FTIR-ATR was used to study the effect of roasting conditions on the flavor of brewed coffee using Guatemala Antigua coffee beans. The 1800-1680 cm(-1) carbonyl region for vinyl esters/lactones, esters, aldehydes, ketones, and acids was found to provide a flavor-print of the brewed coffee. A study of light, medium, and dark roasts indicated that when the rate of heating to the onset of the first and second cracks was kept constant, the types of carbonyl compounds formed were similar, varying only in their concentration. This difference in concentration is apparently due to the additional heating of the coffee bean beyond the second crack. When the heating rate to the onset of the first and second crack was varied, both the types and concentration of the carbonyl compounds formed during roasting were affected. Thus, heating rates of green coffee beans to the onset of the first and second cracks are important determinants of the basic taste and aroma of brewed coffee.

Adsorption of bovine albumin, gamma-globulin and fibrinogen from phosphate buffer solution (pH = 7.5) onto several polymer films was studied using the radioiodinated proteins (125I). The kinetics of desorption of the proteinated polymer films in bovine plasma was determined. Contact angle measurements on these same polymers allowed the calculation of dispersive (WA d) and polar (Ip) components of the polymer-protein solution system. Results from these measurements show that the nondispersive-dispersive force balance at the polymer-protein solution interface, expressed by the Ip/WA d ratio, is an important factor for binding of proteins on polymer surfaces. The purity of fibrinogen and the cleaning procedures for the polymer surfaces influence the absolute values of proteins adsorbed on polymer surfaces.

SummaryInfrared internal reflection spectroscopy has been used to study the adsorption of certain plasma proteins on a variety of hydrophobic polymer surfaces. The behavior of the systems studied was almost identical. Under static conditions the proteins appear to be rapidly adsorbed as monomolecular layers from solutions varying in concentration between a few me-% and normal plasma levels. These monolayers are deduced to be closely packed arrays in which the protein molecules appear to retain their native globular form. The bearing of these results on the mechanism of surface-induced coagulation is significant.