The Temperature Trick To Easily Clarify Scummy Broth
Making stock for clear soup (consommé) or enriching a sauce or other dish with homemade stock can be a rewarding experience if done correctly. First, you need to have some knowledge about clarifying stock without compromising its flavor. One of the traditional methods of clarifying "scummy" broth is to use egg whites. This method starts by putting egg whites (plus a few crushed shells, if you want) into a cold pot of stock and slowly heating it. As the broth heats, the impurities will rise and form atop the liquid. After this happens, you can skim what rises to the top off of your broth. Unfortunately, you'd be skimming off not only the impurities but also the much-needed flavor. This can result in a clear, but flat-tasting stock.
Another method is to freeze the stock with its scum intact. You can then let the stock melt through a filter to gradually correct the clarified stock. Heston Blumenthal, chef and owner of The Fat Duke in Bray, Berkshire, advocates for doing things this way (via The Guardian). That said, this technique is not only time-consuming but also cumbersome. What if we told you there is a simple temperature trick that can clarify broth without risking any loss of flavor?
Start with cold water and boil slowly
Rosemary Trout, a culinary and food science professor at Drexel University in Philadelphia, told Bon Appétit that the trick to clarifying broth starts by gradually heating cold water — which is key — to a boiling point. By doing this, you'll be creating time for the proteins to come together more slowly versus at a faster rate when boiled from the start. When the broth starts to boil and you can see the scum, Trout advises that you reduce the temperature quickly and bring the pot to a bubble. "If you don't skim the scum before it rapidly boils, it can drop back into the soup," said McKenzie Johnson, a chef-instructor at the Auguste Escoffier School of Culinary Arts (via HuffPost). From there, cookbook author Andrea Nguyen recommends using a fine-mesh skimming tool to remove the scum (per Bon Appétit).
While it's nice to clarify scummy broth, this is done more for cosmetic purposes, as the scum itself does not pose any threats. "Skimming the scum is not a food safety issue. If there is some scum left over, the soup is still consumable," food scientist Brian Chau told HuffPost. Chau added that "Flavor is subjective to each person, and some people may like the proteins floating on top." Whether you drink bone broth every day or just want to save some money by making stock at home, the choice to reduce scum or not is entirely up to you.