Effects of storage temperature and duration on quality of unshelled and shelled almonds

Almonds (Prunus dulcis Mill.) kernels stored in uncontrolled environmental conditions can show drastic quality loss. The aim of this work was to evaluate how removing the shell and storage at different temperatures may affect almonds quality. For 2 following years, dried almonds ('Marta') were stored: I) unshelled at 20°C; II) unshelled at 0°C; III) shelled at 20°C; IV) shelled at 0°C. Initially and after 2, 5 and 9 months of storage the following analyses were carried out: rupture force, color, sensorial evaluation (on the kernels), acidity and tocopherols content (on the oil), sugar content, antioxidant activity and total phenols (on the defatted powder). In both years, the presence of shell reduced the variation in some color parameters, while the effect of temperature was less evident. No differences were observed in rupture force, sensorial attributes, antioxidant activity and sucrose content according to the storage temperature and the presence of shell. Phenols content was affected by storage modality; in 2007, a lower decrease in unshelled almonds than in shelled ones was observed, while in 2008 almonds stored in shell at 0°C showed a delay in phenols loss during storage, with no effect of storage temperature. Tocopherols content did not show evident variation, while acidity increased during storage, regardless storage temperature and the presence of shell.