Extraction Versus Time

The Merit Interval is an interval of time in which your extraction yield is optimal. As you are aware, and to your utmost subjectivity, there is some place during extraction where the after yield is either over or under extracted. The merit Interval would be the in-between area in which is neither over, nor under extracted. It is an area with a buffer, some play room, and is where every barista strives to cease extraction during - for producing the best tasting cup to their individual aspiration. It is also proportional to time and closely correlated with the rate of extraction. Here if a visual representation, where the area underneath the extraction verses time curve, from a to b, provides you with the Merit Interval. 

As you can see by the graph - a larger interval should produce a larger buffer. This means that you have a wider target to hit and will provide an interval that is easier to produce consistent, satisfactory extractions. The larger the area, the more forgiving the extraction should be. For example, it is no secret that pulling espresso shots is extremely sensitive. Compressing an extraction time around 25 seconds creates very small room for error - hence having a very tiny merit interval. However, looking at the near end of the spectrum - it becomes very difficult to mess up cold brewed coffee. With extraction times around 24 hours, you could cease extraction within a two hour interval and still have a perfectly adequate brew. 

I would like to take the aeropress into consideration. A typical aeropress extraction time may vary around 1.5 minutes having one of the shortest brewing times out of most methods. Because of this, and consequently having a small merit interval, both Jose and I have found it fairly difficult to produce consistent yields from. Comparing this to espresso, and although pulling a shot is very delicate, at the same time the elements are very much within your control. Granted your machine is dependable - and temporarily ignoring parameters - the extraction time is reasonable enough to consider consistent. The aeropress however is not quite so simplistic. While the infusion time is generally manageable - when adding it with pour time, rotation, temperature drop, agitation, plunge speed - it becomes a bit more to keep attention too. All of this while trying to end it on a dime can become quite the challenge. 

Looking at the curve below shows that the closer you are to zero on the time-axis, the higher the rate of extraction will be, and the less area the merit interval will have. Since there will always be coffee extracting, the extraction curve will be ever increasing, but at a slower and slower rate. In the graph it shows identical time intervals, in which the merit interval M2 is larger than M1. However, these time intervals should really decrease as they are shifted left (a1-b1 < b1-b2), but for illustrative purposes in the graph below, even if the time chuck was identical, the merit interval of M1 would still be less than M2. What this means is that by stopping extraction while the rate of extraction is very high and the total elapsed brew time is shorter, this will entail for a smaller target to hit. Again referring to espresso, because the rate of extraction is so entirely fast, you have very little time until being drastically bitter or astringent. With brewing coffee this is similar, but on a much larger scale. Things do not happen as fast, but at the same time the mechanical aspect can play a larger role because of how much more time there is for error. 

Looking at any traditional pourover brew method presents many volatile details. It can be a struggle to extract a uniform amount holistically because of things like high and dry grounds, erratic turbulences from varying pour speeds and heights, water temperature dropping in both the kettle and slurry, and even the inconsistency as water percolates through the slurry in a general sense. Despite these lovely battles, you could perhaps save yourself some sweat and coarsen up a bit, and extend your extraction time. I'm not trying to associate tastier coffee with longer extraction times, but conceivably produce tastier coffee more frequently and consistently instead. Extending extraction times is not always something that is even an option, for the quality of your grinder plays a large role in that as well. Having too many fines inside of your grind makes things trickier due to an even more dramatic over extraction, and may indeed lead to poor coffee. This is really an alliance towards pushing the best extraction out of a single brew, and then being able to repeat that same cup within a small deviation. 

Improving Your Grind

I have been thinking about upgrading coffee grinders lately. I currently have the Baratza Virtuoso, but I feel that the particle size distribution is just not cutting it. It generally does a decent job, but as soon as I coarsen up a bit past twenty, which I often do for pourover, I can see significant differences of particle size throughout the grind, which unsettles me to brew with. 

