The Science of Brewing the Perfect Cup of Coffee
Commercial Coffee Makers: The Science of Brewing the Perfect Cup of Coffee
Coffee Brewing Basics
To brew the perfect rich and steamy cup of coffee, you first need to know the basic elements of brewing. There are several major factors that affect the flavor and extraction of your coffee: water, temperature, time, turbulence, filtration, and cleanliness. This section will outline each of these elements and explain how to perfect each of them.
Water
Pure, filtered water aides in producing the best tasting and smelling coffee every time you brew. Clean water is key in the process because water makes up more than 98% of the coffee in your cup. When the water in coffee has a high mineral deposit content, it can negatively affect the taste of your coffee. To ensure that you offer the most pleasing cup of coffee possible, the water used in brewing should not exceed 50-100 parts per million (ppm) dissolved minerals; however anywhere below 300 ppm will produce an acceptable cup of coffee. To achieve that goal, you should inspect your commercial coffee maker frequently and make sure it is free from contamination and odors.
If you find the tap water in your area is too high in mineral content, you may want to install a water filter on the line serving the commercial coffee maker or purchase a sytem that has a filter built in. Bottled water can also be substituted, but it is important not to use softened or distilled water, as each of these can negatively impact both the water's interaction with the coffee grounds and the flavor of the end product.
The grounds
It makes sense that water and the grounds that are the two major components of coffee should be the top two factors in making a great cup, right? Obviously the quality of the grounds will have a major impact on the quality of the drink. There are a few things you can do to ensure your customers get the best possible product.
First, you want grounds that have been roasted as recently as possible, which means they're fresher. Most commercial coffee is stamped with a date to indicate its age. One way to protect the quality of the grounds is to buy no more coffee than your commercial kitchen will use within a week or two, which ensures you won't be leaving coffee-to-be on the shelf for too long.
Second, get freshly-ground beans or, better yet, get your own commercial coffee grinder or a commercial coffee maker that will do that and the brewing in one unit. From the moment the bean is cracked, it begins releasing its flavor and aroma, so fresher grounds make better-tasting coffee.
Third and finally, make sure you're using the right grind texture for your commercial coffee maker. Believe it or not, different consistencies will provide different flavors and qualities of coffee. It may take some experimentation for your to get just the right grind.
Temperature
The water temperature will affect the flavor and extraction of each cup of coffee you drink. Ideal water temperature is within the range of 195 degrees Fahrenheit to 205 degrees Fahrenheit or 92-96 degrees Celsius. If your commercial coffee maker heats the water below that level, your coffee may not end up with much of the flavor customers are looking for. Meanwhile, water that is above that range can over-steep the coffee grounds, producing a cup of joe that is either bitter or just doesn't taste right.
Time
Depending on the amount of time that each pot of coffee is brewed and the amount of time the water is in direct contact with the coffee grains, the flavor can either be enhanced or reduced. The ideal time for brewing in most drip-style commercial coffee makers is 5 minutes. If the coffee grounds are in direct contact with the water or are brewed for an excessive amount of time, the flavor and aroma of the java will dramatically decrease, causing the cup to become "watered down." In contrast, if the coffee grounds are not brewed or in contact with the water for long enough, the coffee will have a strong flavor and aroma that might prove offensive to some people.
Turbulence
When water passes over and through the coffee grains, turbulence is created which causes the particles to separate. When that happens, a uniform flow of water is produced around the grains, allowing perfect extraction to occur. When proper extraction occurs, the result will be a tasty and aromatic cup of coffee each time. Commercial coffee makers are designed to create the proper level of turbulence in the filter basket.
Filtration
The type of filter used in a commercial coffee maker affects each cup of coffee produced. Paper filters will provide the best tasting, clearest cup of coffee available. Bunn paper filters are excellent choices because they are porous enough to allow coffee grains to flow freely during extraction. The filters are also made from oxygen process paper that is strong enough to prevent collapsing, yet gentle enough to strain particles without taking away the flavor.
