeans with IMC of 22% wet basis. The result shows that fan control strategies, air flow rates, harvest date, and initial MC of the soybeans significantly (P?χ² was 0.88.     

Impact of rewetting and drying of rough rice on predicted moisture content profiles during in-bin drying and storage

Accurate prediction of moisture content (MC) is vital for effective control of on-farm, in-bin drying and storage of rough rice, especially for systems using recently introduced technology to automate fan run time. The study used simulations, laboratory, and field experiments to investigate the extent to which rewetting and drying, during in-bin drying and storage, affect accuracy of predicted MC—a critical parameter for automated fan control. Vapor sorption analysis (VSA) was used to generate MC prediction models for rough rice. Simulations of in-bin drying and storage, using in-field weather data, were performed while segregating effects resulting from rewetting and drying of the rough rice and the type of fan control strategy used. Predicted MC profiles of rough rice and drying durations were compared with those resulting from using standard constants in the literature for modeling. The root mean square error associated with predicting the MC by model constants developed using the VSA was 0.54% MC and 1.32% MC dry basis (d.b.), for desorption and adsorption, respectively. Deviation in MC logged by in-bin built, field sensors and that simulated by taking into account the influence of rewetting and drying were generally within 1.5% point difference. Therefore, rewetting and drying did not affect drying duration. However, drying duration was significantly influenced by fan control strategy (p?相似文献   

Influence of blanching treatment and drying methods on the drying characteristics and quality changes of dried sardine (Sardinella gibbosa) during storage

The aim of this study is to examine the drying characteristics of blanched and unblanched sardine during indoor and open sun drying processes. Changes in temperature and relative humidity of the air during drying were recorded. The color, peroxide value (PV), thiobarbituric acid reactive substances (TBARS), free fatty acid (FFA) content, fatty acid composition, and sensory attributes of dried samples were also evaluated once a month for 5 months of storage. High drying rates were obtained in all samples at the start of drying and then decreased with increasing drying time. The highest drying rate and effective water diffusivity (D_eff) were observed in blanched sardine during open sun drying. Blanching treatment slowed down the FFA progression during product storage but adversely affected the color, PV, and TBARS content as well as sensory properties. Although sardine dried for a longer time under indoor drying conditions, it attained a stable moisture ratio that was lower than in open sun-dried samples. Indoor drying produced a quality stable product with less lipid oxidation and the desired moisture content, higher polyunsaturated fatty acids and sensory properties. Blanching treatment negatively affected the fish quality and is therefore not recommended for commercial sardine drying.     

钛风机在氯气透平压缩机干燥系统中的优化控制

介绍了在隔膜电解系统中,钛风机在氯气透平压缩机干燥系统中的优化控制。     

Drying kinetics and product quality of green soybean under different microwave drying methods

The objective of this study was to investigate the effect of different microwave drying techniques on the drying kinetics and product quality of dried green soybean. Experiments were conducted using microwave vacuum drying (MVD), pulse-spouted vacuum microwave drying (PSMVD), pulse-spouted microwave drying (PSMD), and microwave freeze drying (MFD). Parameters of apparent density, color, processing temperature, expansion ratio, rehydration ratio, texture, and microstructure of the dried products were determined. The results showed that the MFD green soybean had a small change on bright color, compared with the fresh samples, but the drying time was the longest among the four methods. The bright color value of PSMVD/PSMD/MVD, respectively, was 79.77, 71.43, and 55.45, and drying time of them was slightly different. The PSMVD/PSMD showed advantages over MVD by improving the product quality.     

Modeling and simulation of the drying of thin sheets in a continuous infrared dryer

The model gives the temperature and moisture distributions of the air, and of the moist sheet, as a function of time and distance in the dryer. The influence of the sheet's velocity and that of the radiant energy on the dryer performance as well as the effect of the moisture content of the entering sheet have been studied. A set of 27 experiments was carried out using the infrared dryer in order to calibrate the model. In these, the following three variables each had three operational levels: web velocity, initial web moisture and heating power. The model predictions agreed very well with the experimental data. Model predictions using arithmetic averages for the parameters, and parameters correlated with operational variables, are also presented and discussed.     

