QA S2 · Polylang

Author: qa-admin

  • Cold brew at home: ratios and times

    Cold brew is made with cold water and many hours, not with ice over hot coffee. The result is sweet, low in acidity and very refreshing.

    It’s the easiest way to have coffee ready in the fridge all week, and you don’t need any special equipment to make it. A large jar, a strainer, a paper filter and a little patience are enough.

    Steaming cup of coffee, animation

    What it is and what it isn’t

    Cold brew is not the same as iced coffee. With iced coffee you make a hot drink and chill it all at once; with cold brew the coffee is never heated. Cold water extracts more slowly and leaves behind a good part of the acidic and bitter compounds, which is why the result is so smooth.

    Another advantage is that it’s very forgiving. You don’t have to control the water temperature or time it to the second, and an hour more or less barely shows. It’s a good method for when you don’t feel like keeping an eye on the brewer.

    The immersion method we use here is a close cousin of the French press: all the coffee in contact with all the water, just at a different temperature and for many hours instead of four minutes. If you already make coffee in a press, you can use it for this too.

    Ratio and time

    Ratio

    For a concentrate, use one part coffee to eight parts water: 100 g of coffee with a very coarse grind for 800 ml of water.

    That concentrate isn’t meant to be drunk as is. When serving, dilute it with the same amount of water or milk, or a little more, depending on how strong you like it. If you’d rather make it ready to drink, use one part coffee to fifteen parts water and let it steep a few hours longer.

    Time

    Between 12 and 18 hours in the fridge. Less than 12 comes out weak; more than 20 starts to turn bitter.

    Temperature changes the timing. At room temperature extraction is faster and ten or twelve hours can be enough, but in summer it’s better to do it in the fridge so the coffee doesn’t pick up odd flavors. Write down how long you left it and adjust in the next batch. If your fridge is very cold, extraction slows down and you may need the full eighteen hours.

    Which coffee to use

    It works better with a medium roast, with chocolate and nutty notes, than with a very acidic light roast.

    Use filtered water: in the cold, limescale and chlorine show more than in hot coffee. Since the water spends so many hours with the coffee, any flavor it brings ends up in the bottle.

    Buy whole beans and grind them yourself. With the amount of coffee each batch takes, a grind that’s a few days old shows in the result much more than in a single hot cup.

    If you feel like something different, try natural-process Ethiopian coffees: cold, they bring out very pleasant strawberry and blueberry notes. A floral washed coffee, on the other hand, can come out too light and does better in the V60.

    Step by step

    • Grind the coffee very coarse right before you start.
    • Mix it with the cold water in a jar and stir so no dry clumps are left.
    • Cover it and let it steep in the fridge for 12 to 18 hours.
    • Filter it twice, first with a strainer and then with paper.
    • Bottle the concentrate and dilute it when serving.

    Filtering

    Pour it first through a fine strainer and then through a paper filter. That second step removes the sediment and makes it last longer.

    Common mistakes

    • Grinding fine: the sediment gets through the filter and the drink turns cloudy and bitter.
    • Leaving it for more than a day: woody, dry notes appear.
    • Not stirring at the start: pockets of dry coffee are left that never extract.
    • Storing it unfiltered: the sediment keeps extracting inside the bottle.

    Storage

    The concentrate keeps for about seven days in the fridge, in a closed bottle. The same storage rules for the beans apply to the drink.

    Keep it in a tightly closed glass bottle and away from strong-smelling food. If you notice a vinegary or flat taste, it’s past its best. Make as much as you’ll drink in a week and no more.

    Ways to serve it

    On its own over ice, with cold milk, or with sparkling water and a strip of orange peel. It also works as a base for desserts, like a granita. Since it has no marked acidity, it pairs well with plant-based milks, which sometimes curdle with a hot, acidic coffee.

    If you want it sweeter, add the sugar or syrup to the concentrate before diluting it and stir well, because sugar takes a long time to dissolve in the cold.

  • Water for coffee: hardness, temperature and ratio

    A cup of filter coffee is more than 98% water. With bad water, no bean or recipe can save it. That’s why it pays to spend a little time understanding what water you use, at what temperature and in what amount.

    You don’t need a lab. If you know where your water comes from and have a kettle that lets you control the temperature and a scale, you have everything you need to stop fighting with coffees that never quite taste the way you expected.

    Hardness

    Water needs some minerals to extract well, but not too many. The ideal water hardness is around 50 to 100 mg/l. Very hard water mutes the acidity and leaves limescale in the brewer; very soft water gives flat cups.

    Why minerals matter

    Magnesium and calcium help pull aromatic compounds out of the bean, while bicarbonates neutralize part of the acidity. Water with a lot of bicarbonate leaves a dull cup, however good the coffee. That’s why two waters with a similar total hardness can give very different results.

    How to know what water you have

    The company that runs your town’s water supply usually publishes its analyses by area. There are also cheap test strips that give you a rough idea of the hardness. If your brewer builds up limescale often or your kettle has a white crust, your water is almost certainly hard.

    What to do if your water isn’t good

    • Filter pitcher: it reduces chlorine and some of the limescale, and it’s the most convenient fix.
    • Low-mineral bottled water: useful for comparing and for delicate coffees.
    • Mixing tap water with very soft water: an easy way to bring the hardness down.
    • Avoid distilled water on its own: without minerals, the extraction falls flat.

    With a delicate coffee, like many Ethiopian coffees, the difference between hard water and balanced water shows right away. With the second, the acidity and floral notes come through; with the first, they stay buried under an earthy background.

    Temperature

    Between 90 and 96 °C. Hotter extracts more bitterness, and cooler falls short. If you don’t have a thermometer, let the water rest for 30 seconds after it boils.