Cleanliness
While it may seem like running nearly-boiling water through your commercial coffee maker every day would be enough to keep it clean, that's simply not the case and not maintaining the unit properly can ruin the taste of the product. You should clean your commercial coffee maker daily by running hot water through it, then drying it thoroughly. Any remaining coffee grinds or even remnants of the oils produced by the beans can ruin subsequent brews. Be sure to check the entire system, from the grind basket to the sprayhead or funnel to the water reservoir and even the decanter, to ensure cleanliness. The serving area around the brewer should also be cleaned daily. The sprayhead or funnel, water reservoir, and
coffee decanter should be checked daily as well.
Be In the Know About Holding and Serving
Once you have brewed the perfect cup of coffee, you will want to enjoy it while the flavor and aromatic qualities are at their peak. In order for customers to be able to relish your joe, you need to know how long and at what temperature the coffee should be held, and at what temperature it should be served. The ideal temperature for holding the coffee until serving is between 175-185 degrees Fahrenheit. Even at these temperatures, a pot of coffee should not be held for more than 20 minutes in an open top container or 30 minutes in a closed top container. After this time, coffee will begin to take on a burnt flavor.
The Science of Brewing Perfect Coffee
In order to create an impeccable cup of coffee, you need to understand the essential elements of controlling the brewing process. The basic elements of brewing are wetting, extraction, and hydrolysis.
Wetting
Coffee grounds absorb hot water from the sprayhead and then release gasses from the coffee. In order to achieve consistent extraction, the entire bed of coffee grounds must be wet during the first 10% of the brew cycle time.
Extraction
During the beginning of the brewing process, the water-soluble materials dissolve and move out of the grounds and into the water. The best flavors are extracted during the first few
minutes of the brewing process.
Hydrolysis
Hydrolysis is a chemical reaction or process in which a chemical compound is broken down by the reaction with water. In relation to coffee, the materials created during the extraction process break down further into water soluble proteins and sugars.
Match the Grind to the Time
The brewing time or water contact time can be determined by the size of the coffee grind and bed depth. The larger the coffee grounds, the longer the brew time should be. In turn, if you are brewing more finely ground coffee, you should have a shorter water contact time. The recommended brewing contact times are shown on the chart below.
Brewer Cycle Timing
Depending on the specific brewer purchased, you can experiment with coarser or finer grind cycles to obtain the perfect cup of coffee. Each brewer will have a delivery cycle that is slightly different from the rest, so your manual can help to assist by providing recommended times for each type of coffee.
Bed Depth
Another factor in brewing an exemplary cup of coffee is the bed depth in the brewing basket. The ideal depth is 1-2 inches. If your coffee bed varies from these recommended depths, your coffee can be negatively affected, depending on whether the depth is too low or too high. If the bed is less than 1 inch, the water may move through the coffee too quickly, causing under extraction, which produces a less intense flavor and aroma. If the coffee bed is a greater depth than 2 inches, the water will flow slowly through the coffee grounds and over extract, causing an overly strong or bitter taste.
Brewing Control
The flavor of the newly brewed coffee is determined by the amount of coffee being extracted and the amount of coffee solubles. The chart below shows the relationship between all three factors, brewing ratio, strength, and extraction.
On the above chart, brewing ration is defined as the relationship between the amount of ground coffee used per half gallon of water and extraction. This is shown by the diagonal red lines. The strength/solubles concentration is the goal for percentage of coffee flavoring material as compared to the amount of water in the finished cup. This percentage is 1.15% - 1.35%, which is measured by the Brew Strength Meter, also known as the Hydrometer. At the bottom, the extraction/solubles yield is the ideal percentage of coffee material removed. This should generally be between 18% - 22% of the solubles in the coffee. The deep yellow box in the center of the chart shown the optimum balance field. This yellow box shows the perfect balance between strength and extraction that should be used in order to create the perfect cup of coffee.
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One of the simple, but great joys of life is a good cup of hot coffee
And just in case you wondered how the perfect cup of coffee is prepared.......
