884 resultados para Freeze Drying


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The effect of ultrasound and osmotic dehydration pretreatments on papaya drying kinetics was investigated. The ultrasound pretreatment was carried out in an ultrasonic bath at 30 A degrees C. The osmotic pretreatment in sucrose solution was carried out in an incubator at 34 A degrees C and agitation of 80 rpm for 210 min. The drying process was conducted in a fixed bed dryer at 70 A degrees C. Experimental data were fitted successfully using the Page model for dried fresh and pretreated fruits, with coefficient of determination greater than 0.9992 and average relative error lower that 14.4 %. The diffusional model was used to describe the moisture transfer, and the effective water diffusivity was identified in the order of 10(-9) m(2) s(-1). It was found that drying rates of osmosed fruits were the lowest due to the presence of infused solutes, while the ultrasound pretreatment contributed to faster drying rates. Evaluation of the dried fruit was performed by means of total carotenoids retention. Ultrasound treatments in distilled water prior to air-drying gave rise to dried papayas with retention of carotenoids in the range 30.4-39.8 % and the ultrasonic-assisted osmotic dehydration of papayas showed carotenoids retention values up to 64.9 %, whereas the dried fruit without pretreatment showed carotenoids retention lower than 24 %.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Oxycarotenoids concentration in layer hens’ feed may be increased whenever the consumer market demands for more pigmented egg yolks. Oxycarotenoids present in Rubrivivax gelatinosus biomass grown in industrial wastewater have already proved their ability on enhancing yolk color. Moreover, there is a current interest on the antioxidant properties that some carotenoids may provide to food and health. So, in this experiment, we investigated the effects of oxycarotenoids supplementation in hens´ diets on yolk composition and stability to rancidity. Hy line hens aging 19 weeks were individually housed in wire cages equipped with feeders and drinkers. After 15 days receiving a corn basal diet nutritionally balanced, they were assigned to four different treatments, with six replicates, that lasted for 28 days: T1 – basal diet (control), T2 – basal diet + 1.5 mg/kg canthaxanthin, T3 – basal diet + 4.5 g/kg freeze dried R. gelatinosus biomass and T4 - basal diet + 4.5 g/kg spray dried R. gelatinosus biomass. Eggs laid on the last 5 days of rearing were collected; the yolks were separated, analyzed for pH and then freeze dried for the further analyses. Proximate composition was determined after drying and the rancidity (TBRAS method) was investigated at 0, 30 and 60 days of storage at room temperature/dark conditions. Yolks that received the oxycarotenoids had the lowest moisture content and the highest protein contents (P < 0.05). Lipids and pH were the same for all treatments (P > 0.05) and ashes only were higher for T2 (P < 0.05). All treatments that received oxycarotenoids had lower TBARS than control group and, among them, oxycarotenoids from spray dried R. gelatinosus biomass were the most effective to prevent rancidity (P < 0.05). So, we concluded that the use of R. gelatinosus biomass in hens feed brings positive effects to the yolk quality, since protein content is increased and conservation is increased due to decreased water content and lipid oxidation.

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We evaluated the effects of air-drying distance and bond surface area on the shear bond strength of a 2-step etch-and-rinse adhesive. A total of 120 bovine anterior teeth were equally divided into 6 main groups based on bonding surface area. The main groups were divided into sub-groups (n = 5) according to air-drying distance. The shear strength was determined using a universal testing machine at a crosshead speed of 0.5 mm/min. The averaged results were subjected to two-way ANOVA and Tukey's test (alpha = 0.05). Two-way ANOVA testing identified no significant cross-product interactions (p > 0.05), but the main factors of area (p < 0.0001) and air-drying distance (p < 0.00001) significantly affected the mean bond strength. Shorter air-drying distances improved bond strength, and increased surface area decreased the bond strength.