Anyway, this post was not exactly about my debate in upgrading grinders, but instead a way to get the most out of your grinder. It is essentially inevitable to have fines in your grind despite how flawless your grinder may be. With that said, fines are often a common culprit that make up a decent portion of bitterness in coffee. Since they over extract so quickly, it can be difficult to compensate for. 

So my main thought was, by grinding coarser for what ever brew method that you seek, you are essentially creating a larger gap between particle sizes. You would further over extract the fines in order to amend the coarser particles (when grinding coarser). If you were to instead tighten the grind up a bit, you could shrink your considered confidence interval between sizes, and hence extract less from the fines, while extracting the desired amount from the rest. Well, hopefully the desired amount anyway. 

I don't have any physical data on the amount of fines produced from a grinder during different settings, but was more of just a thought than anything. Generally speaking, I feel that many people (and frequently in the industry setting) tend to grind finer, over dose, and under-extract. This way you get the perception of a correct extraction, but is quite wasteful, and commonly may produce subtle undesirable flavors. Again though, this could be a working get-around method to compensate for the lack of a quality grinder. Or for all that matters, just another way to improve your morning cup.

Preheating Uncertainty

    The other day a light bulb went off as I asked myself, "why am I preheating my coffee cup?" I'm literally going to sit there for seven minutes, salivating, waiting for it to cool down and approach my body temperature. I certainly understand the desire to keep coffee warm for longer, but with the focus of optimizing quality specifically, I think it truly is a necessity to let it cool. I used to really enjoy the thought of getting steaming hot coffee, and then sipping it for a really long time. The problem though, is that you can't taste burning hot coffee nearly as well. 

    A possible reason being that your taste buds don't clearly perceive hot beverages/foods as well as cooler - is that the hot temperatures affectively prompt the tongue to prepare itself from something dangerous (ref 1). For the same reason getting punched in the arm hurts, the tongue should feel no different being burnt. I countlessly watch people hurt themselves by spilling hot coffee on them, and then directly afterward take a sip. It may not be necessarily that you can't taste as much, but that the taste gets masked my the tongue from going into defense mode.  

    Not only might the taste be diluted from exceedingly hot temperatures, but many chemical reactions are functions of temperature. For example, Chlorogenic acid breaks down into other acids in which is a dominant contributor to the acidity that is desired in coffee (ref 2). Without the acidity the coffee may taste flat or dull. Granted after to much of a temperature drop, as it further breaks into quinic and caffeic acid, it may produce overly bearing astringent and sourness. I would also like to encourage separating acidity/sourness to being associated with bitterness, for in the wonderful world of coffee they are essentially unrelated. 

    I think this is particularly relevant to pour over, or other forms where the coffee is brewed and then served instantly. Where as in an insulated vessel the temperature usually drops anyhow, and plus most coffee shops save their most prided coffees to be prepared fresh. It can be hard to serve a customer a great cup of coffee, where it could be even better if they would just wait a few more minutes before enjoying it. Especially when it is sitting there in front of them, because I'm sure not knowing any better I would do the same exact thing. 

    As means to let a customer experience the best cup of coffee that you may provide them - whether they know nothing or everything about coffee and in effort to provide that very cup, perhaps preheating could be just the icing on the cake. 


References: 
1)    leming, Amy. "Hot or Not? How Serving Temperature Affects the Way Food Tastes."Theguardian.com. Guardian News and Media, 17 Sept. 2013. Web. 13 Sept. 2014.

2)    Rao, Scott. "Roasting Chemistry." The Coffee Roaster's Companion. Canada. 89. Print.

Tasty measurements

Coffee is engrossing, and is of utter passion and interest to many people. What I feel separates coffee in respect to competition, and how we collate amongst each other about coffee, is that it's entirely subjective. While taste is foremost relevant, and the other somewhat distracting effects yielded along with coffee (like caffeine!), there must be some system in order to create comparison and measurement. To measure coffee solely by the experience through flavor and aroma is great and all, but it's just not enough. While measuring a brew's total dissolved solids has no assurance of taste or flavor, it does however provide consistency and a method of communication. Communication to understand and allow different outcomes and why they might take place, and also to reduce the guess work and be able to properly discuss and relay information with each other. Replacing something as intimate and personal as taste with numbers and measurement is not exactly what is happening, but instead is a method to refine and purify the ambiguity of why certain results are produced from specific variables and parameters. Although a cup of coffee’s tds turns out to be 1.32%, and is not a guarantee of a good cup - yet I might find out after brewing and testing multiple cups that I far more enjoy coffees brewed in the range of 1.30% rather then 1.40%, and this is useful information. 

