The Sensory Significance of Apocarotenoids in Wine: Importance of Carotenoid Cleavage Dioxygenase 1 (CCD1) in the Production of β-Ionone.

Olfactory cues are key drivers of our multisensory experiences of food and drink. For example, our perception and enjoyment of the flavour and taste of a wine is primarily steered by its aroma. Making sense of the underlying smells that drive consumer preferences is integral to product innovation as a vital source of competitive advantage in the marketplace, which explains the intense interest in the olfactory component of flavour and the sensory significance of individual compounds, such as one of the most important apocarotenoids for the bouquet of wine, β-ionone (violet and woody notes). β-Ionone is formed directly from β-carotene as a by-product of the actions of carotenoid cleavage dioxygenases (CCDs). The biological production of CCDs in microbial cell factories is one way that important aroma compounds can be generated on a large scale and with reduced costs, while retaining the 'natural' moniker. The CCD family includes the CCD1, CCD2, CCD4, CCD7 and CCD8; however, the functions, co-dependency and interactions of these CCDs remain to be fully elucidated. Here, we review the classification, actions and biotechnology of CCDs, particularly CCD1 and its action on β-carotene to produce the aromatic apocarotenoid β-ionone.