title: Composition of pigments and colour changes in green table olives related to processing type.
abstract: Brownish colourations in Natural green table olives (non-treated with alkali) make this product less attractive to consumers than Spanish-style green table olives (treated with alkali), which develop a more appreciated bright golden-yellow colour. These colour differences were studied in relation to changes in the composition of chlorophyll and carotenoid pigments, as well as polyphenolic compounds and polyphenol oxidase enzyme (PPO) activity. Natural green olives showed a different chlorophyll profile than Spanish-style. However, all the chlorophyll pigments formed in both processing types were Mg-free derivatives (mostly pheophytins) with similar colourations, ranging from grey to green brownish. In the carotenoid fraction no appreciable differences were found between both processing types. The fruit's brownish colour was mainly due to polymeric substances with a size of >1000 daltons and polyphenolic nature, resulting from an enzymatic oxidation by PPO of the o-diphenolic compounds present in the fresh fruits.
authors: Instituto de la Grasa (IG-CSIC), Avda. Padre García Tejero 4, 41012 Seville, Spain.
authors: Eva
authors: E
authors: Ramírez
authors: Instituto de la Grasa (IG-CSIC), Avda. Padre García Tejero 4, 41012 Seville, Spain.
authors: Beatriz
authors: B
authors: Gandul-Rojas
authors: Instituto de la Grasa (IG-CSIC), Avda. Padre García Tejero 4, 41012 Seville, Spain.
authors: Concepción
authors: C
authors: Romero
authors: Instituto de la Grasa (IG-CSIC), Avda. Padre García Tejero 4, 41012 Seville, Spain.
authors: Manuel
authors: M
authors: Brenes
authors: Instituto de la Grasa (IG-CSIC), Avda. Padre García Tejero 4, 41012 Seville, Spain. Electronic address: lgallardo@ig.csic.es.
authors: Lourdes
authors: L
authors: Gallardo-Guerrero
mesh_terms: D002338:Carotenoids; D004156:Catechol Oxidase / Q000737:chemistry*; D002734:Chlorophyll / Q000737:chemistry*; D003116:Color; D005638:Fruit / Q000737:chemistry*; D031658:Olea / Q000737:chemistry*; D010084:Oxidation-Reduction
chemical_list: D002734:Chlorophyll; D002338:Carotenoids; D004156:Catechol Oxidase
keywords: Carotenoids; Chlorophyll pigments; Colour; Polyphenol oxidase; Table olives; o-Diphenol oxidation