Conjugate heat and mass transfer model for predicting thin-layer drying uniformity in a compact,crossflow dehydrator

Abstract

A conjugate heat and mass transfer model was implemented into a commercial CFD code to analyze the convective drying of corn. The Navier–Stokes equations for drying air flow were coupled to diffusion equations for heat and moisture transport in a corn kernel during drying. Model formulation and implementation in the commercial software is discussed. Validation simulations were conducted to compare numerical results to experimental, thin-layer drying data. The model was then used to analyze drying performance for a compact, crossflow dehydrator. At low inlet air temperatures, the drying rate in the compact dehydrator matched the thin-layer drying rate. At higher temperatures, heat losses through the external walls resulted in temperature and moisture variations across the dehydrator.     

Model-based multivariable control of the drying of a thin sheet of fibres in a continuous infrared dryer

We developed an Internal Model Control (IMC) algorithm for drying a thin textile fabric, continuously passing through an electric infrared dryer, based on a reduced linear model of the drying dynamics. This model relates the controlled variables, the humidity and temperature of the web at the dryer outlet, to the manipulated variables, the electrical power supplied to the sources and the web speed through the dryer, and also to changes in the initial humidity of the web at the dryer inlet. The control algorithm was first tested by simulation using the model in regulation mode, and in set-point tracking mode, to vary the manipulated variables so as to maintain the controlled variables at their respective set-points when the inlet web temperature and humidity were changed. The performance under simulated operational conditions was compared to that of a conventional feedback proportional-integral (PI) controller coupled with a feedforward control. The IMC controller was then tested directly in regulation mode using a pilot scale infrared dryer, acting simultaneously on the manipulated variables, the emitter power and the web speed, to control the fabric temperature and humidity at the dryer outlet. The experimental results were compared with those from the above feedback-feedforward controller, on the pilot scale dryer. The results have indicated that the closed-loop stability of the process is assured simply by choosing a stable IMC controller. Also, such a controller does not require the design of specific compensators for the strong interactions between variables of the drying process.     

Prediction of crude sunflower oil deterioration after seed drying and storage processes

The effects of air-drying temperature and storage time on several characteristics of crude sunflower oil were evaluated in terms of FFA and PV. Long storage affected oil content to a greater extent than air-drying temperature. FFA and PV varied between 0.53 and 1.22% and between 10.7 and 23.3. meq O₂/kg, respectively, when samples of uniform initial moisture content (approximately 28%) were dried at various temperatures between 25 and 90°C to approximately 7% moisture content, stored for 8 mon, and then analyzed. Both oil quality characteristics increased exponentially with air-drying temperature (T) and linearly with storage time (t). Mathematical functions of the form A·exp(B·T)+C·t (where A, B, and C are parameters adjusted from experimental data) most closely predicted the experimental loss of quality of sunflower oil in terms of FFA and PV with variations in T and t. Statistical analysis showed SE of the estimated parameters of 0.08 and 1.19 and coefficients of determination, R ², of 0.922 and 0.939 for FFA and PV, respectively, which were significant at 95% confidence. High-oleic seeds from a similar experiment were used to validate the proposed equation. The results of applying the mathematical function proposed above showed a reasonable ability to predict the experimental values with SE of 0.037 and 0.808 and R ² of 0.983 and 0.972 for FFA and PV, respectively, which were significant at 95% confidence. Plots of residuals showed random distribution. The results obtained suggested that the equation proposed could be used as a quality-loss model in sunflower drying simulations.     

Effects of spray drying on Lactobacillus plantarum BM-1 viability,resistance to simulated gastrointestinal digestion,and storage stability

The aim of this study was to evaluate the applicability of spray drying in the production of high-viability powder of L. plantarum BM-1. Firstly, in order to improve the survival of L. plantarum BM-1 during spray drying, different protectants were added before drying. The results showed that the highest survival rate of 75.70% and the lowest moisture content of 3.67% were achieved with the combination of reconstituted skim milk (RSM) and equal weight sucrose as protective agent. The cell counts reduction of free L. plantarum BM-1 was 2.58 log CFU/ml after exposure to 60°C for 1 min, whereas the reduction in spray-dried cells protected by RSM and sucrose was only 0.08 log CFU/ml. After 120-min incubation in simulated gastric condition, cell counts of free L. plantarum BM-1 decreased approximately 1.4 log CFU/ml, whereas no significant (p > 0.05) reduction in spray-dried cells was observed. Compared to the free cells, the spray-dried cells also showed higher survival under bile salts stress. In addition, the bacteriocin production of L. plantarum BM-1 was not affected during spray drying. Furthermore, the survival rate of spray-dried powder reached 98% after storage for 2 months at 4°C, and a nitrogen replacement package was shown to be better than a vacuum package and air-sealed package at room temperature. Therefore, the combination of equal weight RSM and sucrose is a promising protective agent for L. plantarum BM-1 during spray drying.     

