Influence of olive fruit colour characteristics on virgin olive oil colour and pigments
The skin and pulp colour of olive (Olea europaea subsp. europaea) fruit is the most widespread and usual parameter for making a decision on harvest time. During the ripening process, the fruit skin changes its colour from green to purple and black. Colour is not a parameter for virgin olive oil evaluation by official standards; however, consumers' decision to buy is still predominately based on olive oil colour. In this study, colour parameters of olive fruit and virgin olive oil from cultivar 'Picholine' cultivated in an orchard situated in Istria (Croatia) were analysed. Fruit colour was measured after classification into four groups (green, spotted, purple and black) by using a benchtop colorimeter. After processing in a laboratory olive mill, pigments and colour characteristics of virgin olive oil were analysed spectrophotometrically. A significant decrease with maturity was found in lightness and intensity of yellow colour of olive fruits. The colour index decreased significantly from green to purple fruits, but the difference between purple and black fruits was not significant. The lightness and green colour intensity increased while Chroma value and intensity of yellow colour decreased in virgin olive oils obtained from green to black olive fruits. During ripening, chlorophylls decreased from 11.65 mg kg-1 (green) to 3.35 mg kg-1 (black) and carotenoids decreased from 6.16 mg kg-1 (green) to 2.07 mg kg-1 (black) in corresponding virgin olive oils. Virgin olive oils with different characteristics can be produced in the same harvest period with separation of olive fruits depending on their colour.
Krapac, M., Brkić Bubola, K., Fruk, G., Gunjača, J., Sladonja, B. and Benčić, Đ. (2018). Influence of olive fruit colour characteristics on virgin olive oil colour and pigments. Acta Hortic. 1199, 477-482
colorimetry, harvest period, virgin olive oil, chlorophylls, carotenoids