A good stock or broth or is an essential part of any good cook’s repertoire because it adds an imitable depth of flavour to dishes. Making it is not an overly complicated affair, and you can enjoy the results for weeks or months to come, depending on how much you make and decide to store in the freezer.
Skimming the fat off stock or broth ensures clarity and lightness of flavour, two ideal qualities of a great soup, especially consommes. Below we share some tips on making stocks and how to skim the fat off, so you end up with a gorgeous clear soup or broth.
Between its abundance of gut-healing amino acids, its benefits for joints and skin, its awesome flavour, and its ability to warm us up on a cold winter day, there are plenty of reasons to eat bone broth (and to make our own! See Why Broth is Awesome and Chicken Bone Broth). But, what about the downsides? We have a wide range of best chicken bone broth at Bone Broth
There are plenty of myths circulating the internet about possible detrimental health effects of broth, most of which are demonstrably false. For example, we’ve already thoroughly busted myths about broth being harmful due to free glutamate levels and heavy metal contamination (see Broth: Hidden Dangers in a Healing Food?). But there’s another possible concern when it comes to this nourishing food: oxidation. I first got thinking about this probability when my functional medicine doctor mentioned seeing a pattern of increasing LDL and triglycerides in clients consuming homemade broth regularly. I think this may be attributable to, not to the broth itself, but that delicious layer of fat that rises to the top of our broth. It might be tempting to save for cooking (or even to slurp down with the broth itself), but could the prolonged exposure to heat and oxygen during the traditional 24-hour to 4-day simmering cause some of it to oxidize and become harmful?
Unfortunately, there aren’t any studies measuring how much oxidation occurs in the fat rendered from bone broth. However, we can apply what we know about oxidative rancidity, the composition of different animal fats, and the broth-making process to get a sense of what’s most likely going on!
Saturated, monounsaturated, and polyunsaturated fats are distinguished by the number of double bonds in their carbon chains (saturated fats have no double bonds, monounsaturated fats have one double bond, and polyunsaturated fats have multiple double bonds). Because these double bonds are essentially missing hydrogen atoms, they’re molecularly unstable. They can easily be oxidized—undergoing a series of reactions leading to free radical production and rancidity in the presence of heat, light, and air.
The oxidation rate for fatty acid increases with the number of double bonds it has. So, while saturated fats are relatively stable, monounsaturated fats are slightly more oxidation-prone, and polyunsaturated fats can be extremely oxidation-prone given the right conditions (such as during cooking!).
Oxidation Potential of Animal Fats
So, how does this apply to the ingredients in bone broth? Although animal fat is sometimes thrown under the umbrella of “saturated fat,” this is a massive oversimplification! All animal fats contain a mixture of saturated and unsaturated fatty acids, including some linoleic acid (the same type of polyunsaturated fat abundant in vegetable oils). The unsaturated fat content in an animal is at risk of oxidation during prolonged, oxygen-exposed, or high-temperature cooking. For example:
- Beef fat: 37% saturated, 61% unsaturated (2% linoleic acid)
- Chicken or turkey fat: 29% saturated, 65% unsaturated (20% linoleic acid)
- Lard: 40% saturated, 59% unsaturated (11% linoleic acid)
To make broth, we simmer bones at a temperature just below boiling (typically 94 degrees C, or 200 degrees F). Although this temperature won’t cause fats to oxidize as rapidly as high-temperature cooking methods like frying, damage still does occur—especially because broth spends such a long time simmering (the cooking process can last anywhere from several hours to 48 hours and beyond!). Studies show that highly unsaturated oils like corn oil, olive oil, and mixed seed oil (canola, sunflower, and safflower) begin showing signs of oxidation after only 40 minutes at 80 degrees C, with oxidation increasing during longer cooking times and higher temperatures. So, especially when using bones from animals with a higher polyunsaturated fat content (like chicken and other poultry), we would expect to see a similar process occur in long-cooked bone broth. This is particularly true because the fat rises to the top of the broth and can spend many hours, or even days, exposed to not only heat but also air (hello, oxidation!). Looking for chicken bone broth ? Look no further! Bone Broth has you covered.
What is scum?
Scum is the foam or froth that floats on the surface of the liquid. Not just broth but other liquids as well. But since this is about the scum that forms when making bone broth, I won’t bother about the “other liquids” anymore.