Serial combination drying processes: A measure to improve quality of dried carrot disks and to reduce drying time

Conventional drying processes like hot air-drying (HAD), freeze-drying (FD) and microwave vacuum drying (MVD) have specific advantages and disadvantages concerning product quality and drying time. Recent studies have shown that serial combinations of these processes can lead to better product quality (water content, color, hardness, rehydration, volume, and ingredient retention) and favorable process parameters (shorter time, less energy consumption). However, little is known about the timing of the changeover point between the different processes. In this study, we investigated the development of quality parameters (volume retention, rehydration properties) during FD, HAD, and MVD either as a single or as a serial combination process with varying changeover point. Therefore, carrot disks were processed in a modular drying processor to different final relative moisture contents. On this basis, recommendations were derived for certain combinations of drying processes to achieve desired product quality parameters, partially with shorter drying times.     

Energy and drying time optimization of convective drying: Taguchi and LBM methods

In this study, a novel method for numerical simulation of drying is proposed and the process is optimized by Taguchi method. A 2D numerical solution is performed to analyze coupled heat and mass transfer occurring during drying of a rectangular moist object. The dryer section and the moist object are conjugately simulated where the coupled heat and mass transfer equations are solved together. The lattice Boltzmann method is employed to solve hydrodynamic, heat, and mass transfer equations. This study applied the Taguchi method to determine optimum conditions for drying so as to minimize the drying time and energy consumption. The control factors included temperature, air velocity, and thickness ratio (the moist object thickness to channel width). The following optimal conditions were obtained: temperature (T?=?60?°C), velocity (V?=?0.1 m/s), and thickness ratio (TR =0.1). The results of numerical solution are then compared to the measured data available in the literature, presenting a reasonable agreement.     

Influence of spray drying temperatures and storage conditions on physical and functional properties of dried egg white

This study investigated the effect of spray drying inlet temperatures (140, 160 and 180°C) and storage conditions (temperature; 25 and 40°C and storage period; 1 and 2 months) on the physical and functional properties of dried egg white. The results showed that the three inlet temperatures did not affect the color of the spray-dried egg white (SDEW) after drying. However, all SDEWs increased in yellow color after storage at 40°C. The solubility (%) of SDEW and gelling properties including gel hardness and water holding capacity of the gel samples were changed when the dried samples were stored, particularly for SDEW drying at 180°C. The changes in gelling properties of the SDEW were related to a decrease in the enthalpy of protein denaturation, an increase in exposed sulfhydryl (SH) contents, a decrease in the total SH contents and the occurrence of protein aggregation as shown by the sodium dodecyl sulfate-polyacrylamide gel electrophoresis pattern.     

变频调速在乳液聚氯乙烯喷雾干燥过程中的应用

阐述了引风机变频调速的节能原理及其优点。介绍了乳液聚氯乙烯喷雾干燥过程及4-73-11.9D引风机采用变频调速后达到的节能效果。     

Recent developments in physical field-based drying techniques for fruits and vegetables

Abstract

Modern physical field technologies mainly include microwave, radio frequency, infrared radiation, ultrasound, pulsed electric field, and so on. Nowadays, the application of physical field technology on conventional drying is one of the recent strategies to solve some problems in traditional drying. In this article, physical field-based drying techniques refer to hybrid drying methods consisting of the conventional heating combined with different physical field technologies, in which physical field technologies provide various heat sources differ from conventional ones. A review is presented of recent five-year literature in the development of selected physical field-based drying technologies (microwave, radio frequency, infrared radiation, and ultrasound) for fruits and vegetables. As shown by examples from the literature, these physical field-based drying techniques provide faster drying kinetics and better thermal efficiency and obtain dried products of improved quality (e.g. color, aroma, texture, and nutrition retention) relative to conventional hot air drying. The combination of these techniques and conventional hot air drying showed enhanced cost-effectiveness as well. Furthermore, recommendations are made for further research and development needs and opportunities in this area.     

