If you want hot coffee but you’re mixing in cold milk, will the coffee stay hotter if you put the milk in earlier or later?

If you want hot coffee but you’re mixing in cold milk, will the coffee stay hotter if you put the milk in earlier or later?

You can check the answer of the people under the question at Quora “she wants this coffee because it has milk

0 thoughts on “If you want hot coffee but you’re mixing in cold milk, will the coffee stay hotter if you put the milk in earlier or later?”

  1. If we can assume that the milk will be the same temperature no matter when we add it, then the coffee will stay hottest if you put the milk in right away.
    Here’s why: we’re cooling the coffee in two ways. By dilution with something that’s colder than the coffee (milk); and by losing heat to the environment (through conduction and convection).
    That second process—losing heat through conduction and convection—happens at a rate that proportional to to the difference in temperature between the coffee and the environment. The hotter the coffee, the faster it’s going to cool. As it cools, the rate of cooling slows. If you were to graph the coffee’s temperature, you’d see something resembling an asymptotic curve approaching the ambient temperature. The rapid heat loss will happen in the beginning.
    The milk’s effect on the coffee’s temperature is more constrained. Technically, its effect is also dependent on the temperature difference between the milk and the coffee, but the significance of this is smaller, because we’re dealing with a finite (and small) amount of milk. In contrast, the environment into which the coffee is losing heat is for all practical purposes infinite and not affected by the coffee.
    By adding the milk early, we’re applying all of the milk’s cooling power to the coffee up front. This reduces the difference between the coffee temperature and the ambient temperature, slowing the rate at which the coffee’s decline will continue.
    Now, someone made the point that if you add the milk later, you could take the milk out of the fridge right away and let it warm up as the coffee is cooling down—basically use the ambient temperature to your advantage at the same time as it’s cooling the coffee.
    If you include this possibility, then you’re introducing too many variables to make a reasonable prediction. At least I couldn’t make one off the top of my head. It would be simplest just to do the experiment.

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  2. I’m not sure if it would make much of a difference. As the milk warms up to room temperature, the coffee will be cooling down to room temperature. Put milk in early, you mix hot coffee with cold milk. Put milk in late, you mix warm coffee with cool milk.
    You could, however, measure your milk out before you make coffee. Let the milk sit on the table as you make your hot coffee. When finished, your small serving of milk will be closer to room temperature and won’t bring the heat down too much.
    Honestly, I prefer the milkomater 3000. It mates coffee beans with milk molecules and makes little coffee milk babies. When brewed, these little guys produce coffee with just the right ratio of milk. Biology is amazing, isn’t it?

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  3. No
    You’d have to wait quite a while to get the milk temperature up just by letting it sit, outside the fridge. Your coffee would have lost to much heat by that time anyway, so earlier is effectively the same.
    Take your milk out before you make the coffee, and pour off the amount you need into a smaller vessel. This will bring it up to temp faster than an entire bottle would if sitting on a countertop. You could also stir it with a spoon to get it moving- which would also bring it up to temp faster. You could use energy-robbing materials like steel to hold the milk to.

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  4. I was asked this question on a college physics exam many years ago. I don’t recall the formulas or the math, but I still remember the answer. If you want to cool the coffee as much as possible, then wait as long as you can before you add the milk. Comveraely, if you want the coffee to stay hot longer, add the milk right away. Of course we are talking about tiny differences, but here is why this answer is correct. The delta between the temperature of hot coffee and that of the surrounding air determines the rate of cooling. Big temperature difference means fast cooling and vice versa. Add the milk early, and you reduce that delta. Keep the two liquids separate, however, and you maintain the maximum temperature delta, so that the milk-free hot coffee can cool faster. Once the milk is added, the coffee temperature drops, the delta between the coffee temperature and that of the surrounding air is reduced, and the rate of cooling slows.

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  5. About the same but if you pour the milk a little earlier, it might warm up in ambient temperature for a fraction of a degree but not enough to make any observable difference.

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  6. In my opinion you need to put the milk in straight away. Leaving it until later affects the taste. As to the temperature I doubt it would make a difference.

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  7. Why would you want blisteringly hot coffee in the first place? Cold milk added to 200F degree coffee makes it a drinkable temperature. This is a GOOD THING.

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