    With a French press it’s best to stay at the top of that range, around 94 °C, because the coffee spends four minutes in contact with the water.

    How to measure it

    A kettle with temperature control is convenient, but not essential. A kitchen thermometer works just as well, and with practice you’ll learn how long your kettle needs to rest to land in the right range. What matters is doing it the same way every time, so temperature stops being a guess.

    Depending on the roast

    A light roast likes the top end of the range, because the bean is denser and harder to extract. A dark roast, on the other hand, extracts easily and turns bitter if the water is too hot. With the V60 and a light coffee, starting at 93 or 94 °C is a good reference.

    Ratio

    The reference is 60 g of coffee per liter of water. From there, adjust to taste. Cold preparations like cold brew use a much more concentrated ratio.

    • Filter: between 60 and 65 g per liter.
    • Immersion: between 60 and 70 g per liter.
    • Espresso: measured differently, by the ratio between ground coffee and the drink in the cup, often one to two.

    Ratio and grind go hand in hand. If you add more coffee without touching the grind size, the cup gains intensity but can also turn more bitter. Adjust the ratio first until the coffee has the strength you like, and then fine-tune the flavor with the grinder.

    Weighing the water instead of measuring it by volume gives you more precision. A milliliter of water weighs practically a gram, so the same scale works for the coffee and the water.

    Habits that help

    Use water fresh from the tap or the pitcher, not water that has been sitting in the kettle for hours or that you have already boiled several times, which keeps getting more concentrated. And descale your brewer regularly: built-up limescale changes the real temperature of the water coming out and the flow at which it passes through the coffee.

    If you’re unsure, try a simple test: brew the same coffee twice, once with tap water and once with filtered or low-mineral water, and taste them side by side. Few comparisons teach you as much in so little time. And if you travel with your coffee, expect it to taste different in another city just because of what comes out of the tap.

  • How to store coffee at home

    Roasted coffee is a fresh product. From the moment it leaves the roaster it starts losing aroma, and the way you store it decides how long it takes before you notice.

    The good news is that you don’t need anything special. With a couple of simple habits, a bag of coffee stays in good shape for as long as it takes you to finish it. Here’s what spoils it, where to keep it and which habits are better forgotten.

    What happens to coffee after roasting

    During the first few days, the beans release carbon dioxide. That’s why good bags have a one-way valve: it lets the gas out without letting air in. This degassing is normal and, in fact, it’s worth waiting a few days before brewing a freshly roasted coffee.

    After that, oxidation begins. The oils and aromatic compounds react with oxygen and the coffee gradually loses its nuances. The most delicate notes go first, like the floral ones in many Ethiopian coffees, and in the end you’re left with a flat cup with a stale background that reminds you of cardboard.

    All of this happens more slowly in whole beans than in ground coffee, and more slowly in the cold than in the heat. That’s why storage advice always comes back to the same thing: keep the bean intact for as long as possible and protect it from its surroundings.

    Coffee’s four enemies

    • Air: it oxidizes the oils and turns them rancid.
    • Light: it breaks down the aromatic compounds.
    • Heat: it speeds up every reaction.
    • Moisture: the beans absorb it, and odors along with it.

    None of them ruins coffee overnight, but they all add up. An open bag next to the stove, in the light from the window and badly closed, ages as much in a week as it would in a month inside a cupboard.

    Where to keep it

    In its own bag if it has a seal and a valve, or in an opaque, airtight canister. Always in a cupboard, away from the oven and the window.

    If you buy from a roaster, check whether the bag can be resealed. Many have a zip closure, and all you have to do is press the air out before closing it.

    Which canister to choose

    Look for an opaque container with a seal that really closes, and about the same size as the amount of coffee you buy. A canister that’s too big leaves a lot of air inside. Clear glass jars look nice on the counter, but they let light through: if you use them, keep them inside a cupboard.

    Fridge or freezer?

    Not the fridge: there’s moisture and odors. The freezer only works if you freeze vacuum-sealed portions and never refreeze them.

    If you decide to freeze, split the coffee into one- or two-week portions, seal each one without air and take it out the night before so it reaches room temperature before you open it. That way you keep moisture from condensing on the cold beans.

    How long it lasts

    Whole beans: a month at their best and up to three months acceptable. Ground: a week. That’s why it pays to choose a good coffee in small bags and buy it more often.

    If you buy your coffee already ground, it loses freshness even faster, because grinding multiplies the surface exposed to air.

    It’s one more reason to grind right before brewing. With a grinder at home, coffee keeps well for weeks and you can match the grind size to each method, whether it’s the V60 or the French press, instead of settling for a one-size-fits-all grind.

    How much to buy at a time

    Work out what you drink in two or three weeks. If you have two cups a day at 15 g each, you go through a little over 200 g a week, so a 250 g bag lasts you a week and a one-kilo bag would be too much. Buying often is cheaper than it looks, because you don’t throw away stale coffee.

    How to tell it has gone off

    Smell the beans when you open the canister. Fresh coffee fills the kitchen; stale coffee barely smells, or smells like rancid nuts. In the cup you’ll notice it as a lack of sweetness and a dry finish. It isn’t harmful, but it’s no longer worth spending a good brewing method on it.

    Common mistakes

    • Moving the coffee into a canister and throwing away the original bag: you lose the valve and the roast date.
    • Keeping it next to spices or cleaning products: the beans absorb the odors.
    • Taking the bag out of the freezer every morning and putting it back.
    • Buying a kilo because it’s cheaper and taking two months to finish it.

    And if you make cold brew, remember that the finished drink goes off too. It has its own rules, but the logic is the same: constant cold, a closed container and drinking it within a few days.