Some refer to scum as “impurities”, others call it a harmless protein and some others label it as a lipoprotein. Whatever its exact definition, you don’t want it in your broth. If you wish to bits of solids or semi-solids in your broth, they better be things that dropped into the pot rather than bits that neglected to remove.
How is scum removed?
If you did nothing to lessen or prevent the formation of scum, a greyish froth would float to the surface. Small bits at first until, finally, most of the surface of the liquid is covered with the foamy substance.
The first thing to remember is that the scum must be removed before the liquid reaches boiling point. By that time, the scum will start boiling into the liquid. Even if you strain the broth later with a double layer of cheesecloth, the scum cannot be completely removed.
So, while the liquid is just starting to bubble and up until it reaches a simmering point, remove the scum. Place a bowl on the counter as near the pot as safely possible. Take a large spoon or a strainer (there is a shallow strainer specifically meant for skimming off scum) and just scoop out the scum and dump into the bowl.
Do the spoon-and-dump process repeatedly. It takes anywhere from 10 to 20 minutes depending on the amount of bones in the pot. When the surface of the liquid is free from foam, cover the pan and simmer the bones to make bone broth.
Fat is not scum
So that’s how a scum-free cooking liquid looks before the pan is covered. I use a large pot for making bone broth. When it is ready, I cool the liquid then strain it into half-gallon containers. I keep the containers in the freezer and take out only what I need for a particular dish.
If you freeze or chill broth, you might notice that, on the surface, a layer forms on top that doesn’t look like frozen broth at all. That is fat. You have the option of scraping it off or leaving it there.
Is there a way to prevent scum from forming?
From my experiences, yes. There are three ways to prevent scum from forming completely, and there is one way to minimize its formation.
Let’s go backwards and start with minimizing the formation of scum.
Most cooks say that when making broth, we should start with cold water. Put the bones and veggies in a pot, fill up with tap water and set on the stove. That was how I did it for years until I realized that it was the best formula to ensure the formation of scum—lots of scum. So, I experimented and discovered that by adding bones to furiously boiling water, the scum that floated on the surface was considerably reduced.
Useful information, yes? But why go for reduction of scum when its formation can be totally prevented? How to do that?
Here are three ways:
- Trim the bones of all meat. Scum comes from the meat, not the bone.
If using bones with bits of meat attached to them and you do not want to remove the meat:
- Roast the bones in the oven until browned, and no “bloody” juices ooze out—30 to 40 minutes at 400F—before adding them to water in a pot. The downside is that roasted bones make a dark broth
- Place the bones in a pot, cover with water and boil—not simmer—for 10 to 15 minutes. Strain the bones, throw out the water then rinse each piece of bone under the tap until no impurities fall out. Clean out the pot or get a clean one, put the bones in, cover with water, add aromatics and simmer away.
Why is your fat content so low in your bone broth? Does it affect the health benefits?
We skim the fat off our broth because a number of our customers prefer it that way. By removing the fat from the broth, none of the health benefits is diminished. The Paleo Mom has an interesting article filled with scientific reasons as to why you should skim the fat off your bone broth.
Most people are surprised to hear that we only have traces of fat in our broth because they observe our broth turning to gel when cold. They wrongly attribute this to the fat content when the reason is the gelatin found in our broth. Bone Broth has a wide range of best chicken bone broth in Melbourne
Making your own bone broth? You can easily skim the fat off your homemade broth. When your broth is hot, strain it through a cheesecloth. The broth will pass right through, leaving the fat behind. Alternatively, once your broth has completely cooled, pop it into the refrigerator. After a while, the fat will solidify on top of the broth (the broth should turn to a gel), and you can easily scrape the fat off with a spoon or spatula. Removing the fat from your homemade bone broth can be a great idea if you don’t like a lot of fat, and it will also reduce the calories.
Skimming Fat from Broth
Make your homemade soups as low-fat and low-calorie as possible by skimming off the extra fat with these techniques.
- To remove fat from hot soup or broth, use a large metal spoon and skim off the fat that rises to the top.
- You also can cover and refrigerate the soup or broth for 6 to 8 hours or until the fat solidifies on the surface. Then use a spoon to lift off the hardened fat.
- A fat-separating pitcher also is useful. It has a spout near the bottom. The broth is poured into the pitcher and allowed to stand for a few minutes. Because fat rises to the top, the broth can be poured off, and the fat will remain in the pitcher.
