Effects of bite size and duration of oral processing on retro-nasal aroma release - features contributing to meal termination.

The brain response to a retro-nasally sensed food odour signals the perception of food and it is suggested to be related to satiation. It is hypothesised that consuming food either in multiple small bite sizes or with a longer durations of oral processing may evoke substantial oral processing per gram consumed and an increase in transit time in the oral cavity. This is expected to result in a higher cumulative retro-nasal aroma stimulation, which in turn may lead to increased feelings of satiation and decreased food intake. Using real-time atmospheric pressure chemical ionisation-MS, in vivo retro-nasal aroma release was assessed for twenty-one young, healthy and normal-weight subjects consuming dark chocolate-flavoured custard. Subjects were exposed to both free or fixed bite size (5 and 15 g) and durations of oral processing before swallowing (3 and 9 s) in a cross-over design. For a fixed amount of dark chocolate-flavoured custard, consumption in multiple small bite sizes resulted in a significantly higher cumulative extent of retro-nasal aroma release per gram consumed compared with a smaller amount of large bite sizes. In addition, a longer duration of oral processing tended to result in a higher cumulative extent of retro-nasal aroma release per gram consumed compared with a short duration of oral processing. An interaction effect of bite size and duration of oral processing was not observed. In conclusion, decreasing bite size or increasing duration of oral processing led to a higher cumulative retro-nasal aroma stimulation per gram consumed. Hence, adapting bite size or duration of oral processing indicates that meal termination can be accelerated by increasing the extent of retro-nasal aroma release and, subsequently, the satiation.