I’m Jonathon. This is a social draft of a new non-fiction book about Batch Brew.
Batch Brew coffee is an alternate brewing style of coffee.
Alternate brewing styles are methods of making coffee that are not espresso.
Espresso is a method of making coffee that developed during the early 19th and 20th Centuries in Italy and was aided by both the creation and control of steam technology and the formation of steel and strong metal welding, it was ultimately perfected in 1961 by Ernesto Valenta who designed the “E61 group” a method of extraction that was precise and effective.
First what do we mean when we “make coffee”. Coffee is a fruit. We take the seed from inside that fruit and we call it a bean. There are many places and ways to grow that fruit, many ways to process and wash the bean. That bean is then cooked. We call this roasting. Roasting coffee is a process of rotating the beans inside a drum that is either turned like a wheel or aerated like lotto. The typical temperature is 212 degrees Celsius (415 Fahrenheit) and cooked for 11 to 14 minutes on average. This creates a lighter, drier form of the bean that is extremely porous gassy. One kilogram of freshly roasted coffee releases 12 Litres of carbon dioxide gas over a 30 day period. That’s 12 balloons full of gas from one bag of coffee!
The process, therefore, of making coffee is actually breaking down that dry, porous and fragile bean into small particles we call “grinds” and using water solvent to carry the coffee into the beverage.
There are many ways to use water as a solventto carry the good stuff in the coffee into our cup. The main ways are: smaller grinds, water temperature, time, agitation, or a combination of these.
By grinding the coffee into smaller grinds or particles the water is then able to penetrate inside the pores of the coffee particle and extract more of the coffee.
Extraction is the process of breaking down the sugars and oils inside of the coffee bean and taking it with the water into the final beverage. A sweet, balanced coffee will always be within 18 to 26% extraction for both filter and espresso brewing methods. Learn More via the Melbourne Coffee Culture Podcast (iTunes).
Temperature of the water also affects the speed at which coffee is extracted. The colder the water the longer extraction takes. For example, “cold drip” coffee will take on average two to twelve hours, whereas “espresso” take seconds. Cold Drip is made with room temperature water around twenty degrees, espresso is made at close to boiling around 94 degrees Celsius.
Time is a fantastic factor when it comes to making coffee and extraction. Water is able to take more of the coffee with it, generally, when it has more contact time. There is however a relationship between particle size and time because a smaller particle will slow down the flow of water in each espresso and filter brewing styles and therefore lead to an increase in both time and extraction.
Agitation will also increase extraction. A pour-over or drip coffee that is stirred will extract more coffee than one that is not agitated.
Now that we have a definition for “making coffee” we can talk about the brewing styles in more detail. Sponsor: Melbourne Coffee Culture Podcast
Pour-over also known as “Chemex”, V60, Kalita Wave is a method for making filter coffee or drip coffee by use of a paper filter and gravity and usually involved pouring hot water over a bed of coffee. In this case the coffee is usually ground coarsely (around 2000 to 20,000 microns and above in median particle size) placed on top of a rinsed piece of paper or cloth, and saturated with hot water. Agitation is optional however even distribution of agitation patterns is recommended. For example spooning a wet bed of coffee (known as a bloom) in a “X” figure without touching the paper is common.
Immersion brewing — such as french press, Aeropress and some crude forms of cold drip — is referring to a combination of filter or drip coffee, where the coffee is steeped or submerged in water for a specific amount of time (or indefinitely), and may or may not involve agitation, and then the grinds are removed from the beverage either by use of a paper or metal filter. Siphon is also an immersion style brew that also acts as a pour-over.
Espresso is the beautiful and romantic version of making coffee that we all know and love and involved high levels of pressure (one and a half atmospheres of pressure — 1.5 — or 9 bars (actually four bars is sufficient) forcing hot water through an extremely fine bed of coffee packed tightly and evenly into a metal portable filter. The portafilter sits inside a brass group head that fits snugly into a machine. The length of brew is usually twenty two to thirty two seconds and produces a rich crema and an oily colloidal suspension of water and coffee.
Batch Brew is an automatic method of making coffee using paper filters and coarsely ground coffee. The Batch Brew method is a giant pour-over and usually makes around one to three litres of coffee however there are machines that produce 18 litres of coffee. Using gravity and water the machine will brew coffee using pulses which act as a form of agitation wetting the coffee, and then pouring more and more water over the coffee in a cycle. This produces very reliable and consistent brewing.
An advantage of Batch Brew is the ability to program the machine to make the coffee and this removes much of the human error. Fetco, Bun and Marco are popular commercial Batch Brew manufacturers. Behmore and Moccamaster and Breville also make home machines which are not suitable for the commercial environment as they do not usually allow for variation of brew temperature and pulses.
My Fetco XTS brewer allows for multiple, almost unlimited variations of brewing including water temperature up to boiling, pulses up to 20, brew time, and drip times up to 12 minutes and more. We use around 180 to 200 grams of freshly roasted, frozen coffee beans, ground using the Mahlkoenig EK43 grinder and brewed for around 6 minutes. It tastes sensational.
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Thank you for reading.