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The effects of drying air inlet temperature (IT) and concentration of Aerosil 200 (C-A) on several properties of spray-dried Apeiba tibourbou extracts were investigated following a 3(2) full factorial design. Powder recovery varied from 9.83 to 46.95% and dried products showed moisture contents below 7%. Although the spray-dried products lost some of their polyphenols, they still present excellent antioxidant activity, opening perspectives for its use to medicinal purpose. C-A exerted a key role on the properties of spray-dried extracts, while IT did not present a significative influence. Aerosil (R) 200 proved to be an interesting alternative as an excipient for the drying of the herbal extract, even at intermediate concentrations such as 15%. The best combination of conditions to use for obtaining dry A. tibourbou extracts with adequate physicochemical and functional properties involves an IT of 100 degrees C and a C-A of 15%.

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The microencapsulation of Lippia sidoides extracts in blends of carbohydrates was investigated. The extraction conditions were determined through a 2(2) factorial design. The effects of the plant:solvent ratio (A - 7.5:100 and 15:100 m/m) and the extraction time (B - 30 and 90 min) on thymol content of extractive solutions were evaluated, using a 2:1 (v/v) of ethanol:water at a temperature of 50 degrees C, as a solvent system. The selected extract was subjected to spray drying. Blends of maltodextrin and gum arabic at different proportions (4:1; 3:2; 2:3; 0:1) (m/m) were used as encapsulating material. The protective effects of the maltodextrin and gum arabic blends were evaluated by determination of the thymol retention in the dried product, which ranged from 70.2 to 84.2% (related to the content in the extractive solution). An increase in the gum arabic to maltodextrin (DE10) ratio has positive effect on thymol retention. L. sidoides extracts and spray-dried products showed antifungal activity against tested fungal strains (Candida albicans - ATCC 64548, Candida glabrata - ATCC 90030, Candida krusei - ATCC 6258, and Candida parapsilosis - ATCC 22019), evidencing their potential as a natural antifungal agent for medicinal, food, and cosmeceutical purposes. (C) 2012 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.

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Microencapsulation can be an alternative to minimize lycopene instability. Thus, the aim of this study was to microencapsulate lycopene by spray drying, using a modified starch (Capsul (R)) as an encapsulating agent, and to assess the functionality of the capsules applying them in cake. The quantity of lycopene was varied at 5, 10 and 15% in a solution containing 30% of solids in order to obtain the microcapsules. These microcapsules were evaluated as to encapsulation efficiency and morphology and then submitted to a stability test and applied in cakes. Encapsulation efficiency values varied between 21 and 29%. The microcapsules had a rounded outer surface with the formation of concavities and they varied in size. The stability test revealed that microencapsulation offered greater protection to lycopene compared to its free form and it was observed that the microcapsules were able to release pigment and color the studied food system in a homogenous manner. (C) 2011 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.

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This article presents an overview of relevant issues to be considered in the development of standardized phytochemical preparations, focusing on the use of the spouted bed as a drying method. Aspects related to the effects of feed composition properties and processing parameters on system performance and product quality are addressed. From the information presented, it can be concluded that the spouted bed technology can be successfully applied for production of high-quality phytochemical preparations suitable for food and pharmaceutical purposes, considering the requirements for product safety, quality, and efficacy. Nevertheless, it should be emphasized that, at this time, the proposed technology is appropriate for small-scale production, mainly due to difficulties concerning scale-up, modeling, and the simulation of spouted bed systems, and also for predicting product properties and system behavior during operation.

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The aim of the present study was to obtain microparticles of hydrochlorothiazide, a diuretic drug that practically insoluble in water, by spray drying and to investigate the influence of process parameters using a three-level, three-factor Box-Behnken design. Process yields, moisture content, particle size, flowability, and solubility were used to evaluate the spray-dried microparticles. The data were analyzed by response surface methodology using analysis of variance. The independent variables studied were outlet temperature, atomization pressure, and drug content. The formulations were prepared using polyvinylpyrrolidone and colloidal silicon dioxide as the hydrophilic carrier and drying aid, respectively. The microparticle yield ranged from 18.15 to 59.02% and resulted in adequate flow (17 to 32 degrees), moisture content between 2.52 to 6.18%, and mean particle size from 45 to 59 mu m. The analysis of variance showed that the factors studied influenced the yields, moisture content, angle of repose, and solubility. Thermal analysis and X-ray diffractometry evidenced no drug interactions or chemical modifications. Photomicrographs obtained by scanning electron microscopy showed spherical particles. The solubility and dissolution rates of hydrochlorothiazide were remarkably improved when compared with pure drug. Therefore, the results confirmed the high potential of the spray-drying technique to obtain microparticulate hydrochlorothiazide with enhanced pharmaceutical and dissolution properties.