Shows the brewing process cut into slices -
the times are displayed underneath. 

As humans, we seem to enjoy competing with one another. I can brew a cup and think mine tastes fantastic, and then Jose can brew another cup and think his tastes better. By creating standards we can actually compare each other's brew with more then just our subjective and opinion based taste buds. Whoever is actually better must be debatable, and is that really of importance anyhow? As arduous as it can be to admit, but there was definitely a time in my life where I did indeed dump an ounce of half & half into my coffee - my dark, over roasted, coffee. I thought I enjoyed it brewed dense and strong, and in fact I assuredly did enjoy it. I recall visiting the SWRBC when it came to Santa Cruz with Jose, and trying my first cup of what was considered properly treated and well extracted coffee. I thought it was drastically weak, and there was such an intensely present sour acidity. What I knew is that it tasted like nothing I had ever previously experienced, and although I didn't necessarily want to experience more - I did want to find out why this was the standard. It was quite distressing, trying to organize my conflicting thoughts of what the perfect cup of coffee was. Jose was actually the first person to present this to me, and it truly threw us for a loop. We couldn't determine what we enjoyed about coffee, nor what was evidently unpleasant. We tripped over this for months before we had realized that the fierce, bright acidity that was once virtually unbearable - was the thing we now craved and looked for in coffee. 
The bewildering part is whether this happened because coffee is truly better this way (and if that is even a fair notion to present as true), or because we changed our expectations of coffee, because of what other people considered superior, or some other possible third thing. I do know that I enjoy coffee brewed and roasted similar to SCAA standards, but what is difficult is the reason why I do. I feel a vast amount of the people that enjoy coffee prefer consistency and assurance in what they already know. It's as if there is a fear of purity, and that uniting a well known quality like sugar is an easy solution to disclose the unsettling thought of an uncharted, and unexplored area. Why not take an adventure, who knows, you might end up in a place that is lovely and enchanted. The hindrance on the other hand is, well, you might not like it. You might not like the new single origin from Kenya, but that shouldn’t mean to turn your back away from anything else new. 
Despite a possible side track - I think the measurement of coffee and espresso is of utmost value and utility. Although I'm not always 100% sure whether my coffee is over extracted, under extracted, or both over and under, but I can assuredly find out, and hint towards the causes and reasons why. 
  

Cuppy Questions

Cupping a coffee from Kenya

Cupping seems to exist as the standard for evaluating coffee, in which every coffee has an honest chance with least external interference possible. It also is generally used to set an expectation that one might experience in a coffee. The often impressive tasty notes written on a freshly purchased bag of coffee doesn't always converge paths with what you may experience at home, or perhaps even at the cafe in which you purchased it from. Cupping is attractive in many aspects: its parameters are easily kept stable between comparison of coffee, it gives you a heavy emphasis to determine aroma, and it also allows full potential without user mistake. Cupping provides a way that takes the absence of error out of most brewing methods, and it keeps the elements minimal so you can evaluate the coffee for what it is. My intrigue about cupping however, is why we use a method such as cupping to determine what people might find in a coffee, when in doubt the consumer isn’t going to cup the coffee and experience the same thing. Perhaps the consumer might actually cup the coffee, but cupping isn’t generally the way people prepare coffee to drink every morning. Maybe the fancy exotic words used to portray a coffee is for the sake of marketing, or maybe my taste buds are lacking, and I just can’t pick up the “fluffy, nougat, starfruit” notes as described on the bag. Without a doubt, I pick up some captivating flavors when trying new coffees, but very rarely would I agree on what the bag says. In a sense I feel like it’s a set up for disappointment, especially for the not as experienced coffee drinker. Someone more familiar on the other hand is more likely to average out the tasty notes along with the origin and the way it was processed for a better prediction of what’s inside. To see something like “loud, bright, tangerine,” tagged on a wet processed African coffee typically makes sense, and rides along with our intuition. But often enough I read things like “jaunty, cheer, buoyant” and just think to myself what a great day those people must have been having when they wrote this. With a thesaurus the limits are endless, and often come off as ridiculous. Indeed, sometimes I do find these strange adjectives riding along my pallet, but more often than not I’m in a whole other ball park.

