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Osmotic Processes (osmotic + process)

Distribution by Scientific Domains

Chemistry	80%

Selected Abstracts

The mathematical modelling of the osmotic dehydration of shark fillets at different brine temperatures

INTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 4 2006
Saheeda Mujaffar
Summary The effect of brine temperature (20, 30, 40 and 50 °C) on the osmotic drying behaviour of shark slabs (10 × 5 × 1 cm) in saturated (100°) brine was investigated. The parameters investigated were weight reduction, water loss, salt gain and water activity. Salt uptake and moisture data were analysed using various mathematical solutions based on Fick's Law of Diffusion and the effective diffusion coefficients were predicted after considering the process variables. The expressions presented by Azuara et al. (1992), based on the model presented by Crank (1975), were successfully used to predict the equilibrium point and to calculate diffusion coefficients at not only the initial stages of dehydration, but also at different times during the osmotic process. [source]

KINETICS OF OSMOTIC DEHYDRATION IN ORANGE AND MANDARIN PEELS

JOURNAL OF FOOD PROCESS ENGINEERING, Issue 4 2001
M. CHÁFER
ABSTRACT The nutritional and health properties of some citrus peel components such as pectin, flavonoids, carotenoids or limonene make interesting developing processing methods to obtain peel stable products, maintaining its quality attributes, increasing its sweetness and improving its sensory acceptability. In this sense, osmotic dehydration represents a useful alternative by using sugar solutions at mild temperature. Kinetics of osmotic treatments of orange and mandarin peels carried out at atmospheric pressure and by applying a vacuum pulse at the beginning of the process were analysed at 30, 40 and 50C, in 65 °Brix sucrose, 55 °Brix glucose and 60 °Brix rectified grape must. Vacuum pulse greatly affected mass transfer behavior of peels due to the greatly porous structure of albedo. So, PVOD treatments greatly accelerate the changes in the product composition in line with an increase in the peel sample thickness. In osmotic processes at atmospheric pressure, sample impregnation occurs coupled with osmotic process, but much longer treatments are required to achieve a reasonable concentration degree which assures sample stability. Low viscosity osmotic solutions seems recommendable in order to promote both diffusional and hydrodynamic transport, in vacuum pulsed pretreatments at mild temperatures. [source]

Influence of Blanching-osmotic Dehydration Treatments on Volatile Fraction of Strawberries

JOURNAL OF FOOD SCIENCE, Issue 7 2000
I. Escriche
ABSTRACT: The effects of steam (S) and microwave (MW) blanching and osmotic treatments, applied either singularly or combined, on the volatile fraction of strawberry have been evaluated. Osmotic dehydration was carried out at atmospheric conditions (OD) and by applying a vacuum pulse at the beginning of the process (PVOD). Volatiles were obtained by a simultaneous distillation-extraction procedure and identified/quantified by gas chromatography-mass spectrometry. Esters and 2,5-dimethyl-4-hydroxy-3(2H)-furanone were the major compounds. Differences in volatile concentration promoted by blanching and/or osmotic processes were evaluated. Osmotic treatments promote formation of esters and furanones, differently for either OD or PVOD treatments, but this effect was greatly inhibited when osmosis was preceded by blanching. The kind of blanching (MW or S) also affected the sample final volatile profile. [source]

Beschichtungen auf direkt befahrenen Tiefgaragenbodenflächen von Weißen Wannen.

BETON- UND STAHLBETONBAU, Issue 7 2006
Physikalische Beanspruchungen, Planungsgrundlagen, alternative Beschichtungsvarianten
Nach DIN 1045-1 müssen direkt befahrene Parkdecks mit zusätzlichen Maßnahmen ausgeführt werden, zu denen man unter anderem rißüberbrückende Beschichtungen mindestens der Klasse OS 11 nach Instandsetzungsrichtlinie des DAfStb zählt. Die auf dem Markt verfügbaren rißüberbrückenden Beschichtungssysteme mit Allgemeinem bauaufsichtlichem Prüfzeugnis sind für die Beschichtung von Betonoberflächen mit extremen Wassergehalten (Wassersättigungsgrade bis 90 %), wie sie häufig in Bodenplatten Weißer Wannen vorkommen, nicht geeignet. Schadensfälle aus der Baupraxis zeigen, daß gelegentlich an eignungsgeprüften OS-11-Systemen osmotisch induzierte Blasenerscheinungen, vorzugsweise bei rückseitig durchfeuchteten Bodenplatten wasserundurchlässiger Tiefgaragengeschosse, auftreten. Daher werden die physikalischen Beanspruchungen der Beschichtung (osmotische Transportvorgänge, Kapillardrücke, hydrostatische Drücke und Gasdrücke) quantitativ abgeschätzt und dem Leistungsvermögen (Beanspruchbarkeit) der marktüblichen Systeme gegenübergestellt sowie alternative Beschichtungsvarianten vorgestellt. Ferner werden baupraktische Empfehlungen zur Vermeidung von Beschichtungsschäden erläutert. Coatings on directly vehicle-carrying floor slabs of watertight concrete constructions in underground carparks physical stresses , design codes , alternative coating systems According to DIN 1045-1 directly vehicle-carrying park decks have to be realized with additional measures (crack-bridging coating systems). At least surface protection system 11 (SPS 11) according to the Guidelines for the Protection and Repair of Concrete Components of the German Committee on Reinforced Concrete (DAfStb) are among others a possibility to meet this requirement. On the market available crack-bridging coating systems with a general technical approval are not usefull on concrete surfaces with high water contents (water saturation values of 90 %) as they may occur in floor slabs of watertight concrete constructions. Experiences with practical damage cases show, that with approved SPS 11-systems osmotic induced bubbles may occur preferably on backside saturated floor slabs of watertight concrete constructions. In consequence the physical stresses of a coating (osmotic processes, capillarity reactions, hydraulic pressures as well as gas pressures) will be quantitatively estimated and compared with the capability of market systems. Alternative coating systems are presented and practical recommendations in order to avoid damages are given. [source]