Lecithin gum rheology and processing implications

The rheology of canola, sunflower, and soybean lecithin gum was examined by studying samples of different moisture contents produced in a batch evapor ator (70 degrees C, 0.1 atm). Soybean lecithin was found to have the lowest viscosity, approximately 10 poise (100 s(-1), 70 degrees C), compared to c anola and sunflower lecithin with viscosities of approximately 90 and 90,00 0 poise, respectively. The high sunflower viscosity was attributed to the p resence of long-chain waxes. Lecithin gum was shown to change from a Bingha m (water continuous phase) to a pseudoplastic (oil continuous phase) type f luid as the moisture content of the lecithin gum decreased. The viscosity m axima occurred between 6.9 and 19.3% moisture content (100 s(-1)), with the variation found to be related to the oil/water ratio of the system. Rheolo gical results indicated that vertical scraped surface evaporator design cou ld be optimized through the addition fluidizing of agents prior to the evap orator and/or increased heating at the evaporator outlet.