Increasing Moisture Content (increasing + moisture_content)

Distribution by Scientific Domains


Selected Abstracts


Prediction of sensory textural properties from rheological analysis for process cheeses varying in emulsifying salt, protein and moisture contents

JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 4 2007
Colm D Everard
Abstract Textural characteristics of process cheeses varying in emulsifying salt (disodium phosphate), protein and moisture contents were evaluated by rheological compression using texture profile analysis and by sensory evaluation. The primary objective of this study was to predict sensory textural parameters using instrumental rheological parameters. All sensory parameters correlated with one or more instrumental parameters, e.g. rheological firmness versus sensory firmness (R = 0.98, P < 0.001), rheological chewiness versus sensory rubbery (R = 0.92, P < 0.001) and rheological chewiness versus sensory chewy (R = 0.86, P < 0.001). Partial least squares calibration models were developed for each of nine sensory parameters using instrumental parameters. Principal component analysis of instrumental and sensory parameters illustrated relationships among parameters. It was shown that instrumental parameters could be used to supplement sensory evaluation of process cheese texture. Increasing emulsifying salt content increased firmness, springiness and chewiness and decreased adhesiveness, mouthcoating and mass formation. Increasing protein content resulted in increased fracture strain and stress and chewiness and decreased melting. Increasing moisture content increased cohesiveness and decreased firmness and chewiness. Copyright © 2007 Society of Chemical Industry [source]


Mechanical and fracture properties for predicting cracking in semi-sweet biscuits

INTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 4 2005
Qasim Saleem
Summary Mechanical and fracture properties required for predicting crack development in semi-sweet (,rich tea') biscuits have been experimentally determined. Pilot-scale biscuits of different fat concentrations were prepared and studied with commercial biscuits at different moisture contents. Bending modulus, fracture stress and strain were measured using three-point bending tests. All biscuit types showed considerable dependence on moisture content over a range of 4,12%. Young's modulus and failure stress showed a uniform decrease and failure strain showed an increase with increasing moisture content. For pilot-scale biscuits of different fat concentrations, an increase in fat level caused a decrease in modulus and failure stress values; however, the failure strains were very similar for all the fat types. The testing of the samples with top surface up and top surface down revealed that the sample orientation does not affect the measured parameters. The measured parameters also did not show any directional dependence within the plane, thus assuring that the assumption of an isotropic material would be valid for modelling. The mechanical and fracture properties measured in this study will serve as a very useful set of data to predict the stress state and cracking of the checked biscuits. [source]


Physicochemical, mechanical and thermal properties of brown rice grain with various moisture contents

INTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 9 2004
Wei Cao
Summary The effects of moisture content on the mechanical and thermal properties of either a short-grain variety (Akitakomachi) or two long-grain varieties (Delta and L201) of brown rice were studied. Total starch contents of the three varieties were comparable, but the amylose content of L201 was significantly higher than that of the other two varieties. The maximum compressive strength of brown rice grain was much higher than the maximum tensile strength. L201 showed the highest maximum compressive and tensile strengths. The phase transition temperatures (glass transition temperature Tg and melting temperature Tm) were examined by differential scanning calorimetry. The Tg and Tm for L201 were higher than those for Delta and Akitakomachi. The maximum compressive strength, maximum tensile strength, Tg and Tm for the three varieties of brown rice grains decreased with increasing moisture content. The Tg of individual brown rice kernels decreased from 53 to 22 °C as moisture content increased from 12 to 25% wet basis. A statistical model was calculated by using linear regression to describe the change in Tg in terms of moisture content. [source]


MOISTURE SORPTION CHARACTERISTICS of STARCH GELS.

JOURNAL OF FOOD PROCESS ENGINEERING, Issue 3 2004
PART II: THERMODYNAMIC PROPERTIES
ABSTRACT A thermodynamic approach was used to interpret the experimental adsorption and desorption isotherm data for potato starch gel. Calculation of the thermodynamic properties (differential enthalpy, integral enthalpy, differential entropy and integral entropy) provides an understanding of the properties of water and energy requirements associated with the sorption behavior. Isosteric heats (differential enthalpies) were calculated through direct use of moisture isotherms by applying the Clausius-Clapeyron equation. the differential enthalpy and entropy decreased with increasing moisture content and were adequately characterized by an exponential model. A plot of differential heat versus entropy satisfied the enthalpy-entropy compensation theory. the spreading pressure increased with increasing water activity, and decreased with increasing temperature. the net integral enthalpy increased with moisture content to a maximum value (around the monolayer moisture content) and then decreased. In a reverse manner, the net integral entropy decreased with moisture content to a minimum value and then increased. [source]


