Effect of relative humidity on the quality and safety of peeled almond kernels (Prunus dulcis Mill.) during simulated maritime transport/storage.

Long-term transport and storage of peeled almonds under unsuitable conditions may cause the product's rejection. To get knowledge in this topic, peeled almonds were stored at 25°C and 60, 70, and 80% relative humidity (RH). The maintenance of high RH (80%) caused some visual defects after 4 months. Even though the 60, 70, and 80% RH did not clearly affect the production of primary and secondary products formed in the lipid oxidation during the 6 months of storage, sometimes an increase in the values of the specific extinction at the wavelength of 268 nm (K ) was observed at 80% RH, suggesting the occurrence to some extent of secondary oxidation. Concerning microbial counts, the almonds stored at 60 and 70% RH presented a satisfactory microbial quality until 6 months; however, at 80% RH, the mold counts were higher than the reference values after 2 months. Several mycotoxins were detected at low levels, including aflatoxins B1 and G1, although some showed higher amounts at 80% RH. In general, it is recommended that almond producers and industrials should consider the use of low RH (< 80%) for maritime transport and long-term storage of almond kernels. PRACTICAL APPLICATION: High levels of relative humidity during storage/transport of almond kernels favor fungal growth, mycotoxin production, and secondary oxidation (rancidity). It is recommended to keep the almond kernels under low RH (< 80%) in maritime transport and long storage, especially in tropical countries.