Chemical Engineering 101: Optimized Extraction Of Aromatic Organic Compounds From Thermally Processed Herbal Rubiaceae Seeds (Commonly Referred To As “HOW TO MAKE GREAT COFFEE”)

​WHAT MAKES GREAT COFFEE?
When we think of great coffee, we think of a rich tasting brew with a deep color, fragrant aroma and full flavor rich in aromatics and some sweetness, with little bitterness or sourness.  We generally think of coffee which tastes as good as it smells out of the bag.
Specific qualities of great coffee are generally:

• Aroma – The coffee smells very fragrant when we are holding the cup.
• Flavor – The coffee tastes as good as it smells when we take a sip.
• Body – The coffee feels smooth when it is our mouth and not astringent (does not make your mouth feel squeaky).
• Sweetness – The coffee does not taste very bitter.
• Clean taste - The coffee does not leave a bad aftertaste in your mouth after you drink it (such as cardboard, paper, wood, plastic, smoke or chemical flavor).

​SO WHERE DO WE START?
THE BASICS, #1 INGREDIENTS
​The first things to look at are the raw ingredients used to make coffee.   Coffee is a natural product and it contains many delicate compounds which make up its aroma, taste, flavors and mouth feel.  Some of these compounds are volatile (they can evaporate out of the coffee as it stands exposed to the air) and some will break down when they are exposed to heat, light (especially sunlight) or moisture (water, humidity in the air, or condensation).  Coffee will also pick up flavors and tastes from its surroundings.
To get the best most flavorful knock-your-socks-off cup of coffee that tastes as good as it smells, you must start with quality coffee beans and you must store them appropriately so as to maximize the delicious life of the coffee and prevent it from going stale for as long as possible.
So here are the basics for managing your coffee supply:

• Pick coffee that you really like – smell it and evaluate all the aromas.  Imagine drinking a cup of this heavenly brew.  There are two types of coffee you should be aware of. 
• Arabica coffee is the more flavorful, fragrant and aromatic type of coffee.  Coffee made from Arabica beans tastes smoother, more delicate and more complex without being bitter.  Arabica beans have a higher acid content than Robusta beans.  Most major brands of coffee are Arabica coffee.  Arabica coffee is more expensive than Robusta coffee.
• Robusta coffee has a harsher flavor and tends to be more bitter than Arabica coffee.  Robusta coffee tends to have a nutty, grainy after taste and has more caffeine content.   It is easier to grow than Arabica coffee and therefore it is less expensive than Arabica coffee.   Robusta coffee is found more in packaged mass produced supermarket coffee or institutional coffee.  It is either used alone or blended with Arabica due to its lower cost.
• Pick a roast that you like.  There are different ways to roast coffee; light, medium, dark, bold, French roast, etc.  This is a matter of taste which you prefer.  Generally, a medium roast has less bitterness than a dark roast, but has more acidity.  The flavor of a dark roast is more intense.  Dark roasts do not necessarily have more caffeine than light or medium roasts.
• Be aware of blended versus single source coffee. Coffee can be a single source or a blend, much like wine.  There is no right or wrong choice to picking one over the other.  This is another matter of taste.  Coffee producers use blends to create unique flavor balances and ensure consistency of this natural product.  The bottom line is to purchase coffee from a reputable roaster who uses fresh quality beans to produce their blends.  You do not want to and up with a blend where stale beans are blended with good ones to reduce the cost.
• Buy fresh coffee.  Ideally this should be from a local roaster so you know that it was roasted recently.  Coffee is in its prime for up to 7 days after it was roasted.  Whole bean coffee can be kept up to 20 days after it was roasted if you store it appropriately.  Ground coffee should be consumed within 7 days of roasting.
• Coffee is best fresh roasted, but you can also buy it prepackaged at a store or online.  The packaged coffee should be in a sealed foil bag with all the air removed or in a sealed can.  Typically the foil bag has a plastic valve on the side.  This is where the air was sucked out of the bag.  The cans are typically purged with Nitrogen to remove the air from the headspace in the can.  This is important as paper bags and containers with air will allow the coffee to lose its flavor and degrade as it stands.  The container should also be marked with a freshness date indicating by what date you should consume the coffee.
• It’s best to buy fresh coffee in small amounts that you can consume within a week.
• Whole bean coffee is preferable to ground coffee because coffee starts to lose its aromas and flavors immediately after it is ground.  So it’s best to keep whole bean coffee on hand and grind the beans just before brewing.
• Not all coffee is available as whole beans and not everyone has access to a grinder and some of us are not allowed to make loud noises grinding coffee at 5AM when they are planning to brew a morning cup before rushing out the door.  So if whole bean coffee is not a practical option for you, you can either:
• Have your coffee ground at the roaster.
• Buy ground coffee in sealed airtight packs (the foil ones with the air removed and the plastic valve in the side (paper bags do not preserve the coffee as they let in air and moisture).
• Store coffee appropriately.  This means keep it in a sealed air-tight container away from heat and sunlight.  Coffee needs to be protected from moisture, contact with air, light, heat and other aromas that it can absorb.  A sealed glass jar in a dark cabinet or a coffee can with a secure lid work best.  Do not store coffee in the freezer or refrigerator.  This exposes the coffee to moisture from condensation and the coffee may pick up aromas from the freezer or refrigerator.​

