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Anomalous Transformation Of Chloroplastic Pigments In Gordal Variety Olives During Processing For Table Olives

M. ISABEL MÍNGUEZ-MOSQUERA, LOURDES GALLARDO-GUERRERO

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The results of a qualitative and quantitative study of pigments, carried out during the processing of Gordal variety olives for table use, has provided valuable information on the type, extent, and mechanism of degradation of the chlorophylls and carotenoids present in the fresh fruit. Unexpected results were obtained, since the initial treatment of the fruits with NaOH did not provoke chlorophyllase activity. However, the alkaline pH brought about the oxidation of chlorophylls, giving rise to Mg-phytyl-chlorin e6 and Mg-phytyl-rhodin g7. Subsequently, as a consequence of the acid pH generated in the fermentation medium, these compounds were transformed into the corresponding Mg-free derivatives, phytyl-ch1orin e6 and phytyl-rhodin g7. At the same time, those chlorophylls which initially escaped transformation were converted into their corresponding pheophytins. In addition, small amounts of pyropheophytin a, pheophorbides a and b, and pyropheophorbide a were detected, As far as the carotenoid fraction is concerned, β-carotene and lutein remained unaltered throughout processing, and only those components with molecular structures sensitive to the acid medium were affected. The total balance of pigment material indicated that there was a slow but progressive decrease in the concentration of the chlorophyllic and carotenoid fractions, which indicates that a certain amount of these pigments is degraded into colorless products.