Why does hot coffee that goes cold taste bad, but iced coffee or cold brew taste fine?



Why does hot coffee that goes cold taste bad, but iced coffee or cold brew taste fine?

In: Other

Coffee contains (among other things) *aromatic oils*, that is, oils that vaporize at lower-than-boiling temperatures. These oils are what make coffee smell so good when it’s being brewed traditionally.

Those oils also help balance the flavor of the coffee, specifically offsetting the bitterness of the roasted beans. More oil in the coffee = less bitter flavor… but less delicious inviting aroma.

Making traditional coffee, and letting it cool in the open, means you lose most of those oils and the remaining drink is bitter.

Making coffee via a cold-brewing method means the coffee never gets warm enough to vaporize the aromatic oils, so they remain in the coffee and balance out the bitterness.

In general, when food or drink is hot, the flavor is mellowed out, and when it’s cold, it’s intensified – and that’s especially true with bitter flavors. With hot coffee, since we want it to be served hot, we brew it to an intensity that tastes good at that temperature. When it cools down, it ends up tasting too strong and bitter, because those flavors are intensified past where we wanted them.

When we make iced coffee or cold brew, we brew it to an intensity that tastes right when it’s cold *and* diluted with ice. So we engineered it to have a good flavor at that temperature – if you took an iced coffee and heated it up, it would actually taste *too* mellow and diluted, compared to what you’d expect from a regular hot cup of coffee.

Hot water pulls out more of the bitter stuff like tannins, cold water doesn’t so it’s not as bitter. Iced coffee I guess just has less bite when it’s cold because it should have the same composition as hot coffee

Ice Coffee is cooled down immediately after brewing so the oils in it have not evaporated away, and other compounds have not oxidized due to exposure to air. It is still fresh and so still tastes good. Standard hot coffee that is allowed to go cold in your cup over the course of an hour or more has had more of the oils evaporate due to being at a high temp longer, and had more of the compounds oxidize due to sitting for an hour or more. The temperature is a very small factor in it starting to taste bad, it effectively going “stale” or the coffee equivalent of going flat over time is the factor.

We brew coffee and then put it in the fridge when it cools off a bit. Flavor is amazing and no bitterness. Don’t put ice in it either as it waters it down nor do we add sugar/milk. We started this by accident after having to run to the hospital after making a fresh pot of coffee. Didn’t want to toss it and didn’t want to leave it on the hot plate, so we put it on a hot pad in the fridge. Sometimes I’ll get new/different brands and taste them hot then cold to see how much the flavors change.

long time specialty coffee barista here. “specialty coffee” is used to denote high-quality beans that are sourced directly from farms, not bought on the commodity markets. the roasters we worked with were extremely dedicated, and the product was often very different than what most people are accustomed to. a light-roasted high quality coffee should have a color like tea, a clean body (not thick!!!!!!!!), and a juicy, flavorful, sweet flavor. good coffee is truly more like tea than the coffee you’d get at starbucks or dunkin donuts, to the point that those latter drinks are almost unrecognizable as coffee to me.

here’s my point.

if you’re drinking GOOD coffee, it tests *best* at lower temperatures, somewhere between hot and room temperature when the flavors have had time to develop and it reaches a temperature that won’t scald your taste buds. it will continue to taste good as it turns lukewarm and cool. so if your coffee tastes bad when it’s cooler, it was never good coffee to begin with. as such, i cannot really answer your question, as the premise of the question (“hot coffee that goes cold taste[s] bad”) is itself flawed. but i’ll try to answer somewhat.

iced coffee that you get at many shops is simply yesterday’s brewed coffee poured over ice. if that tastes good to you, then that’s great, i’m jealous! at best, it’s tolerable to me. i make no apologies for being a snob so save your breath if you want to call me out on it. cold brew makes good coffee because for whatever reason the low temperatures never extract some of the harsher notes from even low-quality coffee. i suspect that most places are doing a better job at filtering cold brew, because partly why warm coffee that goes cold tastes bad is due to unfiltered solids continuing to brew, leaving bitter/sour tastes.

