Optimum Drying Temperature Research Articles

Low temperature and high velocity (LTHV) application in drying: Characteristics and effects on the fish quality

Abstract The present study investigates the cold air drying characteristics and their effects on fish quality. For this purpose, a single layer drying with low temperature and high velocity (LTHV) is applied, and 200 g each of the salted rainbow trout (Oncorhynchus mykiss) is used under the following experimental conditions: drying temperature (4,10,15 and 20 °C), velocity (7 m/s) and relative humidity (∼40–50%). Based on the experimental data for the salted fish samples dried, some key characteristics of such a drying process, namely moisture content, dimensionless mass loss, drying rate, drying time and the best drying temperature are determined and discussed in detail. In addition, some food quality indicators such as mass shrinkage, total volatile nitrogen, thiobarbituric acid, free fatty acids, and microbiological properties are investigated for the salted fish samples. Consequently, an optimum drying temperature is found as 4 °C since the fish samples have the best quality. Therefore, it is suggested that LTHV method be applied to prevent or minimize the microbiological and biochemical decompositions of the fish.

Superheated Steam Vacuum Drying of Rubberwood

The effect of superheated steam vacuum drying (SSVD) on the drying time and mechanical properties of rubberwood was studied. Rubberwood boards with dimensions of 1000 mm × 76.2 mm × 25.4 mm were dried at 86.7–89.3 kPa vacuum pressure (14.6–12.0 kPa absolute) and temperatures of 60, 70, and 80°C. Superheated steam at 110°C was injected intermittently to relieve stress buildup in wood and eliminate cracking. The prong test was used to evaluate the initial acceptability of the dried wood and the mechanical properties of wood were measured. From this study, the total drying time was reduced from 168 h to less than 20 h (MC reduction from 0.80 to 0.06 db). In addition, compared to the reference values shown in the parentheses, the shear parallel-to-grain, the compression parallel-to-grain, the compression perpendicular-to-grain, the modulus of rupture (MOR), the modulus of elasticity (MOE), and the hardness for the optimum drying temperature of 70°C were 28.87 (11.0) MPa, 59.09 (32.0) MPa, 21.09 (5.0) MPa, 101.97 (66.0) MPa, 9838.5 (9240.0) MPa, and 6475 (4350) N, respectively. Thus, the vacuum-dried wood showed a 32% increase in hardness, a 12% increase in compression parallel-to-grain, and an 88% increase in shear parallel-to-grain.

Change of luminescent properties of phosphors through pH and Rw control in sol-gel reaction

In this paper, we describe the luminescent properties of the phosphors synthesized via sol-gel technique. When the phosphor prepared by sol-gel technique, reaction factors, such as pH condition, <TEX>$R_w$</TEX> and drying temperature affected the luminescent intensity, particle size and morphology of final product. Therefore, we attempt to control these reaction factors in order to improve the luminescent efficiency of phosphors. As a result of our study, when the acid catalyst (HCl) was used, emission intensity was higher than the case of base catalyst <TEX>$(NH_4OH)$</TEX>. The product prepared at <TEX>$R_w=60$</TEX> indicated the maximum intensity. As the increase of the <TEX>$R_w$</TEX> value, the particle was agglomerated and emission intensity was decreased. Finally, optimum drying temperature of gel was found to be<TEX>$ 180^{\circ}C$</TEX>.

Synthesis of Solid Superacids and Their Activities for Reactions of Alkanes

AbstractFor Abstract see ChemInform Abstract in Full Text.

