Term for a chemical reaction in which an atom or molecule gives off (oxidizes) electrons and another substance takes up (reduces) these electrons. Oxidation is therefore always associated with a reduction. Both processes together are partial reactions of a so-called redox reaction. Originally, oxidation was exclusively understood as the chemical reaction of a substance with oxygen. Later the term was extended to include reactions in which hydrogen atoms are removed from a compound (dehydrogenation).
Oxidizing agents are those substances that can easily take up electrons, such as oxygen, chlorine and fluorine. The oxidizing agents are themselves reduced in the redox reaction. And reducing agents are substances that easily give off electrons, for example hydrogen, carbon and base metals such as iron, magnesium and sodium. The reducing agents themselves are oxidized during the redox reaction. During vinification, oxidation should only take place in as precisely dosed and controlled a form as possible, as uncontrolled wine defects often occur.