The fact that the bag has not been opened will not ensure that the flour is still okay to use. There is a window of a few months past the Best Before Date (BBD) when the product is still OK, depending on how it was stored. The flour can be okay for a long time after the BBD if stored cold or frozen. If you are unsure, try the hot water test. Put a few tablespoons of flour into boiling water, stir well and sniff. If the product is rancid, the smell will come out with the steam.
Category: PRODUCT INFORMATION FOR FLOURS AND CEREALS