To understand how to cultivate the olive tree well and how to produce oil, it is necessary to know how fats are formed inside the olives. This process, which is characteristic of the olive tree, is influenced by the variety, environmental and seasonal conditions and, indirectly, by fertilization and pruning.
Indicatively towards the end of July, after having passed the hardening phase of the stone, the olive begins to create its own fats. For the first 5 weeks the accumulation is slow, while towards the end of August the training process becomes faster and tends to end 5 or 6 weeks later, around mid-October. Subsequently it remains stable or may undergo a slight reduction before the fall of the olive, if it is not harvested.
La fat formation occurs through a series of reactions in sequence and connected to each other. They contribute to favoring these reactions specific enzymes and, this, represents a natural process, which is called "metabolic path", where at each stage there is a chemical modification of the starting product, which ends with the final formation of fat or triglyceride. The process of formation of fats or lipids is called “lipogenesis” and the period in which it occurs "inolition".
The fats that are formed mainly remain inside the cells of the olive pulp, only 1 or 2% is placed in the seed.
The steps of fatty acid synthesis can be summarized in the following steps:
1) the lipogenesis start by using sugars – the glucose, present in the pulp – through the action of two enzymes, they are transformed into simpler molecules, a reaction called “glycolysis”;
2) from this reaction is generated an enzyme named Acetyl Coenzyme A, which performs several functions: specifically it is the key element of the fat formation process;
3) theAcetyl Coenzyme A in turn is transformed into Malonyl Coenzyme A and a chain of carbon molecules begins to be created, which will make up the fats;
4) at this point they intervene as helpers in the reactions acyl transporter proteins and those of the enzyme complex Fatty Acid Synthetase: both have the task of consolidate carbon bonds until you get thepalmitic acid, a saturated fat with sixteen carbon atoms;
5) once palmitic acid has been produced, this is subject, by the action of enzymes, to lengthening and modifications, joining further carbon bonds, until all the fatty acids present in the olive and in the oil.
At the end we will find present: mainly theoleic acid, 60-80% palmitic acid, 10-15% linoleic acid, 5-10% stearic acid, 2-3%. It's not over! Because now, having formed the fatty acids, it is necessary to come to the creation of triglyceridesthe. This process takes place through theunion of fatty acids with glycerol, an alcohol which is also synthesized in the plant cell of the pulp. Glycerol combines with fatty acids to form oil droplets, union or condensation that is called “esterification”.
As we have seen, the formation of fats is complex, at the base of everything there is an enzymatic activity, which is influenced by the varietal genetics of the olive tree, which acts on the percentage quantity of fatty acids present in the oil, such as oleic, linoleic and linolenic acids.
The production factors that affect these processes are the fertilization, where the lack or excess of some nutritional elements could lead to vegetative imbalances in the plant and, consequently, to alterations to the metabolism. Then enter the game light, which favors the photosynthetic activity necessary to supply the energy for the synthesis of fats, but it is also an important cofactor for obtaining a rapid formation of fatty acids; in this, pruning has so much to express, because, placing the fruiting branches at better exposures, it seems to accelerate the formation of fats. Finally there are le phenological stages of development and, among these, maturation is the one that has the greatest effects on the quantitative aspects of oil production.
It is known, in fact, that as the olive ripens, the concentration of lipids increases and the sugars decrease, therefore an early harvest or a ripening stress could limit the synthesis of the oil, penalizing its yield.
AIPO Director
Interregional Association
Olive producers
