The Difference Between Fresh and Stale Coffee Beans

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Introduction

Many folks who, like me, wish to try pour-over coffee will definitely look into some details online – via articles or videos – about what tools to prepare and how to make the best cup of coffee. Obviously it is without doubt that the pictures and demonstrations displayed will use the highest grade of tools and materials (coffee beans included). Viewers who want to imitate the pour-over technique may be disappointed to find their results to be sub-par and not what the pictures/videos portrayed at all.

As a personal anecdote, I watched many Youtube videos and read many articles (including this guide from Blue Bottle Coffee), but no matter what I tried I wasn’t able to produce the bloom as shown in these guides. One of the other videos I watched was from Tully’s, a local coffee chain, and I even bought some whole coffee beans from them and tried to imitate the video, to disappointing effect. Just as I was about to give up the journey of making beautiful and delicious pour-over coffee, I bought and used some coffee beans from a local store which roasted coffee beans on the spot… and the results were beautiful! The freshness of the coffee beans produced a bloom prettier and more substantial than any of the videos and guides I’ve watched.

To illustrate the difference, I have decided to create a side-by-side comparison guide of various coffee beans purchased from various cafes. In addition, as I am a still an amateur, I would also like to show that even by using non-standard ordinary tools, it is possible to re-create the pour-over effects shown in many other articles and videos on the web.

Lastly, realize that there are multiple ways to perform pour-over coffee technique. Since I live in Japan, I have opted to adopt the Japanese-style pour-over technique. Many other techniques don’t care so much for the bloom nor painstakingly controlling the pour amount/rest time/number of pours, but I find the ceremonial process of the Japanese style to be very soothing and comfortable. Much like with the upscale bartending industry in Japan, the show is just as important as the end result – the careful consideration of the server to handle a singular order from a client shows the importance of every single customer to the establishment. Of course, personally I feel the coffee tastes comparably delicious compared to other techniques I have tried in the past.

Notable Differences Between Fresh and Stale Coffee Beans

This section is basically the TL;DR, if you are not interested in reading on about the specifics.

Stale coffee grounds:

  • Have little to no “bloom” when starting the pour.
  • Is difficult to “maintain” the pour – the water will appear to fill up too quickly in the filter and “overflow”.
  • After the bloom, when pouring in the center, the grounds will not appear to expand around the sides. This suggests that the grounds in the outer area of the filter are not having their flavor properly extracted.
  • Will lack flavor and have a much bitter taste.

Tools Used

  1. Tanita KJ-212 food scale (has both grams and ml measurements, down to one decimal of accuracy)
  2. Kalita KH-3 Manual burr-style coffee mill
  3. Food thermometer
  4. Pour-over kettle
  5. Coffee dripper (Hario V01) + filter (Hario)

Coffee Beans Compared

 

 

Looking at the above pictures, from left to right:

Avi Coffee

Avi Coffee, located about 5 minutes walk from Gakugeidaigaku Station on the Toyoko Line, is a small local shop that offers freshly roasted coffee beans at an affordable price. While they have some common blends they will roast on the same day, you can choose to wait and have them roast the raw coffee beans for you on the spot. I loved that the coffee beans had somewhat of a sheen on it when I first opened the package.

In this guide, I purchased 200g of their premium dark roast, and it was roasted on July 14, 2018 (the experiment was performed on July 22, 2018).

Ueshima Coffee (上島珈琲店)

Ueshima Coffee’s parent company, UCC, has a long history with coffee and interestingly was the first company in the entire world to introduce canned coffee. Just like Starbucks, they operate many coffee shops all over Japan; there is likely not one person in Japan who hasn’t seen or heard of one.

The only coffee they sell is the original Ueshima Coffee blend. I purchased 100g in which the cashier lady measured from a bag behind the counter. Thus, information about its roasted, best-by, or expiration dates are unknown.

Starbucks

No explanations needed here – everyone knows Starbucks (I hope)! While they have bags of coffee beans lined up in the shelves, it is possible to purchase a lesser amount than the 250g that is usually packaged in a single bag: minimum 100g, in increments of 10g. I showed the cashier the Dark French Roast bag, saying I wanted only 100g of it, and she took the bag, opened it up, and measured 100g for me. The bag showed on it a Best-By date of December 2018.