Synthesis of solid superacids and their activities for reactions of alkanes

Our recent works on synthesis of solid superacids are reviewed. For evaluation of the surface acidity, temperature-programmed desorption of argon is proposed. For elucidation of the preparative conditions determining the catalytic activity, sulfated zirconias were prepared under different preparative conditions. The conditions varied were type of hydrated zirconia gel, drying temperature before sulfation, calcination temperature after sulfation. Although the optimum drying temperature and calcination temperature were different depending on the type of zirconia gel, the attainable activities were independent of the type of zirconia gel. We also modified sulfated zirconia by addition of Pt, Ru, and Fe to see the effects of the modification on the catalytic activity. The addition of Pt to sulfated zirconia resulted in an increase of the catalytic activity. The optimum amount of Pt-added was 7.5 wt.%. The optimum amount of Pt could be reduced to 3 wt.% when the catalyst was prepared by the double calcination method in which calcination procedures were performed both before and after impregnation with platinate solution. The role of Pt in enhancement of the catalytic activity is suggested to be caused by enhancement of the acid strength due to the coordination of PtO to SO groups. The catalytic activity of sulfated zirconia was also markedly enhanced by mechanically mixing with sulfated iron oxide. The enhancement was suggested to be caused by Fe 3+ acting as a reservoir for H − formed during the reaction.

Adhesion improvement of epoxy resin/polyimide joints by amine treatment of polyimide surface

Polyimide (PI) surfaces were modified to improve the adhesion strength of epoxy resin/PI joints by immersing in amine solutions. Adhesion strength of epoxy resin/amine-treated PI joints were measured depending on structure, molecular weight, concentration, treatment time and drying temperatures of amines. There was an optimum drying temperature for maximum adhesion strength after amine-treatment of PI surface. The optimum drying temperature and the maximum adhesion strength increased with increasing the molecular weight of diamines or polyamines. Poly(amic amide) was formed by the reaction of primary amine of diamines and imide group of PI, and the other primary amine of poly(amic amide) reacted with the imide groups of adjacent PI chains to form cross-linked structure. In this way, adhesion strength of epoxy resin/PI joints was improved by reinforcing the weak PI surface layer. Another additional adhesion mechanism could be the chemical reaction of epoxide in the epoxy resin and unreacted amine of poly(amic amide). Adhesion strength decreased at above the optimum drying temperature since poly(amic amide) was imidized. The adhesion mechanisms and existence of optimum drying temperature were investigated using FT i.r., contact angle goniometer, X-ray photoelectron spectroscopy and rheometric dynamic spectroscopy.

Slurry Sampling Electrothermal Atomic Absorption Spectrometric Determination of Lead, Cadmium and Manganese in Human Hair Samples Using Rapid Atomizer Programs

Rapid methods for the determination of lead, cadmium and manganese in human scalp hair by ETAAS using rapid atomizer programs and deuterium arc background correction have been developed. Samples were powdered by means of a zirconia vibrating ball mill over a period of 20 min (mean particle size less than 1 µm). Then 0.1 g of the powder was suspended in a few ml of water and diluted to 25 ml. An optimum drying temperature of 250 °C was found for lead, cadmium and manganese. Optimum atomization temperatures of 2200 and 1900 °C were found for cadmium and manganese, and for lead, respectively. The program cycles were 38 s for cadmium and lead, and 37 s for manganese. Glycerol, at an optimum concentration of 0.4% m/v, was used as a stabilizing agent. Simple aqueous calibration was used for all analytes. The limits of detection were 0.03, 0.05 and 0.04 mg kg -1 for cadmium, lead and manganese, respectively. Accuracy was studied by analysing CRM 397 human hair, and the cadmium and lead levels were found to be in accordance with the certified accuracy values. The levels of metals obtained were in agreement with those previously reported for healthy people in Europe, i.e. , less than 3.0 and 0.3 mg kg -1 for lead and cadmium, respectively.

Optimization of the Drying Process: An Application to the Drying of Garlic

ABSTRACT The response surface methodology (RSM) was used to derive an optimum drying condition for garlic drying. The responses analyzed were L* value and Optical Index (OI) as a measure of color and rehydration ratio (RR) as well as final moisture content (Mf) which are important quality attributes of dehydrated products. L*, OI, RR and Mf varied from 70.6 to 85.0, 72.0 to 191.1, 2.2 to 3.2 and 5.4 to 10.2 % MC, respectively. An analysis of variance (ANOVA) revealed that drying temperature and slice thickness significantly (90% confidence level) affected L*, OI and RR while no effect was observed for airflow rate and relative humidity (RH). An optimum drying temperature of 70°C for drying 2 mm garlic slices is recommended.

