Sunday, November 14, 2010

"Weird" Science #7: Brix

I'd never heard the word until maybe a year ago. Amy brought it to my (our family's) attention. "Check this out," she said, and she pulled out a little instrument into which she squeezed some juice from an apple or some other piece of fruit.

"What are you doing?"

"I'm measuring brix: more or less, the nutrient density of the food."

Brix, as I soon learned, is a measure of total dissolved solids (TDS) or total soluble solids (TSS) in liquid. It was originally developed by A. F. W. Brix, a German chemist (1798-1890) who sought to help vintners whether and when their grape crops were ready for harvest and which grapes would produce the best wine. More prosaically, from their perspective, it was a means to determine sugar levels in grapes.

But, as my comment about TDS or TSS implies, brix doesn't merely measure sugars. It measures the total of all solids in the liquid. So, as one source notes, "many other substances can falsely indicate "brix" readings (although those readings are valid in their own right). Try rubbing alcohol, whiskey, vinegar, or wine. Interestingly, cooking oil, molasses, syrup, and other thick liquids require a refractometer calibrated to read 30-90 brix. Honey is checked with a refractometer calibrated to measure the water within it instead of the solids in the water."

However, in general, "The higher the brix, the greater the nutrient density." That should certainly be true of foods you grow. And until professional farmers begin trying to "scam the system" the way the Chinese pet food and children's formula manufacturers did with melamine three or four years ago, it should be true of most store-purchased foods as well.

One day, I have no doubt, someone will attempt to adulterate foods to maximize brix; hopefully it won't be soon.

So what does all this have to do with you?

Have you ever bought fruits or vegetables at your local market that seem to be completely lacking in flavor? --Test them and you will find they are low in brix.

Here's a chart of brix ratings for various fruits and vegetables.

So what difference does a high brix reading make?

Well, as already intimated,
  • It makes a huge difference in flavor.

    Can you imagine celery (12 brix) or broccoli (12 brix) or cabbage (14 brix) that is sweeter than the typical orange (10 brix) you buy in the grocery store? (I have to confess: I can't. But those are results that some growers are claiming they have achieved.)
  • But besides flavor, there really is--or normally will be--an astonishing difference in nutritional content.

    Here is an analyzed difference of various nutrients in green beans comparing the USDA "standard" values, values measured from some 4.2 brix store-bought beans, and the values from some (only marginally better) 6.1 brix, grown late in the fall, just before frost, home garden beans:

    Nutrient USDA %DV Store Garden %DV
    Protein 1.8 g 4% 1.76 g 3.34 g 7%
    Calcium 37 mg 4% 70 mg 130 mg 13%
    Magnesium 25 mg 6% 30 mg 50 mg 13%
    Phosphorous 38 mg 4% 40 mg 80 mg 17%
    Potassium 209 mg 6% 190 mg 580 mg 17%
    Copper 0.1 mg 3% 0.1 mg 0.4 mg 20%
    Iron 1.0 mg 6% 1.3 mg 2.1 mg 12%
    Zinc 0.2 mg 2% 0.72 mg 2.3 mg 15%
    Manganese 0.2 mg 11% 0.29 mg 0.35 mg 18%

    --Chart found at

Are there other benefits one might see with high brix foods?


I'm told that if you're a gardener or farmer,
  • You can expect to invest far less time or effort or money on protecting your plants from insects, weeds, bacterial and/or fungal attacks.

    Over and over I have read or heard (I am listening to lectures presented at the Acres USA 2007 through 2009 conferences): High brix plants are generally immune to the pests that lead conventional farmers to spray their fields with toxic 'cides--pesticides, herbicides, fungicides, and so forth.
  • Unbelievably prolific plants: unusually heavy harvests and fruits and vegetables that mature in ridiculously short periods of time. --For example, celery ready to pick in 45 days when it was normally expected to ripen in 110. --Proper nutrification of the soil for the purpose of raising high brix foods, we are told, is the secret to this kind of bounty. (See the same page as above.)
  • Not just heavier bearing, but longer growing seasons, too.

    Why? For the same reason that sugar water (or salt water; or any water that has high dissolved solids in it) will not freeze at "only" 32 degrees F. Plants die when ice crystals rupture plant cells. "Pure water freezes at 32 degrees Farenheit. However, a 5 brix water-sugar mixture freezes at 26 degrees; a 10 brix mixture at 22 degrees; and a 15 brix mixture won’t freeze until it reaches 17 degrees. . . . Many high brix growers find their production season extended because the first few light frosts no longer harm their crop." (Rex Harrill, Using a Refractometer to Test the Quality of Fruits & Vegetables)
But the benefits continue.

Whether you're a farmer or not, being able to store fruits and vegetables without decay for a longer period of time could be a great boon. So . . .
  • How about tomatoes that won't go bad, even after they have been stored at room temperature for 14 months?!? Click here and do a "Find" for illustrations of high brix produce. This one blew me away.

    I had heard about the flavor from the very beginning. I had heard some stories about how nutrient-dense (i.e., high brix) fruits don't decay as quickly as those that are less dense. (Consider your standard apple, for example. Low brix apples, once you bite into them, turn brown quickly. But high brix, they say, maintain their original color longer.) But to see the photos of tomatoes that have been stored at room temperature for 14 months: that really takes the cake!

    --Again, such a result seems impossible to believe. I have been told tomatoes have an enzyme--polygalacturonase--that starts to make them decompose the moment they are picked, and the standard shelf life of the average tomato is 15 days in a refrigerator. See this article and this for more on the standard tomato rotting characteristics . . . and the work of geneticists to try to extend their shelf life. So what's with the 14-months-at-room-temperature tomatoes? Check out the photos and captions on the page to which I directed you.
If you're growing your own fruits and vegetables, while you're growing them, you want to measure the brix not of the juice in the fruits or vegetables, but the juices in the leaves of the plants. (As the people at Agriculture Solutions say, "Put a leaf or food sample inside some nylon and then use a garlic press to obtain a liquid extract.") You'll get different measurements than you will from the fruits, but you want to measure the brix in the leaves to provide a feedback mechanism to help you know which foliar sprays and/or mineral supplements and soil amendments you ought to be applying. There's a little bit of an explanation about how to do these tests here.

For about the fullest explanation of brix you can find on the web, complete with its history, how to measure it, and some very wise counsel, even, on how to use it practically in your garden and when shopping, check out Rex Harrill's Using a Refractometer to Test the Quality of Fruits & Vegetables.

Enjoy the adventure!
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