Preparation

Here is my pour-over technique. Factors such as pouring time, waiting time, and pour amounts can be individually adjusted to your liking.

  1. Boil enough water so that you are able to use some for warming the coffee pot as well as for the actual coffee. I recommend the amount of coffee + 150ml extra. For this guide I will be using ~270ml of water for the pour.
  2. While waiting for the water to boil, measure and grind your coffee beans. The ratio of coffee to water is not a topic of this post – feel free to adjust due to your taste – but for the purposes of this guide I will be using a 1:15 ratio. A 1:15 ratio with 270ml water means 18g of coffee.
  3. Once the water comes to a boil, remove it from heat and add a small amount (~100ml) into the coffee pot to warm it up.
  4. Prepare your coffee dripper and filter. Whether you wet the filter before putting in the coffee grinds is up to you and the filter you use. Most coffee shops I visit leave the filter dry.
  5. Pour the coffee grind into the filter, and give it a few gentle taps to level the grounds.
  6. Using a food thermometer, measure the water and confirm that it is around 90-92 Celcius (190-200F).
  7. When you are ready to start the pour, remove the water from the coffee pot, put the entire setup on a scale and tare it. Have a timer ready to go.

Pour-Over Technique

Here are the steps I like to use – again, this is for 18g of coffee ground, 270ml of water for a rough 1:15 ratio:

  1. Make sure the scale is zeroed. Start the timer.
  2. Pour ~40ml of water from the center, moving outwards and covering all of the grounds. The pour duration should be roughly five seconds. Allow the coffee ground to bloom.
  3. At the 30 second mark, slowly pour water in the center and in the clockwise direction. Pour an additional 60ml in 30 seconds. The foam which appears in the center should have a diameter of a large coin (quarter, 100yen, etc).
  4. Wait 20 seconds.
  5. Repeat Step 3-4 until desired amount of coffee reached.

During Pour-Over

The most striking difference is the “blooming” of the coffee beans when the first 60ml of water is poured into the dripper. When hot water makes contact with the ground coffee beans CO2 will be released, which creates a blooming effect. This exaggerated “de-gassing” is positively correlated with the freshness of the coffee beans.

(Note that in the ordering of each sets of pictures in this section is the following: Avi, Ueshima, Starbucks)

 

When a strong blooms exists, water that enters through the center will more easily flow throughout the entire dripper, extracting the coffee flavor before coming out of the bottom. For stale coffee beans the entirety of the grounds will not expand, and so the hot water which in from the center will not expand to the outer area of the filter. The result is over-extracted grounds near the center and under-extracted grounds closer to the outer perimeter of the dripper. Also note that a more pronounced bloom results in an outwards expansion (Avi), rather than a collapsed look (Starbucks).

After the initial pour, if a beautiful bloom is produced, there should be no issues with slowly pouring another 60ml of water over the course of 30 seconds. As mentioned above, the water will travel throughout the entirety of the coffee grounds and therefore enables more volume to be held. In stale ground coffee beans with little to no bloom, the hot water will mostly only travel straight down the center. As one can imagine, not only does this under-utilize the entirety of the coffee grounds, it becomes difficult to pour consistently over a 30-40 second interval (in my personal experience, I can only pour ~30ml before “overflowing” to the outer parts of the dripper).

 

When waiting and allowing the coffee grounds to breath between pours, the bloom should stay visible and not decay to the point where it disappears.

Finally, when the desired amount of hot water is reached, here is a side-by-side comparison of what the grounds look:

 

Additional Remarks

I have decided not to comment on the taste of the coffee produced in my experiments because of the various kinds of coffee used. However, from a scientific perspective, stale coffee beans tend to have less “good” coffee taste and more astringency by nature. In addition, the over-extraction of the grounds in the center maximalizes the bitterness while producing a weaker tasting brew. Those who use more stale coffee beans may have to not just pour in the center, but over the entire surface area of the dripper to better saturate all of the grounds.