Different Sizes of the Green Beans

Coffee beans at various stages of growth
Matias Zeledon of Down to Earth Coffee in Costa Rica posted an interesting picture of coffee beans with different sizes on the branch. This is an example of why you have to hand pick coffee to only get the ripe cherries. Here is Matias’ description:

Happy to see the coffee healthy and developing well in the Providencia highlands farm. The different sizes of the green beans are produced by the different waves of blooming, which generate the different stages in the harvest. The big differences in size comes from the fact that this year we had rain on Feb 9th so the first blooming came early and that is why the beans look so well developed compared to the others. This also means that we are going to be harvesting coffee in early November, a sizable bunch and not just a few.


Coffee Smoothie II

In Coffee Smoothie ONE I showed how to make a coffee smoothie with freshly ground coffee. Since writing that post I have probably made a hundred of them and have perfected the recipe.

First I purchased a few bottles of Lorina Lemonade at the grocery store. The drink is amazing but what I really wanted was the resealable bottles.

Lorina Lemonade bottles
Lorina Lemonade bottles

The bottles are strong and the seal is both interesting and functional.

Next rather than making small batches of coffee syrup I moved to a 12 cup French Press. I put in 150 grams of coffee and fill with water. After sitting 24 hours in the fridge I get a full bottle of syrup.

The other bottle is sugar syrup. I tried cocoa rather than Quik and really liked the result. You have to change the amount of sugar syrup as cocoa has no sugar or sweetener in it.

The last change was adding a banana. One issue with the original recipe is the drink tends to separate into the ice on top and the fluid below. The banana adds a pulp that keeps the drink from separating. It also is more creamy.

Here is the revised recipe.
Iced Coffee Smoothie
1/2 cup Cold Brewed Coffee Syrup
1/4 cup cold Sugar Syrup
1 tbsp cocoa
2 tbsps powdered milk
1 peeled banana
1 1/4 cup cold milk
1 1/2 cup ice cubes

  1. In a blender place Cold Brewed Coffee Syrup, milk, Sugar Syrup, banana and cocoa
  2. Add last ice cubes last to avoid melting
  3. Whip and pour

Coffee Smoothie

Coffee Smoothies
Coffee Smoothies
Recently I bought a commercial blender to make fruit smoothies. Being a coffee junkie I wanted a coffee smoothie recipe. Most recipes I found started with instant coffee – not going to happen. I tried making strong hot coffee, adding milk, sugar and ice and blending. The result was a bland cool drink. Yuch.

Then I found an article on making strong coffee base with a french press and cold brewing. Normal hot coffee uses 10-15 grams to a cup of water so this is 2 to 3 times stronger. Cold brewing also reduces bitterness. I have been working on this recipe for months and here is my result. It is interesting how the type of coffee bean and roast changes the taste. A full city roast of Sumatra is one of my favorites.

Since releasing the recipe I had found an improvement. By adding two tablespoons of powered milk the smoothie stays creamier longer and tastes more milk shake like.

Continue reading Coffee Smoothie

Computer Controlling the Ohaus SPE2001 Scout Pro

For some of my coffee roasting experiments I wanted a scale I could connect to a PC or Mac. I looked at many scales and the Ohaus Scout® Pro Balance series was a nice blend of capability vs price. This series is designed for educational applications. RS232 (part 71147376) and USB (part 71147377) interfaces are available. This article documents the use of the USB interface. I assume the RS232 is identical as the user manuals appear identical except for how to connect to the computer.

Ohaus SPE
Ohaus SPE
Model Capacity Readability
SPE123 120 g x 0.001 g
SPE202 200 g x 0.01 g
SPE401 400 g x 0.1 g
SPE402 400 g x 0.01 g
SPE601 600 g x 0.1 g
SPE2001 2000 g x 0.1 g
SPE4001 4000 g x 0.1 g
SPE6000 6000 g x 1 g

Product Data Sheet (PDF)
Instruction Manual (PDF)
USB Interface Manual (PDF)

Continue reading Computer Controlling the Ohaus SPE2001 Scout Pro

Pro-Tips for Home Coffee Roasting

Guest contributor: Samantha Joyce

Behmor 1600
Behmor 1600

Through interviews I conducted for Seattle Coffee Gear’s Coffee Review I have visited and talked with local professional coffee roasters around Seattle, Washington from Caffe Ladro, Caffe Umbria, Middle Fork Roasters, Velton’s Coffee and Zoka Coffee. Roaster set-ups vary in size, capacity and philosophy.  The most common refrain was to pay attention to the sights, sounds and smells. Do not get distracted or try to multi-task. Focus on the roast. Continue reading Pro-Tips for Home Coffee Roasting

Crystal Caffeine – Angel Hair

Caffeine is released during roasting. Some of this caffeine crystalizes on the outside as the smoke escapes.

Temperature Probe Setup on HotTop Roaster

This is a HotTop roaster. The yellow devices on top are temperature probes. As the roast progresses, smoke escapes from the probe holder. Over time, amazingly intricate white crystal structures appear. These caffeine crystals are know as angel hair in coffee jargon.

