ESTIMATION OF PHYSICAL-PROPERTIES OF FOAMED FOODS USING ENERGY-DISSIPATION IN SCRAPED-SURFACE HEAT-EXCHANGERS

A jacketed stirred column simulating a continuous scraped-surface heat exchanger under steady-state conditions was devised and used to produce foamed foods. The physical properties of these were assessed as a function of rotor speed, paddle diameter and gas/liquid ratio. Apparent viscosity of foamed food was calculated using a Newton number-Reynolds number experimental relation for the stirred column and power consumption measurements. It was shown that the mean apparent viscosity was an inverse function of the density of the foamed food and of the rotation speed. Mean bubble diameter was correlated with the mixing conditions by a critical Weber number. For the starting material used the mean bubble diameter reached a stationary value beyond a certain rotation speed. These results were explained theoretically.