Acrylamide and hydroxymethylfurfural formation in roasted almonds (Prunus dulcis)

Almonds (Prunus dulcis) are commonly roasted to enhance their flavour, aroma, colour, and texture. However, the roasting process can also lead to the formation of chemical process contaminants. This study investigated the roasting of both whole and ground almonds using combinations of temperatures (120-195 °C) and times (10–30 min). A thermal load index was applied to evaluate the roasting intensity, categorising the roasts as light, medium, and dark. Samples were evaluated for weight loss, colour, glucose, fructose, sucrose, free asparagine, hydroxymethylfurfural (HMF), and acrylamide. The formation of HMF and acrylamide become remarkable at the boundaries of the medium roasting conditions, with acrylamide reaching a maximum of 480 μg/kg. Notably, the influence of the almond integrity was only observed in the dark roast category, where ground almonds exhibited higher levels of acrylamide and HMF. In contrast, the changes in colour, free asparagine, and sucrose content were similar for both whole and ground almonds. Among commercially available roasted almonds in Spain (n = 32), the mean acrylamide and HMF content was 149 ± 39 μg/kg and 5.4 ± 0.8 mg/kg, respectively. Considering that acrylamide levels are regulated in various food products, a reference value of 470 μg/kg is proposed to guide industry efforts in its control and mitigation.