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Controlling the rheological properties of dispersion has been of great interest in the food processing
industry. Effects of particle size and temperature on oscillatory rheology of pumpkin flour dispersion
were studied. Fresh pumpkin was freeze-dried, grinded and sieved through selected screens to obtain
desired particle size fractions (74–841 lm). Most of the particles are spherical in shape. The glass
transition temperature (Tg) and the melting temperature (Tm) of starch–lipid complex varied with particle
size which is believed to be due to compositional variations. Rheological measurement of reconstituted
particles as a function of temperature (10–90 C) and concentration (4–10% w/w) indicated a solid-like
behavior (G0 > G00). Sediment volume fraction (/) of isolated particle dispersions indicated a gradual
decrease with decrease in particle size, which directly influences the mechanical strength and visco-elasticity
of the dispersion. Particle size influenced the mechanical rigidity of pumpkin dispersion markedly
whereas the temperature had the least effect. An unexpected increase in G0 of finest particle containing
dispersion with temperature could be associated with gelatinization of starch and flocculation of particles
with broken cell walls. Microscopic observation revealed the presence of a continuous network for the
finest particle dispersion, as opposed to discontinuous one for other particle sizes.
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