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Become a Coffee Expert! Guide for Making a Perfect Cup at Home
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Become a Coffee Expert! Guide for Making a Perfect Cup at Home

espresso from the coffee machine

Instant coffee dissolves in water just like sugar or salt. All is necessary is to scoop the required amount of it and mix into the water. Water for the instant coffee making can be of any temperature. You can stir as long as you want and if your coffee is not strong enough, you can always add a little more. Instant coffee is a two-ingredient beverage: coffee powder and water (not counting other optional ingredients, of course). Brewing a cup of natural coffee is a far more complex process. Many variables in coffee brewing contribute to the final product. In reality, natural coffee is a multi-ingredient beverage. Though it seems like there are just two main ingredients: ground coffee and water, the coffee itself is a mixture of different ingredients with a very different taste. Some of them we want more of (like sweetness), while some of them we want less of (like bitterness). The idea is to add them in the right proportions, just like when cooking a meal or making a cocktail. All of the ingredients are blended within the coffee beans.

a cup of coffee

The challenge is to get them out of the beans in the right quantities. Brewing a perfect cup of coffee is mostly science, with a little bit of art added to it. There are several crucial factors: grind size, grind consistency, roast, water temperature, coffee-to-water ratio, brewing method, brewing duration, etc.

Coffee Extraction Basics

As already mentioned, coffee brewing is not the same as simply diluting something in water. Normally just over a quarter of the whole amount of ground coffee beans (by mass) is soluble. The remaining three quarters can’t be diluted. So, no matter how hard we try, we can extract approx. a quarter of the coffee beans content into our coffee cup. This includes all the soluble contents: “good” and “bad”. When ground coffee comes in contact with water, the brewing process begins. For the first few seconds, the coffee particle is getting wet, just soaking in preparation for extraction. The smaller the particle, then the finer the grind, so the faster the “wetting” phase passes. Then the extraction or dissolution begins. It is crucial to remember that different tastes are extracted at a different time. There are three main phases to coffee extraction. Oils and fruit acids come first, these are the easiest to dissolve. Various sugars come next and bitter soluble components are extracted last. Sugars normally take longer to extract than acids. Bitterness that comes from coffee fibers takes the longest to dissolve.

espresso from the machine
Oils and acids extract first

Of course, this is an oversimplified and a very schematic picture. In reality, all three phases overlap one another to some degree. Also, there are more subtle tastes involved. However, understanding this simple extraction formula (oils/acids-sugars-bitterness) is a big step towards brewing a perfect (or optimal) cup of coffee. Why is this so important? By evaluating your not-so-perfect cup of coffee, you will know where you stand. Is your coffee sour? Is it bitter? Is it astringent? Is it not sweet enough? Once you know that, you will also know what coffee brewing adjustments need to be done.

Remember the (oils/acids-sugars-bitterness) brewing formula

Under brewing vs. Over brewing. Achieving the Perfect Balance

Under brewing

Just like many dishes can be undercooked or overcooked, coffee can be under brewed or over brewed. This applies to both the cheapest coffee maker and the most expensive coffee machine. Actually, under brewed or over brewed coffee from the more advanced coffee machines will be even worse than from the cheap ones. Expensive coffee machines have a lot of settings and tweaks, they are designed to take the most out of the coffee beans. Therefore, being more efficient, they are also usually more sensitive for finding the right balance.

Tasting an under brewed coffee is like biting into an unripe green apple with a hint of salt and cigarette ash..

unripe green apple

As we know from the extraction basics, oils and acids dissolve first. Thus, if the cup of coffee is unpleasantly sour and lacks sweetness (like an unripe fruit), then it is most likely under brewed. Dark roast coffee in this case can also have too much of an ashy taste. They can also have a “carbony” flavor, which usually comes from over roasting, when some of the sugars carbonize. Many dark-roasted beans have a bit of a burnt flavor, especially Robusta coffee. Oils, as we know, are also extracted in the first brewing phase and will persist in the absence of sugars and complex acidity. Under brewed coffee also tastes a bit salty. A certain aroma and body will already be present in it, because both also come from oils and fats. However, these nice qualities will be overwhelmed with sourness. Under extracted coffee will also have little to no finish. Finish is the aftertaste that lingers for a minute or so after taking a sip. This is why it is perfectly natural to savor even a small cup of a well-brewed coffee over time, by taking small sips. A taste of under brewed coffee, lacking finish, will vanish right after it is swallowed. Under brewed coffee will also lack brightness or complex acidity. Read below on the difference between sourness (“bad” acidity) and bright and complex (“good” acidity).