A comparative study on hygroscopic and physiochemical properties of chicken powders obtained by different drying methods

Abstract

Different drying methods (spray drying (SD), vacuum drying (VD), microwave vacuum drying (MVD), and infrared vacuum drying (IFVD)) were applied in order to compare the hygroscopicity behavior of chicken powders. The hygroscopicity curves and glass transition temperature were used to evaluate the influence of ambient humidity and temperature on moisture absorption of powders. The results showed that the chicken powder dried by MVD had the lowest moisture absorption, followed by IFVD, VD, and SD. The hygroscopicity of SD chicken powders was different from other three kinds of chicken powders due to the physical properties of particles and the changes of protein secondary structure as detected by the Fourier transform-infrared spectrometer. For the three vacuum drying methods, the difference of protein secondary structure was the main reason of differences in hygroscopicity. Although MVD chicken powders were slightly inferior to SD chicken powders in taste, MVD chicken powders were the best in terms of smell and color as suggested by instrumental sensory parameter evaluations. It was found that MVD had a positive effect on reducing moisture absorption and maintaining sensory quality of chicken powders.     

硫酸系统干吸塔捕沫器的选型及使用实践

结合不同工况用孟山都公司除沫器对原干吸塔所用金属丝网捕沫器进行改造,一吸塔选用ES型玻璃纤维柱式除沫器,二吸塔选用CS-ⅡP型玻璃纤维(内)-金属丝网(外)复合筒式捕沫器,干燥塔选用丝网除沫器。干燥塔同时增设塔内自动酸清洗装置。改造后不仅解决了原捕沫器效果差的问题,还简化了流程,提高了系统作业率。     

Effects of different drying methods on the extraction rate and qualities of oils from demucilaged flaxseed

Effects of different drying methods, i.e., oven drying, freeze drying, vacuum drying, and microwave drying, on the extraction rate and qualities of oil extracted from demucilaged flaxseed were investigated. The results show that microwave drying and freeze drying have higher extraction rate and yield (46.36 and 46.16% vs. 33.90%) of oil compared with native flaxseed. The oil extracted from dried flaxseed, especially the one freeze dried, had higher peroxide value (21.63 vs. 6.15?meq/kg) and specific ultraviolet extinction at 232?nm (4.56 vs. 3.67) and 268?nm (1.23 vs. 1.12), as well as a shorter induction time (1.8 vs. 3.3?h) than the one from native sample. Demucilaging and drying have no significant effect on fatty acid composition of flaxseed oil. However, these processes increased the content of total phenols and total sterols while reduced the content of chlorophyll and carotenoid pigment. In addition, the oil extracted from vacuum dried flaxseed contained more tocols when compared with native sample (447.29 vs. 370.99?mg/kg).     

Evaluation of the air-borne ultrasound on fluidized bed drying of shelled corn: Effectiveness,grain quality,and energy consumption

The objective of the study was to investigate the influence of high power ultrasound on a laboratory-scale fluidized bed shelled corn dryer. The drying time, moisture content variation, specific energy consumption, and quality parameters including ultimate compressive strength, toughness, shrinkage and color of corn kernels were investigated. Furthermore, artificial neural network (ANN) simulation models were developed for predicting the drying variables. Machine vision techniques were used to determine color and shrinkage as qualitative indices. Results showed that the lower frequencies had better penetrations at lower temperatures and cause a significant reduction in drying time. In addition, the ultrasound application led to reduction of ultimate compressive strength and toughness of the dried samples although ultrasound has nonthermal character as the subsidiary factor, it plays an important role in shrinkage and color specification. Based on error analysis results, the prediction capability of ANN model is found to be reasonable for the developed models. Application of ultrasound significantly decreased the specific energy consumption of drying process at the optimal drying condition.     

真空技术在粮食行业的应用与发展

简要介绍了真空技术在粮食行业的应用及发展情况。