There are almost as many different types of flours as there are different uses for them. One thing that all varieties of this pantry staple have in common is that they are not immortal. All types of flour eventually turn bad. Storing flour properly and keeping an eye on how long it's been stored is the best way to keep your different flours fresh and ready to use.
All-Purpose and Self-Rising Flour
All-purpose and self-rising flours are refined, which means that the germ and bran have been removed, so the flours contain less oil. It is oil that goes rancid, so refined flours have a longer shelf life. All-purpose and self-rising flours will stay fresh for one to two years if you store them in a cool, dry place.
Bread flour is refined, meaning that it contains less natural oils than coarser, less processed flours. Store it in a cool, dry place and bread flour will stay fresh for as long as one to two years.
Cake flour, being refined, has a fairly long shelf life. Place it in an airtight container such as a plastic zipper bag, and it store it in a cool, dark place to keep it fresh for up to one year.
Corn flour is a whole grain flour, so it contains a fair amount of oil and will not stay fresh for as long as refined flours will. Store it in an airtight container in a cool dark place and corn flour will stay fresh for between nine and 12 months.
Flours made from nuts such as almonds or hazelnuts contain a high level of oils. The more oil in a flour, the quicker it spoils. Nut flours are best kept in the refrigerator or the freezer. Most will stay fresh in the refrigerator for six months and in the freezer for 12.
Potato flour is made from white potatoes that have been dried and ground into flour. It has a high starch content and is fairly low in oil. Potato flour will keep for six to eight months in a cool, dry place.
The gluten-free heartiness of rice flour makes it a popular ingredient in baked goods from breads to cookies. Rice flour will stay fresh from six to eight months when stored in a cool, dry place.
Whole Grain Flours
Whole grain flours are nutrient dense and delicious, but this is largely because of the high amount of oils they contain. When oil is exposed to the air, it begins to degrade and turn rancid. The best way to slow this process is to store your whole wheat flour in the freezer. It can last for up to six months when frozen in an airtight container and up to four months in an airtight container in the refrigerator.
Trust your nose. The first indication that flour has spoiled is the smell. Color changes may also happen, but spoiled flour smells sour and should be discarded.