Impact of process parameters (temperature & pH) and salts on kinetics and rheological properties of Hibiscus sabdariffa L. leave puree

Meher, J ; Mazumdar, B ; Keshav, A


Thermal kinetics of Hibiscus sabdariffa L. leaves puree (HSLP) were measured to determine the energy of kinetic degradation of chlorophyll a (Chl a) & chlorophyll b (Chl b) of puree at pH (1.4 to 5.8) and temperature (343 K to 363 K). Degradation curves were fitted using first-order reaction kinetic models & the activation energy (Ea) for Chl a & Chl b was found to be 44.623±0.18, 39.158±0.25 & 35.775±0.11 kJ mol-1 and 6.086±0.14, 5.174±0.24 & 4.328±0.20 kJ mol-1 at pH 1.43, 3.8 & 5.8, respectively. Every single rheological estimation was done at different shear rates, temperatures, pH, & in the presence of various salts for the product development, quality control, and engineering applications. Rheological data fitted with the Herschel-Buckley model revealed that puree exhibit non-Newtonian, shear-thinning behavior at all tested concentrations and temperatures. The viscosity reached a maximum value at pH 5.8 and it decreased at lower pH values. Salts caused a reduction in viscosity. Comparatively, NaCl had a more pronounced effect than CaCl2 at a similar concentration.


Color, HSLP, Kinetics, Salt, Viscosity


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