Quantitation and Taste Contribution of Sensory Active Molecules in Oat (Avena sativa L.)

A total of 59 taste-active molecules were quantitated and then rated for their individual taste impact on the basis of dose-over-threshold factors in oat flour (Avena sativa L.). A sensitive high-performance liquid chromatography-tandem mass spectrometry method was developed to quantitate bitter-tasting steroidal and furostanol saponins as well as avenanthramides. Four monoglycerides, five free fatty acids and four saponins were confirmed for the first time to be major contributors to the bitter off-taste of oats, among them 1-linoleoyl-rac-glycerol, 1-stearoyl-rac-glycerol, 1-oleoyl-rac-glycerol, 1-palmitoyl-rac-glycerol, linoleic acid, linolenic acid, oleic acid, palmitic acid, and stearic acid as well as avenacosides A and B and the recently identified furostanosides 3-(O-α-l-rhamnopyranosyl(1→2)-[-d-glucopyranosyl(1→3)-d-glucopyranosyl(1→4)]-d-glucopyranosid)-26-O-d-glucopyranosyl-(25R)-furost-5-ene-3,22,26-triol and 3-(O-α-l-rhamnopyranosyl(1→2)-[-d-glucopyranosyl(1→4)]-d-glucopyranosid)-26-O-d-glucopyranosyl-(25R)-furost-5-ene-3,22,26-triol. By means of a stable isotope dilution assay, quantitated avenanthramides 2c, 2p, 2f, 1p, 1c, 1f, and 3f were found in concentrations below their thresholds and, therefore, did not contribute to the bitter sensation of the tested oat flour.