THE BASICS #2, EQUIPMENT
The next thing to look at is the equipment used to make your coffee.  Everything that touches your coffee should be spotlessly clean.  Think about if you were ordering coffee at a restaurant or coffee house.  You would not want to see old stained coffee pots and coffeemakers full of scale and residue…yuck!

• Make sure your coffee maker, coffee grinder, coffee pot, press, etc. are cleaned with soapy water every day.  Clean out the basket that holds the grounds with hot soapy water.  Coffee contains oils so you need soap to remove the residue.  Just rinsing alone will not remove it.  If you let old coffee sit in your equipment it will create a film that is very hard to get off.  This film will add bitter flavors to the next batches of coffee and the longer you leave it on, the more bitterness will cover up the delicate flavors you want on your coffee. 
• If have residue on your coffee making equipment or cups which will not come out with soap and water, even with scrubbing, here is a quick trick:  Fill the pot with warm water and add a scoop of oxygen cleaner (like Oxyclean). Gently stir and leave it sit overnight.  The next morning you can rinse out all the cleaner and the residue will all disappear.  No scrubbing needed!!  It’s really like magic.  I’ve tried scrubbing and scrubbing with many different abrasives and cleaners and was about to give up before I discovered this trick – it made my coffee pot like brand new again and no work!
• Depending on how hard your water is (how much mineral content it has) and how much coffee you make, you will need to descale your coffee maker and coffee pot on a regular basis.  If you notice a hard white or brown crusty film developing on the surface that is rough and you cannot scrub it off, this is scale.  It is a deposit of minerals like calcium salts and/or magnesium salts which have precipitated out of the water when the water was boiled.  You will need an acidic chemical to dissolve this, but this doesn’t mean you need a harmful chemical.  Vinegar works just fine.  Make sure you use distilled (white) vinegar, as other types of vinegar will leave a residue behind.  Every two or every three weeks, it is recommended that you do the following to descale your coffee maker and coffee pot:
• Combine equal parts of water and white (distilled) vinegar.  Make enough for at least half the volume of your coffee maker.
• Pour it into your coffee maker (where you normally add the water).
• Let it stand for 10-20 minutes.
• Run the coffee maker and let it go through into the pot until half of the water/vinegar solution is through and into the pot.
• Turn off the coffee maker and let it sit for 1-2 hours with the water/vinegar solution in the pot.
• Turn on the coffee maker and let the rest go through.
• Discard the water/vinegar solution.
• Refill the coffee maker with just water and let it run through.
• If you use a glass jar or other reusable container for storing coffee beans or ground coffee, remember to clean this too.

