Kitchen Mysteries is a weekly exploration of oddities surrounding cooking and food. They could be recipes that fail when they shouldn't, conflicting advice from different sources, or just plain weirdness. If it happens in a kitchen, and you're not sure why, send a tweet to The Food Geek to find out what's happening.
Friend of The Food Geek, Crystal, asks:
I have wondered this myself from time to time, but I'd never worked up quite enough curiosity to find out. Thanks to your helpful question, I now can.
The first time I heard of the difference between stock and broth was on an episode of Good Eats, "Behind the Bird". In it, Alton Brown says that the difference between a broth and a stock is that a broth is made from meat or vegetables, but a stock is made from bones. The idea being that a stock is always jam-packed with collagen, whereas a broth is just some nicely-flavored liquid.
This is a great and useful definition, until you look through hundreds of cookbooks and check through items on a grocery store shelf and you see things like Vegetable Stock. Now, it's not like most of the cooking world has never been wrong before,* but this is a bit ridiculous. And a bit odd, because as you hit somewhere around recipe book 92, you start noticing some patterns to the usage of stock and broth. The same recipe will call the preparation stock or broth, but in different but consistent contexts. Something is definitely up. This calls for a trip to the Food Geek Bookshe… er, Library.
This first place I check is Larousse Gastronomique, which seems the ideal sort of reference book to answer this kind of question. It is not. It mentions both, but does not do a particularly good job of differentiating the two. Furthermore, the broth simply told me to see the definition for bouillon, and the entry for bouillon claimed that it's also called stock. So that is just more confusing than it was. However, Larousse Gastronomique did say that there is something called "vegetable stock", so we can't just claim it doesn't exist.
Then I checked The Saucier's Apprentice, because stocks are often used as bases for sauce, but they don't even acknowledge broth. If I weren't pretty sure they're somewhat different, I'd just tell you that they're really the same thing and leave it at that. As it stands, I'm sure there's something different in the usage, so it's time to go to the main source.
I pick up my well-worn copy of Harold McGee's On Food and Cooking, which is perhaps the most complete and useful book on the understanding of how food works ever made. Lo and behold, there's a little sidebar, which answers this question precisely.
Stock, as a word, implies a kind of building block. Stocks are never served on their own, they are used to build other things. "Stock your pantry," is an example of that word used in a different way. Same thing. Broth is an older word, and it essentially means something that is boiled.
So, to summarize, vegetable broth and vegetable stock are the same thing. If the focus of the end preparation is mostly the liquid in question, call it broth. If the focus of the end preparation is something significantly more complicated, like a sauce or a more involved soup, then call it stock. Not that it really matters in the kitchen, but if you write a cookbook or similar, it would probably be nice to differentiate.
With meat-based stocks and broths, I would suggest going with the bones vs meat naming scheme, as proper naming can give you a better understanding of how the final dish will turn out.
*- I cannot tell you how grating it is to hear that searing meat seals in juices.