Sensory analysis and volatile compounds of olive oil (cv. Cobrançosa) from different irrigation regimes

Abstract

The aim of this study was to assess the effect of different irrigation strategies on the sensory quality of virgin olive oil (VOO) from the cv. “cobrancosa” integrated into a protected denomination of origin of “Azeite de Tras-os-Montes” in the Northeast of Portugal. Three irrigation treatments were applied: (T2)-full irrigation, which received a seasonal water equivalent of 100% of the estimated crop evapotranspiration (ET c ), (T1)-continuous deficit irrigation (30% ET c ) and (T0)- rainfed treatment. Data were collected from two consecutive crop years (2005-2006). Olive oil samples were analyzed for volatiles by GC-MS and the results compared with sensory evaluation data. Total volatile compounds tended to decrease with the amount of water applied. The characteristics pungent and bitter were more pronounced in olive oils from T0 and T1, which had higher polyphenolic concentrations, with a strong positive relationship with this variable and the bitter attribute. The Principal Components Analysis clearly separates the three olive oils from 2005, the driest year, and aggregates into a single group the three samples from 2006, suggesting no effect of irrigation on volatile compounds in years with a rainy spring and a marked effect in years with severe drought, suggesting that the effect of the trees’ water status on these variables occurs throughout the crop season and not just during the oil accumulation phase. In general, olive oil from the cv. Cobrancosa is more bitter than pungent and has a typical nutty sensory attribute shown by a strong positive relationship between benzaldehyde and the sensory notes of almonds and nuts.