The core of the coffee brewing process is fairly simple at its most superficial level: ground coffee is mixed with water (in some way shape or form) and the combination results in the water "gaining" some of the coffee's flavour. More technically, flavour is extracted from the coffee by the water, meaning the solid coffee dissolves into it. This extraction is represented by a percentage (i.e. the percentage of the solution that is made up of dissolved coffee) which is incredibly useful for understanding why your coffee tastes the way it does. In the world of coffee, a refractometer is the only way to get that measurement, and DiFluid's R2 Extract Refractometer is an exciting new addition to that tool category.

What a refractometer actually does is pass light through a sample of liquid (placed on a sensor) at a specific angle. Depending on the level of dissolved solubles (in this case, coffee) in the liquid, the light bends, and the angle changes. In the case of coffee, with the base solvent being water, the refractometer correlates the new "bent" angle of the light passing through the water-coffee solution with what it would "expect" the angle to be if light was passing through water alone (this is known as the "refractive index" of water). This is then translated to a percentage indicating the concentration of dissolved coffee, which correlates to its level of extraction. As a reference point, filter coffee usually has a coffee concentration of around 1.3-1.5%, and a shot of espresso will be somewhere between 7% and 9%. Knowing these values allows you to repeat them or adjust them accurately so that you can find and replicate your perfect cup.

Chances are that if you know what a refractometer is, you know this story (or a version of it) already, and you're more likely to be some form of coffee professional than a curious home brewer. However, what makes the DiFluid R2 Extract particularly exciting is that, because of its price point and ease-of-use, we could easily see it entering the home barista's hobbyist toolkit. Granted, like roasting beans at home, keeping a refractometer on the kitchen shelf will likely be of interest to specialty coffee enthusiasts fairly far down the rabbit hole, but the point is you now don't have to be a professional to take your extraction precision to the next level.

The R2 Extract is DiFluid's second refractometer to enter the market and boasts several attractive features. It sports a large, high-resolution colour display and offers a number of testing options so you can find out exactly what's going on inside your coffee at the press of a button. The R2 is highly precise, thanks to a micro-calibration layer and dual temperature sensors which compensate for external factors like temperature changes or undissolved coffee particles. This goes hand-in-hand with the expertly calibrated 2D CMOS imaging sensor, which limits the risk of misalignment, collects more data than DiFluid's previous R1 model, and doesn't require a cap to work like other refractometers.

The DiFluid R2 sensor also includes a hydrophobic layer that prevents liquid from sticking to it, reducing the need to touch it directly and providing an additional barrier against scratches, extending the R2 Extract's overall lifespan. The whole thing is also IP67 water resistant, meaning you can just run it under a tap and then wipe it dry to clean it. It really is all about ease-of-use.

Paired with DiFluid's companion app, Café Connect (as well as DiFluid's Microbalance scale), the R2 Extract makes analysing your coffee's data simple and efficient, granting you precise results in every cup, and you don't even need to be a real coffee scientist to understand how to use it.

What's in the box?

DiFluid's packaging is specifically aimed at avoiding excess plastic waste.

• DiFluid R2 Extract Refractometer
• Metal coffee spoon (instead of single-use plastic pipettes)
• Protective travel pouch
• USB-C charging cable

DiFluid R2 Extract specifications

• Accuracy: ±0.03%
• Precision: ±0.02%
• Resolution: 0.01%
• Range: 0-30% TDS (Total Dissolved Solubles)
• Battery: 430mAh
• Size (BxLxW): 88x36x16mm
• Weight: 36g