Evaluation of minor components, sensory characteristics and quality of virgin olive oil by near infrared (NIR) spectroscopy

Abstract

Chemometric analyses of NIR spectral data (12,500–4000cm−1) combined with analytical and sensory parameters measured in monovarietal Cornicabra virgin olive oils (VOOs) (n=97) produced in the PDO (Protected Denomination of Origin) “Montes de Toledo” geographic area were used to generate calibration and validation models in order to be able to predict the minor composition of VOO, in particular its phenolic and volatile compounds as well as its organoleptic attributes, and thereby the global quality of the product. Acceptable multivariate algorithms were obtained for VOOs' degree of unsaturation (fatty acid profile) (r=0.84–0.96), several minor components – in particular hydroxytyrosol derivatives (r=0.86–0.88) and C6 alcohols (r=0.69–0.80) – as well as for positive sensory attributes — ‘fruity’ (r=0.87) and ‘bitter’ (r=0.85). The results establish that near infrared is a very useful technique that allows rapid screening of VOO samples to estimate their minor composition and sensory characteristics, and thereby their quality and commercial grade. Furthermore, it may give real time information about olive oil composition during processing in order to automatically control technological parameters.