RHEOLOGICAL PROPERTIES OF ALOE VERA (ALOE BARBADENSIS MILLER) JUICE CONCENTRATES

Flow characteristics of aloe vera juice concentrates (1.5-5.5 degrees Brix) were determined over a range of temperatures (15-55C) by using coaxial cylinder geometry. Aloe vera juice exhibited non-Newtonian fluid behavior which was well described by power law model. Functional groups were characterized by Fourier-transform infrared (FTIR) spectroscopy indicating the presence of O-acetyl and shifting of -CH bonds. Effect of test temperatures at different shear rates on viscosity was evaluated using Arrhenius-type equation and the activation energy values were evaluated which ranged between 12.148 and 53.073 kJ/mol. Effect of concentration was evaluated using power type and exponential type equations. An expression for combined effect of temperature and concentration was developed. Small amplitude oscillation sweep measurement was also carried out and the frequency sweep test exhibited viscoelastic nature of juice.