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Microparticles of ketoprofen entrapped in blends of acrylic resins (Eudragit RL 30D and RS 30D) were successfully produced by spray drying. The effects of the proportion ketoprofen : polymer (1: 1 and 1: 3) and of spray-drying parameters (drying gas inlet temperatures of 80 and 100 degrees C; microencapsulating composition feed flow rates of 4 and 6 g/min) on the microparticles properties (drug content, encapsulation efficiency, mean particle size, moisture content, and dissolution behavior) were evaluated. Differential scanning calorimetry (DSC) thermograms and X-ray diffractograms of the spray-dried product, the free drug, and the physical mixture between the free drug and spray-dried composition (blank) were carried out. Microparticles obtained at inlet temperature of 80 degrees C, feed flow rate of 4 g/min, and ketoprofen : acrylic resin ratio of 1: 3 presented an encapsulation efficiency of 88.1%, moisture content of 5.8%, production yield around 50%, and a higher reduction in dissolution rate of the entrapped ketoprofen. Sigmoidal shape dissolution profiles were presented by the spray-dried microparticles. The dissolution profiles were relatively well described by the Weibull model, a showing high coefficient of determination, R-2, and a mean absolute error between experimental and estimated values of between 4.6 and 10.1%.

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The sludge generated by sewage treatment which meets regulatory standards can be used in agriculture. With this understanding, the focus of this study is the evaluation of the agricultural characteristics and inorganic substances in excess activated sludge, which was subjected to drying in a greenhouse. The variables (factor) evaluated during the drying process were: type of sludge (digested or not digested), addition of lime to the sludge, and the physical layout and rotation of sludge in the greenhouse. The parameters monitored for this assessment were moisture, volatile solids and pH. The greenhouse cover and sides were made of translucent plastic to allow the penetration of solar radiation and prevent water from entering. A impermeable floor was used. The sludge was generated in sewage treatment plants located in the metropolitan region of Grande Vitoria, Espirito Santo, Brazil. The solar drying of wastewater sludge in a greenhouse presented satisfactory results.

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Active pharmaceutical ingredients have very strict quality requirements; minor changes in the physical and chemical properties of pharmaceuticals can adversely affect the dissolution rate and therefore the bioavailability of a given drug. Accordingly, the aim of the present study was to investigate the effect of spray drying on the physical and in vitro dissolution properties of four different active pharmaceutical ingredients, namely carbamazepine, indomethacin, piroxicam, and nifedipine. Each drug was dispersed in a solution of ethanol and water (70:30) and subjected to single-step spray drying using similar operational conditions. A complete characterization of the spray-dried drugs was performed via differential scanning calorimetry (DSC), scanning electron microscopy (SEM), X-ray powder diffraction (XRPD), particle size distribution analysis, solubility analysis, and an in vitro dissolution study. The results from the thermal analysis and X-ray diffraction showed that, except for carbamazepine, no chemical modifications occurred as a result of spray drying. Moreover, the particle size distribution of all the spray-dried drugs significantly decreased. In addition, SEM images showed that most of the particles had an irregular shape. There was no significant improvement in the solubility of the spray-dried drugs compared with the unprocessed compounds; however, in general, the dissolution rates of the spray-dried drugs showed a remarkable improvement over their non-spray-dried counterparts. Therefore, the results from this study demonstrate that a single spray-drying step may lead to changes in the physical properties and dissolution characteristics of drugs and thus improve their therapeutic action.