Soil Water Availability in Rainfed Cultivation Affects More than Cultivar Some Nutraceutical Components and the Sensory Profile of Virgin Olive Oil

Abstract

This research considered the varieties 'Frantoio' and 'Moraiolo' growing in rainfed olive trees (Olea europaea) and took place in Tuscany, central Italy. Soil moisture was monitored during the very meteorologically contrasting years 2002 and 2003 in two nearby olive groves. The plots had the same morphological and climatic conditions, but different soil types. Monocultivar oil samples were analyzed to determine fatty acids, minor polar compounds, and tocopherols content and were submitted to organoleptic analysis by a panel of trained tasters. The results highlighted that soil water regimen affects some nutraceutical components and the sensory evaluation of olive oil. Cultivar also affected yield components, polyphenols, and tocopherols content, but less than soil water availability. The plants on the soil inducing a relatively more intense and longer water deficit during summer (a Skeleti Calcaric Regosol) had an early ripening and gave the best results in terms of phenolic compounds and, consequently, antioxidant properties of the olive oil. The sensorial properties of the oil obtained from both cultivars on the Regosol were superior in both years of the trial.

Analytical Evaluation and Antioxidant Properties of Some Secondary Metabolites in Northern Italian Mono- and Multi-Varietal Extra Virgin Olive Oils (EVOOs) from Early and Late Harvested Olives

“…The main environmental factors that probably contribute to the reduction of these compounds are temperature, soil, and water [5]. In fact, rain produces an increase of water content in the drupes.…”

“…The nutritional quality and the health benefits of EVOO are attributed both to its balanced fatty acid composition (high content of oleic acid and optimal ratio between ω-3 and ω-6 fatty acids) and to a significant amount of minor components with antioxidant properties in the unsaponifiable fraction, such as tocopherols and phenolic compounds [4,5]. These latter compounds have been shown, in vivo and in vitro, to possess antimicrobial, antioxidant, anti-allergic, anti-inflammatory, anti-carcinogenic, and antiviral properties [2].…”

“…They are also important to confer aromatic flavor notes [6] and, in comparison with other vegetable oils, to maintain a significant stability in terms of resistance against self-oxidation and thermal oxidation processes [7]. Tocopherols are present in olive oil in the forms α, β, γ, and δ, with 90% being found in the most biologically active α form, vitamin E [5]. Experimental evidence has demonstrated that the phenolic compounds present in EVOO possess numerous biological properties and are, at least partly, responsible for the beneficial effects arising from the consumption of EVOO [8,9,10].…”

“…For example, following foliar fertilization no effects were found on either general physico-chemical characteristics or fatty acid composition but a significant decrease in both polyphenol and o -diphenol contents was detected [16]. There is a wealth of studies on the influence of irrigation, cultivar, and soil properties on the nutraceutical components and organoleptic properties of EVOO, particularly as regards tocopherols, phenolic fraction, oleic and linoleic acid contents, stability, and sensorial characteristics [5,17]. Olives reach their full size in the fall but may not fully ripen from green to black until late winter.…”

Pigments in Extra-Virgin Olive Oils Produced in Tuscany (Italy) in Different Years

“…The scientific interest in these cultivars is demonstrated by numerous studies, mainly dealing with the phenolic profiles and antioxidant properties [17,30,31], as well as sensorial and organoleptic features [32,33,34] of Tuscan EVOOs. Several works have investigated the effect of the ripening period and climate conditions [31,35], olive processing and extraction methods [36], and the effect of different storage conditions [34] on extra-virgin and virgin olive oils produced by these three Tuscan cultivars. So far, no works have been reported concerning the pigment content in extra virgin olive oils produced in Tuscany from the main cultivars Frantoio , Moraiolo , and Leccino .…”