To summarize, under brewed coffee tastes: unpleasantly sour, lacking sweetness, a bit salty with a bit of a burnt, “carbony” or ashy flavor. It also lacks body, or fullness, and bright complex acidity. It exudes salty and sour taste.

The most common reasons for under brewing are too coarse of a grind and too short of an extraction time. Other reasons include too low of a water temperature, lack of agitation, not enough brewing water, water “short circuiting” coffee grounds, etc.

Over brewing

Over extraction or over brewing is at the other extreme of our coffee-making process. This is the part where nearly all acids, oils, fats and sugars are taken out of the grounds, and the extraction of hydrolyzed insoluble carbs begins. The stage in which bitter insoluble components become bitter soluble ones is the last part of the coffee extraction. At this point these components start to dissolve into our coffee more and more. It is mostly the fibers in the coffee that contribute to the bitterness.

Over brewed coffee produces an alarmingly bitter, astringent, empty and simply dead sensations. It tastes like everything.

It almost tastes like a cup of hell: dark, dry, hollow and bitter. If under extracted coffee is still OK to swallow (it is mostly just sour), the over brewed one just doesn’t go in. It is like the body rejects it as something totally unnatural, like food or wine that has gone bad. It gives such a dry sensation as if you just scraped your tongue. Such a kind of coffee tastes like everything, it is like a letter the text in which is so dense that words overlap and it is unreadable. You just want to crumple it up and throw it away.

crumpled paper

The most common reason for over brewing is literally brewing for too long or using too much of brewing water. Sometimes, like with the Aeropress coffee maker, ten extra seconds can be already brewing for too long. When it comes to expensive sophisticated coffee machines, one extra second of brewing may result in overly extracted bitter coffee. Another common mistake is grinding beans too finely. Too fine of a grind provides much more surface for water to come in contact with. Therefore, extraction will begin sooner, go faster and may reach the point of over extraction before you know it. A fine grind is mostly used for making espresso, which takes just seconds to brew.

To summarize, over brewed coffee is bitter, dry, hollow and astringent.

Luckily, it takes the longest amount of time for the bitter fibers to release their specific taste. For desired oils, acids and sugars it takes much less time to release them. In other words, bitterness comes last. Therefore, this process is relatively easy to control. Basically, it means ceasing the brewing process just before over extraction begins.

Needless to say, you can’t get a balanced cup of coffee by mixing under brewed coffee with an over brewed one; or by adding water to an over brewed coffee.

Perfectly Brewed Coffee. Balanced and Multidimensional

 A cup of a good coffee will harmoniously combine sweetness, aroma, body, bright acidity and a hint of bitterness and saltiness. This will happen when everything falls into place: grind size, water temperature, water-to-coffee ratio, etc. The brewing process of an optimal cup will stop at that perfect spot, just before over extraction will begin. In a perfect world a cup of coffee will have extracted all that we want from the beans. All that we don’t want will remain behind in the grounds. Such coffee will be perfect, or optimal. It will have good body or fullness, complex acidity or brightness, and a good finish.

blight and balanced coffee
“Bright” and balanced coffee

It will be sweet, flavorful and slightly bitter. As opposed to under brewed and flat and over brewed and dead, a good balanced cup is multidimensional. There will be several aspects of sweetness, brightness and complex acidity in it.


Body is the “fullness” of coffee. It is very similar to the body of red wine, and it is about coffee richness. The more oils and acids are extracted out of the beans, the more body it will have and the less watery it will taste.

coffee bean

Body normally increases as coffee beans age. Aging coffee beans reduces its acidity and gradually makes coffee rather dull and flat.

