Cold Brew vs. Iced Coffee
What’s the difference? Why has cold brew become so trendy? This rabbit hole may be even deeper than the Water for Coffee rabbit hole. Let’s dive in!
What is cold brew?
Cold brew is coffee that is brewed using cold water (room temperature or lower).
Cold brew is coffee that is brewed using cold water (room temperature or lower). It may have a “hot bloom” phase where a small amount of hot water is poured onto the grounds first, followed by the cold water, or it may not. Fundamentally, it’s just like doing a French Press brew with cold water (you can actually do literally that). The grind size for cold brew is typically very coarse and the brew time is typically 14+ hours. Brew ratios for cold brew are usually very strong, somewhere in the 1:8 to 1:10 region (that ratio is grams of coffee to grams of water). At that strength, it is really more of a concentrate than ready-to-drink (RTD), though it isn’t uncommon to drink it as a concentrate. The flavor profile? Pretty one-dimensional, kind of like stale chocolate to be honest. The cold brew process is the great equalizer - it makes really bad quality coffee taste much better than it would if you brewed it hot, but it makes really good quality coffee taste a lot worse than it would if you brewed it hot. Why is this? Temperature is a measure of energy. With cold brew, there just isn’t enough energy to extract a lot of the really interesting flavor compounds that make good coffees good, no matter how long you let it brew for. People often say that they like cold brew because it is less sour than traditional iced coffee but we’re always a little confused by that. The pH (measurement of acidity/sourness) of cold brew is more or less identical to the pH of iced coffee. Our take is that they are actually enjoying the cold brew more than the iced coffee not because it is less sour but because it is less bitter - with the lower extraction that you get with the cold brew process, you will get a lot less bitterness. And bitterness is typically one of the major complaints about traditional iced coffee, which leads us right into that.
Traditional iced coffee was nothing more than hot coffee (brewed at normal strength) that got poured onto a cup full of ice. Because it was already at normal strength before getting poured over ice, the resulting iced coffee was very weak and watery. Furthermore, because most coffee used to be roasted fairly dark (and still is, apart from in the specialty market), not only was it watery, it was also very bitter, as the darker the roast, the more bitter the coffee is. It is easier to taste the bitterness when the coffee is cold. So traditional iced coffee was really pretty terrible - that’s why cold brew became so popular.
Flash Brew
This is coffee that is brewed hot at a much stronger ratio than normal hot coffee, but brewed directly onto a specific amount of ice.
However, there’s another option, which goes by several names: “Japanese iced coffee” or “flash brew” or “flash chilled iced coffee.” This is coffee that is brewed hot at a much stronger ratio than normal hot coffee, but brewed directly onto a specific amount of ice. The ice of course melts, which makes the hot liquid become cold, and it dilutes it back to normal coffee strength. So you end up with cold coffee in just a few minutes. Since it was brewed hot, you get all the nuances in flavor that you get with normal hot brewing (remember, you need that additional energy from the hot water to extract those interesting flavor compounds), but you get to drink it cold. Since the roasting for this style of iced coffee is typically lighter, you don’t have the bitterness problem either.
Note that the kind of iced coffee described in the previous paragraph is different from “Kyoto style cold drip,” which is more or less the same thing as normal cold brew, the only difference is that cold water is dripped very slowly through coffee grounds over the course of many hours, rather than having the cold water sit with the coffee grounds for many hours.
Flash brew seems to have a hard time gaining the popularity of cold brew. In our experience, this is because in a quick conversation about cold coffee with someone who has really only experienced bad, traditional iced coffee and cold brew, the main question that gets asked is “is this cold brew?” or “was it brewed with cold water?” When the answer is no, that is off-putting. And it’s perfectly reasonable for people to think this way! Every time they’ve tasted cold coffee that was brewed hot, it has been bitter and watery, and every time they’ve tasted actual cold brew, it has been strong and chocolatey. So of course they want cold brew!
However, in blind tastings, even with people who self-identified as cold brew lovers prior to the tasting, an enormous majority of people prefer the flavor of flash brew. The flavor profile is more complex and nuanced. There is sweetness and acidity and bitterness that work together to create balance.
Here's how outrageous the situation is: at our cafes, for cold coffee, we serve flash brew only. But the menu on the wall says "cold brew" not "flash brew" because literally 99% of people walk in and just say "can I have a cold brew" without even looking at the menu. It is a brew that is cold after all so it's not lying though we admit it is very misleading. When the small number of people who ask about it ask about it, we of course explain that it's actually flash brew.
At our sister company’s cafe, they used to have it say "flash chilled iced coffee" on the menu, and then they’d go down the rabbit hole having to explain what it is and how it's different from cold brew and also different from old school iced coffee. The customers response would end up with a "wow that sounds interesting, I'll have an iced vanilla latte." Some people would think it sounded good and would get it. But it was on the menu for many years and they never made much progress with it in terms of getting people to specifically ask for it. It was and is quite popular. People like it. But they still ask for it by the name “cold brew.”
At our cafes, we have canned 4-packs of cold brew in the fridge, and we used to have canned 4-packs of flash brew (we called it Ice Brew). And people would look at the cans and we'd explain that if they liked the "cold brew" that we serve by the cup normally (which was actually flash brew) that they would like the Ice Brew better, but if they preferred a more traditional cold brew kind of flavor profile better, they'd like the Cold Brew cans better. The Cold Brew cans outsold the Ice Brew cans by at least 10:1 ratio, maybe even more. So we stopped creating the Ice Brew cans. The "cold brew" that we sell by the cup is very popular. People really like it. But they want a product that is called "cold brew." And, if presented with choices about flavor profile, they picked the chocolatey profile EVEN IF THEY HAVE TASTED THE FRUITIER STUFF AND LIKED IT SO MUCH THAT THEY COME BACK SPECIFICALLY FOR IT. Consumer behavior/psychology is wild, friends.
