TonyTuanx 

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You can still gain lifetime access to the Google sheet with my brewing database by donating 5$ with your email address, so you don't necessarily have to subscribe.

Additionally, I'm still thinking about whether I should build this platform just for English speaking audience or try to translate it to Russian. Either way, my goal is to share information and excitement about coffee to any and every coffee enthusiasts, so it doesn't matter in the long run if I split the content into different languages in different platforms or create it all in one place, as long as it becomes a sustainable thing. I have time to think about it, and I'd like to hear your thoughts on it too.

Greetings, coffee enthusiast! I am very excited to announce that the crowdfunding campaign for the "Mini Caffeine" project has successfully gained enough fundings, or exactly 33% of the goal, for me to be able to do this project in a smaller format, as I have said in my previous post! As for how this project will go, I'm going to provide the details in this post, including:

1) The goals of the "Mini Caffeine" project;

2) Results of the crowdfunding campaign;

3) What the smaller format entails;

4) Experimental details of the caffeine analysis.

What I hope to obtain from this project the dependences of caffeine extraction on extraction yields of the coffee and compare it between pourover, brewed on a V60, vs fast flow, soup-style coffee, brewed on an Oxo Rapid Brewer. We know that caffeine extraction differs between espresso vs pourover, and the difference between them is that espresso is pressurized puck percolation and the pourover is unpressurized percolation. Soup-style coffee is unpressurized/low-pressure puck percolation, so we might expect the caffeine extraction to be different from pourovers too! 

The reason I chose Oxo Rapid Brewer for brewing the soup-style coffee is due to its ability to serve as an extreme case for fast flow brew, resulting in a finished cup within a short amount of time; the V60 serves as the opposite, albeit not particularly "extreme". Extremums are useful in research, as we are able to infer from these extreme cases the caffeine content of other percolation brewing methods, e.g. puck percolation AeroPress. Oxo Rapid Brewer also provides smoother workflow, which will help with faster brewing process and data obtaining.

Because majority of coffee consumers drink either medium roasts (which is the most popular choice for general population) or light roasts (which is popular among coffee enthusiasts), the caffeine analysis for both roast degrees is warranted. I have chosen for this analysis the roasted beans, both light and medium, from the same exact green bean, which I believe will be more insightful, and it is going to show us how the caffeine content and the caffeine extraction dynamics change during the roasting process. As a byproduct of the caffeine analysis, we'll get a data on chlorogenic acids content in brewed cups, which might or might not have some positive health and negative taste implications. All of this data will give us, coffee consumers, evidences towards a better coffee consumption guideline for our health and enjoyment purposes. 

Greetings, coffee enthusiasts!

In this post, I'm going to go into details about the "Mini Caffeine" project, including the goals, objectives, experimental design and the outcome of this little study. I want to keep it as transparent as I can, so that you can decide if you want to participate in this endeavor! I'll try as hard as I can to pitch it to you professionally, but I will not deny that I'm very inexperienced in doing this kind of thing and there is a personal burning enthusiasm regarding this topic. I also want it to be as clear and understandable for general audience as I can, so I will simplify things where I can.

It is intended to be a small crowdfunded coffee study with a primary goal of developing a quick and fast method of estimating caffeine concentration in brewed coffee samples with UV-spectrophotometry. I want these brewed coffee samples to be reflective of what people drink in day-to-day life, and for this study I want to compare caffeine concentrations from pourover coffee vs soup-style coffee, i.e. percolation vs puck percolation.

This project/study is NOT about precision, but about estimation. This is a small study that will NOT be HPLC-validated (compared to something like a Lighttells CA-700 caffeine analyzer), rather, the funding will allow me to buy pure caffeine samples and use it as a reference for estimation in this method.

I would like to plot estimated caffeine concentration vs estimated extraction yield of coffee for pourover (brewed on V60) and soup-style coffee (brewed on Oxo Rapid Brewer) for three different coffee beans (representing America, Africa and Asia, for example, Colombia, Ethiopia and Indonesia, preferably washed process) at two roast levels (filter/espresso or light/medium). This will allow us to get more evidence towards making a coffee consumption guideline in the future with more rigorous testings and replications from fellow researchers and coffee enthusiasts.

My goal is to collect 100000 rubles (or ~1333 USD) to start this project.

Recently, I've tried to brew AeroPress soup with a modified technique, which produced the thickest, heaviest in the body cups I've ever tasted. I called this technique a "Soak Pass".

