Interesting and valuable information is
available in the NIR spectral region for many agricultural
products. This application uses a NIR spectrometer to measure
the percent of soluble solids in an onion by simply shining a
light thru it! This allows non-destructive determination of a
harvest. This information tells the grower which onions to send
to market and which onions to use for seeding for next years
crop.
Using this technique a farmer can increase his market price by
producing "heavier" onions without planting additional acres of
crop! Onions with a higher percent of soluable solids will
produce seed with similar genetics.
In order acurately measure the soluble solids in terms of
absorbance quantitatively, a PLS (partial least squares) method
is used on the spectral region of interest. Spectral absorbance
data must be taken from at least 100 onions in the NIR region
from 600-800nm. Each onion is then measured using a
refractometer to determine its percent soluble solids. The
onion must be cut and therefore destroyed in order to take these
readings. A PLS is then run on the second derivative spectral
data and the PLS prediction vector is produced.
The SpectraWiz software then loads the PLS prediction vector
for final operations that will indicate and direct the sorting
of the remaining onion crop. Each new unknown onion will be
placed in a sample holder where a light is mounted to penetrate
the onion skin. A nearby colimating lens detects the light as
it exits the onion skin and returns the signal into the fiber
optic cable attached to the NIR spectrometer.
We give many thanks to the innovative efforts provided by Dr.
Gerold Dull and Dick Lefler at the University of Georgia and all
of their Agricultural Innovations. |
