What's That White Stuff On Canned Asparagus, And Is It Safe To Eat?

Canned goods are a necessary evil. While fresh vegetables are usually a preferred choice, canned veggies offer a convenience that we can't deny.

However, sometimes what you find inside can be a bit off-putting if you don't know exactly what you're looking at. Such is the case with asparagus, which has a tendency to develop some questionable-looking white spots during the canning process. If you don't know what that white stuff is, you may be tempted to toss it and try another can or forego the asparagus altogether. But rest assured, the white spots are nothing to be afraid of.

That white stuff is called "rutin," but what exactly does that mean? Simply put, rutin is a crystalized bioflavonoid that is drawn out of the asparagus when it is heated with vinegar. During the process, rutin becomes insoluble, resulting in white deposits on the outside of the spear.  

What, though, are bioflavonoids? To shed a bit more light on this subject, bioflavonoids are a class of phytochemicals found in fruits, vegetables, and herbs, as well as things like chocolate, wine, and tea. They are believed to have numerous health benefits, which leads to the ultimate answer to the question — the white spots on your asparagus have no effect on the taste and are absolutely safe to eat.

There are some interesting facts about canning, including the way people opened canned goods before the invention of the can opener — here's a hint: it involved a weapon! You might also be interested to know that the white spots, the rutin, that show up on canned asparagus is something that is more common when you can your own asparagus at home. 

You don't typically see them in canned asparagus from the store, however. Professionally canned goods, i.e. store-bought goods, are heavily treated with preservatives and, in the case of asparagus, tend to also have a special additive that prevents the rutin from crystalizing to the surface. The extra additives are safe to eat, don't change the flavor, and make the food more visually appealing so unknowing consumers won't be tempted to toss the asparagus spears out of fear they have gone bad.