Most people are not aware that vanilla beans are grown in many different geographic areas of the world, nor are they aware that there are different grades to those vanilla beans which indicate their level of quality. These grades of vanilla beans are also used to determine which kinds of applications they are best suited for, and in which foods and beverages their qualities are used to best advantage. The main points of variation among all grades of vanilla beans have to do with the moisture content and the appearance of the beans. Here's how those two variables are expressed in each of the different grades of quality vanilla beans.
Grade A beans
Grade A vanilla beans are considered to be the gourmet beans among all varieties, and they will have a considerably higher moisture content than any other variety of vanilla beans. This being the case, the flavor in gourmet beans will seem to be somewhat diluted, but on the other hand, it will transfer flavor to any dish you're preparing much more quickly. Gourmet chefs generally prefer Grade A vanilla beans when they're preparing their masterpieces, for this very reason. It's because of the high moisture content that so much vanilla flavor can be imparted to a dish being prepared so quickly. To look at it another way, gourmet vanilla beans are capable of surrendering their flavor much more readily than any other grade of vanilla beans. If you're looking to quickly infuse a high amount of vanilla flavor into a dish you're preparing, your best bet will always be to work with Grade A vanilla beans. In terms of appearance, Grade A beans are far more attractive than either Grade B or Grade C vanilla beans, which means they contain almost no imperfections. Their appearance is one featuring a rich chocolatey brown color, which sometimes includes reddish hues. They are generally fairly uniform in size, and are noticeably longer than either Grade B or Grade C vanilla beans. It's also fairly easy to notice the oil content of Grade A vanilla beans, because it is exuded right from the skin. Grade A beans tend to be more plump than the other types of beans because they contain so much moisture, generally something like 30% of the bean. This high moisture content also makes them a great deal more pliable than the other types of beans.
Grade B beans
Grade B vanilla beans are often referred to as extraction beans, because they are quite often used to make vanilla extract. Since they have a much lower moisture content, they will also have a very highly concentrated vanilla flavor. This means you will get much more of the earthy flavor of vanilla beans from Grade B beans, provided that they have been steeped in liquid beforehand for a while. In terms of their appearance, Grade B beans are generally much more slender than Grade A beans, and because of the lower moisture content, they usually feel somewhat dry when they're touched.
They lack the oily sheen that Grade A beans typically have, although they have a similar reddish-brown hue to them. The moisture level content generally hovers around 20%, and since they're much lower in moisture content than Grade a beans, they are much more likely to split or crack if you were to attempt to bend them. They lack the flexibility of Grade A beans because they have less moisture and less oil. Any vanilla beans which contain imperfections are generally classified as Grade B vanilla beans, regardless of the type of imperfection. For the most part, these imperfections will consist of being sunburnt, cracked or split, none of which affects the flavor of the vanilla bean itself.
Grade C beans
Vanilla beans which are less than 12 cm in length are generally classified as Grade C beans, and as such are sometimes referred to as 'short Vanilla' or unclassified vanilla beans. These types of beans are often used in vanilla extract or in ground vanilla powder. Because the pods are considerably smaller than those of Grade A beans, they are much harder to work with, so they are not generally used by gourmet chefs in the preparation of high-quality dishes. Although the flavor is virtually the same as with Grade A or Grade B beans, these unclassified beans are not as popular with chefs because they are drier, less attractive, and generally more difficult to use in recipes.