May 29, 2020
The art of brewing and grinding coffee has a mystery to it that should not be unpacked too much. This blog is intended to discuss the two fundamental principles behind every brew - extraction, and filtration. The following is not just specific to Mountain Top coffee. Due to our conditions and the nature of the varietal we produce, Mt Top Coffee is what is called a dense coffee*, meaning it holds integrity due to its cellular structure. That, plus the added advantage that it is inherently smooth, means it is hard to mess up when brewing.
The key to brewing is extraction, and the key to good extraction is filtering.
I have taken whole roasted beans and placed them in a sealed jar in clean water and left it in the fridge for over a week. In that time the coffee extracted virtually all it needed to extract without detriment. Indeed, its unique flavours were enhanced in many ways whilst other, less savoury and harsh flavours that can be incurred via hot water extraction, were absent.
Grinding coffee is a necessity for expedient extraction, but it can alter flavours detrimentally. The other expedient is heat. The method of extracting using cold water, without grinding the bean at all, works because the bean acts as its own filter - the ultimate filter – whilst cold water does not produce some of the nasties that hot water can. Particles that escape into the cup from whatever brewing method you use: espresso, plunger, stovetop, pour-over, etcetera, will continue to extract in the cup, even as it cools. That is why a cup of coffee can taste bitter or sour after only 10 minutes left to sit alone after brewing. Fine particles are the main culprits. The addition of heat when extracting produces some great flavours that cold brewing cannot. This is due mainly to the breakdown of oils into flavours and aromas, though a long extraction time in cold water will go some way to the same end. It is universally recognised that cooler extractions bring out flavours unique to specialty coffees. Play with extractions between 0 and 100 degrees Celsius of the same grind to explore this for yourself.
It stands to reason then that the coarser the grind the less chance there is for things to go wrong, and for a cup of coffee to wait there for you on the bench and still be delicious when it's cooled down.
As given in the recipe above, one trick is to further filter a plunger coffee that has just brewed through a paper filter to make sure the cup is free of the sludge that spoils. The common device used, as pictured, is the V60 conical filters, but a clean piece of fine cloth can work too.
My talk of whole bean extraction in this blog is mainly for didactic purposes, I am not expounding whole bean extraction as the optimum way to brew coffee. Indeed, Mt Top Coffee has been said to best suit the espresso method.
You can research easily what grinds are needed for specific brewing methods. Mountain Top Coffees, as stated earlier, are generally very dense yet smooth coffees. You can really hammer them hard on an espresso machine or, with practice, leave them to extract for longer than the usual 2-4 minutes in a plunger without deleterious results and get deeper, richer goodies.
One last thing with grinding is that as soon as you grind the shelf life decreases quantifiably. In general, the shelf life of exposed to air ground roasted bean will decrease in 20 minutes at a rate the same as one day of exposed whole roasted bean will.... the finer the grind the more amplified the degradation.
I may have missed a few obvious things here, so please feel free to ask questions.
*There is a nice blog here for those who want to go deeper into what dense coffee is: https://www.torchcoffee.asia/blog-1/2018/7/9/why-does-density-matter-and-what-affects-the-density-of-coffee
Until next time, Bernie.
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