I have some Pale Malt and some Vienna malt in my basement environment which is cool and a relative humidity of 50%± I have no idea how long Ive had them but if i were to guess I would have to say 24 months. The Pale malt is soft to the bite but doesn’t tastes “bad” at all. The Vienna still has a hardness to it when chewed and it also tastes good. So how old is too old? I would use them in a recipe but am leery of a poor outcome.
Thoughts
It’s not about age, it’s about quality. I recently made beers using 8 year old Mecca Grade, and 11 year old Weyermann pils and Munich. The kernels were hard and tasted good. I got my normal efficiency and the beers tasted great. In your case, I’d consider the pale questionable (but probably use it anyway) and it sounds like the Vienna is fine.
That’s basically what I am thinking, The pale will be a small percentage to the overall bill anyways. I might possibly mill up a few ounces and steep them to taste for any perceived off flavors/aromas.
Consider keeping the malt in a food grade bucket with lid. This also helps if any unwanted visitors, mice, get into the basement.
I agree with Denny. If the kernels are hard and it tastes good use it. As a rule, I have found that the darker roasted malts have a longer shelf life than my base malts. Some of my roasted malts are still good after several years. Storage is important as well. Keep you malt in a cool place and store in a container that keeps the humidity out.
It is really easy to tell if you malt is still OK. take some kernels and chew on them. If they are crunchy and taste good, the malt is OK. Malt that has gone slack will be pasty when chewed and lack the flavor of fresh malt.