Coffee Data Science
A Review of Vietnamese Robusta
A quick data driven review
Bazan sent me a few samples of their coffee because of my expressed love of robusta, but this is not a sponsored review. These packets were single serving for pourover, and in fact, they were packaged as a pouch that you could brew without anything other than hot water in a cup.
I prefer espresso, so I reground the coffee, and brewed some single shots using a 7g VST basket with a screen and a silicone gasket.
Tasting Equipment/Technique
Espresso Machine: Decent Espresso, Thermal Pre-infusion
Coffee Grinder: Zerno
Pre-infusion: Long, ~25 seconds, 30 second ramp bloom, 0.5 ml/s flow during infusion
Filter Basket: 7g VST
Other Equipment: Acaia Pyxis Scale, DiFluid R2 TDS Meter
Metrics of Performance
I used two sets of metrics for evaluating the differences between techniques: Final Score and Coffee Extraction.
Final score is the average of a scorecard of 7 metrics (Sharp, Rich, Syrup, Sweet, Sour, Bitter, and Aftertaste). These scores were subjective, of course, but they were calibrated to my tastes and helped me improve my shots. There is some variation in the scores. My aim was to be consistent for each metric, but some times the granularity was difficult.
Total Dissolved Solids (TDS) is measured using a refractometer, and this number combined with the output weight of the shot and the input weight of the coffee is used to determine the percentage of coffee extracted into the cup, called Extraction Yield (EY).
Data
I only had one shot per each, but I did notice some differences. I should also note because the coffee was ground before it arrived, it wouldn’t be as fresh as if I had whole beans and ground them myself.
There was an expected lack of sweetness because that is robusta, but I like the mouthfeel of robusta. I was surprised the blend did not do as well.
In terms of extraction, they all had similar extractions except for the arabica. I accidentally pulled it longer. I usually aim for 1:1 or 1.1:1, but for the arabica, I pulled a 1.6:1. It was surprisingly enjoyable probably because it was not over-extracted.
These coffees were definitely interesting and enjoyable. I like the potential for a user to brew without much equipment. My only suggestion is to pull these using a cold bloom because robusta greatly benefits from a cold bloom.
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Further readings of mine:
My Second Book: Advanced Espresso
My First Book: Engineering Better Espresso
