Formation of Spiro‐ and A‐Type‐Linked Procyanidins Through Oxidation of Dimeric B‐Type Procyanidins

B‐type procyanidins (PCs) are a subclass of flavonoids that are found in a wide variety of plant sources. These bioactive compounds have various health‐promoting properties, such as antioxidant, antiproliferative and anti‐inflammatory. Oxidation, which may lead to changes in chemical structure and colour, can occur during food processing and storage. Depending on the chemical structure of dimeric B‐type PCs and the conditions applied, the oxidation gives rise to A‐type‐linked PCs, macrocyclic ether compounds or spirocyclisation products, which are produced by the formation of additional C–C bonds through intramolecular rearrangements. These products may have an impact on food quality and biological activity. This review aims to provide an overview of the oxidation products of B‐type dimeric PCs.