R W
My youngest son (San Francisco) has a similar device for brewing his coffee
The wife and I swear by our Bunn coffee pot for our daily (sometimes multiple) coffee fix
Thanks for the feedback
R W
We are very fortunate that my son on San Francisco frequents several coffee shops which sell a variety of gourmet coffees and he periodically (and on birthdays and Christmas) sends several pounds of various coffees from around the world.
On a daily basis we are Folgers all the way Colombian and Black Silk
R W
He has sent us some delicious coffee from Guatemala on several occasions that is as rich and full tasting as any coffee I have ever had.
Pour one cup of water into the top of the machine. Place cup on holder. Open machine (water runs down into machine). Insert plastic container of coffee flavor of choice. Close cover. Push button. Wait about 5 minutes. 1 cup of coffee.
I LOVE MY KEURIG!!!
I LOVE MY KEURIG!!!
I love mine too! We bought one for the Master bedroom, but I kept going in to make coffee that we bought another one for the kitchen. I like strong coffee and also enjoy a couple of cups of de-caf while watching TV or the occasional cup of hot chocolate in the evening.
RW, the flavors are available are in regular coffee too. In fact mostly in regular types of coffee from light to very strong. Most of the major manufacturers make cups for the machine now too. Folgers, Maxwell House, etc. That's what I usually use mine for.
We used to have one of those fancy ones that ground the beans and made espresso and cappuccino and such, but my wife doesn't drink coffee (she uses her's for cocoa), but the problem was trying to make enough coffee for me for the day without letting any of it go stale or to waste. Yes, the Keurig cups are more expensive per cup, but I think it evens out because there is no waste and it's a fresh cup every time. Besides I don't think we ever made an espresso or cappuccino anyway.
You can even get Keurig compatible cups in Hazelnut too.
I like the different flavors of coffee, but I think there are unflavored coffees out there.
I almost always only drink the unflavored ones. And there are lots of those to choose from.
I like Newman's and Breakfast Blend...and I HAVE to have French Vanilla Cream in it.
I don't mind if the coffee is unflavored, I add flavor to it with my French Vanilla...
Very strong roast and some cream and sugar. Mmmmmmmmmmmmmmm!!!!!
We have a friend who is a pain in the patootie. Actually, he is my husband's friend, and his poor wife is my friend. Me? I want to beat him over the head with something.
The fellow has a coffee brewing apparatus-- he is into "immersion coffee". Don't ask me what that is-- but he tinkers with this thing like he's separating uranium for an atom bomb. The apparatus looks like this:
At any rate, not long ago, he called us up, ranting and raving about the minerals in the Louisville Water Company's water-- where I worked at the time. All the gunk in the water, he exclaimed, kept him for having his perfect cup of coffee.
He called up a water filter company, who came out and tested his water, and the test yielded 950! (He never said 950 whats-- no unit of measurement was given-- nor what they measured.) Since I worked at the water company, it was very easy for me to call up the lab and ask what our total dissolved solids are in our finished water. If you added up all the minerals, it came to 300 ppm. Not possible for his home to have 950 TDS, if the original water coming to the faucet was 300. And that 300 ppm included everything, even things that aren't usually tested.
I have spoken with many people about water filters, and have come to the conclusion that the majority of people who scream about the minerals in their water, test out at 950. Again, the don't say 950 whats.
People go out and by these $1000 water filters, thinking that they are getting pure water. They're not. They're just getting filtered water. Most of the icky things in water can't be filtered out. The water has to be treated, and there are still things that can get in the water that you can't get out.
If you have one of these apparatus type things and you don't want to have to boil it out with vinegar to get the minerals out, just buy plain old distilled water. On another note, Louisville Water has won the Best-Tasting Water in the USA award about 7 years in a row. Guess what makes water taste good? Minerals-- not too much and not too little-- just right. Otherwise, the water is tasteless and flat.
Everyone I know that has purchased a hunga gunga water filter say that the water from their faucet is at 950. They con't say what units, they don't know what was tested, and they don't have any idea what they are talking about. The salesman uses a little black box mechanism, that shines a light in a test tube of water and reads 950. VERY likely the filter just takes out some particles that you can almost see, and seems to be cleaner-- much like an aquarium filter. But, in reality, it isn't removing anything important.