As an old nurse, I can tell you that coffee at any temperature is acceptable. We often pour coffee that we don’t get to for an hour or more.

Coffee from a gas station that cools down tastes terrible because first its low quality, and second, its over cooked sitting in the machine ready to serve.

I make high quality coffee via pour over method, and when it cools, it tastes different than when it was hot, but not at all bad.

The difference between the two is astonishing. Ive had gas station coffee that tasted fine hot, and like a tire cold. This doesnt exactly answer your question via chemistry, but I suspect if you’re running into this situation, lower quality coffee is part of the equation.

Our coffee maker doesn’t have a heating element and instead stores the hot coffee in an insulated thermos carafe. Even when the coffee goes cold it retains its flavor quite well. The open top glass carafes that sit on a hot plate are death to good coffee.

I prefer my iced coffee brewed hot, then allowed to cool before putting it in the fridge. I tried cold brewing my coffee, but I didn’t like it. To each their own 🤷🏻‍♀️

I get so upset when people try to dump out the old coffee. SAVE it for MEEEE. I am gross and have no taste, and prefer any coffee that is not hot. Obviously iced and cold brew are slightly better than day old, but I will drink the hell out of that shit.

The science here made me finally understand (a little) why people are so grossed out that I insist they save me the old coffee.

Pease porridge hot, pease porridge cold,
Pease porridge in the pot, nine days old;
Some like it hot, some like it cold,
Some like it in the pot, nine days old.

This is my theme song when it comes to coffee.

I was wondering if it’s considered a cold brew if you use instant coffee and cold water and then add ice?

You know what we call Iced coffee here in Australia?

Ice coffee

I think it comes down to expectations of what your drinking. I’ve never thought cold coffee tastes bad

I hope this comment can stay up. To add onto the reply about aromatics: you can preserve them and easily make delicious iced coffee quickly at home by brewing your coffee regularly, stirring it (a little aeration really helps coffee taste better according to blind taste tests), pouring it into a good mason jar all the way up and lidding it tightly (scary I know), putting that jar into an ice + water bucket so it’s covered completely, putting that whole bucket arrangement into the freezer for ~15 minutes, you end up with coffee that is ice cold; uses your trusted recipe; and tastes the same but cold. I work in an award winning espresso bar and this is the way we do it when we want to make a special batch.

Otherwise using more ground coffee and brewing directly over ice (about half of the normal water by weight) is standard but you really gotta fine tune the grind settings and amounts of water and beans (by weight). It’s easier small scale to not change your recipe and use the double ice sarcophagus method.

If your coffee tastes bad when it goes cold, you need to buy better coffee.

Buying better beans and grinding them yourself will result in better coffee all around, and can be MUCH cheaper than stuff like [email protected]*cks.

Do your own due diligence, but if you are getting bad tasting coffee after it goes cold, it is generally bad coffee.

It doesn’t always taste bad though. I think it’s mostly to do with the raw product.

The Folgers brewed in a drip coffer maker I used to chug just to keep going back in the day tasted like motor oil when it got cold.

The decent quality whole bean Sumatran (or a few other varieties of Indo coffee) is another story. A lot of different flavors are more noticeable when it cools down and I’ve never considered it unpleasant.

fwiw i love cooled down coffee, it has intense chocolatey flavours, to these taste buds anyway.

Coffee just tastes bad, when its hot you cant taste it as much imo. I hate the taste of black coffee, so I usually just let it cool down to room temperature anyway so i can just chug it and get it out of the way.Unless its cold outside, ill drink hot coffee to warm up. I do like iced coffee with cream and sugar though

Hello. Professional coffee roaster here. There is some useful and interesting information posted here, but another explanation is that you are drinking low quality coffee. One reason why people like hot coffee is that burning your tongue a little bit prevents you from fully appreciating the negative aspects of what you’re drinking. When evaluating coffees, we always taste them at a range of different temperatures, and all of the best coffees I’ve ever had have tasted best between body temperature (or just above) and room temperature.