Inverse gas chromatographic evaluation of the influence of soy protein on the binding of selected butter flavor compounds in a wheat soda cracker system

Binding of selected volatile butter flavor compounds to wheat vs soy-containing crackers was studied by inverse gas chromatography (IGC), sensory evaluation, and equilibrium sorption measurements. IGC data showed greater binding of gamma-butyrolactone and butyric acid to both types of crackers than either diacetyl or hexanal, possibly due to the involvement of stronger binding forces such as hydrogen bonding and even ionic forces in the case of butyric acid. The presence of soy proteins did not affect binding of diacetyl and hexanal but increased binding of strongly interacting compounds gamma-butyrolactone and especially butyric acid, probably through enhanced matrix polarity. In agreement with the IGC data, sensory evaluation results showed that the headspace aroma intensities were similar between the two diacetyl-flavored crackers, while they significantly differed between the butyric acid-flavored crackers. In addition, equilibrium sorption measurement data showed that binding of butyric acid was higher in the soy-containing cracker, but sorption of diacetyl to the two crackers did not significantly differ.