Many people don't know that store-bought flour does, indeed, go bad. Flour is rather susceptible to spoilage because of the natural oils in the grain, nut or starch in it, and its shelf life depends on the fat content from these oils. The less refined it is, the more fat it will contain, and the faster it will go bad. For example, processed white flour contains 1.81% fat, while whole-grain flour contains 3.63%. Therefore, the enriched white flour that more than 95% of Americans buy will last substantially longer than whole wheat, since there’s less oil to spoil. While leaveners may be added to some types of flour — like self-rising varieties and mixes — most flour is just the raw grain, root, bean, nut or seed grain. The addition of ingredients like salt and baking powder, which don’t go bad, doesn’t affect the shelf life on the base flour type. However, it may affect performance. So, how can you tell if your flour is bad? It’s actually pretty hard to miss. Fresh flour has a neutral, clean powder scent to it, if any at all, with the subtle sweetness of grain. Flour that’s turned will smell off, with a markedly sour, unpleasant mustiness to it. If you already see traces of mold, you can skip the sniff test — you definitely don’t want to inhale those spores. If you don’t trust your nose to do the job, check the color of the flour. All-purpose bread, cake and other refined white flours should be bright white an fluffy, as is tapioca flour. Whole-grain flour is usually a sandy brown, and almond flour tends to be off-white. If you see a yellow tinge to any of your flour, the oil has turned rancid. Signs of mold can include visible clumps of green or blue growth, which means you should immediately discard it. Finally, any critters in your flour is a no-brainer, but don’t toss it right away. Freeze the flour first; this will kill the bugs and help you avoid a pest infestation in your trash can.
