Impact of extrusion on the content and bioaccessibility of fat soluble nutraceuticals, phenolics and antioxidants activity in whole maize

The present study investigated the changes in fat soluble nutraceuticals, phenolics and antioxidant activity in extrudates of whole maize flour processed at 20 %, 25 % and 30 % feed moisture (M). Bioaccessibility of them in extrudates was also investigated at 20 % M. Extrusion resulted in a significant reduction in the content of components and antioxidant activity. Retention of phytosterols was more (77 %-100 %) followed by phenolics and flavonoids in extrudates. Reducing power decreased more than threefold, while DPPH radical scavenging activity and total antioxidant activity were half of its activity observed in raw. In bioaccessible fraction, the content of stigmasterol, β-sitosterol and flavonoids was higher than in raw while phenolics and antioxidant activity were unchanged. Bioaccessibility of carotenoids, phytosterols, phenolics, and flavonoids, as well as antioxidant activity was high, except tocopherols and tocotrienols. Overall, extrusion of maize flour with 20 % M enhanced bioaccessibility most of fat solubles, phenolics and antioxidants activity.