Another critical piece of your brewing system which makes contact with the coffee and greatly influences its quality is the filter.  A good filter will produce a clean tasting flavorful cup of delicious coffee, while a bad filter can produce a bland cup of coffee with a cardboard like flavor.  So always use good quality filters. This means:

• Look for paper filters which say “oxygen-bleached” or “dioxin-free”.  These are white filters which have been bleached without using harmful chemicals which you should not be drinking.
• Even better, use unbleached filters.  These are more natural and are brown in color.  They do not have any bleaching chemicals (bleaching chemicals can add flavors to the coffee).  The unbleached filters will not add flavors to the coffee but they are brown.  Paper is naturally brown since it is made from wood pulp from trees.   Some people prefer white filters, although I could never understand why as the filter will become brown very quickly anyway once you fill it with coffee.
• To reduce the possibility of any flavors imparted on the coffee by the filter, first wet the empty filter with hot water to saturate the filter and let the hot water drip through.  This washes out any substances that would have been released by the paper.  Then add the coffee to the filter and proceed with brewing.
• Another option is to use a reusable filter.  These are typically gold plated metal filters, like fine screens or sieves.  These will produce brewed coffee with richer flavors, as they do not filter out any of the oils from the coffee, but they will let through sediment of finely ground coffee into the brewed coffee which some people may find objectionable.  They also need to be cleaned after each use.  But you are benefitting the environment by saving trees and using fewer chemicals.

THE BREWING PROCESS – HOW COFFEE GETS FROM THE BEANS TO YOUR CUP
Have you heard this statement before? “I like how coffee smells, but I don’t like how it tastes”

So why is it that coffee which starts out smelling heavenly out of the bag ends up not tasting so great when it’s in your cup?  What happened to all those great flavors and aromas?

The answer to this has to do with the chemistry of the coffee brewing process.  Roasted coffee beans contain many compounds (chemicals) which make up the characteristics of the qualities of the coffee.  Some of these compounds have great aromas and flavors.  Some are sweet.  Some make the coffee feel smooth when you drink it.  But others are bitter, or sour.  Some taste like cardboard and some make your teeth feel squeaky when you drink them.  And then there is caffeine which is also a compound extracted from coffee.  Caffeine tastes bitter at high concentrations, but in coffee there is not enough caffeine to add any flavor.

The balance of flavors in the cup of coffee you drink is determined by the brewing process used to extract out or dissolve out the compounds from the coffee beans and get them into your cup.  Brewing is a chemical process known as “extraction” which removes compounds from one substance (coffee beans) by using a solvent (water).  The purpose of the brewing process is to extract out the greatest amount of the good compounds (flavors, aromas, sweetness, smoothness) and leave behind as many of the bad compounds (sourness, bitterness, off flavors) as possible. 

Hot water works much faster than cold water in extracting out compounds from solid materials, especially compounds which contain oil.  Cold water will work too, but it will take a long time, just like making ice tea using a pitcher of cold water and tea bags. 
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For brewing coffee, the typical brewing process is to grind the beans and then pass hot water over them to extract out the desired compounds.  The coffee is ground to increase its surface area.  More surface area means more contact with the hot water and that means more compounds are extracted.   The coffee/water mixture is then filtered to separate out the solid parts (the coffee grounds), and the result is the delicious cup of coffee you can drink.

It might sound like more extraction is better because it means more flavor, but this is not the case since the extraction is taking out the good and bad compounds from the coffee and dissolving them into the coffee you will drink.  More extraction means more bad compounds which can overpower the good compounds and result in a very bitter flavorless cup of coffee.  The trick is to extract out the right balance of compounds mostly good ones and a minimum of bad ones.  There is a point in the extraction process where the quality of the brewed coffee is optimized (the best you will get).  Too little or too much extraction will make less than great coffee.

In general coffee that is under extracted (too little extraction of compounds out of the coffee) has a weak flavor and tastes sour.  And coffee that is over extracted (too much extraction of compounds out of the coffee) has a strong but bitter flavor and may cause your teeth to feel squeaky.
The extraction is determined by the following factors:

• The type of brewing method used (drip, percolator, pour-over, French press, espresso, Turkish coffee, etc.)
• The grind of the coffee (how coarse or fine)
• The quality of the water (tap water, filtered, bottled, etc.)
• The temperature of the water
• The amount of time the coffee is in contact with the water
• The ratio of coffee to water (how much of each)