Acidity vs. Sourness

Acidity and sourness are two seemingly identical characteristics of a solution. However, when it comes to coffee, they are not the same. The difference between sourness and acidity is in the overall coffee taste. Acidity in coffee is usually a positive quality and equals a pleasant combination of various fruity acids along with the sweetness of sugars. Sourness in coffee is usually referred to a as simple sour taste coupled with a lack of sweetness.  For example, lemon juice (even mixed with water) is sour (a sharp and rather a bad taste to savor). A mixture of lemon, orange, apple, etc. juices in the right proportions with some added sweetness, is positively acidic and bright. This is an example of a good complex taste. Though total acidity (speaking in chemical terms) of the resulting beverage may be higher, the overall taste is more complex and pleasant. Sourness. on the contrary, is strikingly unpleasant and is a result of under brewing.

Acidity is multifaceted and deep, it is where we want to land in the brewing process. Coca Cola is a good example to understand the difference between sourness and acidity. Is Coca Cola acidic? It definitely is, as its pH is around 2.5. But is it sour? Not at all, its taste is well balanced, the acids and sugars (sweeteners) are in harmony.

cola and ice

Going back to our lemon juice, that has the same pH Coca Cola of about 2.5. It is also very much acidic, and it is really sour, even if mixed with water. Lemon water may be one of the healthiest beverages that exist, but it is hard to swallow it without puckering your face. By the way, lemon water or juice is a great alkalizer and is one of the best morning drinks.

lemon water

Acidity is not necessarily well balanced. This means that there can be more or less of different acids in a particular coffee. It is perfectly normal that one or more acidic tones are more prevalent in coffee beans of different origins. There are several acids normally found in coffee. These are citric acid, malic acid, phosphoric, tartaric, lactic, acetic acids and a few others. As a rule, the amount of acids in coffee diminishes with roasting, some more than others. Storing time and temperature also influences total acidity, which reduces as the coffee beans age. Storing coffee beans in the fridge in a special airtight container preserves acidity best.

 Coffee lacking acidity is flat. Acidity is also known as brightness, which is an easier-to-grasp term. Bright coffee has literally bright, luminous and “expanded” taste. Acidity reduces as the roast gets darker. Light (or blond) roasts are probably the acidity champions, because more acids are retained when they are not being broken down by high temperature.

As opposed to coffee brewing vocabulary, in chemical terms sourness and acidity are all the same. Coffee has a pH of less than 7.0 and, therefore, considered acidic. Excessive coffee consumption can shift the body acid-alkaline balance to the acidic side. It is important to compensate for this extra sourness by balancing the diet.

vintage coffee machine

Where to Start?

Brew a test cup and evaluate it. For example, you have a French press and want to brew with it. It is best to use the press with multiple strainers to avoid tiny particles in your cup. Record all the brewing parameters, everything is important. Having a precision scale is very much recommended. Set you grinder somewhere in the middle, it is best if there is a scale with numbers on the adjustment wheel. For example, the Baratza Encore grinder has a scale from 0 to 40, so set the grind size to 20 to begin with (the manual recommends 28 for French press). Use a typical coffee-to-water ratio, for example, 1:17 by mass. Use water from the kettle that just came to a boil. This will eventually result in approx. 90 C/195 F brewing temperature, depending on the coffee maker temperature and material. Set the test cup brewing time to 2 minutes.

The parameters list will look something like this:

  • Coffee Beans: 10 grams of Lavazza Super Crema Medium Roast
  • Grind: 20 units on the scale
  • Water: 170 ml that just has come to a boil in the kettle
  • Brewing time: 2 minutes
  • Stirring: 20 times in circular motion
  • Water-coffee mixture temperature after stirring (a recommended measurement if you have an electronic thermometer): 90 C/195 F

A recommended list of accessories besides a brewer and a kettle looks like this:

So, once you are ready, measure the desired amount of coffee beans (10 g) and grind them. Remember, that the ground coffee shelf life is 20 minutes, so its better not to grind it in advance. Boil some water in the kettle. Briefly rinse the coffee maker with a small amount of hot water from the kettle. Pour your ground coffee into it. At this point it is best to place the press on a scale and reset it to “0”. Then start the timer and begin pouring the water evenly over the grounds, stop when the scale shows 170 g. Stir 20 times, measure the temperature, and record it. Cover your French press with the lid. In the meantime, rinse the cup you are going to use with some hot water from the kettle. Once the timer sounds, push on the French press plunger all the way down and pour your coffee into the cup. Coffee is best served at 60 C/140 F, so initially it might be too hot for tasting. Leave it to cool down for a minute or so and take a sip of purified natural water in the meantime. This will prepare the digestive tract for the coffee and will reset the taste buds. Read more about it here. Now taste your coffee and evaluate it. Usually, one sip is enough to tell where it stands. If you feel like taking another test sip, make sure to have a sip of water first. What does the coffee taste like? As a quick reminder:

Sour, salty, not sweet enough, unripe, lacking finish, and sometimes ashy or carbony (with dark roasts) means it is under brewed.

Bitter, dry and astringent means it is over brewed.

The taste will not necessarily be at one of the extremities. It might be slightly sour, but not really acidic (see the definitions above); or it might be just a bit too bitter, but also sweet and ripe. It might be just a bit watery and lacking body or finish. In any case, chances of brewing a perfect cup right away are slim. It is always good to take a corrective action, and there is always room to make the coffee even better.

Try this if your coffee is under brewed (do these steps one at a time):

  • Grind it finer, move the adjustment wheel a couple of notches to the “fine” grind selection
  • Brew longer, by adding 10-20 second increments to the brewing time
  • Brew at a higher temperature, you may want to preheat your coffee maker with boiling water before the actual brewing. This will give you some extra degrees
  • Stir better. Increase the amount of stirring by 10-20 (up to 30-40 stirs)
  • If you are brewing with an infusion-type coffee maker (like a pour-over or an espresso machine) try prewetting (or preinfusion for the latter), this will ensure better extraction. Infusion coffee makers sometimes create channeling or a bypass effect when water finds an easier way through coffee grounds and the brew becomes not uniform. Moistening the grounds before the actual brewing will eliminate this effect. Also, it will improve extraction because of the increase of the contact time with water. Expensive coffee machines don’t necessarily use these terms. Preinfusion may “hide” under “coffee quality index” or similar, read the manual carefully. Just by altering preinfusion settings, you can significantly change the taste of your coffee without making any other adjustments. If you are brewing with pour-over, prewetting is a must anyway, so try increasing the time between prewetting and the main brew. This will also improve extraction. Note: prewetting doesn’t normally apply to immersion-type coffee makers, such as Aeropress, French press, etc. However, this doesn’t mean you can’t give it a try. For example, if you brew a test cup with Aeropress for 60 seconds, try prewetting it followed by a 20-30 seconds pause, then followed by a 40 second brew.
  • Another way of extracting more using an infusion coffee maker is increasing the amount of water

As a reminder, immersion type means coffee and water are mixed within one vessel during brewing; infusion type means water passes through the coffee bed.

Try these if your coffee is over brewed, (do one at a time):

  • Grind coffee coarser, move the adjustment wheel a couple of notches to the “coarse” grind selection
  • Reduce the brewing time with 10-20 second increments
  • Brew at a lower temperature, this is especially true for dark roasts (for more sweetness)
  • Try not to reduce stirring below 10 in any case, this is important for wetting the grounds
  • If you are using an infusion-type coffee maker, reduce the preinfusion intensity (with espresso machines), or reduce the pause between prewetting and the main brew (for pour-over). Using less water will also extract less for the infusion types

To summarize, the strategy of coffee brewing tuning is:

Brew a test cup. If under brewed, keep altering the parameters to improve extraction until you reach comfortable bitterness. If over brewed, alter the parameters to reduce extraction until unpleasant bitterness disappears. After that, you can make further adjustments.

vintage grinder

Other Contributing Factors of Good Coffee


Water is almost 99% of your coffee. This means the water quality and composition will determine the coffee’s taste to some degree. Choose water for your coffee that tastes the best.


Usually it will be soft and purified natural water with a relatively low TDS. Avoid water produced with reverse osmosis technology, such water is unnatural and lacks minerals. Hard water from the tap, apart from its bad taste, can also be damaging to certain coffee machines. Read more about choosing the right water in the next article.


