Measuring Success – Brix

If you read my last post reviewing the butternut squash competition that illustrated the correlation between brix and nutrient density, you may have wondered where my initial assumption had come from, the grades given by each squash’s refractometer value:

6 - Poor
8 - Average
12 - Good
14 - Excellent

These values didn’t come from me, but rather a lifetime of agricultural research by Dr. Carey Reams. What’s interesting for us though, is what these grades actually mean:

  • Poor – zero to terrible flavor, rots very quickly, very bad nourishment
  • Average – bland to somewhat flavorful, lasts longer in storage but still not very nourishing
  • Good – great flavor, stores a long time without decay and good nutrition
  • Excellent – legendary flavor, dries out long before rotting, superior health through food is now possible

We have already shown how nutrient density relates to brix, but also flavor and storage too? Indeed it does, but I will save those explanations for a later post when we discuss monitoring plant health and the role that insects and disease organisms play. Our goal here is to give you a new tool, the ability to relate your own brix readings to a meaningful measurement of quality.

Following this are the charts that you will need. It was the genius of Dr. Carey Reams that deserves full credit for compiling the original data and then freely giving it away in the early 1970’s. Since then, there have been several updates and additions made by the observations of other agricultural researches. What I’ve done here is created a greater composite chart of all of them together, choosing the highest values available.

The charts use the PAGE method: Poor-Average-Good-Excellent. There is an additional column in there called “Resistant”, I will explain that later, feel free to ignore it for now.


In the process of writing this I discovered that I had used Dr. Reams’s original values for my article on the Squash Contest and not the values I have listed here. That was an over-site on my part. So instead of the 6-8-12-14 values I should have used 6-10-14-16. If you go back to that article and look again, you will see that no one had submitted the best possible class of fruits to the contest.


Assessing Quality – Refractometer

In the early 1800’s, European vintners were seeking a reliable way to determine the perfect time to harvest wine grapes, an important objective when a high quality bottle sold for hundreds more. Several methods were pioneered, but the one that most interests us most is the measure of total dissolved solids: the amount of stuff in the grape juice. With this understanding European vintners were better able to manage plant health and produce consistently higher quality grapes. This technique can easily be applied at home with a nifty little gadget called a refractometer.

The refractometer measures in degrees Brix (°Bx). The scale is based upon the quantity of dissolved cane sugar in water and equates to percentage. Thus a reading of 1° Brix is 1% dissolved sugar and 99% water, and 25° Brix is 25% dissolved sugar and 75% water. The tool is calibrated to 0° using distilled water.

The refractometer works like a prism. When light is passed through different substances it bends and reacts slightly differently from one another. To take a measurement, a small drop of liquid is placed on the refractometer window and pointed at the light. The degree of light bend is then displayed on a scale you can read through the eyepiece.

zerobrixThis is what a drop of water and 0° Brix looks like through my camera phone.

Since a large part of plant juices are made up of sugars and water, this is an excellent way for us to obtain a usable and very accurate reading. For example, grape must is mostly glucose, not sucrose, but the Brix is still within 0.1 degrees, a level of accuracy more than sufficient for our use. Like grape must, all plant juices contain a whole lot more than simple sugar (minerals, proteins, fats, vitamins, amino acids, etc), so when the tool is used  in this way it is referred to as “total dissolved solids” or “total soluable solids”.

In addition to 200 years of use among grape growers, the refractometer is well known within the food industry for things like fruit juice, jams and jellies, soft drinks, beer and numerous scientific and industrial applications.

There are numerous types of refractometers on the market, but we just need one: a hand held refractometer with a scale from 0-32 degrees. The only garden vegetable you will encounter that exceeds 32° are garlic cloves. The brix reading is also somewhat temperature sensitive, so getting a device with ATR (Automatic Temperature Regulator) will save you from doing some extra math.

This is what I recommend:

  • Refractometer, 0-32 degrees, with ATR
  • small pocket notebook and pencil
  • garlic press

Brix testing is one of the easiest and most informative tools available for gardening. You can use it to monitor your plant health, including the health of your weeds, and it allows you to grade the quality of fruits and vegetables at harvest.

I record all my readings into a notebook sorted by plant type: apples, oranges, carrots, broccoli, etc. To take a measurement carefully squeeze a drop or two of liquid from your plant leaf, fruit or vegetable. If the plant part is refusing to give you a good drop, use the garlic press. Place the drops onto the prism and look through the eyepiece and record the reading. You now have a point of reference you can use to measure your success with.refractometer

You can actually use your refractometer to measure any liquid, and I’ve had a lot of fun with mine. I test milk, tap water, bottled water, coffee, tea and all the soda’s at work. I also test every fruit and vegetable I can get my hands on: the store, the farmers market, backyards; and I always record whether it was organic or not.

The refractometer has proved itself in giving results in the field for 200 years of viticulture, and is an accepted tool in biological agriculture. It’s a great tool, but it’s not the only tool, and it does take some knowledge to use effectively, but more detail on that later. You can get a refractometer quite inexpensively, I bought mine (Vee Gee BTX-1) off of Amazon.

Happy Brix’ing,