What I do love about cupping, is not only the knowledge obtained from it, but the knowledge that gets shared during it. It’s really quite a social event, and while I’ve tried cupping alone, it is really quite unfortunate and dismal. After all, coffee is heavily communal and revolves around social interaction. And if more than two people can agree that a coffee tastes like brown sugar, then I suppose all the more reason to write it on the bag. Is cupping really that beneficial to helping the customer select a coffee? I don’t know, but it's definitely beneficial for education and analysis. This wasn’t supposed to question the cupping process, but instead dispute how we use the information we collect from it. I feel that you shouldn’t have to pull out a dictionary to comprehend a short summary of what you might experience in a coffee, but perchance that’s just me. 

Mysteries of the Pour Over

There seems to be a continual force present among ourselves to resolve the issue of uneven extraction. With the exclusion of espresso, there’s copious variety when it comes to brewing methods and the intricate subtleties of style and technique. From the agitation being sourced due to the flow and contact of water with grounds, to the perpetual struggle of channeling and uniform pouring - everything seems to make such substantial alterations to the final extraction. Grind consistency and distribution, maintaining proper slurry temperature, low and flat beds, brew ratios, degassing, and so many other parameters and elements to disarrange and contort - and when it comes down to it, it’s all an effort to evade the well known and unpleasant taste of simple bitterness. It’s all a fight, and quite frankly one that we often lose. So what truly is the most dependable method for extracting coffee, and is dependency and the ability to remain uniformity even relevant? I enjoy and appreciate the labor, effort, and reward of manually brewing a cup of coffee. Where you can express personal characteristics and convey specific attributes that you want present more than others, and in each cup there is something new and unique whether good or bad. I dislike the idea of a machined robot making my coffee, despite if there is consistency there or not, there is frankly a lack of love and focused disposition. Also, and quite surprisingly - I very infrequently get an exceptional cup from an automated coffee machine. I mean seriously, have you seen those beds? High, dry, channeled, and all over the place. Perhaps one day I'll be united with the perfect machine that brews the perfect cup every time, but until then lets discuss the good ole pour over. 

Without stirring

With Stirring

In a pour over, there are many inconsistencies and obstacles that present themselves. First off water temperature. What ever temperature it is that you deem optimal is going to dramatically drop in the actual slurry. So perhaps you over compensate for the temperature loss by five degrees, but now you have an undesirable and overly heated water temperature coming out on top, and a decreasing temperature as it subsides. This is quite unreliable, and is dependent on other elements such as room temperature, and unless you have a heat regulated pouring vessel, then the temperature of your pouring vessel is dropping as well. Each dispersion of water you make is another opportunity to create non-uniformity among the slurry. The pour over's design is somewhat flawed in the sense that it's nearly impossible to always have all grounds being extracted at the same time (and evenly at that). Due to that charming thing called gravity, the water is constantly being pulled down, and unfortunately wet grounds create a lot of surface tension, and clench to the sides as the water depletes. All this means is that the water level is leaving the grounds high and dry above, where extraction ceases, and the lower section of the bed becomes extracted at a higher rate. So how do you avoid this? Well, keep your slurry as low and even as possible. I'm a large fan of stirring - during the bloom, as needed during extraction, and after the final saturation. I truly believe it assures uniformity and even agitation with a little practice. Stirring the slurry will encapsulate the grounds grasping onto the sides, and mix them with the rest. This is fantastic as well, because while extracting it's of good practice to avoid pouring directly down the filter because it's an easy place to channel, and by stirring you get the grounds you miss while pouring. Next time you brew, look at the differentiation between colors throughout the slurry (as in the pictures above). It's quite apparent the different levels of extraction, usually being under extracted and darker on the outer perimeter, and further even and lighter in the center. Stirring may have a draw back as well, depending on how you look at it, and should be accounted for the additional agitation which may induce extraction. This could be a simple fix as to slightly coarsening the grind. The pour over is traditional, and manages to still be one of the dominant methods to produce coffee, but is most assuredly far from perfect. 

