The Effects of Different Irrigation Treatments on Olive Oil Quality and Composition: A Comparative Study between Treated and Olive Mill Wastewater

Abstract

In the present paper, two irrigation treatments were applied to olive trees cv. Chemlali: irrigation with treated wastewater (TWW) and with olive mill wastewater (OMW), which was spread at three levels (50, 100, and 200 m(3)/ha). This work is interested in two topics: (1) the influence of different irrigation treatments on olive oil composition and quality and (2) the comparison between OMW and TWW application using different statistical analyses. The obtained variance analysis (ANOVA) has confirmed that there are no significant differences in oil quality indices and flavonoids between the control and treatments amended by OMW or TWW (p > 0.05). However, the irrigation affected some aspects of olive oil composition such as the reduction in palmitic acid (16.32%) and increase in linoleic acid (19.55%). Furthermore, the total phenols and α-tocopherol contents increased significantly following OMW and TWW treatments. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) defined three irrigation groups: OMW 50 and 100 m(3)/ha, OMW 200 m(3)/ha and control, and TWW treatment. The full factorial design revealed that OMW amendment by 100 m(3)/ha is the best irrigation treatment. Thus, the optimal performances in terms of olive oil quality and composition were shown by olive oil extracted from olives grown under irrigation with 100 m(3)/ha of OMW.

Irrigation‐induced salinity affects olive oil quality and health‐promoting properties

“…Differences in response were explained by different pedoclimatic conditions in the production area, as well as by agronomic parameters (irrigation, plantation density, fruit maturity, etc.) . Information regarding the effects on polyphenols is relevant in respect to food quality because, as mentioned, polyphenol levels directly affect health‐promoting effects of the oil, as well as its sensory quality.…”

“…17,19,20 Chlorophyll levels of oil consistently declined when irrigation water EC values increased 15,16 while carotenoid levels were not consistently affected by salinity, and were alternatively found to either rise, 16 decline, 15 or not change. 17 Oil stability, measured as induction time, was reported either to increase 16 or decrease, 15 and correlated well with polyphenol contents. 14,15 Nevertheless, as explained, exposure to salinity occurs in the root zone and irrigation salinity level is insufficient to define/describe related effects.…”

“…14,15 These changes, however, differed greatly among the studies, to an extent where no general statement can be made concerning characteristic tendencies. With respect to nutritional and health-related quality, levels of tocopherols (vitamin E isomers) 16,17 and phytosterols 18 were reported to increase significantly with increased salinity but to then decrease with very high salinity, whereas total polyphenol concentrations were reported to rise with increasing water salinity, and continued to increase even for high EC values. 17,19,20 Chlorophyll levels of oil consistently declined when irrigation water EC values increased 15,16 while carotenoid levels were not consistently affected by salinity, and were alternatively found to either rise, 16 decline, 15 or not change.…”

Protective Effects of α-Tocopherol, γ-Tocopherol and Oleic Acid, Three Compounds of Olive Oils, and No Effect of Trolox, on 7-Ketocholesterol-Induced Mitochondrial and Peroxisomal Dysfunction in Microglial BV-2 Cells

“…The performances of olive oils in terms of quality and composition depend on numerous parameters: genetic and environmental factors, especially climate and altitude but also the oil extraction process, soil type (arid or semi-arid, and irrigation), the temperature, rain, drought, fruit maturity and the harvest year [53,54,55,56]. It is thus important to determine the composition of extra virgin olive oils (EVOO) used as the reference in the present study and to establish whether particular compounds of these oils have cytoprotective effects on relevant in vitro models [57].…”

Effects of reclaimed wastewater irrigation and fertigation level on olive oil composition and quality

“…Although olive is well adapted to the Mediterranean semi‐arid conditions, irrigation leads to a substantial increase in fruit and oil yields . Severe scarcity of freshwater in traditional olive growing regions has led to the use of alternative water sources, including saline groundwater and reclaimed wastewater (RWW) for irrigation . RWW are domestic liquid wastes treated by screening, oxidation, sedimentation and biological digestion; and typically contain high amounts of organic matter, nitrogen (N) and minerals such phosphorus (P) and potassium (K) .…”