There is an optimal point for all these factors where the best coffee is produced.  All of these factors need to be considered to get to this point.  Let’s look at each one.
THE TYPE OF BREWING METHOD USED
Making coffee is a type of chemical process known as extraction where compounds in one material (ground coffee beans) are dissolved out into a liquid solvent (water).  There are different methods for doing this extraction.  Some use electronic systems to control the extraction and others are manual which allow the process to be varied but also requires someone to perform and closely monitor the process.
The most common electric coffee making systems are drip coffee makers and percolator systems.  There also espresso making systems which use a different process where hot water under pressure is forced through the coffee beans in a very short time.
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DRIP BREWING
Drip coffee makers are the most common type of coffee making systems.  In this system, water is heated to a set temperature and then the hot water is showered over the ground coffee which is in a basket lined with either a paper filter or metal screen.  The water passes over and through the ground coffee and drips out the bottom of the basket into a coffee pot.  The coffee pot is either glass or it can be stainless steel. Coffee makers with glass coffee pots typically have a hot plate under the pot to keep the brewed coffee warm.  Stainless steel coffee pots are typically thermal type carafes which keep the brewed coffee warm through their insulating properties, much like a Thermos bottle where there are 2 walls of the bottle with air space in between to reduce the conduction of heat out of the pot.  Of the two types of coffee pots, stainless steel thermal carafes are more expensive but they are able to maintain coffee for a longer time without losing any flavor.  The heated glass pots will tend to drive off the flavors and aromas of the coffee as more heat is added after brewing.  Many restaurants use drip coffee making systems, as do coffee shops since they are reliable, consistent, economical, and easy to clean.

PERCOLATOR BREWING
Percolators used to be the standard coffee making systems before drip became more popular but they are still used.  Usually at large gatherings you see coffee urns which are large percolating systems.  In a percolator, the coarse ground coffee is placed into a basket at the top of the coffee pot.  Water is added to the bottom.  The percolator heats water to boiling and then uses the pressure created by the steam to force the hot water up through a tube and sprays it over the basket where it comes into contact with the ground coffee.  The water is recycled many times until the desired strength of the coffee is reached.  For electric systems, the percolator will automatically turn off at a preset time.  For stove top systems, the person making the coffee must keep track of the time and turn off the stove when the coffee is done.  This method is different from drip coffee where the water passes through the coffee only one time.  Percolator systems are used for large gatherings like conventions, weddings, church events etc. because you can make a large amount of coffee quickly without needing to watch over it and the pot keeps it hot.

ESPRESSO BREWING
Espresso requires a specialized coffee making system where hot water under pressure is forced through finely ground coffee to extract out the maximum amount of flavor in a very short time.
There are also the pod type coffee makers.  These systems are fully automatic and do not allow for any variation on the brewing process beyond the settings on the user panel (i.e. some allow for “Strong” vs. “Regular”).   The coffee is contained in a sealed plastic cup with a filter at the bottom.  Therefore the amount of coffee used is set by the supplier and cannot be varied.  The water temperature and brew time are automatically controlled by the machine.  So the only part of the brewing process that the person making the coffee can control is the type of water used to make the coffee.

FRENCH PRESS
Popular manual methods for making coffee include French press and pour-over.  The French press is a cylindrical glass coffee pot with a stainless steel plunger with a screen at the bottom.  The ground coffee and hot water are added to the pot and then the plunger/screen are placed at the top of the pot.  After a set amount of time, the person making the coffee presses the plunger down and the screen slides down the pot and strains out and compresses the ground coffee at the bottom of the pot.  The brewed coffee above the screen is then poured out into a cup to drink.  People like this method because it results in a more full flavored and full bodied coffee than drip coffee.  Paper filters used in drip coffee tend to remove some of oils in coffee which contain the flavors and aromas of the coffee beans.

POUR-OVER
The Pour-over is much like a manual version of drip coffee.  The ground coffee is placed in a screen or paper or cloth filter in a funnel which is placed over the coffee pot.  The person making the coffee boils the water in a kettle and then lets it sit for a minute before pouring the hot water slowly over the ground coffee in a circular motion so as to wet all the ground coffee evenly.  The water passes over and through the ground coffee and then drips out the bottom of the funnel into the coffee pot. This method requires that the person carefully pours the hot water at a controlled rate so all of the ground coffee is in contact with the hot water for a set amount of time.  Specialty coffee shops use this method to produce very flavorful coffees.

