Analytical comparison of monovarietal virgin olive oils obtained by both a continuous industrial plant and a low-scale mill

In this paper, two monovarietal extravirgin olive oils, obtained from Ghiacciolo and Nostrana di Brisighella cvv. olives, were produced by two different extraction plants, a low-scale mill equipped with a two-phase decanter and a continuous water-saving industrial plant. The olive ripening index, the fatty acid analysis by capillary gas chromatography, the spectrophotometric determinations of total phenols and o-diphenols, the phenolic profile by HPLC-DAD/MSD and the oxidative stability by OSI, together with the sensory analysis on the oil produced, were evaluated. Independently of the olive processing plant, the oils originating from two cultivars of olive fruit showed different fatty acid compositions (particularly the C18:1/C18:2 ratio), phenol compositions and oxidative stabilities. Concerning the extraction system, for both cultivars, the oxidative resistance and the content of phenols and o-diphenols were higher for the oils produced by the low-scale mill. The quantitative descriptive analysis sensory analysis was not able to discriminate the oil samples from both cultivars obtained from the two plants, even if it underlined a higher bitter attribute for the Ghiacciolo cv. oil when it was obtained from the low-scale mill. The data of the sensory analysis were correlated with simple phenol and the secoiridoid contents, both determined by HPLC-DAD-MSD.