After Water and Tea, the 3rd one most consumed drink must be the coffee. At some point I am tempted to put coffee in the same position as tea as both being the 2nd most consumed drinks on the planet. Like Tea, coffee is also an art. You must know how to make a good one.
While tea can be harvested from plants which can grow anywhere on Earth, coffee typically grows in forests, in countries like Brazil or Guatemala, where they have high summer temperatures and plenty of rainfall. Like the tea plant, the coffee bush has evolved chemical defences to protect itself against being eaten by animals and insects, in the form of powerful alkaloids like caffeine, which can disrupt the metabolism of an organism. Caffeine’s bitterness is a biological signal from our mouth warning us that we are about to drink something that may be toxic – but, in the case of caffeine, we ignore it; why is that? It’s probably because we’ve grown to like the effect of caffeine on our bodies, as well as other naturally derived alkaloids, like nicotine, morphine and cocaine.
But, of all these psychoactive substances, caffeine is the most widely consumed. It stimulates the nervous system, relieving us of drowsiness, making us more alert. It is also a diuretic, which means it increases the production of urine. The upshot is that after you drink a strong coffee you often need the toilet. At high doses, caffeine can cause insomnia and anxiousness. Caffeine, like alcohol, goes straight into our bloodstream, so its effects are immediatelly noticeable; and, as with the other alkaloids, it’s addictive.
Once you start drinking it regularly, it can be incredibly hard to stop; the withdrawal symptoms can be severe, giving you headaches, making you tired, crabby, sluggish. The coffee we drink is ground from beans, which are the seeds of the coffee bush. They contain a lot of carbohydrates, in the form of sugars, which give the seed the energy it needs to produce new shoots. The bean also contains proteins, which provide the core molecular machinery for the plant, and instruct the seed through the reproductive process – the growth of a new coffee plant. Once the beans ripen, they’re harvested, fermented, removed from the pulp and dried. At this point, they’re hard, pale, green beans. The next step is to roast them; this is where the huge array of flavour in coffee is developed. You can roast your own coffee if you want; I have done it in the past. I bought raw coffee beans from my local coffee supplier, put them into a stainless-steel sieve, and held a hot-air gun over them for a while, constantly shaking the sieve. I was able to roast enough beans to make a cup of coffe in about 5 minutes. If you love coffee, you should really give it a go; you’ll learn so much about the drink.
The first thing you’ll notice as you heat up the beans is their changing colour. They’ll turn yellow first, as the sugars inside the bean begin to caramelize. Then, as the temperature increases, the water inside the bean starts to boil, and pressure from the steam starts to build up; you’ll know this is happening when you hear the beans cracking open under pressure. As you heat them still more, the molecular constituents of the bean start to fall apart, but they also react with each other. This is a very different way of using heat compared to the manufacture of tea leaves. There, heat is used mostly to stop chemical reactions, while with coffee it’s the roasting that starts the chemical reactions which produce most of the flavour. One of the most important reactions occurs between the bean’s proteins and its carbohydrates. This is called the Mailard reaction and it happens when the bean reaches between 160°C and 220°C. The Maillard reaction produces a vast array of flavour molecules; when it starts you can immediately smell them – this is when your beans get that characteristic coffee aroma, as well as many of their savoury qualities, it’s the same chemical reaction that makes the delicious crust when you’re baking bread, and the tasty crispy outer layer on a steak, if you’re roasting or frying the meat. The reaction changes the colour of the bean from yellow to brown, and produces carbon dioxide gas, which will eventually go on to produce the crema foam that sits on top of a cup of coffee. At this point you’ll hear crackling from the beans, as their inner structure ruptures, a result of the gas building up inside them, causing them to swell in size.
