Tea and Coffee
To understand differences in preparation styles for tea and coffee, it’s first necessary to understand what we are tasting in the cup.
What we taste in brewed coffee can be mostly categorized into five categories: fruit acids and sugars, that come from contact the coffee fruit has with the coffee seed; caramelized and complex sugars developed from the roasting process; and bitter and dry plant materials leftover from other plant stuff in the coffee seed. There are also some oils in coffee, and depending on the filtration method, you might get some insoluble actual coffee particles. Other than that, all previous listed coffee flavoring material is made up of soluble particles.
In tea, your three main flavor categories are polyphenols, amino acids, and essential oils. These three groups not only make up the bulk of what we taste in teas, but are actually intentionally developed inside different types of cultivars and different growing conditions in order to be developed in particular ways for certain types of tea processing. For example: most green tea in Japan will have an intentionally high development of amino acids, but low essential oil compounds. To contrast, most high mountain oolong teas in Taiwan will have strong essential oil concentrations.
The kicker, here, is that essential oils are not soluble.
Now, in coffee preparation, much like when making lemonade, the acids are the most soluble, then the sugars, then the bitter, pithy plant flavors (if you begin smashing up the lemon segments). The process of brewing coffee is centered around monitoring the variables that affect the rate solubility of our flavoring material: ratio, grind, contact time, temperature, and agitation (among some other items, etc.). In utilizing these brewing variables, there becomes two immediate styles of coffee brewing that become apparent: drip brewing, and immersion. Drip brewing relies on the coffee bed staying static while water drains through it, forming a small amount of percolation in the coffee bed. Immersion brewing requires the coffee bed to stay static at the bottom of a chamber, and the brewing water to essentially just sort of sit on top of it, extracting mostly through osmosis.
Because adding agitation into the brewing process more aggressively exposes the surface area of extractable material from coffee grinds to the brewing water, it exponentially speeds up the extraction process. Therefore, drip brewing is always more efficient than immersion brewing at getting extracted coffee out of the coffee grounds. Then comes the question of the filtration medium. For ease of use, drip brewing is standardly paired with a paper filter, while immersion brewing typically happens in the press pot with a metal mesh screen.
A paper filter will remove all coffee sediment, and most of the coffee oils, or lipids, as well. Lipids don’t serve much flavor purpose in coffee, but can contribute a fatty mouthfeel. Some people prefer that added mouthfeel, so they enjoy the press pot — however, the mesh filter will allow coffee sediment to pass through, as well, and this will inherently contribute bitter flavors, as by consuming the coffee particulate you consume all the dry, bitter plant material that might not have extracted into the water yet.
With tea, the extraction process is a little simpler. The brewing water will penetrate the leaves, and the soluble material will extract depending on the processing of the tea leaf and the size, shape, and cut of the leaf. Secondarily, the essential oils, over time, will be released from the leaf after the brewing water has broken down the cellular structure of the tea leaf’s walls, and enter the brewed tea. So, it is, then, most important to the tea brewing process to understand what the intended flavor profile of that tea is relying on in order to produce the desired flavor profile in order to fully be able to adjust the brewing variables of ratio, temperature, and time. Time being the key issue, as essential oils will only release over a period of time.
Attempting some type of drip tea process is nearly a fool’s errand. In order to produce a slower flow restriction to get enough time to get essential oils released from the leaf, one must use a paper filter in which essential oils would then be filtered out and trapped in. If attempting a drip method with a paper filter for a tea with low emphasis on essential oil content and a short brew time, like a green tea from Japan, you become stuck knowing that most green teas from Japan also rely fairly heavily on tiny particulate getting knocked loose into the cup to accentuate mouthfeel and flavor.
But, in the end, the simpler answer relies on how tea is processed: the first step is picking the leaf. Once picked, the leaves will start to oxidize, and turn color. In order to stop oxidation, heat will be applied. Then, the leaves are shaped, they might enter extra firing processes, and are dried. How these steps are applied will define which type of tea it is. It is important to always remember, though, that tea is a dried leaf. In order to allow even the most simple easily extracted soluble polyphenols to dissolve, the leaves must first fully saturate and expand, allowing the water to penetrate the leaves deeper. And steeping will always have a more profoundly efficient and better result than a drip method for tea preparation.
It should be noted that all the coffee information is much, much better explained and mostly learned from The Coffee Brewing Handbook by Ted Lingle, available here: http://www.scaaeducation.org/bookstore/the-coffee-brewing-handbook/