Effect of maturity index on olive oil quality: effect of ripening on quality attributes of extra virgin olive oils from "Megaritiki" and "Chondrolia Chalkidiki" Greek cultivars

Abstract

Because of the well-documented health benefits associated solely with better grade products, interest and demand for high quality olive oils has recently increased. Nonetheless, several pre- and post-harvest elements are known to influence olive oil quality. The optimal harvesting period might vary significantly depending on a variety of conditions, therefore determining it demands a careful assessment of each situation. To our knowledge, there is little data on the impact of harvest time on the qualitative features of olive oil produced from Greek varieties. The purpose of this research is to assess the impact of five harvest periods on several quality characteristics of extra virgin olive oils derived from two significant cultivars of north Greece, namely ‘Chondrolia Chalkidiki' (X) and ‘Megaritiki' (M). All of the oils tested of different maturity indices (0.59-6.01 and 0.58-4.16 for M and X respectively), were classed as extra virgin since they had low acid (0.2-0.5 and 1.2-0.3% oleic acid for M and X, respectively), peroxide (4-7 meq O2/kg oil for M and X), and K values (K232: 1.42-1.54 and 1.31-1.44, as well as K270: 0.08-0.12 and 0.08-0.13 for M and X respectively). For these levels, there was no statistically significant trend due to the effect of ripening. Carotenoids (3.6-1.6 and 2.8-1.2mg lutein for M and X) and chlorophylls (4.2-1.3 and 4.4-1.0mg pheophytin-a for M and X) were found to be statistically significant to decrease as ripening progressed. After ripening, there was no discernible trend in chlorophyll and carotenoid levels (R2=0.82-0.94 percent for both cultivars). Total phenol (TP) content was rather low (86-209 and 78-168 mg/kg oil for M and X, respectively), which was mostly due to the excessive watering of trees and did not follow a specific pattern following ripening. M and X had Induction Periods (IP) of 13-26 and 16-27 hours, respectively. Only M's IP values had a moderate (R2~0.7%) association with maturity index and TP values.