Sensory characterisation and oxidative stability of walnut oil

Abstract

SummaryThis study was carried out in order to probe the extent of oxidative and flavour stability of walnut oil (WO) under conditions normally used for selling in retail markets, during a period of four months. Fresh WO was characterised by higher intensity ratings of nutty and oily film, and lesser ratings for pungent and astringent attributes. Low and similar values for sweetness and bitterness were also detected. The ratings for negative attributes (oxidised and painty) were close to zero. During the long‐term storage period, the extent of the oil oxidative degradation was more pronounced than flavour attributes deterioration. Peroxide values (PV), conjugated dienes and trienes increased significantly throughout the storage period, whereas tocopherol content and oxidative stability index showed significant reductions. Minor changes were observed in the overall flavour stability. Using a PV of 10 mequiv. O2 kg−1 oil as a quality criterion, WO stored in transparent glass bottles, exposed to fluorescent light (1100 Lux) and room temperature conditions, without addition of any antioxidant, could maintain an acceptable quality until two months of storage.