So where does this bring us now? Well, there are some imperfections in percolation style brewing, and yet it's still my go to method every morning. Perhaps the hassle and time put into a syphon pot isn't something I want to go through every morning, but does it actually produce a better cup anyway? I think that's for another post - and discussion of infusion styled brewing methods. I really do enjoy brewing pour overs, It's sincerely and simply fun. Funny enough, sometimes I find myself sad once it's finished, almost like beating a game and then not knowing what to do after. But then you realize that you just produced something (hopefully) delicious, and you get to indulge in a creative and beautiful beverage. A cup of coffee that has been touched by the hands of many, all just to get onto your counter for you to take pleasure in brewing and drinking. 

Hario Woodneck: First Impressions

The Hario Woodneck drip brewer is of most intrigue due to it's simple elegance, reusable cloth filter, and ability to produce one of the most defined cups, yet truly exemplifies body without the loss of crispness (which is something that can be difficult to achieve). Jose and I have already had a fair share of Woodneck brews, but we were certain we needed one in possession. Out of the box it was fairly simplistic to get up and going. It provided a nifty Hario branded spoon for that oh so perfect volume measurement, and the device itself looking quite dashing with it's wooden accents (quite similar to that of a chemex). On the down side the glass seemed a bit flimsy, although maybe thats because we are so used to the hardy chemex build. The cloth filter slides around a ring attached to a wooden handle, and is then placed on top of the wood neck for brewing. We poured a solid liter of hot water through the brand new filter just for good measure and fear of a cloth-like tang.

The cloth filter really brings a lucid body out of the coffee, and preserves the sweet acidity that we simply crave. An interesting aspect of the Woodneck is the absence of any directly guiding support along the filter, it's essentially hanging from the metal ring. It's also quite a bit more narrow and long compared to your average dripper. This could be of assist because of a smaller surface area to assure an even extraction (perhaps anyway). It's interesting because a lot of the time when I order a Woodneck brew form a cafe, they pour directly down the center for the last hundred or so grams of water. They also fill the filter up just shy of the metal ring, which as far as I'm concerned is doing nothing but unevenly extracting, and under-extracting the pour coffee grounds stuck high and dry. I originally thought on behalf of the diminutive surface area of the slurry, and with account of it's length that it might be less significant to worry about these things.

Since then I've made my fair share of drips, and with solid coffee to begin with it's a difficult dripper to really screw up, but the cups I've made - according to the cafe's I've gone to - always turn out with something slightly unpleasant or less interesting. After the initial bloom, what I've found to really bring out those sweet and acidic notes is to then do two more slow continuous pours (fast enough to retain constant flow, but slow enough so that the drip rate is around 1/3 the rate of pouring). Once you hit your mark on the second pour, I like to give it a gentile one rotation swirl to assure uniformity while extracting. It generally should sit around two minutes and thirty seconds, which is a trusty was to assure your pouring speed is on time. Also for proper storage and reuse of the cloth filter, make sure it's slightly damp, seal it inside of a zip-lock bag, and then store it inside of the fridge or freezer. Then when you are ready to use it again, revive it with a dose of hot water. I've probably made a solid thirty+ cups and still rocking the same filter. So let us know if you have a faithful procedure for brewing one of these puppies, and I'll certainly give it a go.