Coffee is slightly acidic, milk in coffee will curdle before it totally curdles in the carton. If you are not mistreating your milk by contaminating it with dirty utensils, drinking out of the carton or leaving it at ambient temperatures for hours, the milk will be safe to drink until the expiration date.
Almond milk doesn't curdle, at least not in the way dairy milk will. Many brands of almond milk, even those formulated for coffee, have a tendency to separate, especially when served cold.
As Buzzfeed reports, the heat and acidity can also affect non-dairy milks such as soy milks in a similar way. Although this curdling is not necessarily bad for your health, it's also not exactly ideal (who wants to drink coffee with chunky milk in it?).
Almond milk curdles in coffee because of the heat and acidity of the black coffee. The protein in the almond milk coagulate when they come into contact with the acid of the coffee. Most non-dairy or plant-based milks curdle in the same way.
The high levels of lactic acid are also what give curdled milk its characteristically sour smell. In both cases, the curdled milk is as dangerous as it was before curdling. Spoiled or rotten milk is caused by microbial contamination of the milk, and it is not considered safe by human consumption.
How to stop almond milk curdling
- Heat the milk and let the coffee cool so they're more similar in temperature. This may stop the almond milk from splitting.
- Mix a little coffee with your almond milk before adding the rest of the coffee.
- Use coffee with low acidity.
- Get a barista to make it!
The key factors that cause soy and almond milk to curdle are the high acidity of black coffee and temperature. The coffee acts as a coagulant, causing the milk to split and curdle in a cup.
When coconut milk heats up, the curds still form but they are smaller and harder to see. Coconut milk curds change the look but not the taste and texture. Simply stirring the coconut milk will blend the curds back again. To prevent large curds from forming when you cook coconut milk, 'stir often' does the trick.
It can cause food poisoning that may result in uncomfortable digestive symptoms, such as stomach pain, nausea, vomiting, and diarrhea. You don't need to worry if you accidentally ingest a small sip of spoiled milk, but avoid drinking it in large — or even moderate — quantities.
The two factors behind the curdling of soy milk are acidity and temperature. Black coffee is more acidic than soy milk and can act like a coagulant, making a kind of loose tofu in your coffee cup. We've heard that heating the soy milk first helps avoid coagulation, but hot soy milk will actually curdle more.
Coconut milk is a suspension - a solid suspended in a liquid. Mixing an emulsion into another similar liquid base tends to remain emulsified. Mixing a suspension into another liquid, there is a distinct possibility that the two will re-separate, due to the heat-shock, & form clumps.
Due to its composition, camel milk does not curdle naturally and won't coagulate as easily as other types of milk. This may be a result of its unique casein micelles, the multi-molecular structure formed by caseins and held together by calcium.
If the milk curdles when boiling, the first thing to do is to strain it and remove all the excess water. But before that make sure you boil it for some extra time. You can also wash this in water to remove any smell that irritates you and then squeeze out all the water.
Once a sauce has curdled, it can be very difficult to return proteins to their original state. And while it's perfectly safe to eat sauces that have curdled, it's not especially appetizing. If a dairy-based sauce curdles, immediately halt the cooking process. Take your pan off the heat and place it in an ice bath.
One factor that can change the charge of the casein proteins is acidity. Eventually, the milk becomes acidic and develops a sour smell, and the casein proteins clump together in large curds. The effect of acidity on the milk proteins is accentuated by heat, which is often why your milk curdles when heated.
To find out whether your milk has spoiled, you'll need to do a sniff test. One of the biggest signs of spoiled milk is a sour odor. Next, check out the appearance of the milk while it's still inside the actual carton. If it's curdling in there, that's another sign it's gone bad.
Remove the saucepan from the heat and let the milk stand at room temperature for 5 to 10 minutes. Do not stir the milk as it stands. If you would like the milk to curdle more, you can let it stand for a longer period of time or return it to the heat and continue boiling it until larger curds form.
There's no use crying over spoiled milk — because you can still totally use it. But first, a very important warning: Don't consume milk if it's curdled because of age. This can make you very sick. We're talking about milk that has a sour taste but hasn't curdled yet and is safe to consume.
Cheese is made the same way — by curdling milk — except the milk is curdled on purpose. Most cheese is made in factories. After milk is poured into big vats, a “starter culture” of bacteria is added to convert the lactose into lactic acid. Then an enzyme called rennet is added to curdle the milk.
