30G-8 |
Rheological characteristics of papaya puree: effect of temperature, pH, TSS and pectic enzyme |
J. AHMED and H. S. Ramaswamy. Department of Food Science, McGill University, Macdonald Campus, Ste Anne de Bellevue, H9X 3V9, Canada Rheology of fruit puree has a great importance in the food processing industry as it governs the design of pump, pipe and heat exchangers, and predicts their flow characteristics. It is also an integrated part of quality assessment of finished products. The objective of this study was to evaluate the rheological characteristics of papaya puree as influenced by temperature , total soluble solids, pH and addition of pectic enzymes. A central coposite design was used to evaluate the effects of five levels temperature (5 to 65C), total soluble solids (10-30%), pH (3-7) and addition of pectic enzymes (0.25-1.25%) on rheological properties of papaya puree which was evaluated using a Haake rotational viscometer under a programmed shearing sequence increasing and decreasing at pre-selected rate. The rheograms were analyzed based on conventional models such as Newtonian, power-law, Herschel-Bulkley and logarithmic models. The puree exhibited a pseudoplastic shear-thinning behavior with yield stress. The Herschel-Bulkley model well described the shear stress-shear rate relationship over the wide range of shear rate under the different conditions employed in the study. The flow behavior index (n) and consistency coefficient were modeled as a function of soluble solids concentration, temperature, pH and enzyme activity. The associated flow activation energies were also evaluated based on the Arrhenius model. The study provided a useful data base data for a subsequent study evaluating the effect of pectic enzymes on the flow behavior and consistency of papaya puree.
Session 30G, Fruit & Vegetable Product: Processed Fruits and Vegetables
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