Olives and olive products contain a diversified array of phenolic compounds with important biological properties and positive health effects on humans. An effort is necessary to minimize the loss of phenolic compounds in olives and their derived products. Various factors, from intrinsic to agronomic, affect phenolic compounds. Olive cultivars, together with geographical origin, are responsible for the typicality of olives, table olives, and olive oils. A most accurate optimum harvest period needs to be estimated according to the olive cultivar and the type of olive product to be produced to reduce the impact of ripening on olives' phenolic composition. Attention has to be paid to agricultural practices and cultivation systems. The introduction of irrigation systems in olive orchards considerably reduces phenolic compounds in olives and olive oil. Over fertilization of olive orchards must be avoided because it may contradict its initial intention-the improvement of olive production and oil yield-and may result in a reduction of phenolic compounds in olives and derived products. Therefore, it is imperative to assess the real needs of the olive tree and apply correct amounts of water and mineral nutrients without considerably influencing the amounts of phytochemicals present. Proper control programs, preferably biological control programs, need to be implemented in olive orchards to control olive pests and disease dissemination. All these factors, in an isolated way or in conjunction, greatly influence olives, table olives, and olive oil phenolic composition. Without a proper control of these factors, the availability of phenolic compounds in olive products will be reduced drastically, with serious adverse effects on in the quality, stability, sensory characteristics, and favorable health properties of the oil.
