The refractometer is a hand-held device with a prism at one end, and an eyepiece at the other. When just a few drops of sap or juice are placed on the prism and held up to the light, the light passing through the sap is refracted (bent) according to the composition of that sap.
The Brix measurement can be read off the scale, showing levels of sugar, minerals and proteins in the plant's juices (dissolved solids).
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Brix meter provides more than just an indication of the nutritional value of the produce itself, it can be used to help monitor underlying problems in the soil in which the produce is grown.
A plant with low brix makes an easy target for insects who sense the plant's ill health,healthy plants registering a high brix level indicate superior resistance to pests and diseases.