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Air Drying (air + drying)
Kinds of Air Drying Selected AbstractsFluidized Bed Air Drying: Experimental Study and Model DevelopmentTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 2 2003Markus Henneberg Abstract The presented study describes the processes and mechanisms of batch fluidized bed drying. The influencing factors of hot air drying are theoretically and experimentally examined, in order to present the relations between temperature and humidity profiles and all other drying parameters. A physical model is presented to facilitate the calculation of the drying processes under defined conditions. Three succeeding drying stages are therefore modeled. Mass and energy balances including all components taking part in the process are formulated. The model clarities the drying process under the assumption of pure heat transfer mechanisms. It does not contain adaptive parameters and takes into account an inactive bypass fraction of the fluidization and drying medium. The evaluation of the model was successful for two fluidized bed plants with nominal widths of 100 mm and 400 mm. The experiments showed sufficient accuracy and transferability of the model to equipment of application-oriented dimensions. On décrit dans la présente étude les procédés et mécanismes de séchage en lit fluidisé discontinu. Les facteurs importants du séchage à air chaud sont examinés de façon théorique et expérimentale dans le but d'expliquer les relations entre les profils de température et d'humidité et tous les autres paramètres de séchage. On présente un modèle physique pour faciliter le calcul des procédés de séchage dans des conditions définies. Trois étapes de séchage consécutives sont modélisées. Les bilans de matière et d'énergie faisant intervenir tous les composants qui prennent part au procédé sont formulés. Le procédé de séchage est modélisé en supposant des mécanismes de transfert de chaleur purs. Il ne comporte pas de paramètres adaptatifs et prend en compte une fraction de dérivation inactive du milieu de fluidisation et de séchage. L'évaluation du modèle s'est avérée concluante pour deux lits fluidisés de largeur nominale de 100 mm et 400 mm. Les expériences montrent une précision et une transférabilité suffisantes du modèle à des équipements de dimensions industrielles. [source] Air drying of milk droplet under constant and time-dependent conditionsAICHE JOURNAL, Issue 6 2005Xiao Dong Chen Abstract Spray drying is the prime process for many years for manufacturing food powders. Dairy powders are one of the main products consumed worldwide. There has been a stream of studies published previously on both modeling the drying characteristics of a single milk droplet and the dryer wide simulations incorporating computational fluid dynamics (CFD). In CFD simulations, large numbers of particles of different sizes need be tracked to represent the size distribution; it is desirable to have an accurate yet simple model for drying of a single droplet, which does not require partial differential equation. Here for the first time, two such models are validated. One model is of the characteristic drying rate curve approach and the other (new) model is of the reaction engineering approach. The model predictions are compared against a very wide range of experimental results including isothermal and time-varying temperature conditions. © 2005 American Institute of Chemical Engineers AIChE J, 2005 [source] Modelling of air drying of fresh and blanched sweet potato slicesINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 2 2010Kolawole O. Falade Summary Effects of blanching, drying temperatures (50,80 °C) and thickness (5, 10 and 15 mm) on drying characteristics of sweet potato slices were investigated. Lewis, Henderson and Pabis, Modified Page and Page models were tested with the drying patterns. Page and Modified Page models best described the drying curves. Moisture ratio vs. drying time profiles of the models showed high correlation coefficient (R2 = 0.9864,0.9967), and low root mean squared error (RMSE = 0.0018,0.0130) and chi-squared (,2 = 3.446 × 10,6,1.03 × 10,2). Drying of sweet potato was predominantly in the falling rate period. The temperature dependence of the diffusion coefficient (Deff) was described by Arrhenius relationship. Deff increased with increasing thickness and air temperature. Deff of fresh and blanched sweet potato slices varied between 6.36 × 10,11,1.78 × 10,9 and 1.25 × 10,10,9.75 × 10,9 m2 s,1, respectively. Activation energy for moisture diffusion of the slices ranged between 11.1 and 30.4 kJ mol,1. [source] Hot air drying of yacon (Smallanthus sonchifolius) and its effect on sugar concentrationsINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 11 2009Caroline Fenner Scher Summary This work aimed to experimentally study the drying behaviour of yacon tubers with and without steam blanching. Drying was carried out for 5 h and 30 min in a forced air dryer at 50 °C, 60 °C and 70 °C. The results indicated that the shortest drying time was obtained at 70 °C for blanched samples, and that the equilibrium water activity values were significantly lower for the blanched samples at all temperatures. The yacon dried without prior blanching showed lowest concentrations of reducing sugars when dried at 70 °C, significantly lower than those dried at 50 °C and 60 °C. This indicates hydrolysis of the