FACTORS AFFECTING THE VISCO-AMYLOGRAPH AND RAPID VISCO-ANALYZER EVALUATION OF THE IMPACT OF ANNEALING ON STARCH PASTING PROPERTIES

Annealing affects the pasting properties of potato, pea, wheat and ric e starches. as shown by both rapid visco-analyzer and visco-amylograph results. The evaluation of the impact of annealing on starch pasting curves not only depends on the starch source but also on the type of m easuring instrument. Thus, rapid visco-analyzer results (measured with a 40 min or a 20 min cycle) are comparable to visco-amylograph result s (measured with a 120 min cycle) for potato and rice starches but not for pea and wheat starches. The different results for the two instrum ents have to do with differences in heating and cooling rates, differe nt start and end temperatures, and/or different shear and shear rate c onditions.