Think twice before you toss that bag of flour into the pantry. Flour options available at grocery stores have vastly expanded and each type has its own set of rules for proper storage. Your flour might need to be stored in the freezer or, depending on the package it came in, stored in a different container to protect it from grain bugs. Properly storing whichever type of flour you purchase will ensure maximum freshness and quality.

All flour, no matter what type, must be kept in a moisture-free environment to keep it fresh for as long as possible. Keeping flour in the regular paper or burlap bag it came in doesn't protect it well for long-term storage. Transfer the flour to a glass or plastic storage container with an airtight lid, which also keeps grain weevils and other insects that can chew through paper out of your flour. If you prefer to keep the flour in the bag it came in, place the whole bag inside of a large, resealable freezer bag, squeezing out as much air as possible.

Refined flour, such as all-purpose, pastry and self-rising flour, has a relatively long shelf life, as the naturally oily bran and germ layers of the wheat have been removed. It can be stored in an airtight container in a cool, dark and dry area, like a pantry with a temperature kept below 75 degrees Fahrenheit. Before storing it in the pantry, place the flour in the freezer for at least a week, which will destroy any possible grain weevils and eggs. If you choose to store refined flour in the refrigerator, it can last at least a year, or in the freezer at 0 F, for several years.

Whole-grain flour, including whole wheat, oat and buckwheat, starts to go rancid as soon as it is exposed to air, because of its high amounts of natural oils. Store it in the refrigerator or freezer to extend its shelf life for as long as possible. If you prefer to store these kinds of flour in the pantry, keep them in the freezer for a week first, as with refined flour, to kill off any possible grain weevils. Whole-grain flour can be stored in the pantry for up to three months. If stored in the fridge, use the flour within eight months, or store in the freezer for up to a year. Alternative flours, such as almond, hemp seed or coconut flour, tend to have very high levels of oil and should not be kept at room temperature at all. Keep them in the refrigerator for six months or the freezer for up to a year.

If you are storing flour in the refrigerator, keep it away from any foods that have a strong odor, such as onions, cooked eggs and leftover foods. Keep a container of baking soda open in the back of the refrigerator to help absorb the odors.

Let flour that has been in the refrigerator or freezer come up to room temperature before using for best results.

Sniff the flour before each use, and discard any that has a sour or burnt rubber type of smell. Nut and seed flours should have a nutty, slightly sweet smell as well. If it has any type of "off" smell, toss it out. If you're not sure, taste the flour. If it tastes bitter, don't use it.