As children, olive oil was perhaps something we associated primarily with the cartoon character Popeye. But today, olive oil has become a staple ingredient in most of our kitchens. Much more healthful than most other oils, olive oil is high in monounsaturated fats and antioxidants, which has led to its increasing popularity in American diets.
But as a consumer, you may be overwhelmed when faced with the growing spectrum of types, brands, grades, and prices. Is there really much difference? Are the highest priced oils always the best? How do you choose the “right” kind?
Though all olive oil comes from the pressing and crushing of olives, the processes used determine the type of olive oil extracted.
Perfect storage conditions are essential for the protection of olive oil from its worst enemies--light, heat and air, which can cause irreparable damage to the chemical and sensory characteristics of even the finest extra virgin oil.
The oil in olives is contained in special cells mainly in the pulp and pit. In the first stage of processing, they are crushed to release the oil. During this phase, the oil and the water contained in the olives (50%) emulsify. The prolonged mixing of the paste, at a constant temperature, breaks down the emulsion and causes the minute drops of oil to combine into a large mass which will be more easily separated in subsequent phases. This operation is called kneading.
The oil extracted from the paste still contains emulsified water, fruit particles and mucilage in suspension. These substances compromise the quality of the oil inasmuch as they promote oxidation, hydrolysis and fermentation. They are removed by processes of clarification.
The olive paste contains a percentage of oil varying from 18% to 27%, which can be extracted with different methods. The yield, that is to say the quantity in weight of oil that can be extracted from 100 kg of olives, depends on the type of olives, on the amount of water received by the plant, on the fertilizing, on the harvesting system, and above all on the extraction technique.