PTR-TOF-MS monitoring of in vitro and in vivo flavour release in cereal bars with varying sugar composition

► The first application of PTR-TOF-MS to nose-space analysis is presented. ► We monitored flavour release in a complex real system both in vitro and in vivo. ► We quantified the effect of sugar substitution on the release of many flavour compounds. ► The role of oral processing in nose-space release is highlighted.