Almonds, botanically a fruit, are the most widely produced and consumed tree nut in the world.  Almonds are a good source of protein in vegetarian and vegan diets and consumption is linked with numerous health benefits. Raw almonds produced in California are required by law (since 2007) to undergo pasteurization to reduce the potential for foodborne illness. Thermal moist air pasteurization (TMA) involves exposing almonds to hot moist air for a short time, followed by a cooling/drying step. Propylene oxide (PO) is a fumigant used on raw agricultural products for pasteurization. In almonds, the approved process involves exposing kernels to PO for 4 hours in a heated chamber (47-51 °C), followed by ventilation at 38-43 °C for 2 days or 15 °C for 5 days. Because almonds are 50-60 % lipid by weight, of which is 95 % are unsaturated fatty acids, they are susceptible to lipid oxidation during storage. During either pasteurization process, almonds are exposed to heat and/or moisture, which can influence the activity of enzymes related to fatty acid hydrolysis and lipid oxidation. Fumigation agents such as PO, also have the potential to deactivate enzyme through protein alkylation. This talk will describe the main sensory and chemical characteristics of raw almond flavor and discuss how varietal selection and pasteurization influence raw almond flavor and quality as it relates to consumer liking and acceptance. Main results indicate that pasteurization protects almonds by decreasing lipid oxidation during storage. Chemical measurements demonstrate lower amounts of free fatty acids and lower levels of headspace volatiles related to lipid oxidation in pasteurized almonds as compared to controls. Descriptive analysis indicates that PO and TMA pasteurized samples have significantly lower total oxidized flavor and painty/solvent flavor over storage relative to controls.

Influence of varietal selection and pasteurization on raw almond flavor, quality and consumer acceptance

ACS Spring Meeting 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.