Fouling characteristics of model carbohydrate mixtures and their interaction effects

Fouling resistances of carbohydrate mixtures were measured using an annular probe at bulk fluid temperature of 75 °C and initial probe surface temperature of 120 °C. Induction period, maximum fouling resistance and mean fouling rates were determined. Two experiments were performed with two varieties of starch (waxy and high amylose) and short chain carbohydrates, corn syrup solids and glucose. Interaction effects of glucose with starch varieties were studied. In the first experiment, short chain carbohydrates individual and interaction effects with starch were studied. Glucose and corn syrup solids showed no fouling, whereas starch, a long glucose polymer, showed marked fouling. Corn syrup solids and glucose mixed with pure starch decreased the mean fouling rates and maximum fouling resistances. Between corn syrup solids and glucose, starch fouling rates were reduced with addition of glucose. Induction periods of pure mixtures of either glucose or corn syrup solids were longer than the test period (5 h). Pure starch mixture had no induction period. Maximum fouling resistance was higher for mixtures with higher concentration of longer polymers. Waxy starch had a longer induction period than high amylose starch. Maximum fouling resistance was higher for waxy than high amylose starch. Addition of glucose to waxy or high amylose starch increased induction period of mixtures longer than 5 h test period.