I have a very sensitive stomach; I get an upset stomach (watery stools) and pimples all over my forehead and head when I have coffee. With cold brew, (if made properly), I do not get any of this. So there is definitely some difference in the chemical constituents of hot-coffee vs cold-brew-coffee. Some other papers state less caffeic acid and less quinic acid.

https://www.nature.com/articles/s41598-018-34392-w

In the Abstract part of the paper, they highlight some distinct chemical differences to validate that their process works more like cold brew vs hot brew:

>> "Furthermore, the liquid phase’s alkaloid content, analyzed by reversed-phase liquid chromatography coupled to high-resolution mass spectrometry, is dominated by caffeine and trigonelline and is comparable to traditional cold-brewed coffee rather than hot-brewed coffee. Furthermore, analyzing the head-space of the prepared coffee variants, using in-tube extraction dynamic head-space followed by gas chromatography coupled to mass spectrometry, gives evidence that the lack of heating leads to the preservation of more (semi-)volatile substances like pyridine, which provide cold-brew coffee its unique taste. "

Different fats dissolve at rates that are temperature-dependent (which is why cold brew has a different flavor to espresso - a different subset of the oils in the bean have dissolved into the water). As a result, each brewing temperature would have a different rate of extraction for each fatty compound.

This is why temperature / pressure / flow rate are so important to good espresso - some of the heavier compounds taste very bitter and including much of them in the brew makes for an unpleasant drink.

Fungus and mold will likely appear if you brew anything with water at room temperature.

Use the fridge - trust my experience. It may take a bit longer to brew at colder temperatures, due to decreased convection of the liquid, but it will taste much better, as it prevents bacterial and fungal growth.

I'm not a doctor or a biologist. But I do have a water cooler and have brewed both alcohol and cold brew in the past. There's no super special sterilization process for cold brew, we don't use sterilite on the spike that opens up the bottles, we don't store the water in an especially cool place, or otherwise take any special precautions.

That water turns out fine, often for weeks at a time.

Store the cold brew out of direct sunlight, don't leave the grounds in for a super long time, and you'll be fine. It's not like brewing alcohol, you're not adding a bunch of sugar to it or anything like that. The coffee grounds you're adding are shelf-stable, the water you're adding it to is shelf-stable, you're not introducing any real food for bacteria/fungus. Water will eventually go off if you leave it in direct sunlight (mostly due to algae), especially after introducing extra organic matter, but the actual risks of following established methods for brewing cold-brew at room temperature are very low in my opinion. Especially chlorinated water like you probably get out of your pipes.

This is nonsense. Fungus and mold takes a while to develop, and most probably that timeframe is not over night in ground coffee (or tea). It is still better to do it in the fridge, because if you put it straight in it's less work and tastes good if you leave it overnight.

Overnight, sure. But I like my extracts/brews super strong. After a couple of days you will get mold growth.

Cold-brewing can reliably be done at food-safe refrigerator temperatures over multiple days, safely. The longest brew I've heard used at any coffee shop is 8 days, though I've never tried more than 5 (usually 1 to 3).

Right, that's what I'm saying. If you try to cold-brew non-refrigerated for more than a day, you'll get mold.

I believe fungi aren't too fond of caffeine.

As someone who has terrible kitchen cleaning habits- definitely not true lol.

Wet coffee grounds will grow mold quicker than any other food product I've seen.

Even a pot of coffee will get mold on the top within like a week.

I wonder if this is that the grounds, post use, are somewhat sterilized and vulnerable to rapid colonization.

I believe it has more about the lack of airflow and the compaction and moisture.

Mold (a fungus) has grown in my refrigerated cold brew enough times for this to be false.

More here - https://kitchenappliancehq.com/can-cold-brew-coffee-mold/

Huh... that hasn't been my experience. I notice that article uses a lot of affiliate links, are you sure it's not fear-mongering in order to sell it's special cold brew coffee maker?

Not saying that mold is impossible, but I don't think the solutions is to buy their amazon affiliate coffee maker and special coffee butter.

If you have mold issues after 24 hours of cold brewing I think you have some deeper issues at play. Consider getting mold tests for your house, sterilizing the tools/containers you use, and switching out your beans.

I wasn’t endorsing the article, merely providing it as evidence of mold following my anecdote.

I generally face it 3-4 days in, not 24 hours.

Perhaps, but I've cold brewed black tea enough times with moldy results to forewarn y'all.

Takes more time to get the right amount of extraction

Maybe lower extraction, but honestly, I'd have to get a refractometer or some shit to test it, and I can't really justify that expense.