If you keep roasting the beans, you’ll start to see them turn a very dark brown as the acid and tannins break down, mellowing the flavour profile. Then you’ll hear a second crack as their interior structure becomes increasingly brittle and weak. You’ll observe small amounts of oil leaking on to the surface of the beans at this point, signalling the complete disintegration of the bean’s cellular structure. These oils, which make up approximately 15% of the bean, leave a glossiness on the surface that’s characteristic of a French roast. If you keep roasting past this point, you’ll get a shinier bean, but also a less tasty one; the high temperatures break down the molecules into smaller structures that produce less flavour. You’ll also lose a lot of the soluble carbohydrates, which
are responsible for the syrupy mouth-feel of the coffee. In general, the blacker the beans, the more generic and simplistic the flavour profile.
When you roast your own beans, you can play around with the flavour profiles as much as you want, until you find a style that perfectly suits your palate. Doing it myself gave me a deep respect for coffee manufacturers; even with two apparently simple variables – temperature and duration of the roast – you can create an enormous range of flavours with the same beans. Once you’ve roasted the beans, you’ve got to extract all of their flavour and get it into your cup. The earliest known methods for grinding and brewing coffee are from the 15th century, in Yemen.
Arab communities there ground the coffee with a simple pestle and mortar, added it to water and then boiled the mixture. This is still a popular way of making coffee in the Middle East; it’s often called Turkish coffee. Making coffee this way gives you a very strong, dark brew; the liquid contains not just the taste compounds of the coffee, but also the grounds themselves, which affects the mouth-feel of the drink, giving it a velvety texture. But this smoothness can turn gritty as you get towards the end of the cup, where the bigger solids form a thick sediment on the bottom. Turkish coffee is also quite bitter; brewing the grounds at boiling point allows a lot of the highly bitter-tasting molecules, like caffeine, to dissolve into the water in large quantities. Generally, people mix a fair amount of sugar into their coffee to offset this, resulting in a bittersweet drink with a high caffeine content. Just what the doctor ordered, if you want to be hopped up on a strong wallop of flavour, combined with the one-two punch of a lot of sugar and caffeine.
But, as satisfying as this can be, brewing coffee this way does eliminate a lot of the fruity flavours from the bean’ s fermentation, and the nutty and chocolatey flavours you develop through the roasting. Thus we discover one of the biggest problems with coffee – it often smells better than it actually tastes. Why? Because so many of the aromas that should have been released inside your mouth have already been released into the air while the coffee was brewing, leaving behind just the bitterness and acidity, with very few of the aromatics. To keep from losing so much of the aroma during the brewing process, it’s best to brew at lower temperatures. This also limits the bitterness, and gives you coffee with a lower caffeine content. While the velvety texture of Turkish coffee can be quite pleasant, those last sips of grit aren’t great. As such, separating the coffee grounds from the liquid became a major objective in the brewing process – welcome, the coffee filter.
Making coffee by filtering it through a fine mesh or a filter paper allows the coffee to be brewed as the hot water comes in contact with the fine grains, but then the liquid drips through the filter, and into another collecting vessel, leaving the grains behind. The speed of the process is determined by how hard it is for the water to be pulled through the grounds. If there are too many grounds, or the powder is too fine, then the water takes a long time to drip through, thus dropping in temperature, which makes it impossible for the liquid to extract all of the molecules that could give the drink flavour. Likewise, brewing the coffee with too much water, or too-coarse grains, will give you a weak cup, with little body and too much acidiry, because the water won’t be in contact with the grains long enough. But if you do it right, filtering will give a warm pot of clear, golden, grain-free coffee. There won’t be a crema, though.
For a lot of people, the perfect cup of coffee has a crema floating on top of the liquid – a foam created by the carbon dioxide gas that’s produced during the roasting process, then released from the ground beans while the coffee’ s brewing. When you use a coffee filter, all the carbon dioxide is released during the filtering. No matter, though; over the last 400 years, many other brewing methods have been invented that preserve the crema, induding the Moka, the cafetiere and, of course, the espreso machine. Along with producing a crema, the cafetiere is generally faster than using a filter because the coffee grounds are first mixed with the water at about 100°C, and as the coffee brews – usually for a few minutes (further brewing releases a diminishing return of flavour, and increases bitterness) – the temperature decreases to about 70°C. So, the flavour molecules are, at first, extracted quite rapidly, as the surface of the coffee grains are exposed to the hot water, but that declines as the temperature goes down, and it becomes increasingly difficult for the water to access the interior of the partides. This is when the carbon dioxide is released from the grains, and escapes to the surface of the pot, trapping the liquid and forming the crema.