I drink a variety of beverages, including coffee but also green tea & experiment with various herbal teas.
I have been using the Chemex for a while. The paper filter does seem to filter out bitterness exceptionally well. (Of course if you use good beans and brew it correctly, it shouldn't be bitter in the first place).
Actually, one of the reasons I tried it in the first place was because I thought it looked really cool (I thought it looked like something in a chem lab-- supposedly I was an Alchemist in a past life..heh :^).
Unfortunately the only grinder I have is one of those hand-operated ones, so after spending hours turning the damn thing I acquiesced to buying pre-ground coffee beans. I do use a similar brewer as in the article picture, though, and it does make pretty good coffee.
The company that makes the coffee make sells two types of paper filters. One is "natural"-- unbleached brown coloured paper. The other is white (beached). I started by using the more "natural" ones-- but the coffee wasn't great.Then I tried the while filters-- and strangely, the taste was really good. The supposedly more natural brown paper ones did give it a slight unpleasant taste.
I've had Bodum coffee-- it was very good. I think if you use the same type of bean in a Bodum and a Chemex, the Bodum coffee does tend to come out a bit stronger than the Chemex. But I haven't really done much comparison tasting.
The Bodum is also more convenient.
Have you considered getting an electric coffee grinder?
They are really great-- fast, convenient.
I also used to use mine to grind Flax seeds (you need to grind them to get the full nutritional value), because my old blender wouldn't do it, but I have since bought a high power blender that does.
I had an electric grinder in Canada, but for some reason whole coffee beans here are outlandishly expensive, so I can live with sealed canned pre-ground.
My wife purchased a Nespresso when we lived up in Finland. I have to say it makes a much better cup of the old "shut-up-and-chew" style coffee I had gotten use to.
I don't know if it has made it to the states yet, but here we can buy Bailey's Chocolate Lux which has Belgian chocolate in it. Great on ice cream, excellent in coffee.
At my cottage on a lake called "Gull Lake" we would brew some coffee very early in the morning and pour cups of 2/3 coffee and 1/3 Bailey's Irish Cream (which we called "Gull Lake Coffee), go out and sit on the dock to watch the sunrise through the mist and listen to the loons calling.
Not a great photo, but this is what we looked at:
Yep. Bailey's, coffee, and a view like that. Good in the morning, good in the evening.
If you can.... try the Chocolate Lux. You won't be disappointed.
I love to drop a mint flavored, dark chocolate Kiss in my coffee--- let it melt, stir it up well, and Oh Boy!
Dowser
Sounds like you really know how to relax with a cup of coffee
FLY
Good coffee and a beautiful view - can't ask for much more than that
Buzz
You may say it is not a great photo, I disagree, but it is a magnificent view
Thanks for sharing it
H K
We have an electric grinder, but it is used for spices rather than coffee
We rely on ground coffee for our daily fix - easier and faster
Perhaps it is time to try grinding our own
H K
My neighbor has a pot such as this one, but it is displayed on a shelf rather than used for daily coffee. I forget where she said it came from.
M M
I know a lot of folks that love the Keurig (sp) machines and the variety of blends that can be enjoyed.
Thanks for the feedback
I am very pleased by the exchange of information about something so simple as a cup of coffee (not so simple I guess) and thank everyone that has participated and provided input, feedback and perspective on the subject.
I apologize for not answering every comment that came in over night, but you all did a great job of keeping the conversation going in my absence ad I thank you one and all
The devices (coffee pots is too trite for some of them) are fabulous and I feel somewhat inadequate with my Bunn (which we love), but I enjoy my coffee and always willing to try new blends and flavors.
Thanks again to everyone
That sounds YUMMY! Once in a while I put some cinnamon in my coffee....mmm!
I agree RIO.....It is a beautiful picture!
I wish I could add the sound of the loons.
Buzz
You must be talking about to the picture, because the sound of loons is seldom missing arounf here.