fructo-oligosaccharides at 70 °C, a fact verified by the significant increase in reducing sugars content from 36.65 ± 0.54,44.10 ± 0.96% and reduction in the non-reducing sugars from 31.62 ± 0.55,26.18 ± 0.29%. [source] Convective hot air drying of blanched yam slicesINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 7 2008Olajide Philip Sobukola Summary In this study, a laboratory convective hot air dryer was used for the thin layer drying of blanched yam slices and experimental moisture ratio was compared with Newton, Logarithmic, Henderson and Pabis, modified Henderson and Pabis, approximation of diffusion, modified page 1, two-term exponential, Verma et al. and Wang and Singh models. Among all the models, the approximation of diffusion model was found to satisfactorily describe the kinetics of air-drying of blanched yam slices. The increase in air temperature significantly reduced the drying time with no constant rate period but drying occurs in falling rate period. The effective diffusivity values varied between 7.62 × 10,8 to 9.06 × 10,8 m2 s,1 and increased with increase in temperature. An Arrhenius relation with an activation energy value of 8.831 kJ mol,1 showed the effect of temperature on moisture diffusivity. [source] A Novel Method for Air Drying Aloe Leaf Slices by Covering with Filter Papers as a Shrink-Proof LayerJOURNAL OF FOOD SCIENCE, Issue 9 2009S.A. Kim ABSTRACT:, To prevent the shrinkage of aloe vera slices during air drying, a method utilizing a shrink-proof layer was developed. The sample was configured of whole leaf aloe slices, where 1 side or both sides were covered with filter papers as shrink-proof layers. After air drying by varying the air temperature and the slice thickness, the drying characteristics, as well as several quality factors of the dried aloe vera leaf slices, were analyzed. In the simulation of the drying curves, the modified Page model showed the best fitness, representing a diffusion-controlled drying mechanism. Nonetheless, there was a trace of a constant-rate drying period in the samples dried by the method. Shrinkage was greatly reduced, and the rehydration ratios increased by approximately 50%. Scanning electron microscopic analysis revealed that the surface structure of original fibrous form was well sustained. FT-IR characteristics showed that the dried samples could sustain aloe polysaccharide acetylation. Furthermore, the functional properties of the dried slices including water holding capacity, swelling, and fat absorption capability were improved, and polysaccharide retention levels increased by 20% to 30%. Therefore, we concluded that application of shrink-proof layers on aloe slices provides a novel way to overcome the shrinkage problems commonly found in air drying, thereby improving their functional properties with less cost. Practical Application: This research article demonstrates a novel air drying method using shrink-proof layers to prevent the shrinkage of aloe slices. We analyzed extensively the characteristics of shrinkage mechanism and physical properties of aloe flesh gels in this drying system. We concluded that this method can be a beneficial means to retain the functional properties of dried aloe, and a potential alternative to freeze drying, which is still costly. [source] Comparative Study of Quality Changes Occurring on Dehydration and Rehydration of Cooked Chickpeas (Cicer Arietinum L.) Subjected to Combined Microwave,Convective and Convective Hot Air DehydrationJOURNAL OF FOOD SCIENCE, Issue 6 2006A.A. Gowen ABSTRACT:, Convective hot air dehydration (100 °C) of cooked chickpeas was compared with the combination of microwave,convective hot air dehydration, in terms of microstructure, density, color, texture, dehydration, and rehydration. In the combined drying experiments, 2 levels of microwave power (100 W and 200 W) were investigated, combined continuously with convective air drying at 100 °C. Compared with convective hot air drying, combination drying led to a considerable reduction in dehydration time. Combination drying also improved the porosity of the finished dehydrated product, leading to faster rehydration kinetics. Cryogenic scanning electron microscopy micrographs showed that chickpeas subjected to combined drying experienced less shrinkage than those dried by convective hot air. Combination drying at the higher (200 W) level produced a darker (P < 0.05) rehydrated product with significantly lower relative rehydrated moisture content (P < 0.05) when compared with the lower (100 W) level of combination drying. [source] Stabilization of alum-adjuvanted vaccine dry powder formulations: Mechanism and applicationJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 2 2003Yuh-Fun Maa Abstract Studies were performed to elucidate the mechanism of alum gel coagulation upon freezing and drying and its relationship to vaccine potency loss and to develop a novel freeze-drying process for the production of stable alum-adjuvanted vaccine formulations suitable for conventional needle injection and epidermal powder immunization (EPI). The alum hydroxide-adjuvanted hepatitis-B surface antigen (Alum-HBsAg) and the alum phosphate-adjuvanted diphtheria and tetanus toxoids (Alum-DT) were dehydrated by freeze drying (FD), spray drying (SD), air drying (AD), or spray freeze drying (SFD). After drying by FD, SD, or AD, alum gels coagulated when examined by optical microscopy and particle size