OLIVE FRUIT GROWTH AND METABOLISM

One month since fruit set, after an intense cell division, the exocarp, mesocarp and endocarp can be identified. While the endocarp cells stop the division and become stony, the mesocarp cells slow the division and start to produce oil 45 days after full bloom (AFB). The oil accumulation is very intense during two months between 60 and 120 days AFB. The fruit respiration is intense during cell division, moderate during oil synthesis and reduced during last period of maturation, when a climacteric rise seems to occur only on fruits attached to the tree. The fruit photosynthesis is connected to chlorophyll content and it is high until the blackening of fruits. Fruit starch and soluble sugar contents decrease during maturation. The young fruits have high proportions of polar lipids in relation to neutral lipids that predominate at maturity, largely as triglycerides of oleic acid, but with significative amounts of 16:0, 18:0 and 18:2 fatty acids. During fruit ripening the fatty acid synthesis shows specific evolutive patterns. Dry matter acquisition is continuous and constant during fruit growth, while seed, stone, pulp and oil show specific intense periods of growth, when they can be influenced by change of source-sink ratio. Because of economical importance of oil a probable pathway for the biosynthesis of fatty acids and triglycerides as well as the translocation of feeding compounds from leaves are discussed. In the last period of ripening the fruits acquire specialized flavour compounds that are transferred to oil during the extraction or contribute to characterize the pickled olives. The texture changes and the activities of cellulolytic and pectinolytic enzymes are evaluated in different way according to fruit utilization. The olive fruit ripening is a combination of physiological and biochemical pathways that can be influenced by climatic and cultural conditions even if most of the events are under strict genetic control.