When the coffee’s done brewing, you just have to plunge the cafetiere’ s filter to stop the brewing and trap the coffee grounds. If you pour the coffee immediately, you’II have a balanced, hot cup with that pleasing crema on top. To make stronger coffee without increasing its bitterness, you can use either lots of coarse grains or fewer fine grains, the problem with the latter being that they can escape through the plunge filter and make their way into your cup, and the problem with the former being that you won’t be able to extract as much flavour from the grains.
The easiest and fastest way to make a coffee that is to let the esspresso machine do it for you in less than a 1minute. But it can happen that the coffee the esspresso machine is giving you might not really entertain your taste as you might expect, so there must be an alternative. Such alternative can be the coffe made in a Moka pot. But then comes the question which one is better?
One way around this dilemma is to try a Moka coffee pot. In this device, the water is kept separate from the coffee grounds in a sealed compartment. When it’s heated to a boil, the water produces hot steam, which increases the pressure in the pot, eventually reaching about one and a half times the atmospheric pressure, and pushing the hot water through the coffee grains, and into an upper compartment once its brewed. Using the Moka extracts a lot more flavour than the cafetiere or a coffee filter, and it makes a strong cup. The downside of the Moka, though, is that, as the water level in the boiling chamber decreases, incredibly hot steam mixes with the water, and as that steam passes through the coffee grounds, its high temperature extracts a lot of bitterness, often giving the coffee a burnt edge.
The espresso machine refines the principles of the Moka into the most reliable – and some say the best-tasting – coffee that can be made. The espresso machine, so named because it can make coffee in 30 seconds, heats water to between 88°C and 92°C, and then puts it under intense pressure (about 9 times atmospheric pressure), before pushing it through the coffee grounds. The high pressure extracts the maximum amount of flavour and, because the system doesn’t rely on steam, it doesn’t overdo the bitterness and astringency. The speed of the system is important: it means there is very little time for the volatiles from the coffee to escape into the air. So you end up with a full-bodied coffee, with a great balance of nutty, earthy, savoury flavours, both fruity and acidic, with a wine-like astringency. Because the mechanisms of an espresso machine are so controlled, it produces great coffee every time, and it’s incredibly fast. This is why it’s used in most commercial coffee shops, and the number of drinks you can make with it seems to have no end. Served on its own, it’s called an espresso. If you add hot water to it, you’ve got an Americano; equal amounts of hot milk and foamed milk make it a flat white; foamed milk on its own makes a cappuccino; and so on.
As with tea, milk changes the flavour profile of coffee quite radically, smooting the astringency, but also flattening the flavour profile and replacing it with a maltier, creamier flavour. Aeroplanes use smaller versions of espresso machines to serve first-class passengers, but the coffee served to everyone else made with a filter. Due to the lower air pressure on an aircraft, the boiling point of water is around 92°C – which, incidentally, is perfect for coffee. That being said, coffee that’s been kept warm for too long a period of time between brewing and drinking – as might happen on a plane, or in your office coffee machine – will lose a lot of its aromatic flavour, leaving you with just bitterness and astringency.
And that’s not the only thing keeping you from enjoying that sort-of-hot aeroplane coffee. Studies have shown that our sensitivity to the 5 basic tastes – sweet, sour, salty, bitter and unmami – is affected by aeroplane noise, as well as our sense of smell. Because of this, it’s impossible to taste the coffee you’re drinking with the same nuance you might on the ground. This confirms my experience of flying; I generally don’t enjoy coffee on planes as much as I think I’m going to. So which drink is better – coffee or tea? Certainly, each one suits different moods and moments in life. But there are times, such as when you’re on a plane in economy class, when you need to recognize that even if tea suits your mood, the chances of getting a good cup are so slim, you should just say no. I say this really as a note to myself.
