الفهرس 
REVIEW OF LITERATUREOnly 14 pages are availabe for public view
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Abstract
The rheological properties of strawberry jam puree as a sample of food gels were studied at different shear rates, concentrations and temperatures.
In this study strawberry jam puree behaved as a non-Newtonian pseudo plastic fluid at all the studied temperatures and concentrations. The results showed that the apparent viscosity of strawberry jam puree as a sample of some food gels decreases with increasing shear rate. The decrease in viscosity can be attributed to the increase in intermolecular distances, because of the thermal expansion caused by the increase in temperature.
The effect of temperature on the apparent viscosity of strawberry jam puree was studied and the apparent viscosity of strawberry jam puree decreased with increasing temperature. The results followed Arrhenius model. A fluctuation in viscosity decreased over a certain range of shear rates was appeared, this may be due to agglomeration of dispersed solid particles around the spindle which leads to a fictitious increase in viscosity. However, at higher shear, the fluctuations in viscosity decreased where the curves tend to be parallel to each other. The magnitudes of activation energy of the samples for the entire temperature range were determined by linear regression analysis using Arrhenius equation.
The effect of concentration on the apparent viscosity of strawberry jam puree as a sample of some food gels at shear rate (9.3, 18.6, 27.9, 37.2, 46.5, 55.8, 65.1, 74.4, 83.7, 93 sec^(-1)) was investigated over a temperature range (30, 40, 50, 60, 70 ̊ C). The variation of viscosity with concentration described by an exponential or a power model. The concentration dependence became stronger at higher temperatures. This could be due to increasing intermolecular interaction in the extract solutions at elevated temperatures.
Recommendation:
It is recommended that rheological properties of strawberry jam puree should be studied and developed to produce the strawberry jam puree to fit the end consumer.
It is recommended to study the effect of the rheological properties on unit operation.
The recommended concentration of commercial strawberry jam puree is 63%.
The recommended range of activation energy was found in 25.26–97.78 KJ/mol.