[Show abstract][Hide abstract] ABSTRACT: The influence of macronutrient status on olive oil properties was studied for three years. Data were analyzed by a multivariate model considering N, P, K, and fruiting year as explanatory factors. Oil quality parameters were primarily associated with N concentration in leaves and fruits which increased with N in irrigation solution. The effect of P on oil quality was mainly indirect since increased P availability increased N accumulation. The potassium level had negligible effects. The oil phenolic content decreased linearly as a function of increased leaf N, indicating protein-phenol competition in leaves. The overall saturation level of the fatty acids decreased with fruit N, resulting in increased polyunsaturated fatty acids. Free fatty acids increased with increased levels of fruit N. High fruit load tended to reduce fruit N and subsequently improve oil quality. The effect of N on oil properties depended solely on its concentration in leaves or fruits, regardless of the cause.
Journal of Agricultural and Food Chemistry 11/2013; · 3.11 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Five rates of water application were applied in a 4 year study on olive (Olea europaea) varieties 'Barnea' and 'Souri'. Increased irrigation lead to increased tree-scale oil yields, lower polyphenol content, and, frequently, higher oil acidity. These effects were predominant in "off" years. The fatty acid profile was influenced primarily by bearing level and variety and secondarily by irrigation rate. The saturated to unsaturated fatty acid ratio was higher in "off" than in "on" years, and the monounsaturated fatty acid to polyunsaturated fatty acid ratio was higher in "on" years as a result of the fact that oleic and stearic acids were higher in "on" years, while palmitic, palmitoleic, and linoleic acids were greater in "off" years. Squalene was higher in 'Souri' than in 'Barnea' oils, was not affected by bearing cycle, and was consistently lower in oil from trees receiving the lowest irrigation level.
Journal of Agricultural and Food Chemistry 09/2011; 59(21):11667-75. · 3.11 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Irrigators of modernized olive orchards are challenged to determine regional
and cultivar specific water regimes that increase yield while not jeopardizing olive oil
quality. We have investigated olive irrigation regimes, including severe deficit
strategies, on two Israeli cultivars (‘Souri’ and ‘Barnea’) in a two year field experiment.
Trees received 25, 50, 75, 100 or 125% of potential evapotranspiration throughout
the dry seasons. Increasing irrigation increased stem water potential, vegetative
growth, and olive fruit yield with the increases tapering off at application rates above
the 75-100% treatments. Increases in oil yield as a function of increased irrigation
were measured only after the second year of treatments, and only for the cultivar
‘Barnea’ that had been in an ‘off’ year during the first season in which the treatments
lead to higher vegetative growth. Increasing irrigation lead to fruits with greater water
content (lower oil percentage) as well as to relative decreases in total polyphenol
content and to increased free fatty acids in the ‘off’ years.
These preliminary results suggest a number of methods that could be beneficial
to irrigation management including cultivar specific irrigation regimes and irrigation
systems. Stress levels and water requirements are highly dependent on fruit load and
best irrigation management should account for biennial bearing effects. Of specific
interest is that oil quality of trees in ‘off’ years is particularly negatively affected by
excess water. More work is necessary in order to determine optimum water stress
scheduling (stress levels and timing) for best yield-quality combinations and to further
develop methods for monitoring and maintaining water stress levels.
[Show abstract][Hide abstract] ABSTRACT: Studying the composition of olive oil requires cold-press olive oil extraction. One of the most common laboratorial mills is the Abencor system. However, its operation protocol was formulated decades ago for Spanish olive varieties from traditionally rain-fed orchards. We modified this protocol for use with “Barnea” and “Picual” olives from irrigated orchards that are characterized by high water content. Independent effects of malaxation time, temperature, water addition and talc addition on extraction efficiency, and major quality indices of virgin olive oil were studied. Overall, addition of talc to the fruit paste was the most significant treatment in terms of yield and quality of the oil although its effect was cultivar dependent. Improved oil yield was particularly significant for “Picual.” Extended malaxation time was also effective in improving oil extractability. Addition of talc generally improved oil-quality parameters, while water addition had the opposite effect. Yet, quality parameters remained within the extra virgin level. Temperature increments reduced oil quality. The need to adapt a modified protocol for use with fruits from irrigated orchards that will facilitate critical comparison of results obtained from different agronomic theses and different laboratories is highlighted. It is recommended that each laboratory develops an appropriate protocol for the operation of the Abencor system in accordance to the characteristics of the olive fruit they are working with.Practical applications: Abencor system serves as the major laboratorial mill world-wide. Those mills allow the researchers to characterize olive oil in accordance to the treatments received by the trees. This cannot be done in commercial mills. The system operation protocol was established decades ago for fruits from rain-fed orchards. In the past decade there was a rapid increase in the use of irrigation in olive orchards and therefore it is crucial to optimize the operation protocol for fruit with relatively high water content. In the current work we have evaluated the influence of a series of technological parameters (i.e., talc and water addition, malaxation time, and temperature) on the extraction efficiency and quality indices of olive oil. This allowed us to present a modified protocol for the Abencor system operation suitable for olive fruit of irrigated orchards that will facilitate a reliable representation of the influence of different treatments on the yield and characteristics of the olive oil.
European Journal of Lipid Science and Technology 08/2010; 112(10):1158 - 1165. · 2.27 Impact Factor