- Another tool to try is fat-skimming ladle. Slots near the upper edge catch the fat, which stays in the ladle.
Saving The Fat From Your Nourishing Bone Broth
We say it time and time again: making your own bone broth is one of the most wonderful, healing things you can do for your body. But did you know you can also use the fat from the bone broth as a wonderful healthy cooking fat? As fall settles into the air and days crawl to shorter lengths, the desire to sip wonderful brimming bowls of soup grows irresistibly. While bone broth is beautiful at any time of the year, there is something about the golden spoonfuls and curls of aromatic steam that are particularly appealing in colder months. In the theme of traditional cooking, wherein no part of a meal goes to waste, saving the skimmed fat from the top of bone broth is also an excellent way to have yourself a truly nutrient-dense cooking fat. By storing the collected fat in a small glass container, you are not only penny savvy but ensuring that you have an incredible source of pure animal fat to incorporate into your diet. This is especially important in the winter months when we need rich nourishment to sustain our energy levels.
Once you have simmered the broth for an adequate amount of time (the time varies considerably whether using beef, fowl or fish), the bones are strained out and the remaining golden liquid transferred into a glass bowl. Chill the bowl in the freezer of the refrigerator until a thin layer of whitish fat forms on the top of the now gel-like broth. This fat, though some people might look at it in alarming fear and disgust, is wonderful for high heat cooking. It adds a rich flavour to meals and is incredibly nutrient-dense.
Removing the fat is extremely simple. Using a thin flat spatula, slide it slowly across the bowl of broth, trying your best to remove only the fat. The fat readily separates from the broth if it has gelled properly. To make things easier, we usually use another spatula and scoop the fat onto a flat plate first before placing it in a mason jar far for storage.
Reducing the Risk
Prolonged cooking times for bone broth have become the norm in recent years because it maximized bone demineralization, thereby increasing the mineral content of the finished product. I prefer to simmer my bone broth for 36 to 48 hours until the bones can easily crumble in my hands (at that point, the bones are perfectly edible too, although they aren’t the tastiest of things). Fortunately, we don’t need to give up the benefits of a low-and-slow-cooked bone broth to minimize the risk from consuming oxidized fats.
So, how do we reduce our exposure to potentially oxidized fat from bone broth without forgoing this wonderful food entirely?
- Skim the fat off the top of the broth and discard it instead of eating it (this is the easiest route!). We can scoop off the oily layer while the broth is simmering, or remove it after refrigeration when the fat hardens and turns whitish or yellowish. (Keep in mind, animal fat can easily gunk up plumbing, so put the fat in a waste receptacle and not down the sink!)
- Use bones from animals with a higher saturated fat content (more heat-stable) and lower polyunsaturated fat content (think: beef and lamb bones rather than chicken, duck, or turkey bones).
- Use bones from animals raised in non-industrial-polluted areas that are free from heavy metal contaminants. (Along with being harmful to the human body when consumed in excess, certain heavy metals—especially copper and iron—act as oxidation promoters and can increase the oxidation rate of fragile fats.)
- Avoid eating any broth fat that tastes “off” (rancid fat has a distinctly unpleasant taste!).
- Make broth using a pressure cooker in order to limit the fat’s exposure to oxygen. Go Instant Pot!
- Choose high-quality pre-made bone broths that already have the fat skimmed, like Kettle & Fire.
With these tips in mind, we can reap the benefits of bone broth without ingesting harmful oxidized fats!
If you plan on whipping up a gourmet pan sauce with your bone broth, removing the fat is a good idea to keep your sauce from breaking. If you are making bone broth to drink, it’s all about preference. If you have gone to the trouble of getting bones from pastured, grass-fed animals, why remove the fats? They are very healthy. Bone marrow is approximately 80% fat in a healthy animal. If you want the bone marrow nutrients, you need the fat. Industrial processes far more sophisticated than the home cook has access to could separate the fat from the nutrients. Some of the nutrients in broth require fat to be properly absorbed. Check out our Melbourne chicken bone broth here.
Moreover, you need not chill your broth at all. When your broth is complete, let the broth sit for an hour. Check the temperature to make sure it does not go below 160 F. I scoop a 4 cup Pyrex measuring cup into the broth and begin filling jars and bags. If you are using glass jars and are worried about temperature, run your jars through a quick wash cycle in the dishwasher – or soak them in toasty warm water in the sink – before you fill the jars. You do want to avoid big temperature changes in thinner jars.