MOKA POT
Moka pot is a two-chamber pot used on the stovetop, typically used in Europe and Latin America, for making espresso-like coffee. The Moka pot uses stem to brew the coffee by boiling water in the lower chamber and then passing the steam pressurized hot water through the coffee basket and then into the top collection chamber. 
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This pot uses steam to pressurize the hot brewing water, which allows for higher brewing and extracting temperatures. This is similar to the espresso brewing process, however the pressure is lower than pressures used during espresso brewing. The result is a bolder more intense flavorful coffee than drip brewed coffee, somewhere between drip and espresso brew.

TURKISH & GREEK COFFEE
Turkish coffee is made by taking very finely ground coffee beans and boiling them in a special pot (with a narrow neck and a long handle) on top of the stove.  After a set amount of time, the heat is removed and the ground coffee sinks to the bottom of the pot.  The brewed coffee is poured off the top of the pot.  It still contains suspended solids after it is poured into the cup. This sinks to the bottom and laves a layer of sediment in the cup.

Each of these methods noted above requires the coffee beans to be ground to a specific size range to achieve the best results.
GRIND OF THE COFFEE
Each brewing method works best with a specific grind size.  The rule is:

• Coarse - good for French press and percolated coffee where no filter is used
• Medium - good for Drip or Pour-Over coffee where the coffee is filtered using a paper, screen or cloth filter
• Fine - good for espresso where the coffee is compressed and extracted under pressure
• Extra Fine - good for Turkish coffee where the coffee is boiled and the bold flavor and sediment are desired in the brewed coffee

Using the wrong grind for the brewing method will give you coffee that is either over extracted (grind is too fine for the brewing method) or coffee that is under extracted (coffee is too coarse for the brewing method).  This is because each brewing method results in a different contact time (time hot water is in contact with the coffee) and if the surface area is too great, the result will be too much extraction and if the surface area is too small the water will not have time to extract enough compounds from the coffee.

The finer the grind of the coffee, the greater the extraction of compounds.  If the coffee is ground too fine for the brewing method, the brewed coffee will be too strong and bitter and might make your mouth squeaky.  You will end up with ground coffee that smells great before you brew it but does not taste great after you brew it.

If the ground coffee is too coarse, the coffee will be too weak and have too little flavor, aroma and body.  Once again you will end up with ground coffee that smells great before you brew it but does not taste great after you brew it.

The method of grinding is important as it is important for all the ground coffee to be uniform in size.  If there is variation in the size of the ground coffee (some pieces are big and some are very small) then the quality of the brewed coffee will not be consistent as some of the ground coffee is over extracted, some is perfectly extracted and some is under extracted. 

BURR GRINDERS
The best way to get a grind which is uniform is size is to use what is known as a burr grinder.  This is the type of coffee grinder used in coffee shops and supermarkets.  It works by crushing the coffee beans between two disks called burrs.  The distance between the burrs is adjustable and this allows you to select the size of the grind you want.  The ground coffee that comes out of this type of coffee grinder is very uniform in size.  The problem with these types of coffee grinders is that they tend to be more expensive than the lower cost blade grinders. 

BLADE GRINDERS
Blade grinders work by breaking up the coffee beans using a spinning blade (like a food processor or blender).  These types of grinders are inexpensive but they produce ground coffee which is not uniform in size (some pieces are big and some are small).  Also, the high speed action of a blade grinder can heat up the coffee and cause it to lose some of its aroma and flavor oils.  These are less expensive but they are not perfect. 

Another problem is that you cannot select the size of the ground coffee.  You must judge this by eye as you grind it.  If you do use a blade type grinder, it is recommended that you pulse it on for a few seconds and then let the ground coffee rest for a few seconds, then tap the grinder to redistribute the coffee and then pulse again.  This increases the uniformity of the final grind and reduces the amount of heating of the ground coffee.  For drip or pour-over coffee, grind the coffee beans for a total of 15-20 seconds. For French press or percolated coffee, grind the beans for 10-12 seconds
QUALITY OF WATER
Since water is the solvent used to extract the compounds from the coffee and water is 98% of the coffee you are drinking, the quality of the water used for making coffee is very important to the quality of the coffee you make.

Not all water is the same. There are many different sources of water and each source contains different chemicals which change the flavors and qualities of the water. 
Distilled water is produced by boiling water and condensing the steam back to liquid.  Distilled water is ultra-pure and contains no dissolved chemicals. 