Effects of Water on the Performance of Sulfated Zirconia Catalysts for Butane Isomerization

The activity, selectivity, and rate of deactivation of sulfated zirconia catalysts for isomerization ofn-butane at 423 K depend on the temperature at which the catalyst is dried following initial calcination and exposure to air. The optimum drying temperature for the sample of this study is 548 K. The addition of 75 μmol/g of water to a sample dehydrated at 773 K restores high catalytic activity. Excessive catalyst hydration leads to low catalytic activity by causing extensive hydrogen bonding at the active sites. Changes in catalytic activity with drying temperature are not directly related to a transformation of Brønsted to Lewis acid sites. Rather, the surface sulfate species may participate in butane isomerization via a reduction–oxidation cycle, and water may promote the catalytic activity by altering the oxidation–reduction properties of the surface sulfate species.

塗布型クロメートの耐食性に及ぼすシリカの添加効果

The effects of fine silica particles on dry-in-place chromate coating system were examined in terms of the amount of silica addition, the drying temperature in treatment, and the corrosive environment on corrosion resistance. The mechanism behind corrosion resistance was analyzed in the terms of the corrosion prevention of silica particles in the chromate coatings by AC impedance and XPS.When silica is added to a solution of dry-in-place chromate, the anticorrosion effect is clearly improved due to the chemical and physical effect of silica particles, i. e., the chemical adsorption-desorption action of chromium ion and the physical resistance against the transmission of corrosive factors through the coating.We found that the optimum amount of silica addition and the optimum drying temperature for obtaining high corrosion resistance differed with the environment. These results indicate that the coating properties of silica contained in dry-in-place chromate are extrinsically determined by the corrosive environment.

Optimization of Concrete Drying Temperature for Monomer Impregnation

The optimum drying temperature of concrete prior to monomer impregnation was investigated. Mortar cubes were cast, dried at different temperatures between room temperature and 316°C (600°C), and impregnated with monomer and polymerized in situ. The cubes were then vacuum-saturated and their resistivities were measured. The cubes were cut and dried to 104°C (220°F), and the influence of drying temperature on the degree of impregnation was evaluated using a mercury porosimeter and a scanning electron microscope - energy dispersive spectroscope. Companion cubes were subjected to ponding-drying cycles in a sodium chloride solution, and the ingress of chloride was determined from powdered samples. Results were used to optimize the drying temperature of concrete for monomer impregnation. The results demonstrated that monomer impregnation of concrete to a desired depth can be achieved at a lower temperature than previously believed.

Dehydration of Low-Grade Asparagus

ABSTRACT Dehydration by a forced convection process is one potential method to add value to low-grade asparagus for marketing purposes. The objectives of this study were to determine the optimum drying temperature, air velocity, and predrying blanching treatment and study the effects of those parameters on the drying curves for low-grade asparagus and the efficiency of the drying process. The ranges of investigation were 60 to 93°C and 0.14 to 0.44 m/s for drying temperature and air velocity, respectively. Drying at 51 °C and 0.30 m/s yielded product with an optimum quality, and drying at 79° C and 0.18 m/s yielded the optimum process efficiency of 17.9%. Drying temperature, air velocity, and predrying blanching treatment all affected the rate of drying in the constant-rate drying period and the length of the constant-rate drying period. In the falling-rate period, all of the process parameters studied had some effect on the shape of the drying curve.

Textile processing of continuous basalt fibre coated with polyvinyl acetate emulsion

The possibility of textile processing of continuous basalt fibre treated with a polyvinyl acetate emulsion was investigated. The optimum concentration of the solution was determined. The strength characteristics of continuous basalt fibres were investigated as a function of the concentration of polyvinyl acetate in the emulsion used to impregnate the fibres. The optimum drying temperature was determined.

Optimization of Batch-in-Bin Corn Drying Systems

A mathematical model was developed to predict the least cost bin diameter, bin height, and number of bins for the high temperature (50-70 C; 122-158 F) drying of shelled corn. Additionally, the model determines the optimum drying temperature, air flow, and drying cycle time. The model is based on the primary user inputs of annual capacity, drying rate, initial and target grain moistures, ambient air conditions, unit energy costs, and interest rate. The model contains cost estimates for system components, including land rent, site preparation, bins, fans, and augers; but the user has the opportunity to modify those costs.

