Testing fruits and vegetables for brix, the percent sugar, does not appear to be as reliable a method for testing their mineral density as previously thought. International Ag Labs released a report earlier this year in which they tested butternut squash samples for nutrient density from 29 different sources. Unfortunately, I was not able to find the explanation of the nutrient density standard that was used to rank the samples. However, the results show some interesting things:
The brix reading does not correlate with protein content.
The brix reading does not correlate with calcium content.
The brix reading does not seem to correlate with any other mineral content.

What this report shows is that testing the brix of fruits and vegetables produced by someone else, such as from the grocery store or from a farmer’s market, or even from your own garden, is not a reliable indicator of nutrient density. However, that does not mean that testing the brix content is worthless. In general, a higher brix squash tended to have a higher mineral content. Also, this test was an evaluation of only butternut squashes and not all fruits and vegetables.

Last summer, I started questioning the accuracy of testing fruits and vegetables for brix to find the mineral content. Our green beans were only 7 brix (between good and average on the brix chart with 10 being excellent), but the yield was incredible, and the taste was some of the best I had ever eaten and the beans were very tender. The leaves of the green bean plants were 15 brix. I did a little testing and found that doubling the moisture content cuts the brix reading in half. Cutting the moisture content in half doubles the brix reading. Therefore, knowing the moisture content (dry matter percent) is important if you are comparing the brix between two fruits or vegetables grown in two different locations.

But! Before you throw out your refractometer as a worthless test instrument, the refractometer is an important test instrument in your garden. If you can get the brix of the leaf of the plants above 12 brix, the bugs will pretty much leave the plants alone. You can test the plants to make sure that any nutritional spray, such as milk, honey and egg spray, is increasing the brix reading in the leaf. Also, if you have put down soft rock phosphate and high calcium limestone on your garden, you know that the minerals are there at a higher level, even if the brix reading of the vegetables does not test in the excellent range, especially if the leaves of the plant test 12 brix or higher.

This summer, it has been difficult to keep the brix reading of the leaf high because of all the rain and cloudy weather that we have had. It is the sun shining on the leaf that helps make the sugar in the leaf. We have had a lot more problems with Japanese beetles this year, and I believe it is because of all the rainy weather.

The squash study by International Ag Labs highlights the importance of growing our own food or purchasing it from someone we know who has put the minerals into the soil. Eating nutrient dense foods is not as easy to accomplish as we would like it to be, but it is vitally important for our health.

The results of the butternut squash study can be found at this link:
http://marketgardens.com/wp-content/uploads/2013/01/Compiled-Butternut-Squash-Data.pdf