THE THEORY
This post details methods to prevent chicken stock or broth from becoming cloudy. It ends with an overview of my personal approach for a crystal clear stock, which I pride for being a balance between efficacy, efficiency, and taste.
WHY IS MY STOCK CLOUDY?
There are two primary reasons why stocks and broths end up cloudy:
Emulsification of fats: Just like how water and oil can emulsify into an opaque mayonnaise, fats from meat or bones can emulsify into the water of your stock, making it cloudy. The culprit? Boiling. Fats in your stock emulsify with the water when the stock boils. This is why a milky white tonkotsu ramen broth (which is produced via a rapid boil) is much cloudier than a stock with the same ingredients that is never boiled.
Impurities: If you start with a liquid that isn’t clear, it’s hard to make it clear later! Impurities are introduced to stock via the non-water ingredients. Some ingredients (e.g. tomato puree) have finer impurities than others (e.g. onions), so ingredient selection and prep can have a big impact.
Based on the above, it stands to reason that you can prevent broths from becoming cloudy by (1) avoiding fats, (2) preventing unavoidable fats from emulsifying, (3) avoiding impurities and (4) removing impurities after the fact. Let’s review each of these in more detail.
1. AVOIDING FATS
If there are no fats in your stock, you can’t emulsify them! This is why it is much easier to produce a clear vegetable stock than a clear meat-based stock. Here are the best ways to avoid fats to produce a clearer stock:
Blanch fatty ingredients first: The process of blanching bones seeps fat from your ingredients — especially when you start the blanch from cold water. I explain the process in the final section of this post; as the ingredients reach temperature, they release fats into the liquid that are effectively “removed” from your ingredients.*
Exclude fatty ingredients: I don’t see the need to add particularly fatty ingredients (e.g. chicken skin) to your stock. Save it for something else!
Skim fat as you go: Once your stock or broth is cooking, occasionally remove the fats that rise to the top. This is easier on pots with a smaller diameter.
*I love chicken fat (especially for ramen), so I make sure not to let the fat I “avoid” go to waste. For this reason, I don’t dump my blanching liquid into the sink. Instead, I preserve my blanching liquid then put it in the fridge for the fat to solidify for easy removal and use.
2. PREVENTING UNAVOIDABLE FATS FROM EMULSIFYING
It’s near impossible to avoid fats in your stock altogether, so you can employ other techniques to prevent them from emulsifying:
Avoid boiling your stock: Boiling (and even simmering) is a surefire way to emulsify fat. By keeping the temperature just below a simmer (e.g. 190ºF), you can avoid this problem while still maximizing flavor extraction.
Capture fats in a meat raft: By adding ground chicken or pork to your stock, you can use meat to capture fats as they are released — locking them from exposure to emulsification. Simply add about 1/8th the weight of your bones in ground chicken breast (broken up into a few pieces) atop your ingredients in the pot. Over time, little pockets of chicken raft will appear, locking fat and other impurities with them. This method is similar to a consommé (described in section 4) but serves to prevent emulsification rather than undo it.
Cook without a lid: When you cook with a lid, evaporated stock inevitably trickles back into the pot. This can emulsify fat too, albeit slightly. If I’m not taking other precautions, I don’t use a lid when cooking stocks.
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3. AVOIDING IMPURITIES
Do what you can to start with a liquid that’s already as clear as possible.
Avoid ingredients with impurities: This one seems straightforward — avoid things that are obviously not clear to begin with. Some aromatics, particularly napa cabbage, are unintuitively “impure” in this regard (probably because of their high water content).
Clean your ingredients: I blanch my meat-based ingredients to help clean them. After, I clean my chicken bones in cold water like folks clean rice — constantly rinsing them in water until the water is clear — before adding them to my pot.
Pour softly: No need to jostle your ingredients when adding them to your pot. I add all meat to the pot then gently pour the water in a steady stream in a single location (avoiding hard splashes to multiple parts of the pot).
Strain softly, too: You also want to avoid jostling the ingredients (or emulsifying fat) when straining. To do so, remove the large ingredients with tongs before you strain the rest.
4. REMOVING IMPURITIES
When all else fails, here’s what you can do to remove impurities introduced to your broth.
Use a really fine strainer: To avoid all possible impurities, I strain my broths through increasingly fine strainers. First a fine metal strainer, then a nut milk bag or brew bag. The Michelin star restaurant I worked at strained through industrial paper towels as a final step.
Use the consommé method: The French technique of clarifying a stock with an egg raft (described here) is surprisingly effective (and simpler than it sounds). This method will also help with accidental emulsification. The downside? The egg rafts impacts the flavor a bit.
Sous vide consommé method: This modern technique avoids all cooking skills required to pull off the consommé method above. But it also impacts the flavor. To do it, put your stock and 20% of its weight in egg whites into a blender, then cook this liquid sous vide at 185ºF until it separates into a clear broth and other stuff.
Methylcellulose method: Methylcellulose is a modernist ingredient that gels at high temperatures. You can replace the egg in the above two techniques with methylcellulose to capture impurities while avoiding an eggy flavor. Learn more about the technique here. Unfortunately, this method is very inefficient (e.g. 70% yield).
Freezer-based clarification: You’ll find this technique used in my garum recipe. It’s straightforward: freeze your stock (ideally in ice cubes to make things easier), then let the frozen stock defrost in the refrigerator over a strainer over multiple days. This method is difficult to do for large volume.
Agar agar or gelatin-based clarification: To achieve the above in a shorter period of time, you can “gel” the ingredients with agar agar or gelatin rather than freeze them. Here’s an example, but it’s also inefficient and hard to do for large volumes.
Centrifuge: Including this for completeness, but it is not practical for home cooks.
MY PERSONAL APPROACH FOR CLEARER BROTH
Reviewing the above approaches, the most effective techniques (e.g. freezer-based clarification or methylcellulose) are the least efficient.
I theorized that these techniques are inefficient because they use modern ingredients to undo emulsification and impurities rather than prevent them, so I created a broth approach that uses the best of both worlds: prevention and modern ingredients. It does so by avoiding all impurities from the start, then leveraging methylcellulose as an emulsification and impurity prevention tool. Here’s the recipe.