Caffeine Angel Hair formed on the bean temperature probe handle

These are microscope shots of the crystals after removed from the probe.

Caffeine Crystals under a microscope

Same cluster under higher power.

Caffeine Crystals under higher power

Surprise Roasted Coffee Bean Degassing Discovery

Degas 3 Setup

The degassing experiment three was drawing to a close. To recap 100 grams of dark roasted beans were put in one flask, 100 grams of the same beans but ground were put in the other flask. After 24 hours 294 mls of CO2 were released from the ground coffee. Even after 3 days the ground coffee maxed out at 300 mls supporting the literature (1) that ground coffee degasses in 12-24 hours depending on grind.

The whole beans were a different story. The 130 ml of day one grew to 290 mls in nine days. The literature said about 7 days for most degassing. I was getting ready to clean up the experiment when I had an idea. Just for “shits and giggles” why not grind the nine day old beans. They had stopped releasing CO2 but was there any inside that grinding would release? Using the same grinder settings as previous experiments I ground the 100 grams and quickly returned to the flask and stoppered. I was surprised to see gas released with a similar curve to freshly roasted coffee.

In one day 112 mls of CO2 were released. Like fresh roast beans almost all of the release was in the first 24 hours. While only 38% of what a fresh roast grind release, the total release was 406 mls versus 296 for fresh ground.

Grind Nine Day Old Beans

I have not found any literature on CO2 degassing in older coffee. I am going to continue other degassing experiments to open up the parameters of cause/effect.

My color spectrometer has not arrived yet. Really looking forward to experimenting with it.


  1. Development of an apparatus for measuring the degassing behavior of coffee with the option to examine the influence of protective gases for aroma preservation : KOZIOROWSKI, Thomas; BAUMEISTER, Heinrich; JANSEN, Gerhard; BONGERS, Sandra; PROBAT-WERKE, Emmerich, Germany – Probat

Coffee Degassing Experiment 3 – Ground vs Whole Bean

Experiment three was a chance to apply all of the lessons learned in measuring CO2 degassing of roasted coffee.

Degas 3 Setup

Lesson 1: A photo copy stand was used to support the graduated cylinders. Fill the cylinders with water and place upside down in the tank. Lower the photo rack then support the cylinders with square wooden rods, hold with several rubber bands then raise the attached cylinders with the camera holder adjuster.

Eye Droppers on Tubing

Lesson 2: Using eyedroppers is very effective but you have to slightly point them downhill or the air will escape, just slower. The most effective dropper has a turn on the end pointing down. This made it easier to prevent gas escaping and water filling the line. The eye droppers were purchased at Walmart for $2 a pair. Keep the eyedroppers as close to the cylinder bottom without touching. Water pressure becomes a factor if you put them deep in the water.

Flask with Funnel on Scale

Lesson 3: The critical timing is from grinding the coffee, place in the flask, weigh and stopper. By putting a funnel in the flask on the scale ground coffee could be scooped quickly and accurately.

Lesson 4: I wrote a trivial program to log the time vs the readings. This meant recording readings was just typing in the levels. The program tracked the time. For the time value I used a Unix Timestamp, the number of seconds since January 1 1970 00:00:00 GMT. So to calculate offset is simple subtraction from the first reading. The data was then copy/pasted into a spreadsheet for calculations and graphing.

Costa Rica Degas Exp 3 w Degas 2 in Background

Lesson 5: Track as many variables as possible. By using Artisan I could compare degas roast 2 to degas 3 roast.

Hours Ground ml CO2 Whole ml CO2
30 0
0.05 45 0
0.10 58 0
0.12 62 0
0.13 66 0
0.18 75 0
0.20 80 0
0.27 90 0
0.34 100 0
0.44 110 0
0.51 118 0
0.53 120 0
0.65 130 0
0.75 136 0
1.04 154 0
1.17 160 0
1.28 165 0
1.76 183 15
1.94 190 18
3.79 226 37
11.69 270 89
12.12 280 94
22.12 290 124
23.36 290 126
24.04 290 128
24.58 294 130
25.61 296 132
27.25 296 135
35.65 296 145
36.87 296 154
46.35 300 170
47.62 178
48.65 182
50.75 182
59.44 188
60.89 194
72.75 198
85.32 210
91.38 220
100.10 227
108.91 236
111.60 240
114.28 243
117.01 246
120.31 248
155.70 264
157.01 267
166.09 270
Hours vs ml CO2 Ground (Blue) vs Bean (Red)

Conclusion 1: Ground degassing is pretty well complete in this experiment at 12 hours. 280 ml of CO2 released at 12 hours while 300 by 48 hours. After day 3 the whole beans are still degassing but slowing down.

Next experiment is to repeat this setup but with a medium roast (430o drop.) I also ordered a school grade color spectrometer and am investigating roast colour analysis.

Most Important Conclusion: Crawling into the raw science basics of roasting is really fun.