Elucidating the antioxidative mechanisms by blending rice bran oil with canola oil at ambient temperature

Oil blending is a useful way to modify the unique properties of vegetable oils such as oxidative stability. Rice bran oil (RBO) has excellent oxidative stability due to its fatty acid (FA) composition with relatively more saturated FA and less polyunsaturated FA along with a variety of antioxidants and is therefore expected to be used in blend with other vegetable oils. However, there are limited studies demonstrating the benefits of blending RBO. Our earlier study revealed that blending RBO, even with a small amount, can significantly suppress volatile aldehydes (propanal and acrolein) during oxidation, especially at ambient temperature (around 40 °C). In this study, the potential antioxidative effect and mechanism responsible for the prior condition were investigated using canola oils (CO) blended with two types of RBO (original form and antioxidant-stripped), focusing on oxidation products (aldehyde and hydroperoxide), unoxidized FAs, and antioxidants (tocopherol (Toc), tocotrienol (T3), and γ-oryzanol (OZ)). The results showed that aldehydes, hydroperoxides (peroxide value), and FA degradation were significantly suppressed in CO blended with 10 % RBO but not with 10 % antioxidant-stripped RBO during oxidation at 40 °C. The analysis of triacylglycerol hydroperoxide isomers and antioxidant profile revealed that blending RBO could preserve the antioxidant activity (proton donation ability) and maintain Toc. This might be attributed to the maintained antioxidant activity of primary antioxidants (Toc), possibly sustained by other certain antioxidants in RBO (e.g., OZ). Consequently, RBO-blended oil exhibited prolonged antioxidant activity, especially at ambient temperature, demonstrating a promising practice to extend shelf-life across multiple applications.