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  • Are virgin olive oils obtai...
    Boselli, Emanuele; Di Lecce, Giuseppe; Strabbioli, Rosanna; Pieralisi, Gennaro; Frega, Natale G.

    Food science & technology, 04/2009, Letnik: 42, Številka: 3
    Journal Article

    Within the European Union, indications of ‘first cold pressing’ and ‘cold extraction’ can only be used for virgin olive oil (VOO) obtained below 27 °C from mechanical processing. Three different malaxing temperatures (25, 35 and 45 °C) are here evaluated for the quality of the VOO obtained in a continuous industrial plant. The oils were stored at room temperature in the dark for 12 months. Initially, oil obtained from a blend of Frantoio/Leccino cultivars (F/L) had higher acidity and peroxide levels and lower phenolic content than a Coratina cultivar (Cor). The oxidative stability of the oils positively correlated with malaxation temperature (F/L, R 2 = 0.818; Cor, R 2 = 0.987) as the phenolic content was directly proportional to the temperature (F/L, R 2 = 0.887; Cor, R 2 = 0.992). Only oils obtained at 45 °C were rejected because of ‘heated or burnt’ off-flavour. Decarboxymethylation of secoiridoids and further hydrolysis of phenolic esters occurred during storage. The oxidation products of derivatives of tyrosol and hydroxytyrosol were detected after nine months in both the F/L and Cor samples. Thus, VOO obtained at a processing temperature lower than 27 °C does not show higher chemical and sensory qualities than VOO obtained at 35 °C.