Having observed and tasted different coffee types like the ones shown below:
I have now learnded that the following 9 rules to make a good coffee can give execelent results:
RULE 1 = Buy Fresh Beans: Without question, coffee is best when used within days of being roasted. Buying from a local roaster (but you can roast coffee yourself) is the surest way to get the absolute freshest beans. Be wary of buying bulk coffee from supermarket display bins. Oxygen and bright light are the worst flavor busters for roasted beans, so unless the store is conscientious about selling fresh coffee, the storage tubes get coated with coffee oils, which turn rancid. Coffee beans packaged by quality-conscious roasters and sold in sturdy, vacuum-sealed bags are often a better bet.
RULE 2 = Keep Coffee Beans Fresh: Always store opened coffee beans in an airtight container. Glass canning jars or ceramic storage crocks with rubber-gasket seals are good choices. Never refrigerate (roasted beans are porous and readily take up moisture and food odors). Flavor experts strongly advise against ever freezing coffee, especially dark roasts. Optimally, buy a five- to seven-day supply of fresh beans at a time and keep them at room temperature.
RULE 3 = Choose Good Coffee If It’s Within Your Budget: Snobbism among coffee drinkers can rival that of wine drinkers, but the fact is that an astonishing world of coffee tastes awaits anyone willing to venture beyond mass-marketed commercial brands. Specialty coffees that clearly state the country, region or estate of origin can provide a lifetime of tasting experiences. There are two major beans on the market–Arabica and Robusta. Arabica beans are more widely produced, have a wider range of flavors and are generally considered the “better bean.” By all means, look for 100% pure Arabica beans. The cheap alternatives may contain Robusta beans, noted for their higher caffeine content but harsh flavors. “Nasty” is a term commonly linked to Robusta coffees by Arabica devotees. But these types of coffee can be expensive. If your barista budget has taken a hit, there are plenty of good grocery store brands that deliver your morning buzz at half the price of fancy beans.
RULE 4 = Grind Your Own: Coffee starts losing quality almost immediately upon grinding. The best-tasting brews are made from beans ground just before brewing. Coffee connoisseurs prefer to grind in expensive burr mills, but affordable electric “whirly blade” grinders like Bodum will do a serviceable job, especially if the mill is rocked during grinding to get a fine, even particle size. Scoop for scoop, finer grinds yield more flavor.
RULE 5 = Use Good Water: Nothing can ruin a pot of coffee more surely than tap water with chlorine or off-flavors. Serious coffee lovers use bottled spring water or activated charcoal/carbon filters on their taps. Note: Softened or distilled water makes terrible coffee–the minerals in good water are essential.
RULE 6 = Avoid Cheap Filters: Bargain-priced paper coffee filters yield inferior coffee, according to the experts. Look for “oxygen-bleached” or “dioxin-free” paper filters (e.g., Filtropa, Melitta). Alternatively, you may wish to invest in a long-lived gold-plated filter (e.g., SwissGold). These are reputed to deliver maximum flavor, but may let sediment through if the coffee is ground too finely.
RULE 7 = Don’t Skimp on the Coffee: The standard measure for brewing coffee of proper strength is 2 level tablespoons per 180ml cup or about 2 3/4 tablespoons per 240ml cup. Tricks like using less coffee and hotter water to extract more cups per pound tend to make for bitter brews.
RULE 8 = Beware the Heat: Water that is too hot will extract compounds in the coffee that are bitter rather than pleasant. The proper water temperature for brewing is 90°C, or about 45 seconds off a full boil. (Most good coffee makers regulate this automatically.) Once brewed, don’t expect coffee to hold its best flavors for long. Reheating, boiling or prolonged holding on a warming platform will turn even the best coffee bitter and foul-tasting.
RULE 9 = Keep Your Equipment Clean: Clean storage containers and grinders every few weeks to remove any oily buildup. At least monthly, run a strong solution of vinegar or specialty coffee-equipement cleaner like Urnex through your coffee maker to dissolve away any mineral deposits. Rinse thoroughly before reuse.
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