Changes in volatile compounds and sensory quality during toasting of Spanish almonds

Toasting is one of the most important unit operations in turrón manufacture. The main objective was to study changes in volatile compounds and sensory odour and aroma during almond toasting. Two almond cultivars were studied 'Comuna' and 'Marcona'. CIEL*a*b* colour, instrumental aroma and sensory odour and flavour were evaluated in toasted almonds (200 °C: the most popular temperature for almond toasting in convection ovens) at five times from 12 to 23 min. The main pyrazines found were: 2,5-dimethylpyrazine, 2-ethyl-3-methylpyrazine, 2-methylpyrazine and 2,4-dimethyl-3-ethylpyrazine. Pyrazines, furans and pyrroles concentrations in 'Comuna' almonds were higher than in 'Marcona' samples at the end of toasting; however, sensory analysis showed that 23 min were too long for 'Comuna' almonds (burnt notes) and shorter toasting time must be applied. Based on both instrumental and sensory colour and aroma data, the recommended toasting time at 200 °C in convection ovens for 'Comuna' and 'Marcona' almonds should be 20 min.