Reducing free acidity and acrolein formation of omega-3-rich oils by blending with extra virgin olive oil during microwave heating

In recent years, microwave food processing has been increasingly utilized worldwide. Omega-3-rich oils, which have various health benefits, must be protected from heat treatment, including microwave heating, due to their thermosensitivity. In this study, we investigated oxidative stability of blends of omega-3-rich oils, such as flaxseed, sesame, and perilla oils, with extra virgin olive oil (EVOO) in order to reduce concentration of acrolein during microwave heating. Microwaving flaxseed oil increased the free acidity and the formation of undesirable and irritating odors (e.g., acrolein). In contrast, microwave treatment of EVOO resulted in a much lower level of free acidity and acrolein formation. Blending 10% EVOO in flaxseed oil enhanced the antioxidant capacity and effectively reduced free acidity and acrolein formation during microwave heating. The enhancing effect was also partially achieved in flaxseed oil blended with both 10% refined olive oil and α-tocopherol, which are bioactive components in EVOO. Similarly, blending 10% EVOO in other omega-3-rich oils, including sesame oil and perilla oil, also decreased free acidity and acrolein formation during microwave heating. These results suggest that blending with EVOO facilitates the use of omega-3-rich oils in microwave food processing while retaining their health benefits.