Hint: It has to do with sugar.
Now that fall is here, you may be updating your pantry with seasonal sweeteners. But not all sugar is the same, and this is especially true when it comes down to batches of molasses. We've already broken down the difference between unsulphured and sulphured molasses. Now, let's clear up the confusion surrounding blackstrap molasses.
Refining sugarcane and sugar beets (a.k.a. removing sugar crystals from the plants) involves three boils, producing three different types of molasses (which is a byproduct of the whole process, but hey, it tastes good). The first boil creates light or "first" molasses, the stuff we're most familiar with. First molasses is lighter and milder than the varieties produced from second and third boils and also contains the most sugar. The next boil yields dark or "second" molasses, which has a darker color, slightly less sugar, and a more pronounced flavor.
The third and final boil is what produces blackstrap molasses, which is the darkest and bitterest of all. It's often used in livestock feed or as fertilizer, but it's also touted by health enthusiasts as an alternative to its sweeter siblings. Blackstrap molasses has less sugar and is more nutritionally dense than any other cane product (and contains antioxidants and electrolytes), so it makes sense.
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You may be tempted to substitute blackstrap for true molasses, but don't—you'll significantly alter the recipe's taste, as blackstrap molasses is nowhere near as sweet as the regular stuff. Remember, blackstrap is the result of triple boiling, so there's much less sugar. Don't switch true molasses out unless the recipe (many savory dishes use blackstrap molasses, as well as healthier versions of sweets) specifically calls for blackstrap.