analysis. In addition, desorption of antigen molecules from the coagulated when examined by optical microscopy and particle size analysis. In addition, desorption of antigen molecules from the coagulated alum gel upon reconstitution appeared to be difficult, as indicated by attenuated band intensity on SDS-PAGE. In contrast, SFD alum gels turned a homogenous suspension upon reconstitution, suggesting minimal alum coagulation. In the mouse model, the in vivo immunogenicity of SFD Alum-HBsAg was preserved, whereas the FD Alum-HBsAg suffered significant immunogenicity loss. Grinding of coagulated FD Alum-HBsAg into smaller particles could partially recover the immunogenicity. In a guinea pig study using EPI, the SD Alum-DT formulation was not immunogenic, but the SFD Alum-DT formulations had a vaccine potency comparable to that of the untreated DT administered by I.M. injection. Overall, the relationship of coagulation of alum gel upon reconstitution and the loss of vaccine potency was established in this study. Alum gels became highly coagulated after dehydration by spray drying and traditional freeze-drying processes. However, freezing rate played a critical role in preserving the adjuvant effect of alum and fast freezing decreased the tendency of alum coagulation. Spraying the alum gel into liquid nitrogen represents the fastest freezing rate achievable and resulted in no discernible alum coagulation. Therefore, SFD presents a novel and effective drying process for alum-adjuvanted vaccine formulations and is particularly valuable for dry powder applications such as EPI. © 2003 Wiley-Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 92:319,332, 2003 [source] 2-Furoylmethyl amino acids, hydroxymethylfurfural, carbohydrates and ,-carotene as quality markers of dehydrated carrotsJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 2 2009Ana C Soria Abstract BACKGROUND: Processing of vegetables in the food industry usually includes dehydration as a preservation process. Industrial convective air drying of carrot can involve steam blanching of the raw product after peeling and cutting, and different stages of dehydration (first space, second space and final drying). Although the shelf-life of carrot is significantly extended, important changes in its chemical composition can take place during dehydration since high temperatures and long times are used. This research is a preliminary study to evaluate the usefulness of ,-carotene, carbohydrates, hydroxymethylfurfural (HMF) and 2-furoylmethyl amino acids (2-FM-AA) as quality markers of dehydrated carrots. RESULTS: A considerable decrease in ,-carotene and reducing carbohydrates was observed during dehydration. HMF, absent in raw carrots, increased during the whole drying process and the highest formation was found during the steam blanching stage. 2-FM-AA of lysine, arginine, ,-aminobutyric acid and alanine were progressively originated up to the second space and decreased during the final drying. CONCLUSION: The combined use of HMF and 2-FM-AA seems to be advantageous for the assessment of the optimal processing conditions to obtain high-quality dehydrated carrots. Copyright © 2008 Society of Chemical Industry [source] Modelling of air drying of Hac,haliloglu-type apricotsJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 2 2006Hakan Okyay Menges Abstract In this study a laboratory dryer was used for the thin layer drying of sulfured and non-sulfured apricots. The moisture ratio values throughout the drying process were calculated by 14 different mathematical models, namely Newton, Page, modified Page, modified Page-II, Henderson and Pabis, logarithmic, two-term, two-term exponential, Wang and Singh, Thompson, diffusion approximation, modified Henderson and Papis, Verma et al. and Midilli et al. models. Root mean square error, reduced chi-square, mean bias error, adjusted R -square and modelling efficiency were used as statistical parameters to determine the most suitable model among them. According to the results, the Page model was chosen to explain the thin layer drying behaviour of sulfured and non-sulfured apricots. The effects of drying air temperature (T) and velocity (V) on the constants and coefficients of the best moisture ratio model were determined by multiple regression analysis. The moisture ratio (MR) could be predicted by the Page model equation MR = exp(,ktn) with constants and coefficients k = 0.470893 + 0.078775V and n = 0.017786 exp(0.051935T) for sulfured apricots and k = 4.578252 + 1.144643T and n = 0.888040 + 0.145559V for non-sulfured apricots. It is possible to predict the moisture content of the product with the generalised Page model incorporating the effects of drying air temperature and velocity on the model constants and coefficients in the ranges T = 70,80 °C and V = 1,3 m s,1. This developed model showed acceptable agreement with the experimental results, explained the drying behaviour of the product and could also be used for engineering applications. Copyright © 2005 Society of Chemical Industry [source] Oral health status in epileptic childrenPEDIATRICS INTERNATIONAL, Issue 2 2010Taskin Gurbuz Abstract Background:, The aim of the present study was to evaluate the oral hygiene status and dental treatment requirements in children with epilepsy. Methods:, The treatment group consisted of 211 children with epilepsy (120 boys and 91 girls, 4,15 years old, mean age 7.85 ± 2.98 