Correlation between perceived flavour and volatile compounds of processed oat

Although oat is perceived as a healthy and tasty cereal, its bitter off-flavour and tendency to rancidity limits its use.In addition of using oat in cereals and flaked products, entirely new food applications could be developed through tailoring of its sensory properties.Germination, used to date mostly for barley, is a well-known process for intensifying both the colour and flavour of grain products.In this investigation it was specified how and why the sensory profile of oat is altered by the germination process followed by heat-treatment.The sensory profile of oat changed significantly during the germination, when two oat cultivars, Veli and Lisbeth, were studied.The native grain was cereal-like, tough and hard, whereas the germinated, undried grain had a moist, musty and earthy flavour and a soft, moist texture.The most salient sensory attributes for the processed oat were a roasted odour and flavour, a sweet taste, an intense odour and aftertaste, and a hard, crisp and brittle texture (p < 0.05).High temperatures exceeding 85ºC, were necessary for the formation of the sensory attributes described above, and quick drying after germination resulted in higher attribute intensities of the favourable sensory descriptors.The identified volatile compounds responsible for odour of oat were dimethyl sulphide, hexanal, pentanal and isobutanal.The relative amount of dimethyl sulphide increased as a function of temperature in drying, whereas hexanal, pentanal and isobutanal disappeared during heating.Several of the identified volatile compounds correlated significantly with the sensory attributes evaluated.The germinated oat dried at high temperatures was perceived as being roasted, sweet and nutty, and it was clearly related to dimethyl sulphides and isobutanol when sensory and instrumental profiles of selected volatile compounds were analysed using statistical multivariate techniques (PLS).A moist and earthy odour correlated with cymene, limonene and isobutanal.In addition, phenolic compounds significantly influenced the oat flavour.The composition of volatile compounds obtained is dependent on the heat- treatment used.For example in Maillard reaction, which requires a high temperature and a dry atmosphere to occur, heterocyclic products, such as pyrazines, pyrroles and furans, mainly affect the roasted flavour.As a consequence of relatively low temperatures and high moisture levels in this study, detectable amount of these compounds were not formed althrough a roasted odour and flavour developed.