Abstract

Concealed Damage (CD), as defined by the almond industry, is a brown discoloration of the kernel interior which is only detectable after the nuts are roasted. High moisture in raw almonds is the key factor in the development of CD; which is related to hydrolytic lipid oxidation. Typically when almonds have a moisture content >6% the processor will dry the almonds to this moisture level. To date, little is know between the relationship between drying almonds, the incidence of CD and shelf-life of almonds. To address this, we evaluated drying temperatures between 45°C – 95°C on the the incidence of CD. Almonds were exposed to conditions that promote CD formation and dried. Dried samples were analyzed for volatiles (HS-SPME-GC/MS), reducing sugars, and Amadori compounds. Drying temperatures below 65°C decreases CD up to 40% while drying temperatures above 75°C increases CD up to 100%. No significant differences were found for reducing sugar, protein and Amadori compounds. Volatile compounds were related with lipid oxidation (alcohols, aldehydes and ketones) which increased by increasing the drying temperature. Above 85°C volatile corresponding to Maillard reaction were found (pyrrole, phenylacetaldehyde). Our results suggest that raw almonds that have been exposed to moisture damage and dried at temperatures below 65°C to reduce the level of CD, may present quality defect due to endogenous lipid oxidation by-products.