What are the proper Brachos before and after eating a cereal made with corn flour and whole grain oat flour?

 

The Bracha reshona is Mezonos.

Regarding the Bracha achrona, it depends on the ratio of oat flour and corn flour. If there is over 1/6, approx. 17% of oat flour, the bracha achrona is al hamichya.

If there is less than 1/6 of oat flour, you should eat something which the bracha Achrona is definitely Al Hamichya and something in which the bracha achrona is boreh nefoshos.

 

Sources:

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Halacha2go.com #493: Bread made from Wheat Flour and other Flour

 

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