Conclusion
As processing of Natural green olives does not include any alkaline treatment, the main difference found in the chloroplastic pigment composition, regarding Spanish-style table olives, was the absence of chlorophyll derivatives with a chlorin or rhodin-type structure. However, this result could not explain the different colour shown by olives processed by one or another style since all the chlorophyll pigments formed were Mg-free derivatives (mostly pheophytins in both cases), which have similar colourations, ranging from grey to green brownish. The results of the present study indicate that the browning observed in Natural green olives was mainly due to compounds of a polyphenolic nature, resulting from an enzymatic oxidation by the PPO of the o-diphenolic compounds present in the fresh fruits. In the case of Spanish-style table olives, the colour was due to chloroplastic pigments because the PPO enzyme was probably inactivated by the initial alkaline treatment of the process which prevented the oxidation of the o-diphenolic compounds in the fruits.