Effect of Pasteurization on Raw Almond (<i>Prunus dulcis</i>) Oxidation during Storage

Abstract

The majority of commercial almonds grown in California undergo pasteurization using a validated process such as moist heat exposure (MH) or fumigation with propylene oxide (PO) to reduce the potential of Salmonella bacteria contamination. Although these treatments are common, their effect on raw almond storage quality is not well understood. To address this, almonds were either pasteurized with MH and PO or left unpasteurized (control) and stored for 12 months under accelerated shelf life conditions. Lipid oxidation markers, headspace volatiles, and descriptive analysis were evaluated monthly. Significant differences were observed between treatments, with control samples expressing significantly higher levels of alcohols and organic acids and up to 3 times higher overall headspace volatile concentrations. At 8 months of storage, panelists distinguished the MH sample from the control sample with lower scores in rancidity-related attributes. MH > PO pasteurization decreases the rate of lipid oxidation during storage compared with controls, thereby increasing shelf life.