S17 - Session O4 - Maintaining Almond Quality for a Warmer World.

Authors: Alyson Mitchell *, Kathleen Luo, Guangwei Huang

Almonds are an excellent alternative to animal protein, dairy and wheat flours and consumption is linked to positive impacts on serum lipids, heart health, and weight management. California is the world leader in almond production; producing 1.4 billion kilograms in 2020 and providing 78% of the world's almond supply. The almond crop is increasingly impacted by extreme and less predictable weather patterns in response to climate change. California is experiencing more extreme seasonal drought (summer) and heavy rain events (fall/winter), and is predicted to have larger storm events during the next century. Almond production continues to increase fueled by consumer demand, on-farm improvements (e.g. micro-irrigation and remote sensing) and through valorization of co-products. However, production now exceeds processing capabilities, and almonds are frequently left on the orchard floor and/or in stockpiles for longer periods, where they are more susceptible to severe rain events and potential Salmonella contamination. Elevated moisture content of in-hull almonds promotes kernel damage during processing (removal of hulls and shells) and increases the risk of lipid oxidation and rancidity development in kernels during storage; leading to food waste. When almonds are exposed to the elevated moisture, they need to be dried before processing and kernel storage. However, heat can promote lipid oxidation. To reduce the potential of Salmonella contamination, almonds grown in California are pasteurized prior to sale within North America using a validated process such as moist heat exposure (MH) or fumigation with propylene oxide (PO). Although these treatments are becoming more common, their effect on raw almond quality is not well understood. Herein we discuss how in-field moisture exposure and post-harvest drying, and PO and MH pasteurization influence almond quality in relationship to lipid oxidation which is the key determinant of shelf life and consumer acceptance. A multiplatform approach was used to monitor multiple markers of lipid oxidation (i.e. peroxide values, free fatty acids, conjugated dienes), and headspace volatiles (SPME-HS-GC/MS) and these data were correlated with consumer hedonic and descriptive analysis. Additionally, we will discuss levels of the cyanogenic glycoside amygdalin in major California sweet almond varieties from five crop seasons (2012-2020). Hydrolysis of amygdalin by endogenous b-glucosidases results in the release of benzaldehyde (amaretto-like aroma) and hydrogen cyanide (HCN). Our data indicate that amygdalin levels differ with varieties, with averages ranging from 1n135 ppm. The highest levels are found in Aldrich and Fritz. Measured and estimated HCN levels correlate with amygdalin levels, with varietal averages ranging from 0.8n6.0 ppm. The highest detected HCN level was 10.8 ppm, while the highest estimated HCN level based on the amygdalin content is about 12.9 ppm. The highest level, either detected or estimated, is well below the proposed EU Food Safety Authority limit of 35 ppm. The trace amount of amygdalin in sweet almonds release a sufficient sensation of benzaldehyde flavor when consumed without any concern of overexposure to HCN. Monitoring almond chemistry in response to changing environmental factors and post-harvest processing is essential for sustainability of this popular food.