Effects of Summer Water Deficit Stress on Olive Fruits and Oil Quality

The Mediterranean basin is the leading worldwide region for olive production. Extreme weather is increasingly frequent in this region, and how these climate extremes will affect olive products and quality remains unknown. We aim to study the effects of the water deficit stress, which occurred in the summer of 2017, on olive fruit and oil quality from a 30-year-old orchard. Fruits from olive trees standing on (i) one hydrated and (ii) one dry area of an orchard at the north of Portugal were harvested. Fruits’ water content, oil yield and quality, fruit carbohydrates, and fruit and oil phenolic metabolite profiles were analyzed. Fruits from the dry area presented low water availability and increased carbohydrates, oleuropein, oleoside, and elenolic acid glucoside abundance. Oil yield was lower in the dry area, but the abundance of oleacein increased, together with traits of some sensory sensations. Climate stress events can reduce oil yield but stimulate the accumulation of bioactive compounds that improve oil quality and nutritional value.