Thin-layer Air Research Articles

Oxidation of chlorosilanes by atmospheric air in thin layers

Oxidation of chlorosilanes by atmospheric air in thin layers

Drying Kinetics of American Ginseng Slices in Thin-layer Air Impingement Dryer

Abstract Thin-layer air impingement drying kinetics of American ginseng slices were investigated under different drying temperatures (35, 40, 45, 50, 55, 60, and 65°C), air velocities (3, 6, 9, and 12 m/s), and sample thicknesses (1, 2, 3, and 4 mm). Results indicated that the drying time is more significantly affected by drying temperature followed by sample thickness and air velocity. Drying rate curves illustrated that the whole drying process happened in the falling rate period. Additionally, from initial drying to the moisture content of about 0.5 kg/kg, the drying rate increased with the increase of drying temperature and air velocity or decreased with the increase of sample thickness. The moisture effective diffusivity (D eff) was determined both neglecting shrinkage and considering shrinkage. The drying activation energy of American ginseng slices was 46.64 kJ/mol determined by Arrhenius relationship. The moisture effective diffusivity and drying activation energy of American ginseng slices were compared to other biomaterials and related issues were also discussed. The current work is useful for designing air impingement drying system, evaluating and saving energy consumption of American ginseng slices.

Thin-layer air impingement drying enhances drying rate of American ginseng (Panax quinquefolium L.) slices with quality attributes considered

The effect of drying temperature, air velocity, and sample thickness on thin-layer air impingement drying characteristics and quality of American ginseng slices in terms of color parameters (L*, a*, and b*), ginsenosides content (Rg1, Re, and Rb1), rehydration ratio (RR), and microstructure were investigated. Results indicated that thin-layer air impingement drying enhances drying rate dramatically compared with other drying methods, and that the drying time was principally affected by drying temperature followed by sample thickness and air velocity. Quality evaluation revealed that both drying temperature and sample thickness had significant effects on the change of color, whereas, air velocity did not have any significant effect. It was also observed that ginsenosides Rg1 and Re decreased with increasing drying temperature. Drying temperature, air velocity, and sample thickness had significant negative effects on the RR of dried slices. Microstructure comparison illustrated that starch gelatinization occurred at a drying temperature of 65°C and that a gel layer was formed on the sample's surface. On the basis of the drying time and quality of the dried products, the most favorable drying conditions were recommended.

SIMULATION OF PLUM DRYING IN DEEP BED

ABSTRACT Thin layer air drying of plum was studied. The drying conditions in this study are : dry bulb temperature ranging from 60 to 100 °C, air moisture content ranging from 0.008 to 0.089 kg water/kg dry air and air velocity ranging from 0.5 to 2 1x11s. An exponential model was used to describe the drying curve. The heat and moisture balances on the air were used to calculate the outlet air temperature and its moisture content. The heat balance on the product was used to calculate the product temperature. These equations were used to predict the drying of plum in deep bed. A good agreement between the experimental and calculated product moisture content, the product temperature and the outlet air temperature were obtained

The influence of temperature, heating time, and aeration upon the nutritive value of fats

AbstractIn order to determine the biological significance of the changes which occur when fats are heated to high temperatures in air, cottonseed oils were heated and aerated under several controlled conditions. In general, the data indicate that the changes induced are proportional to the severity of the conditions and that treatments more severe than those usually encountered in processing or cooking are necessary to produce detectable damage.Oils which had been subjected to prolonged aeration at 60C (16 days or more) or exposed to air in thin layers maintained at 180舑220C supplied less available energy and caused development of larger livers than untreated samples when compared in rat feeding tests. Heating in deep layers caused less damage than heating to the same temperatures in thin films, indicating that exposure to oxygen accelerates nutritional impairment.The cooking of food in fats changes condition so greatly that direct extrapolation of data obtained in tests using fat alone is not justified. Fat extracted from foods has not been found to contain harmful substances by the tests used.

QUANTITATIVE STUDIES OF THE PHOTOCHEMICAL DESPECIATION OF HORSE SERUM

1. Normal horse serum was irradiated for periods of 3 to 4 days, with visible light or with ultraviolet light of known intensity and wave length. The photosensitizer hematoporphyrin was employed in some instances. The serum was exposed to the air in thin layers, and thoroughly agitated throughout irradiation. 2. The irradiated sera were unchanged in color, and over 90 per cent of the original protein content remained precipitable by phosphotungstic acid. 3. Studies of the antigenicity of the sera were carried out on guinea pigs and rabbits. Fresh antigenicities of deviated specificity and of an activity of the order of 1/50th, 1/1,000th, and less than 1/20,000th that of normal horse serum were obtained. The residual content of material having the same antigenic specificity as normal horse serum was estimated as approximately equivalent in activity to dilutions of normal horse serum of 1 cc., 1/10 cc., and less than 1/100 cc. per litre respectively.