## 3 Results and Discussion
### Evolution of Color Parameters  
Figure 2 shows the evolution of the chromatic coordinates L, a, and b of oils from fresh and frozen olives. The color of the virgin olive oil samples was determined by chromatic coordinates of CIELAB colorimetric system. In the early ripening stage (May), the oils from fresh and frozen Arbequina olives showed high values of L* Luminosity at 89.10 and 87.65, respectively, negative values of a* at \(-13.43\) and \(-13.76\), respectively, representing medium greenish colors, and positive values of b* of 64.40 and 74.30, respectively, representing yellow colors. These values characterize the Arbequina variety, generally known for its \"golden yellow\" color, being of a less intense color than other varieties such as Picual, which displays more intense greenish shades [47], due to a lower chlorophyll content compared with other VOO varieties, and other pigments being predominant, such as pheophytins and carotenoids (lutein, \(\beta\)-carotene, violaxanthin, neoxanthin, xanthophylls), which give the yellow color to the oil.  
An increase of the lightness parameter (L*) with harvesting time was observed for both types of oils, showing significant differences only at the early ripening stage. The L* values for frozen olive oils were slightly higher in June, August, and September, but were not significant. The chromatic coordinate a* varied between \(-13.43\) and \(-5.71\) and \(-13.76\) and \(-7.78\) for fresh and frozen olive oils, respectively, moving to less green tone, presenting significant differences in the month of September at the advanced ripening stage. The chromatic coordinate b varied between 64.40 and 21.87 and 74.30 and 27.52 for fresh and frozen olive oils, respectively, decreasing the yellow tonality, and showing significant differences between early and advanced ripening stages (\(p<0.05\)). Studies have shown that, with the ripening of the fruit, as the harvest months progress, the color of the olive fruit changes from deep green to yellow-green, and then to purple and black, due to the progressive decrease of chlorophyll and carotenoid pigments, which are responsible for the green color of the fruit [47], as the chlorophyll fraction the one that disappears faster than the carotenoid fraction [48]. This gives way to the synthesis of anthocyanin compounds, which appear first as small reddish spots on the skin until it becomes black at full maturation. Only chlorophylls and carotenoids, which are fat-soluble, are transferred to the virgin olive oil [47], giving its characteristic color, which will vary depending on the month of harvest. [PERSON] et al. [25] observed slight differences in the carotenoid and chlorophyll contents, reflected in higher luminosity values (L*) in oils from olives damaged by frost; however, chromatic ordinates a* and b* were not affected by the low temperatures.  
The \(\Delta\)E values for oils from fresh and frozen olives were 43.26 \(\pm\) 4.00 and 47.36 \(\pm\) 1.29, respectively, which points out a greater loss of color in oils from olives damaged by frost. The loss of the characteristic yellowish-green hue of EVOO would be due to the loss of carotenoid and chlorophyll pigments, probably due to the action of chlorophyllase and lipoxygenase enzymes favored by the deterioration of the olive fruit [25].  
Figure 2: Color expressed as chromatic ordinates (**a**) L*, (**b**) a* and (**c**) b*, in VOO from fresh and frozen olives harvested between May and September. (**d**) Three-dimensional colour space CIELab.