Prediction and measurement of volatile retention during extrusion processing

The loss of volatiles during extrusion of a corn‐based product was studied. Four organic flavour compounds were tested: n‐butanol, octane, benzaldehyde and limonene. A method was developed to calculate the vapour pressure of the volatile at the extruder die exit temperature through use of the Henry's law coefficient. Two models were developed to predict loss of volatiles. The thermodynamic model assumed complete equilibrium between the solid and vapour phase. This model gave moderate to poor prediction of retention for n‐butanol but was within 20–30% for limonene and benzaldehyde. A second model based on relative volatility with respect to water loss, as assessed by steam distillation, gave predictions which were good for both n‐butanol and benzaldehyde. This latter model has potential for prediction of retention of polar flavour compounds.