years). The control group consisted of healthy children, matched by age and gender. Clinical features of the patients were obtained from hospital records. Clinical examinations were conducted, under standard light, using a plane buccal mirror, a dental probe and air drying to evaluate caries experience and to record the periodontal health of each child. Statistical analysis was performed using ,2 test, Fisher exact test and anova. Results:, The number of decayed and missing teeth, the degree of abrasion and periodontal indexes were significantly worse in patients with epilepsy, compared to the control group (P < 0.001). Gingival enlargement was documented in 42% of patients on valproate monotherapy compared to only in 16% of patients on phenobarbital. Dental caries and halitosis were the most common oral disorders. Generalized tonic,clonic seizures often cause minor oral injuries and traumatized anterior teeth. Conclusions:, Epileptic children are at an increased risk of developing caries and gingivitis compared with healthy subjects. [source] Fluidized Bed Air Drying: Experimental Study and Model DevelopmentTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 2 2003Markus Henneberg Abstract The presented study describes the processes and mechanisms of batch fluidized bed drying. The influencing factors of hot air drying are theoretically and experimentally examined, in order to present the relations between temperature and humidity profiles and all other drying parameters. A physical model is presented to facilitate the calculation of the drying processes under defined conditions. Three succeeding drying stages are therefore modeled. Mass and energy balances including all components taking part in the process are formulated. The model clarities the drying process under the assumption of pure heat transfer mechanisms. It does not contain adaptive parameters and takes into account an inactive bypass fraction of the fluidization and drying medium. The evaluation of the model was successful for two fluidized bed plants with nominal widths of 100 mm and 400 mm. The experiments showed sufficient accuracy and transferability of the model to equipment of application-oriented dimensions. On décrit dans la présente étude les procédés et mécanismes de séchage en lit fluidisé discontinu. Les facteurs importants du séchage à air chaud sont examinés de façon théorique et expérimentale dans le but d'expliquer les relations entre les profils de température et d'humidité et tous les autres paramètres de séchage. On présente un modèle physique pour faciliter le calcul des procédés de séchage dans des conditions définies. Trois étapes de séchage consécutives sont modélisées. Les bilans de matière et d'énergie faisant intervenir tous les composants qui prennent part au procédé sont formulés. Le procédé de séchage est modélisé en supposant des mécanismes de transfert de chaleur purs. Il ne comporte pas de paramètres adaptatifs et prend en compte une fraction de dérivation inactive du milieu de fluidisation et de séchage. L'évaluation du modèle s'est avérée concluante pour deux lits fluidisés de largeur nominale de 100 mm et 400 mm. Les expériences montrent une précision et une transférabilité suffisantes du modèle à des équipements de dimensions industrielles. [source] Effect of spatial architecture on cellular colonizationBIOTECHNOLOGY & BIOENGINEERING, Issue 1 2006Yan Huang Abstract The spatial cell-material interaction remains vital issue in forming biodegradable scaffolds in Tissue Engineering. In this study, to understand the influence of spatial architecture on cellular behavior, 2D and 3D chitosan scaffolds of 50,190 kD and >310 kD MW were synthesized through air drying and controlled rate freezing/lypohilization technique, respectively. In addition, chitosan was emulsified with 19, 76, and 160 kD 50:50 poly lactide-co-glycolide (PLGA) using 1,2-Dimyristoyl-sn-Glycero-3-Phosphocholine (DMPC) as stabilizer. 2D and 3D scaffolds were formed by air drying and lyophilization as before. Tensile and compressive properties of films and scaffolds were analyzed in wet conditions at 37°C. Alterations in the cell spreading, proliferation, and cytoskeletal organization of human umbilical vein endothelial cells (HUVECs) and mouse embryonic fibroblasts (MEFs) were studied. These results showed that the formed 3D chitosan scaffolds had interconnected open pore architecture (50,200 µm size). HUVECs and MEFs had reduced spreading areas and circular morphology on 2D chitosan membranes compared with 3D chitosan scaffolds. The fluorescence photomicrographs for actin (using Alexa Fluor 488 phalloidin) and cytoplasm staining (using carboxyfluorescein diacetate-succinimidyl ester) demonstrated that the cells spread within 3D chitosan matrix. 2D and 3D emulsified chitosan and chitosan/PLGA scaffolds reduced the spreading of HUVECs and MEFs even further. Proliferation results, analyzed via MTT-Formazan assay and BrdU uptake assay, correlated with the spreading characteristics. The reductions in cell spreading area on emulsified surfaces were not detrimental to the viability and endocytic activity but to proliferation. The observed alterations in cellular colonization are in part due to the substrate stiffness and surface topography. In summary, these results suggest a significant influence of spatial architecture on cellular colonization. © 2005 Wiley Periodicals, Inc. [source] | ||||||||||||||||||||||