Yes, you can almost certainly use your unopened brown sugar, as sugar doesn't truly expire and the "best by" date refers to peak quality, not safety; just check for hardness, off-smells (like fermentation), or mold, and if hard, soften it with a damp paper towel or bread slice.
Even though the shelf life of brown sugar is indefinite, it's best to use it within two years of purchase for maximum flavor. Don't store brown sugar in the refrigerator. However, if you are in a very dry area or are going to keep it for a long time, you may want to freeze it.
Sam Ellis, a food scientist and the creator of Culinary Compass, names the following warning signs that your brown sugar has officially spoiled: "If you notice that brown sugar has wet clumps or a sour smell, insects, or any mold growth, be sure to discard it."
All brown sugars, and for that matter, granulated and powdered sugars, have an indefinite shelf life as they do not support microbial growth. Sellers are required to stamp on their product's bag a 2-year "Best By" date — not a "Use By" date — but it is still safe to consume after that.
Sugar won't go bad on its own, in fact, an unopened bag of sugar will last years. However, once exposed to other foods, liquids, bugs, or more can end up ruining your supply. There are a few things you can look for if you are uncertain whether your sugar is safe to eat.
Hard to tell from this pic. The molasses can separate from the sugar and/or sometimes it looks like this if you've scraped it while it's hard. Brown sugar can mold due to to the moisture content of the molasses, but it is not common.
Commercial sugars (granular, syrup, and honey) have an indefinite shelf life due to their resistance to microbial growth. However, sugars have a best-if-used by date of approximately 2 years for quality concerns.
Common sweet products that attract pests:
Granulated sugar, brown sugar, and powdered sugar containers.
Brown sugar can also be stored in any type of re-sealable, moisture-proof plastic bag. The quality of brown sugar is best when consumed within six months of purchase and opening.
What Are the Signs of Spoiled Sugar? Sugar can last for a long time, but smells, water, and bugs can ruin it. It's more likely to be contaminated than old, so be careful before you eat it.
Truth About Hard Lumps. Brown sugar doesn't go bad, but it can get hard or lose quality if it's not stored properly. If you keep it dry and sealed, it can last for many years without becoming unsafe, though quality may decline over time.
Can date sugar be used after best by date? Under proper date sugar storage conditions, it is generally safe to use date sugar after the best by date as long as there are no signs of spoilage, such as mold or a strange odor.
Technically, sugar never spoils. While it's recommended that granulated sugar be discarded after two years, chances are it will still serve its baking purpose even beyond that. The same guidelines apply to brown sugar and confectioner's or powdered sugar. When do sugar, flour, baking soda and other ingredients expire?
Even though the shelf life of brown sugar is indefinite, it's best to use it within two years of purchase for maximum flavor. Don't store brown sugar in the refrigerator. However, if you are in a very dry area or will keep it for a long time, you may want to freeze it.
The good news with hard brown sugar is that it can easily be re-hydrated. Molasses can absorb moisture from either bread or a clay plate or water (see above) and then you can proceed to use it in whatever recipe or way you like.
Sugar molds generally take the form of a long solid block with a series of depressions into which raw sugar cane syrup could be poured. Once it dried, the syrup formed a raw brown sugar cone, which was how sugar was once sold to customers.
Sugar bugs is another name for plaque that forms on your teeth when you have poor oral hygiene habits. Plaque is a thin, colourless to white/yellow, and sticky deposit full of bacteria that may form on your teeth when the food you eat combines with the bacteria in your mouth.
Generally speaking, consuming sugar past its expiration date is not a safety issue. Sugar is a stable substance and doesn't harbor bacteria or mold like other foods. The lack of moisture in sugar acts as a deterrent against microbial growth, making it unlikely to become unsafe for consumption over time.
The good news: Sugar doesn't really expire. (Unlike some other baking ingredients, like flours!) Here's what you need to know about sugar's staying power, including a little delve into sugar's history as a preservative (really!) and info about how different types of sugar fare when you're storing them long-term.
In Japan, the presence of Clostridium botulinum type A spores was reported in raw sugar and molasses, and in 2 of 41 brown sugar lump samples.