Effect of industrial processing on the volatiles, enzymes and lipids of wholegrain and rolled oats

Abstract

The aim of this research was to study the effect of industrial processing stages (kilning, cutting, steaming, rolling and packaging) on the enzymes (lipase and peroxidase), lipids and volatiles of wholegrain and rolled oats. Chemometric data analysis was used to assess the evolution of flavor-related compounds, investigate the relationships between the attributes and select discriminant marker compounds. Oat groats (dehulled oat grain) had significantly (p < 0.05) higher lipase and peroxidase activities, and possessed higher amounts of short-chain volatile fatty acids than the processed oats. The combined effect of kilning and subsequent steaming significantly (p < 0.05) reduced the activity of these enzymes. The use of high temperatures during kilning and steaming triggered the Maillard reaction and Strecker degradation reactions, leading to the formation of odor-active volatile compounds, such as pyrazines, furans and Strecker aldehydes. These compounds are commonly associated with the desirable nutty and toasted aroma of oat-based products. Overall, this study successfully identified key volatile markers and their associated reaction pathways, which can be used to control and optimize the industrial oat processing steps.

Keywords: Chemometric data analysis; Enzymatic oxidation; Lipid oxidation; Maillard reaction; Oat processing; Volatile fingerprinting.