Optimization of solar grain drying in a continuous flow dryer

The optimum method of using a solar air collector combined with a grain drying system was investigated. Two types of solar collectors, integrated into a roof are considered; one uncovered (flow under absorber) and one covered (flow over absorber). A computer model was developed to minimize the cost of drying and in doing so optimize the geometry of the collector and the specific rate of air flow through the collector. The ratio of the cost of drying in a solar-supplemented system to the cost of drying in a conventional system was minimized. This ratio represents the maximum possible savings for the given drying conditions. Sensitivity analyses were carried out for drying air temperatures in the range 40 to 90°C and for grain initial moisture contents of 16 to 35% d.b.(dry basis). The effect of daily drying times, the length of the drying season and the specific cost of collector and fuel was also investigated. Two types of farm management systems were considered for various drying conditions: use of the dryer to operate for a fixed number of hours per day and, alternatively, drying a given quantity of grain per day. The results show that there is an optimum number of hours of operation per day, optimum drying temperature and optimum initial moisture content for any combination of the other variables. The most critical factors affecting annual savings are the length of the drying season and the specific cost of the collector. The optimum geometry of the collector and the specific flow rate are also functions of these factors.

The storage and drying characteristics of papaya (Carica papaya L.) latex

AbstractA range of latex storage and air drying conditions were studied with regard to the proteolytic activity of the dried latex (‘crude papain’). The optimum drying temperature is between 50–55°C, activity losses on drying can be restricted to about 7% under these conditions. The activity of crude papain is the same if it is derived either from exuded latex or from that portion (about 20% of latex yield) which coagulates on the fruit surface on tapping. Latex storage at tropical ambient for 2–24 h prior to drying (with or without exposure to sunlight) causes maximum losses of about 20% in the proteolytic activity of the crude papain. Sodium chloride addition has an anti‐coagulating effect on latex and accelerates the later stages of drying. Contrary to earlier reports, this causes a decreased activity in the product, which may be related to changes in latex pH. Addition of EDTA or sodium bisulphite, singly or in combination, protects the latex activity (increases of 20–25% relative to controls).

TECHNOLOGICAL ASPECTS OF HIGH QUALITY RAW MATERIAL OBTAINING FOR PECTIN PRODUCTION

&#x0D; The article is devoted to the study of the chemical composition, physical and thermal-pfysical characteristics of damp apple pomaces and the identifying patterns of influence of drying temperature the functional composition and gel-forming ability of pectin. The research is aimed at obtaining initial data for the subsequent calculation of the main technological, hydro-mechanical, thermal, structural and economic characteristics of devices for drying the plant raw materials, ensuring the environmental safety and high quality of pectin-containing raw materials, the reducing heat and energy costs. As a result of the study of the thermal characteristics of apple pomaces, the critical points (temperature conductivity – 16.5 x 10-8 m2/s, thermal conductivity – 0.28 W/m K, heat capacity – 1627 j/(kg K)) at a humidity of 56 % are determined, which characterizing the transition from the extraction of weakly bound moisture to the extraction of moisture with strong bonds (colloidal, adsorption). It was found that the pomaces obtained from apples of late ripening have a higher content of solids (21-23 %), soluble pectin and protopectin (2.5-4.5 %). Dried pomaces obtained from apple varieties of late ripening contain up to 25 % pectin, which allow us to recommend them as a source of raw materials for the production of pectin. The optimum modes of preliminary washing of raw materials are offered, allowing to the remove the ballast substances as much as possible. It is established that when the drying temperature increases, the destructive processes are catalyzed: the strength of the pectin jelly and the uronide component and the degree of pectin esterification are reduced. The optimum drying temperature of damp apple pomaces is 80 0C, at which the quality of pectin extracted from the dried raw materials is maintained as much as possible. It is shown that the most effective for the pectin production is a fraction with a particle size of 3-5 mm, which allow us to extract up to 71 % of pectin from raw materials.