It is not enough to just choose the right grind size for your coffee. It is important that it is also consistent, and the coffee particles are more or less the same size. The more consistent the grind is, the easier it is to control the brewing process. If your grounds are a mix of differently-sized particles, then there will be two (or more) parallel brewing processes happening at the same time. This will result in a mixed brew. For example, it will be under extracted in combination with a balanced brew, or a balanced one together with an over extracted. Mixed brews like this are far from optimal and will not taste good.

grind comparison
Coffee beans ground with Baratza Encore burr grinder (left) and a cheaper electric burr grinder (right)

A good quality burr grinder is the best choice for grinding coffee. Professional coffee brewers never use blade grinders because they will always produce inconsistently ground beans. Also, this kind of grinders create a lot of tiny particles that pass through the coffee maker’s filtration system. These particles will continue to “brew” in the cup, extracting more unwanted bitterness into the coffee. A precision burr grinder is the best choice for coffee brewing. TIMEMORE NANO is another example of a good coffee grinder. It is very compact and convenient to travel with, it can literally fit in the pocket.

TIMEMORE NANO grinder provides a very consistent grind and is also very compact. It is very easy to grind with too.

Coffee Beans Freshness

As coffee ages, acids begin to break down. This process accelerates in higher storage temperatures Keeping coffee beans in the fridge in a sealed container is the best way to preserve the freshness. It is important that the container is airtight; otherwise, beans will absorb moisture and flavors from food. Oxygen is another damaging factor for coffee beans. Another option for storing coffee beans is a special canister that prevents oxygen from coming in. A basic rule that is easy to remember: “20 days, 20 minutes”. Coffee beans are considered fresh within 20 days after roasting, ground coffee is considered fresh within 20 minutes after grinding.

vintage coffee grinder and ground beans
Remember the “20 days, 20 minutes” rule

Most of the coffee you can buy is stale, because it usually has passed the 20-day mark by the time it is consumed. Of course, coffee beans will not just go bad on the 21st day after roasting, they will begin to break down slowly. So, the goal is to get the “freshest” coffee possible and check the roasting date that is usually printed on the package. Another way of getting freshly-roasted beans is buying them from your local roasters. They usually roast using small batches and can always offer fresh coffee.

Brewing Temperature

A regular brewing temperature is 195-205 F or 91-96 C. Water boiling point is 212 F or 100 C. It is perfectly fine to use water that has just boiled, because it will cool down by several degrees anyway. This happens once the water is poured down and mixed with coffee, and also after it releases its heat to the coffee maker. The temperature can actually drop quite a bit, especially when using a large pour-over coffee maker. Therefore, it is a good idea to measure the brewing temperature after the hot water and coffee are properly mixed. This is best done with an electronic thermometer that measures temperature instantly. When using a pour-over, pouring hot water over the filter before brewing is essential. This is to make sure the coffee maker is preheated and will not give you cold coffee. Too low of a water temperature will generally result in under brewing, unless you are making a cold brew.

cold brew coffee
Cold brew coffee

Dark roasts are usually sweeter at lower brewing temperatures. Light roasts are usually best brewed at higher temperatures.

Coffee to Water Ratio

An average coffee-to-water ratio is 1:17 by mass, but it can vary, of course, like espresso. A general rule is by using less water we get less extracted coffee with more acidity and more body. It will also be less bitter. With more water we are extracting more out the beans, which gives us a more bitter coffee higher in caffeine, but with less body and acidity.

Avoid Adding Sugar, Milk or Sweeteners Before You Brew a Good Cup

Adding sugar to an espresso can be a good idea, but not so much for other coffees. The love of sweet coffee is only formed by habit; any habit can be easily replaced with a better one. Having your coffee in its purest form is is the best and most honest way to evaluate it. If coffee “needs” anything else, then it is not optimal or balanced.

coffee and milk
A good coffee doesn’t necessarily need milk

Perhaps it is just under or over brewed. Before adding anything, it is better to optimize your coffee first. Chances are, after that it will not need sugar, milk or anything else.


Cappuccino, for instance, was created not to conceal the taste of incorrectly brewed coffee. On the contrary, it has always been one of the best ways of enjoying a good coffee.

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