Tap water is what comes out of the faucet.  This water contains different minerals like calcium and magnesium, depending on where the water comes from.  It also contains added chemicals like fluoride (for the health of your teeth) and chlorine (for killing germs and bacteria). 

There is bottled water which contains minerals similar to tap water but without the chlorine and fluoride. 
And then there is treated water such as tap water you filter in your home or city water which is processed through a reverse osmosis (RO) system in a restaurant.  The filter or RO system removes sediment, bacteria, chlorine and other chemicals which give the water a bad taste.

For the purpose of making coffee, distilled water is not acceptable.  Some mineral content is needed in the water or else the coffee will taste flat and lacking in flavor. 

Tap water is generally not the best choice because the chlorine will add undesirable flavors to the coffee.  Some tap water may also contain minerals such as gypsum (calcium sulfate) which add an undesirable flavor (like sulfur – rotten eggs) to the water and to the coffee.

The best choice for water to use for making great coffee is water that tastes great to drink.  The ideal type of water to use for brewing coffee contains some mineral content but does not contain any compounds which produce bad flavors (like chlorine or rotten eggs). 

Good choices include bottled drinking water (spring water or purified drinking water, not distilled water) or tap water which has been filtered or conditioned using a purification system designed for drinking water. 

Softened water is not good for making coffee as most of the beneficial minerals such as calcium have been replaced with sodium, which will result in a duller flavor and add to your intake of sodium which many people are trying to limit.

Most coffee shops use treated tap water.  This enables them to have control of the quality and consistency of the water they use.  Bottled drinking water is fine as well.  Or if you live in an area where the quality of the local water supply is very good (such as ground water from deep wells or aquifers) and does not need treatment with chemicals, then feel free to try this out for brewing coffee. 
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The bottom line is that if the water does not taste good to drink by itself, then it will not make good coffee.

​Just one thing to keep in mind with ground water (such as well water) is that it tends to contain higher levels of minerals such as calcium and magnesium which will leave deposits (scale) behind in your coffee making equipment at a faster rate than water with lower mineral content.  This means that you will need to clean and descale your equipment more frequently.  Soaking your equipment in a vinegar/water solution for an hour or so will generally remove the scale from the surfaces.
TEMPERATURE OF THE WATER
The temperature of the water when it comes in contact with the coffee has a big effect on the extraction.  Different compounds in coffee (and there are tons of them) are soluble at different rates depending on the temperature of the water.  As the water gets hotter, the rate at which compounds can dissolve out of the coffee and into the water gets faster (think about dissolving sugar in hot water vs. cold water).  Also as the water gets hotter, it is easier to remove more of the water resistant (oily) chemicals from the coffee.  This is why it is much faster to make coffee and tea using hot water than using cold.

The problem is that hotter is not always better.  Some of the compounds taste bitter or taste “off” (i.e. taste bad, such as tasting like cardboard) and you want to limit the dissolution of these into the water but you still want to maximize the dissolution of the good chemicals (the flavors and aromas and sweetness).  If the water is too hot, you will end up with coffee with a lot of extra flavors and bitterness which may cover up the good flavors and qualities.  You will get coffee that smells great but does not taste too good.
If the water is colder, the rate of dissolution will be slower.  This means there will be less bitterness, but there will also be less flavor as some of the important compounds may not be dissolved into the water in sufficient quantities to give the coffee the qualities you want.  Once again you will get coffee that smells great but does not taste too good.

The trick is that you need to have water that is sufficiently hot but not too hot so that you will extract out the exact balance of compounds needed to give you the qualities of coffee you want; smooth, full of flavor and rich aromas with some sweetness and little bitterness.  To achieve this when brewing hot coffee, the ideal water temperature is just slightly below boiling.  This is 200-205 degrees F (93.3-96.1 degrees C).
If you are using an electric coffee maker (drip, pod or percolator), the temperature is automatically controlled for you, so you do not need to worry about this.