The idea is that the most easily extracted compounds in the coffee are low molecular weight compounds, which contribute to acidity and saltiness, even umami taste perceptions. If you discard the first portion of the brew, you can make the brew more balanced with less sourness and salty/umami tastes. This concept is not new, and some people have been practicing this for quite some time in the context of pourovers, competitions and just brewing coffee at home as far as I know.

However, what I was more interested in was the applicability of this concept to low ratio percolation brews, such as AeroPress soup/espresso-strengths, to enhance the body of the brew. In theory, the latter extracted compounds are less soluble, have higher molecular weight and contribute to tactile sensations more.

I've tried to brew it three times so far, and the results were delicious, in my opinion, of course. Here's what I did:

1) As usual, added 18g of finely ground light roast Kenyan coffee (ZP6S at 1.0) to an AeroPress, tamped with the plunger and added paper filter on top of the puck;

2) Added 27g of room temperature and immediately inserted the plunger and pressed to the bottom of number 4 on AeroPress to drain the soaking water. The first portion of the extraction usually weighted around 8-10g, so the grounds absorbed water at a 1:1 ratio at this stage;

3) Removed the plunger and added 36-54g of boiling water, drained the coffee for around 50-60 sec and pushed to the hiss. The amount of boiling water depended on how much coffee I wanted out, and because the puck was almost saturated in the previous step, the output was usually the amount of boiling water added at this step plus/minus 1g.

I was amazed at how balanced the cups turned out with a lot of sweetness and body. These Kenyan beans were very acidic in other recipes, but with the "Soak Pass" the acidity was just right. Of course, the TDS was less at around 5-6.8%, because the sour and salty first portion contained a huge amount of solubles, but if it's that tasty then I'm all for it.

So I've been gathering data on AeroPress Pourover style brews (this recipe: https://youtu.be/njxTlITJ6Ds), and I noticed something really interesting (which I mentioned in the video): the grind size has a significant impact on the resulting extraction yield, when dose and brewing ratio is kept under constant across different beans with different roasts and processes, albeit the water temperature ranged from 60 to 70C. The data is scarce, sure, so I decided to test out the formula from the linear regression ("before" graph), which predicts 28% extraction yield by grinding coffee at 1.0 on ZP6S.

It did not hit 28%! It only reached 23% EY, which is still pretty high, but I was wondering what might be the reason for it. My first thought was to inspect the puck, and surely enough, it had several channels (see if you can find dark spots):

Hello! Here is weekly review of the brews that I made this week; all of them have been added to my Brewing Database, which you can get a lifetime access to if you subscribe to CoffeeTonoia tier or donate 5$ with your email address, so that I can add you to the Google Sheet. Anyways, here are the brews:

1) Brazil Cerrado (natural, medium roast by Energy Coffee) - brewed several times

1.1) 18.0g (ZP6S at 1.0), 27g boiling water soak and 30.7g boiling water

Method: Modified Espresso-Strength Puck Percolation. No tamp! TBT 2 min 40 sec, 35.0 g out

A bit heavier body, not offensive, drinkable, but a little salty and highly astringent; puck looks HORRIBLE, huge dark area, suggesting channeling; pretty common stuff with boiling soak, I should say. Brix 9.2, so 7.8% TDS and 15.2% EY

1.2) 18.2g (ZP6S at 1.0), 36g boiling water soak and 30g boiling water

Method: Modified Espresso-Strength Puck Percolation. No tamp! TBT 2 min 45 sec, 43.3 g out

Used a cotton pad on top of bottom paper filter to see if the channeling could be reduced; the puck still looks terrible with dark region; still a bit heavier body, still a little bit saltiness. Despite this, okayish niceish brew, I think. Less astringency, less bitterness. Brix 8.2, so ~7.0% TDS and 16.6% EY.

1.3) 18.2g (ZP6S at 1.0), 30g room temp soak and 30g boiling water

Method: Standard Espresso-Strength Puck Percolation. No tamp! TBT 2 min 20 sec, 38.1 g out

Watery, very light body; I actually liked this brew, but it's reeally underextracted. Puck is pretty uniform with some dark regions. Brix 7.8, so ~6.6% TDS and 13.9% EY.

1.4) 18.2g (ZP6S at 2.0), 57g boiling water

Method: No Tamp AeroPress soup (high flow). No soak, just add water and press. TBT 45 sec, 39.3 g out

Silty mouthfeel, unpleasant sourness, felt some fermented apples though? Puck with dark spots. Brix 7.6, so ~6.5% TDS and 13.9% EY.