How long will a vanilla bean stay potent?

It depends highly on how fresh the vanilla is when you buy it. At least here in Germany, vanilla beans from the most common super market brands are mostly parched and IMHO already out of order when you pick them up in the store. For several years, I have ordered my vanilla in larger batches from an independent importer (current price is about 30US$ for 60 beans) and I've at least kept them for a year and a half or perhaps two. The quality of course deteriorates with time, but they are not going bad as in "cannot be used anymore".

One problem is however that if the beans are too fresh, they are a little bit tricky to store properly. As scientifics already wrote, it is usually recommended to keep vanilla in an air tight container to prevent them to dry out. If the beans are very fresh and still moist, this will cause water to condensate and I suppose it is not good for the beans to soak in water for a longer period of time.

I've always been told that they last for about a year stored in an airtight container in a cool, dark place (just like the rest of your spices). It is good to let them breathe every few weeks.

The shelf life and quality of a vanilla bean depends at what time it was cut from the vine. A vanilla bean that was cut when yellow at the tip (fully mature) will develop higher % of vanillin 2 % up is best. The higher the vanillin the better the aroma and it's other attributes which show in your final dish. Vanilla bean "crystals" can take up to 2 or 3 years to develop as the bean cures and matures. Even if the bean dries as hard as wood a properly cut and cured bean will have an "indefinite" shelf life. Just keep it in a tight container away from the light and change in temperature. Under no circumstances you should put them in the freezer. The best way to store vanilla beans is in sugar and use the sugar for your meringue. Beans in sugar will impregnate the sugar and you still have use of the bean. You can have long and plum beans but that does not mean that the beans are better. Vanillin in vanilla beans can be measured in the laboratory just like saffron. So ask for the vanillin range content 1.6% to 2% means that your product is of good quality. The same with saffron as for the lab report 240 units of color up good product long shelf life.

I've had this question myself because I'm finally down to my last bean from a package of 4-5 I bought at Williams-Sonoma years ago. When I say years ago, I mean YEARS ago, approximately 30-35 years ago. I have used them mainly for vanilla sugar, and over time they dry out and lose their potency, but it takes years. So I just inspected the last bean I have, and it's fine. It was stored in its original glass vial, and is soft, squishy, dark glossy brown, with a very strong vanilla scent. There are no off odors, or residue on the bean. It's been stored in a dark cabinet in a normal 70°F household, in a place you'd store your spices. From recollection it is not as oily and pungent as when new, but there are no signs of rancidity.

From research I just did, they say beans won't last more than 1-2 years, but clearly this bean has lasted considerably longer. Why? Was it such a rarity 30+ years ago that W-S would only source the very highest grade perfect maturity beans? Are the current guides very conservative because of liability issues and/or the desire to sell more product? I don't know.

But clearly the bean has the ability to last a very long time, given the right circumstances. I do not think this bean is at 100%, and if the vanilla flavor were critical, let's say I were making creme brulee, I would use a newer bean. But for my purposes, which is to make vanilla sugar, it is more than serviceable.

By the way, the bean I am replacing is not. It has lost much of its vanilla, has dried out, and I can smell off odors, a slight rancidity. The sugar itself was not superb either, so clearly when exposed to air the beans do age the way the online guides say they do.