If you are using a manual brewing method like French press or pour-over, the best way to get the correct water temperature is to bring the water to a boil in the kettle, then turn off the heat and let it sit for 1 minute before pouring it over the coffee.
AMOUNT OF TIME THE COFFEE IS IN CONTACT WITH THE WATER
The next big factor which determines the amount of extraction of compounds from the coffee is the amount of time the water is in contact with the coffee.  Since each of the compounds can dissolve out of the coffee at different rates, some will be completely dissolved quickly and other will take longer. 
The amount of time that the water stays in contact with the coffee will determine how much of each compound is dissolved out or extracted out into the coffee.  Ideally you want the good compounds (flavors, aromas, sweetness, smoothness) to be completely dissolved out and the bad ones (sourness, bitterness, astringent quality – makes your mouth squeaky) to be left behind as much as possible.

If the coffee is in contact with the hot water for a time that is too short, not enough of the good compounds will be dissolved out and the coffee will be bland and not have the full flavor and aroma it should have.  You will get coffee that smells great but does not taste too good.
If the coffee is in contact with the water for a time that is too long, too many of the bad compounds will be dissolved out and the coffee will be too bitter and may have off flavors (stale, cardboard, etc.).  Once again you will get coffee that smells great but does not taste too good.

The ideal time for the hot water to be in contact with the coffee is 4 – 5 minutes.  If you are using an electric brewing system (drip, pod or percolator) and you have the correct grind size, the brewing system will pass the water through the coffee for the correct amount of time.  If you are using a manual brewing system like French press or pour-over, you will need to manually control the amount of time the water is in contact with the coffee. For French press this means setting a timer and then removing the coffee from the pot (otherwise the extraction will continue for too long).  And for pour-over this means having a timer and controlling the rate at which you pour the water over the coffee.
THE RATIO OF COFFEE TO WATER (HOW MUCH OF EACH)
The amount of ground coffee compared to the amount of water used to brew coffee is critical for getting the right extraction.  If the amount of ground coffee is too little for the amount of water, there will be too little of the good compounds dissolved out into the brewed coffee.  The bad compounds (bitterness, off flavors and astringency – makes your mouth feel squeaky) will be more apparent in the brewed coffee.  You will get coffee that smells great but does not taste too good.

If the amount of ground coffee is too much for the amount of water, the brewed coffee will not achieve the full flavor, but the coffee may be very bitter, as the water will not be able to completely dissolve or extract out all of the good compounds from the ground coffee in the right proportion to the bad compounds.  Once again you will get coffee that smells great but does not taste too good.

You need to have the right ratio of ground coffee to water in order to provide right balance of compounds extracted or dissolved out into the brewed coffee.  This perfect ratio is generally 2 Tablespoons of ground coffee to 6 ounces of water.  This can be varied slightly but not too much. Always read the directions on the coffee package or start with this ratio of 2 Tablespoons ground coffee to 6 ounces water when first brewing a new type of coffee and then try experimenting by changing the amounts in small quantities up and down and see what the results are.
QUICK CHECKLIST – DO’S AND DON’TS OF MAKING GREAT COFFEE
Do Make Sure You:

• Buy fresh coffee that you plan to use within 7 days of opening.
• Use whole bean coffee if you possibly can and grind it immediately before brewing.
• If you buy packaged coffee make sure it is in a sealed airtight container and it has a freshness date.
• Keep all your coffee making equipment very clean (free of residue and scaling).
• Use filtered or bottled drinking water.
• Use the correct ratio of coffee to water (general rule is 2 Tablespoons coffee per 6 ounces of water).
• Make sure your water temperature is correct (200 – 205 Degrees F), if not using an automatic coffee maker.
• Make sure you control the brewing time to be 3-4 minutes if using a manual brewing method (French press or pour over, etc.).

Don’t Make These Common Mistakes:

• Use Dirty equipment.
• Use Old coffee.
• Store coffee incorrectly.
• Use the wrong size grounds for the type of brewing method you are using.
• Use the wrong ratio of water to coffee.
• Use the wrong water temperature for manual brewing methods.
• Use the wrong brewing time for manual methods
• Use the wrong type of water.
• Reheat coffee or keep coffee hot in a heated pot.
• Leave French press coffee in the press after brewing is complete.

 
That’s it!  If you follow these logical steps you too can brew incredibly rich flavorful coffee without spending a lot of money on fancy equipment or taking lots of time experimenting with different recipes.
 
More information at: https://www.ibrewthebestcoffee.com/
 
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