KINETICS OF HYDROXYMETHYLFURFURAL ACCUMULATION AND COLOR CHANGE IN HONEY DURING STORAGE IN RELATION TO MOISTURE CONTENT

JOURNAL OF FOOD PROCESSING AND PRESERVATION, Issue 1 2009
L. BULUT
ABSTRACT Quality reduction in honey during storage is indicated by hydroxymethylfurfural (HMF) accumulation and darkening of color. The effects of moisture content and temperature on HMF accumulation and color change in honey during storage were investigated. HMF accumulation and color change followed first- and zero-order reaction kinetics, respectively. The moisture content affected the rate of the two degradation reactions depending on the storage temperature. Reduction in moisture content caused an increase in rate constant for HMF accumulation at 20 and 30C, but there was no significant effect of moisture content at 40C. Rate constants for change in lightness and total color change values increased with increasing moisture content at 20 and 30C. The highest rate constant for change in color values was obtained at a moisture content of 18% at 40C. PRACTICAL APPLICATIONS Hydroxymethylfurfural accumulation and color change are two major quality degradations in honey during storage. This study shows that the rates of these two degradations are dependent on moisture content of honey. In addition, effect of moisture content on the rates of reactions was dependent on temperature of storage. Therefore, producers need to consider the effects of both moisture content and storage temperature in reducing quality loss in honey during storage. [source]


Moisture sorption in moulded fibre trays and effect on static compression strength

PACKAGING TECHNOLOGY AND SCIENCE, Issue 4 2003
Gitte Sørensen
Abstract This study provides a basic understanding of moisture sorption in moulded fibre packaging for food at varying environmental temperatures and humidities, and the resultant effects on static compression strength. The Guggenheim,Anderson,de Boer (GAB) model is used successfully to construct moisture sorption isotherms in the range 2,25°C and 33,98% relative humidity (% r.h.) (R2 = 0.949,0.999), in which moisture content varies from 5.4 to 28.3,g/100,g dry fibre. Static compression strength (SCS) is substantially affected by changes in moisture content of moulded fibre and decreases exponentially with increasing moisture content. The results indicate a minor hysteresis effect on static compression strength. For adsorption of moisture, a relative strength measure, % SCS (experimental SCS in kg divided by a standard SCS in kg), is given by % SCS = 13.83 + 166.50,·,e,0.0978,m (m is moisture content). The temperature dependence of moisture adsorption is incorporated in the GAB model by relating GAB coefficients, m0 and C, exponentially to temperature, T. By combining this with the exponential model for % SCS, static compression strength can be predicted directly from the surrounding temperature and humidity. Illustrated in a response surface plot the effects of changes in the surroundings are simple and readily accessible, e.g. for packaging designers and sales people. It is noted that an increase in humidity from 50% r.h. to 95% r.h. at constant temperature results in a drastic reduction in % SCS from 100% to 40%, whereas the temperature effect is typically less than 10% SCS when reducing temperature from 25°C to 2°C. Copyright © 2003 John Wiley & Sons, Ltd. [source]


Glass Transition Temperatures and Fermentative Activity of Heat-Treated Commercial Active Dry Yeasts

BIOTECHNOLOGY PROGRESS, Issue 2 2000
Carolina Schebor
Differential scanning calorimetry thermograms of various samples of commercial instant active dry yeasts revealed a clear glass transition typical of amorphous carbohydrates and sugars. The resulting glass transition temperatures were found to decrease with increasing moisture content. The observed glass curve was similar to that of pure trehalose, which is known to accumulate in large amounts in baker's yeast. The effect of heat treatment at various temperatures on the fermentative activity (as measured by the metabolic production of CO2) of dry yeast was studied. First-order plots were obtained representing the loss of fermentative activity as a function of heating time at the various temperatures assayed. Significant losses of fermentative activity were observed in vitrified yeast samples. The dependence of rate constants with temperature was found to follow Arrhenius behavior. The relationship between the loss of fermentative activity and glass transition was not verified, and the glass transition was not reflected on the temperature dependence of fermentative activity loss. [source]