Gardeners use science to measure taste

Wednesday, December 5, 2007 | 10:00 a.m. CST; updated 7:54 a.m. CDT, Tuesday, July 22, 2008

In my first years in Missouri I grew melons in native unexcavated topsoil alongside a creek in a subdvision new at that time. Those melons remain the best I’ve ever tasted despite all efforts, over many years, to build the best soil I can on my now rural acres of natural loess soil.

Add to that my experience that fruits and vegetables I’ve enjoyed in Europe and Taiwan simply taste better — they consistently have an edge, beyond anything I buy or grow here. There can be many reasons for this, and no doubt our cultural bias for industrial agriculture, valuing price-quantity above price-quality, is one, but for the vegetables we grow in our own gardens there ought to be some handle for growing exceptional taste that we can grab and use. Yet taste — flavor — is subjective, ineffable, to each his or her own.

The concept of “terroir,” initially meaning the soil and climate of micro-regions of Burgundy or Bordeaux, has been a featured claim of French wines for their superiority over centuries, a superiority no longer uncontested and, at the “vin de table” level, no longer valid to my tasting. But that leads us to the Brix scale, named after its creator, Professor A. F. W. Brix, a 19th Century German chemist. The Brix reading of grape juice has since then been used as an indicator of the quality of wine. Now a group of gardeners is arguing that it is Brix that defines quality of taste, quality of flavor, in fruit and garden vegetables, just as it does for the wines of France or California or anywhere else. What is there to it?

The Brix number of a solution is a measure of the angle of refraction (bending) of light as it passes through the solution. This bending is determined by the percentage of sucrose in the solution because the concentration of sucrose changes the exiting angle of light from the angle at which it entered the solution, based on a basic principle of light refraction known as Snell’s Law. For $80 or so one can buy a refractometer that makes the measurement and requires no lab expertise or experience. You can easily use a refractometer to measure the Brix of any vegetable or fruit you grow or buy.

But why would you care? The claim of Brix devotees is that good taste — indeed excellence of taste, because excellence is the only goal — is directly proportional to the Brix reading ­— because the sucrose concentration also reflects the concentration of minerals and proteins in a drop of solution taken from the fruit or vegetable, and these things all together are what make taste. A peach with a Brix reading of 18 will be unforgettable, while one with a reading of 10 is OK, ordinary, and one with a Brix 6 is the flat tasteless thing one regrets having paid for. Brix takes us beyond plant genetics to what the genetics produce from the soil in which the plant grows.

There is no reason to believe any of this but it is easy to test. Beg or borrow a refractometer, measure and eat. A good test subject would be the Fuji apples that appear here in our summer from New Zealand’s fall and those that appear here in our fall from the state of Washington.

There is a spectrum of evolutionary and nutritional argument to support the high Brix hypothesis. Even more appealing to the gardener, there is experimental evidence that high Brix plants are much less appealing to garden pests even as they are much more appealing to us, and other testing shows that high Brix vegetables and fruit have better shelf life and storage qualities. The basic arguments and a lot more, including health and nutritional benefits — not all scientific or unquestionable — can be found here.

So here is a handle, something definite and objectively measurable that one can work toward in the garden to produce world-class taste: develop a soil that consistently grows a high Brix reading in the plants that grow in it. How one might do this will be the subject of next month’s article.

Dennis Sentilles, MU professor emeritus of mathematics, is a Missouri Master Gardener and a member of Katy Trail Slow Food International with a love for working outdoors and eating simply and well every day. He can be reached at

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