Omix Plus for Home Roasters: Start Here
The handful of readings that matter on a home setup, why they change how you roast, and how to start logging them so every batch teaches you something. When you want the full hardware reference, read Omix Plus Complete Guide.
Part 1: What to measure, and why
Why measure at home
Home roasting will change the way you think about coffee. The direct connection from seeing the raw seed and having to make the decision of exactly how to roast it, forces you to think about how you want your coffee to taste. Roasting by smell, sound, and the color your eye sees works well for professionals, but that intuition and skill takes years and thousands of pounds of coffee roasting time to accumulate. Incorporating concrete measurements to your process gives you a fixed point to start from and a way to check the result. By applying hard numbers to what you see, smell, and hear, you’ll help to quickly build the intuition needed to roast coffee with complete control.
Moisture and water activity
Moisture content refers to the actual amount of water that remains inside the coffee bean. Water activity refers to how available that water is; how free it is to move around and react with its environment. The water activity directly correlates with how active the organic compounds inside the seed can be, which is why this number tells you whether a green coffee will hold steady in the bag or start to fade and pick up flat, papery notes. On a home shelf, where a lot might sit for months between roasts, in non-climate controlled places, these two numbers will help you understand the state of your coffee before each roast, and when you need to quickly use it up before it will no longer be enjoyable to drink. Read these numbers when a bag arrives, and again before a roast, and you know what you are working with instead of assuming.
Density
Dense beans hold more heat and take more energy to develop, so density is what points you at a charge temperature and tells you how hard to push once the beans are in. Omix Plus gives you two figures. Bulk density, which is the packed weight-to-volume of the lot, and Estimated “true density” which is the material density of the bean itself. Omix Plus achieves this reading by digitally removing the gaps from a photo of the packed surface. Read side by side these two numbers tell you how to approach the roast, before you have committed a single gram to the drum.
Screen size
Screen size is the spread of bean sizes in the lot. Mixed sizes roast at different rates, small beans running ahead of large ones, so your spread tells you whether to expect a clean, even roast or to sort the lot first. Omix Plus reads it off the same packed sample, no physical sieve required. It will not replace a sieve for grading, but a validated range will contain the sieve true value, which is all a roast decision needs.
Roast color
After the roast, color is your most important flavor indicator and consistency metric. Omix Plus reads roasted whole beans and grounds and builds a color distribution, the same scale specialty coffee runs on, the same one Omni produces. Reading both whole beans and grounds allows you to calculate your roast delta, a number most home roasters never see. The Roast Delta refers to the gap in color between the outside of the bean and the interior that grinding exposes. A wide gap means the surface is darker than the inside, like a medium rare steak with a dark crust. A tight gap means the roast carried evenly through. Ask around, and you’ll find roasters disagree on what your Roast Delta should be. There is no should. This is just information that you can act on in the next batch. Perhaps you enjoy the complexity of the medium rare coffee. Perhaps you like the uniformity of a strong, one note coffee. When you’re roasting at home, the choice is yours.
The summary page
Left on auto-detect, Omix Plus works out what it is looking at from the image, color, size, capacitance, and density all at once, then runs only the measurements that make sense for that sample. Green coffee skips color. Roasted skips water activity. You press the button once and get a single summary page with everything relevant on it, plus the room temperature and humidity the reading was taken in. Tap any block for the details behind it.
Part 2: Getting started
What you need to start
Omix Plus consists of two halves that click together over a magnetic connector: the main unit on top, with the screen and the optics, and the sample base underneath, which weighs the coffee and reads it. Four containers come in the box. Container A, the one with an indented hole in the bottom, reads moisture, density, water activity, screen size, bean volume, total sample weight, and roast color. Container B holds roasted whole beans for color by itself. Container C holds ground coffee for color. Container D is for calibration. The step by step procedure and specific details are in Omix Plus Complete Guide.
Prepare a sample
Density depends on how consistently you fill the container, because the same beans packed two ways weigh out differently, and pulling even fifteen beans out afterward moves the number. The goal every time is a container filled the same way as last time. Pour green beans into Container A, then draw the included scraper flat across the top so the coffee sits as level as possible with the rim. Omix Bean Sweeper gives a more repeatable fill and is worth using once you are measuring often, but the scraper in the box gets you started.
Take the reading
Drop the filled container into the sample base, set the main unit on top so the chamber closes, and press the button. The closed chamber shields the sensors from room humidity, airflow, and your hands, all of which would nudge the number if the sample were open to the air. Moisture, density, and color come back in a few seconds; water activity takes about 30 seconds to one minute.
Place the prepared container in the sample base.
Set the main unit on top so the chamber closes, then press the button.
Log it in CoffeeOS
Pair Omix Plus with CoffeeOS and every reading can be assigned to a specific coffee, rather than remaining a detached value living in Omix Plus’s testing history. Power on Omix Plus near your phone and CoffeeOS finds it; tap Connect, and run any firmware update it offers before you measure.
Power on near your phone and CoffeeOS prompts to pair. Tap Connect.
Open Bean Manager, go to the Green tab, and start a new entry. You can add origin, process, and variety by hand, or tap Import, choose photo recognition, and take a photo of the bean information printed on the bag or the included card. CoffeeOS reads the info and fills in what it finds. Confirm the results, set your date received, and move on.
In Crop Info, tap Import and pick photo recognition.
Photograph the bag or the included card, or pull one from your library.
CoffeeOS fills what it finds. Set your date received and adjust anything unclear.
Under Bean Qualities, open Edit Fields and switch on the metrics you want to record. If you’re using Omix Plus, turn them all on, since Omix Plus can fill every one. Then tap Import, choose device autofill, pick your device, set the sample type to Green Beans, and press Test. If water activity is set to run as a separate test in the device settings, open that one field and test it on its own, then save.
Moisture, density, screen size, volume, and the rest drop straight into Bean Qualities, ready to save.
Roast, then link it back
Roasted coffee lives in its own tab. Add a bean, tap Assign Source at the bottom, and pick the green lot it came from; CoffeeOS copies the crop info forward, and you fill in roast date, roaster, roast level, and the rest. Re-measure the roasted beans for color and moisture loss. From there, every session in any tool that you assign to this coffee, a Roast Color Analyzer Session, a Brew Recorder Record, a Particle Analyzer Session, files itself back to the lot on its own. Open that green coffee months later and you see every batch you roasted from it, every recipe, every reading in one place. This way, you’ll have something to go back to and see change over time, stopping your roasts from being a string of one-offs and rather, something you can actually learn from.
Is Omix Plus right for a home setup?
Omix Plus sits at the top of the DiFluid measurement line and is priced at $2,599. It’s for the serious home roaster who wants to measure everything at once, from one prepared sample. If you want to start measuring without that commitment, the same CoffeeOS ecosystem scales down: CoffMeter M1 covers moisture and density, W1 covers water activity, A1 covers color, and Omni handles roast color distribution and grind particle size, each feeding the same Bean Manager. Start narrow and grow into the full picture. What does not change is the habit worth building now: measure, log, and let the record teach you.
Where to go next
For the full hardware reference, every container, calibration step by step, on-screen alerts, and complete specifications, read Omix Plus Complete Guide.
To understand roast color measurement, including why two devices can disagree and both be right, read Understanding Color Measurement in Coffee.