I fattori di variabilità genetici, ambientali e colturali della composizione dell'olio d'oliva

The compositon of olive oil results from a multivariate interaction in which genotype, environment, and agronomic-dependent factors are involved. The genotype controls genetic traits accounting for the rate pattern of fruit growth, oil accumulation in mesocarp cells and fruit ripening, while the genotype x environment interaction changes the rate of fruit growth, oil accumulation and fruit ripening pattern. The latter accounts for large changes in oil composition and sensorial features. The influence of genotype is linked to differences in the fruit growth and ripening patterns, though all those factors that may have an influence on fruit size, flesh/pit ratio and relative growth rate have a lower and more erratic influence on the olive oil composition. The genotype is the principal source of sensorial differences and this has been proved for most of the cultivars, giving them a specific role in gastronomy. The influence on olive oil composition of environmental factors, such as temperatures during fruit growth and ripening or water availability, may also be a function of changes in the fruit growth and ripening patterns and of the oil accumulation rate pattern. Some facts have been generally recognized, such as the changes of saturated vs insaturated fatty acids ratio in relation to temperature and latitude or the progressive reduction of polyphenols content in the oil along with fruit ripening or with the increase of water availability. Crop load influences the fruit ripening rate pattern and the rate pattern of oil accumulation and this may account for differences in oil composition, related to polyphenols and fatty acid content. This review covers different sources of variability of olive oil composition and overall quality, such as genotype, environment, bearing capacity, stage of fruit ripening during harvest and cultural management (irrigation, fertilization, harvest). None of these aspects can be underestimated in order to reduce the site- and year-dependent fluctuactions of olive oil quality of specific genotype.