Scientific Study

Background: Sweet almonds (Prunus dulcis) harvest weights have significantly increased to meet consumer demand and now exceed processing facility capabilities. Crops are stockpiled for longer periods of time increasing the probability of moisture exposure. Wet almonds can be mechanically dried prior to processing; however, it is unclear how this practice influences lipid oxidation, shelf-life and consumer acceptance. To address this, almonds were exposed to 8% moisture and dried with low heat (ME). Almonds were roasted and stored under accelerated conditions for 12 months and markers of lipid oxidation, headspace volatiles, sensory attributes, and consumer liking were evaluated. Results: At 7 months of storage, light roast ME almonds had higher levels of volatiles related to lipid oxidation as compared to non-moisture exposed almonds (NME) and were significantly higher in oxidized, cardboard and painty/solvent flavors. Although untrained consumers did not show significant preferences between the light roast ME and NME almonds, there were quality losses related to lipid oxidation that trained panelists could detect. Dark roast ME almonds demonstrated significant lipid oxidation by 5 months of storage and indicating they will have a compromised shelf-life. Findings also indicate that octanal, nonanal, 2-octenal, and hexanoic acid are good indicators of consumer acceptability. Conclusion: Results of this research illustrate that post-harvest moisture exposure with mechanical drying has a significant effect on the storage quality of roasted almonds and is most pronounced in dark roast product.