How to test the nutrient density of the produce you harvest or buy

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How can we know for sure that money and time invested in planting and harvesting or buying the produce we eat is really converted into nutritious meals? One of the easiest and cheapest way to check how nutritious the produce you harvest or buy is to test it using a hand refractometer. This device can be used to indicate degrees BRIX, a percentage of the sugar (sucrose) content in the produce’s juice. BRIX is also a measure of the percent solids (TSS) in a given weight of plant juice. The name ‘BRIX’ was a tribute to the 19th Century German chemist Professor A. F. W. Brix, the first person to measure the density of plant juices by floating a hydrometer in them.

A reasonably good refractometer can be bought online for approximately AU$40.00. The hand-held models for field tests usually display an internal scale that ranges from 0 to 32 and can be used to test a wide variety of vegetables and fruits. A brand new one sometimes needs to be calibrated. In other words, you need to first test distilled water and check if it the internal display shows a line indicating 0 (zero). If it does not, the refractometer has a screw that can be used to adjust it. (insert image of internal display showing 0)

To test your produce all you need to do is to pour a few drops of juice squeezed out of salad greens, vegetables and fruits over the refractometer’s prism glass and look through the lenses to check its score. While soft-fruits can easily be squeezed by hand, some greens and vegetables will require a garlic press or crushing pliers.

The number you get then needs to be checked against a BRIX chart to see if the produce tested scores ‘poor’, ‘average’, ‘good’ or ‘excellent’ in nutrient density. The higher the produce’s score the better, but there is also another ‘indirect’ measure. While a clear cut line shown in the internal display indicates the sucrose (sugar) percentage, the foggier the line is (showing a gradient of colors from white to blue) the more trace elements and minerals there are in the produce tested. (insert image).

High BRIX scoring vegetable and fruits are more nutritious and tastier. Contrary to the popular believe, they also last longer in storage.

For more technical and historical information on refractometers and the BRIX chart access Rex Harrill’s online book on the subject