Viscosity Changes of Starches As Studied with the Digestion-Flask Viscometer

The beginnings of this experimental work traces back to a graduate course in chemistry taken at Marquette University during which Dr. John R. Koch, head of the Chemistry Department, demonstrated the adaptability of the all-glass digestion-flask viscometer. A considerable amount of work had been done on protein material using this instrument, and a few investigations had been carried out on starches with this viscometer. It was Dr. John R. Koch who suggested in a conference that the most interesting field for a research problem might be in the investigation of starch viscosity with the all-glass digestion-flask viscometer. The following pages are an attempt to describe the application of the all-glass digestion-flask viscometer and the large bore digestion-flask viscometer for the determination of the viscosity changes brought about in starch pastes by mechanical agitation and heat prior to viscosity determinations and to enzymatic action during viscosity determinations. On account of the extreme complexity of the nature of starches no definite method has been adopted universally for the study of the above mentioned effects. The measurement of the viscosity change of starch pastes is quite convenient with this instrument, but disadvantages are encountered when the viscometer is applied to the study of the changes of viscosity caused by enzymes. The procedure is simple and comparatively accurate, since the instrument is constructed so as to eliminate some of the common errors prevalent when working with other types of viscometers. The feature of simple operation makes the instrument well suited for ordinary laboratory analysis