Water desorption characteristics of raw goat meat: Effect of temperature (original) (raw)
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Desorption isotherms for fresh beef: An experimental and modeling approach
Meat Science, 2014
Desorption isotherms for fresh beef were determined at 30, 40 and 50°C by the static gravimetric method. The resulting isotherms exhibited a type II sigmoid shape. The BET, GAB and Halsey models were used to fit these experimental data. The GAB model was most accurate for all temperatures and all levels of water activity, followed by the BET and Halsey models. The temperature dependence of GAB constants was estimated. The isosteric heat of desorption and its evolution in relation to moisture content were calculated using Clausius-Clapeyron equations. The monolayer moisture content was determined using the GAB model: it decreased as the temperature increased. The density of bound water, the number of adsorption sites, the sorption surface area and the percentage of bound water were calculated using the Caurie equation: all these quantities decreased as the temperature increased. The Kelvin and Halsey equations were used for calculation of pore size, which increases with an increase in moisture levels and sorption temperature.
Effect of Temperature on Desorption Isotherms for Beef
Journal of Engineering in Agriculture and the Environment
Desorption isotherms of beef were determined by the standard static gravimetric technique, based on the use of saturated salt solutions with water activities from 0.05 to 0.9. Equilibrium moisture content of each sample at different temperatures and water activities were determined. The stable moisture content for meat during drying was also established. The GAB, BET and Oswin models were used to fit the experimental sorption data. Non-linear regression analysis was performed to estimate model parameters and fitting quality evaluated using the Coefficient of determination (R 2) and the standard error of estimate (SEE). The equilibrium moisture content decreased with increase in temperature at constant water activity and increased with increase in water activity at constant temperature. The critical moisture was 10-20 % (d.b). The high values of R 2 and low values of SEE for the GAB and Oswin models indicated that these models gave the best fit for the desorption data of beef.
Characterization and sorption isotherm of dehydrated beef made in Nigeria
Cogent Food & Agriculture
Sorption isotherms of dehydrated beef were determined at room temperature and Brunauer, Emmett and Teller (BET) isotherm model and Guggenhein, Aderson and Boer isotherm model were used to calculate the monolayer values. It was found that the isotherms were similar and they all exhibited BET type shape (sigmoid). At both desorption and adsorption, samples adsorbed moisture at the 0.9 water activity which resulted in mould growth. The monolayer values were quite useful in assessing the storage stabilities of dehydrated meat.
Prediction of the effect of temperature on water sorption isotherms of food material
International Journal of Food Science & Technology, 1976
An empirically modified two-parameter multilayer adsorption equation is shown to take into account the effect of temperature on the water sorption isotherms of some food materials. Characteristic parameters of the sorption equation for each food tested are presented. The equation should be of value in predicting the shelf life behaviour of food products at different storage temperatures.
Equilibrium moisture contents of air dried beef. Dependence on drying temperature
International Journal of Food Science & Technology, 2006
The water adsorption isotherms at 30°C of precooked beef previously dried at three different temperatures: 30"C, 55°C and 70"C, respectively, were determined. It was found that the higher the drying temperature the lower is the sorption capacity of dried beef. A B.E.T. analysis of the isotherms demonstrated that the quantity of water contained in the monolayer is affected by the temperature of drying. The adsorption and desorption isotherms at 50°C were also determined; no hysteresis was found. A multilayer adsorption equation is used to describe adequately the water sorption behaviour of cooked beef in the range of water activities studied.
Effect of temperature on moisture desorption isotherms of kheer
LWT - Food Science and Technology, 2005
Desorption isotherms of kheer, a rice based partially heat concentrated and sweetened Indian milk dessert, were obtained in the temperature range of 10-40 C. The desorption curves exhibited sigmoid shape corresponding to type II, typical of many foods. There was generally a negative temperature effect on EMC at low a w ; but curves at 25 C and 40 C showed inversion above water activity of 0.60 implying a higher equilibrium moisture content at higher temperature. Of the five sorption models tested, the GAB model gave the best fit at all the three temperatures. Besides monolayer moisture, properties of sorbed water viz. number of adsorbed monolayers, bound or nonfreezable water, density of sorbed water and surface area of sorption were also obtained. Isosteric heat of sorption obtained by applying Clausius-Clapeyron equation decreased exponentially with the increasing moisture content.
Journal of Food Science, 2006
The water activity (aw) of eight salt solutions was determined at three temperatures (25, 30, 45°C) using a pressure transducer-vapor pressure manometer. The aws of the salts showed a decrease with increasing temperature, which was explained with the help of a thermodynamic equation. This is opposite to the increase in aw with increase in temperature for foods. Moisture sorption data for fish flour and cornmeal were obtained at 25–65°C. The Guggenheim-Anderson-deBoer model was evaluated and shown to be comparable to the Brunauer-Emmett-Teller model for prediction of the monolayer. Product was equilibrated at different aws at 25°C then subsequently shifted to 30°C and 45°C in a sealed chamber. The resultant a, change, measured on the Kaymont-Rotronics, was predictable from the isotherm at each temperature using the Clausius Clapeyron relationship.
Effect of temperature on the moisture sorption isotherms of a heat-treated whole milk product, khoa
Journal of Dairy Research, 1991
SummaryMoisture sorption isotherms of khoa were determined at 15, 25, 35 and 45 °C over a water activity (aw) range of O·l 1–0·97. The isotherms were sigmoid (Type II) and were fitted to the Guggenheim–Anderson–de Boer (GAB) equation (Bizot, 1983). The aw of freshly made khoa was found to be 0·96. The aw of khoa increased with increasing temperature up to 0·9; above this the effect of temperature on aw diminished. The monolayer moisture content of khoa decreased with increasing temperature. The equations describing the temperature dependence of GAB constants were determined in the form of the Clausius–Clapeyron equation. The net isosteric heat of desorption of khoa decreased rapidly until a moisture level of 0·1 g/g solids, and approached a constant value of 0·43 kJ/mol above a moisture level of 0·25 g/g solids.
Water desorption isotherms of pork liver and thermodynamic properties
LWT, 2021
For the first time, the relationship between equilibrium moisture content and water activity is reported for the desorption process in pork liver. For that purpose, a standardized conductivity hygrometer was used at four different temperatures (0, 10, 30 and 50 • C) over a wide range of water activity (0.999-0.103). Five models frequently found in the literature (GAB, Oswin, Henderson, Hasley and Ratti) were considered for the purposes of describing the experimental desorption. The GAB model emerged as the best option (explained variance 96.6%) for the physical and mathematical description of the water desorption isotherms in pork liver. The computed isosteric heat, entropy and Gibbs energy illustrated the high water-sorbent affinity, because of a considerable availability of strong sorption sites at low moisture contents. The reported experimental desorption isotherms, and modeling results, are essentials for the optimal design of the drying process of pork liver, which is a necessary step for the further research addressing the extraction of the protein fraction from the dried product. Extraction and isolation of the protein fraction from pork liver could be considered a reasonable strategy considering the demand of protein materials and the high-environmental impact of the meat industry.