|MEASURING ROOT VEGETABLES BY HAND HELD REFRACTOMETERS
It is easy to measure the solids content of pure liquids with a hand held refractometer. Measuring
fruit is quite simple; juice is extracted by pressing or squeezing. It is somewhat harder to measure
drier materials such as potatoes, squash, turnip etc. as the product can not be squeezed.
There are a number of different ways to measure the solids of root vegetables and it is best to experiment
with the different methods with each vegetable to ascertain which gives the most reliable results in terms
of extraction (sample size) and representation of the sample.
This method of measuring the sugar content of root vegetables is to cut a very thin slice and place this on
the refractometer prism. Experimentation with the position of the illuminator flap (up or down) will
help find the best result. As light has to pass through the sample, be sure to cut as thin a slice as
Taking a small cube of the vegetable and placing it in a garlic press sometimes allows enough juice to be
extracted for measurement. It is best to extract juice (not paste) for the best results.
For extremely dry root vegetables such as chicory, turnip, rutabaga etc., it is possible to extract juice by
taking a half of a vegetable and grating it into a dish. Once grated, take the sample and squeeze the
juice by hand (like ringing out a cloth) into a second dish, which can be used for analysis.
In all cases, make sure that the sample is extracted from an area of the vegetable that is representative of
the whole sample. For example, if taken from near the skin, the solids may be different from a sample
taken at the center.
For more information on hand held refractometers which can provide measurements for root vegetables please
see the E-line optical refractometer,
OPTi digital refractometer,
DR portable refractometer, and
Eclipse hand held refractometer web pages.
Every effort has been made to ensure the accuracy of the contents of this FAQ. However, Xylem Inc.
can assume no responsibility for errors contained in this FAQ.