Oxidative formation and structural characterisation of new α-pyranone (lactone) compounds of non-oxonium nature originated from fruit anthocyanins

► Non-oxonium anthocyanin derivative with pyranone ring is formed by two-step reaction. ► The reaction proceeds in mildly acidic solutions with the most favourable pH 4.0-5.5. ► The increase of temperature improves the reaction rate significantly. ► The pyranone ring and non-oxonium nature confer derivative unique spectral features. ► The origin of anthocyanin has very tiny influence on the λmax of new derivatives.