The functional group present in xanthophyll but absent in β-carotene is the hydroxyl group (–OH). Xanthophylls are oxygenated carotenoids; they typically contain one or more –OH groups (and some may also have epoxy groups), which makes them slightly more polar and more hydrophilic than non‑oxygenated carotenes like β‑carotene, which are pure hydrocarbons with only carbon and hydrogen in their structure.