Essential Brewing Parameters
Coffee is a complex drink. It has a variety of notes belonging to broadly 3 categories: sweets, bitters and astringents. While the each of the growing, processing and roasting phases play an important role in defining these notes, the brewing process in itself can be controlled to highlight or suppress different notes in the coffee.
Different methods can be designed to extract the best out of your coffee once you have your first principles in place. This blog has a segment which covers the basics of different brewing methods. Once you have made an investment into a preferred brewing technique, it's time to take things to the next level. And this requires you to start playing with the brewing parameters:
Coffee Roast and freshness
Green coffee beans are roasted to enable faster extraction of caffeine and flavours from the beans. The amount of roasting determines the flavours imparted to the coffee. Roasting follows a chemical process known as the Maillard Reaction, where oils and sugars within the coffee bean combust at different temperatures creating a flavour profile. These profiles can be controlled through the roasting parameters. These roast profiles directly affect the flavour profile of your coffee and roasters tend to keep these profiles proprietary by nature. There are broadly 3 types of roast profiles or coffee roasts:
Preference for a particular roast is personal by nature. But freshness is a criteria which needs to be taken care of whenever you buy a bag of coffee. The fresher the coffee, the better flavours it will have. Older coffees have a stale earthy taste to them. A simple label check also allows you to identify specialty coffee from commercial coffee:
"Best before 9 months" - Commercial Coffee
"Roasted on 3rd March 2020" - Specialty Coffee
A knowledgeable roaster will supply coffees between the 3rd and 10th day after roasting. It takes about 1-2 days to de-gas the coffees (required to remove the astringency due to slow CO2 release). Freshly roasted coffees have a tendency to peak i.e. deliver their best flavours around between the 7th to 12th day. Plan your purchase and consumption accordingly. I will be posting about a longitudinal study about the peak of coffees on my blog soon.
An interesting thing to note here is that there are times when freshness is not desired. An example is that cold brews taste better when made using 1+ month old beans. Certain medium and dark roasts perform better when aged. It is only possible to find that post experimentation.
Coffee-to-water ratio (Brew ratio)
This is the ratio of the amount of coffee to the amount of water.
Golden ratio = 1:16.67 or 60gms coffee in 1000ml water
The amount of coffee to water determines:
Balance - interplay of sweets, bitters and astringents
Body - mouth feel of the coffee - thin, medium, heavy
Acidity - low, medium high
The brew ratio varies across different brewing methods. Espresso's have a brew ratio of 1:2, whereas manually brewed coffees can range from anywhere between 1:6 to 1:20. Here are a few standard ranges that you can use:
French Press: 1:12 to 1:20
Pour over: 1:12 to 1:16.67
AeroPress: 1:6 to 1:16.67
Inverted AeroPress: 1:6 to 1:16.67
Cold brew: 1:12.5 or 80gms coffee in 1000ml water
Iced AeroPress/Pour over: 1:10 for extracting hot brew , dilute to 1:16.67 by pouring over ice
You can even use the following chart to better understand how your extraction changes with the brew ratio.
This is the size of coffee when ground for brewing. The grind size directly impacts the brewing time and extraction yield. Smaller the grind size, higher is the extraction. Brewing methods which specify lower brewing time generally use smaller coffee grounds and vice-versa for a balanced extraction.
Grinds are classified on a spectrum of fine to coarse. While no standards exist for grind size, I have inferred the following based on Coffee Stack Exchange and personal experiments:
Fine: < 0.5mm
Medium: 0.5mm to 1.5mm
Coarse: 1.5mm to 3mm
Coffee is ground using a grinders which can be manual or automatic. High quality grinds are those which are consistent in size. It is recommended to invest in a grinder before a weighing scale or any other equipment as the grind is a determinant of your brew's flavour profile.
Brewing processes look simple but are complex. As one continues their journey through the coffee space, you get much more acclimated to the nuances present in your coffee brews especially if you are into light roasted coffee (dark roast enthusiasts: god bless your taste buds). An often ignored aspect of the home brewing process is temperature control. While brewing temperature is critical to activation of the grounds and extraction levels, we tend to ignore the other aspects of the brewing process i.e. the equipment we use. There are 2 types of equipment:
Coffee reacts to temperature differentials. Pre-heating allows you to minimise these temperature variations and the brew that you get will be much more consistent. Pre-heating allows you control the repeatability of the process and perfect your recipes.
Rinsing paper filters
Paper filters are made of paper (you bet!). This paper is processed using chlorination and bleaching. As a result, the paper may have some of these chemicals remain on them. When you brew without rinsing your paper filters, you end up risking a papery flavour alongside those beautiful mandarin notes or hints of cardboard with a lovely clove-like finish. A simple method to test this is to soak a paper filter in warm water for 10 minutes and compare the taste with a normal cup of warm water. Rinse them every time you brew!
There are studies being conducted by the likes of Scott Rao on whether paper filters can be reused or not. Adam Adler, the inventor of the AeroPress, does mention that the coffee filter of an AeroPress can be reused by washing it. Maybe this is something you can keep in mind, in case you are ever running low on filter papers and are forced to re-use.
I cannot stress how important water temperature is to the entire brewing process. Water temperatures can lead to over-extraction due to too much heat (bitter) or under-extraction due to too less heat (astringent). A standard used is 92°C across the coffee industry.Through my own personal experience, I also found 85-88°C as a great water temperature to target brewing in. If you don't have a thermometer, then use the following scale for reference:
90-92°C - 20-30 seconds off boil
85-88°C - 45-60 seconds off boil
As mentioned earlier, every equipment you chose has a different brewing time standard. Brewing time ensures that the extraction is maximised to the extent that the marginal gains post the standard are minimal. This time is based on extraction yields and balance of the coffee, found through repeat trials done by the manufacturer of the equipment. Here are some of the commonly known standard ranges:
AeroPress: 90 to 100 seconds
Pour over: 2.5 to 3 minutes
French Press: 3 to 4 minutes
Cold brew: 12 to 16 hours
These are the essential brewing parameters that every home brewer should be aware of. Absorb each and every single one of them by putting them to good use. I have shared recipes to some popular methods such as the Pour over, AeroPress, Inverted AeroPress and French Press before. Now, it is imperative for you to also understand that these are standards. Simply standards. Not a rule. You are free to play around with each and every single brewing parameter as you deem fit. Look at the championship winning styles and you will understand that none of them stuck to these standards, constantly challenging them.