Rob's Blog Archive

April 12, 2015

A Scientist's View of Coffee










Dr. Science----he’s smarter than you, he has a master’s degree in science---was once asked if it’s possible to be a scientist performing research at a Ph.D. level without drinking coffee.  His un-equivocating answer was no. 

That was never a problem for me.  My first purchase when I got to Seattle to start graduate school was a coffee grinder.  That was almost forty years ago.  I’ve been brewing with the goal of producing the best tasting coffee since that time.

Like most things, I took very little of the apocrypha for granted.  I learn what’s believed and always start there, but I am not afraid to question and experiment.  That held with coffee as well.  Along with this, I’ve been open to change.  My most recent variation was to start using an espresso machine as my primary means to brew my coffee---that was just a couple of years ago.  

My first and second major discoveries were that, 1) grinding coffee as finely as you can leads to a richer less bitter cup---Peet’s always has its coffee finely ground for a reason and 2) that for drip coffee the amount in the filter is constant regardless of the amount of coffee to be brewed.  The latter is the result of the fact that the strength of the coffee is determined by how long the water remains in contact with the grinds.  Adding more grinds slows the water down and all of the coffee comes out darker.  Conversely, varying the amount of water over a large range while keeping the amount of coffee grinds constant hardly changes the darkness of the brew. 

The coffee lesson that I learned many times is that there is no active heating system that will keep coffee hot without destroying it, usually rather quickly.  Most coffee in this country is now made by some sort of drip method.  The problem is, in many places, the pot stands on a hot plate of some sort.  Under this circumstance, the coffee is good for no more than twenty minutes.  It’s drinkable for, maybe another twenty.  From there, it’s better than what is in a percolator, but that’s a very close call.

The correct way to store brewed coffee is in some sort of thermos.  It’s a joyful reality that even some gas stations now use these.  For this, I personally thank the Starbucks Corporation.  They realized early on that there’s no other choice.  Of course, the good news is there are thermos systems that keep hot coffee very hot for a long time.  BTW, the tricks to getting the most out of your thermos are to get a good one and then make sure it is hot before you pour any coffee in.  My energy wasteful method is to fill it with hot water, let it stand, then dump out the water right before pouring in the coffee. 

The other lesson I learned many years ago is the importance of the material in which the coffee is stored.  Glass and ceramic are clearly the best.  Styrofoam is actually quite good and disperses essentially no contaminants, but there’s something totally unaesthetic about Styrofoam coffee cups.  It’s not quite as bad as drinking wine out of Styrofoam, or other plastic, but it’s close.  Given this, good stainless steel is a reasonable second best choice.  Finally, there are plastics and soft metals like aluminum.

Other items I’ve found include that conical filters work better than flat bottomed filters and, while freshness is worth something, good coffee holds up quite well.  I’ve gone back and forth between freezing my coffee and not---I’m keeping it out now---and expect I’ll cycle on that a couple more times before I die.  What does dominate is that, if it is kept dry, good coffee has a long shelf life.

The most recent twist to my coffee dance is to start using an espresso machine for plain coffee.  Actually, this has the historical precedent of using one of the old time double vesseled espresso makers, the ones with the water container on a stove, a cylinder of packed coffee held in place by various metal screens, and a top container to catch the superheated fluid after it’s passed through the coffee grounds.  The most recent inspiration, however, was from a local high end restaurant where they make single cups of coffee and they have the texture of espresso without the strength, just like the double cylinder gadgets I remember from grad school.  Finally, it solves the problem of storing coffee the Italian way, by brewing quickly one cup at a time.  I’d add that the reason I’m not actually brewing espresso is most of the “coffee” is actually in the first fluid passed through the grounds.  After this, what’s coming out is noticeably weaker.  This being the case, what I’m drinking is arguably a good café Americano. I can live with that.  Along with the convenience and quality, I find that I go through coffee much slower.  Espresso machines are incredibly efficient. 

My final note is that coffee and caffeine have historically been demonized.  Having enjoyed both for so long, I have at least paid attention to the press versions of all of the studies to show how bad it is.  Coffee comes out clean.  Actually, there are some data that show it to be beneficial. 

Asia’s favorite hot beverage is tea.  There, ritual and culture revolve around this beverage.  Our culture has a European origin, and our rituals and culture revolve around coffee. I always savor looking out of my living room window on a cold winter morning drinking my first cup. 

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