Developing a handheld NIR sensor for thedetection of ripening in grapevine

It has already been proven that near infrared (NIR) reflectance
spectroscopy can be used to measure the maturity of
grapes by the determination of the sugar and acid content. Until
now, winegrowers frequently collect a random one hundred
berries sample per plot, to measure these parameters destructively
for the estimation of the ideal harvest time of the gained
product. Meanwhile, inexpensive sensors are available, to build
convenient instruments for the non-destructive, low-priced and
fast control of ripening parameters in the vineyard. For this,
a small handheld device including a NIR sensor (1350nm –
2600 nm) was built from a Raspberry Pi 3 single-board computer
and a NIR sensor. Spectra of individual berries, sampled from
Riesling (Vitis vinifera, L.) were collected. Corresponding reference
data were determined with high performance liquid chromatography
(HPLC). Samples were taken from different fruit as
well as cluster zones and from the beginning of v´eraison until after
harvest, to ensure a broad range of ingredients and the ripening
properties of different berries from the vine. This study is
the first that systematically investigates the ripening parameters
of a whole vineyard with a handheld sensor. The sensor can be
used in viticulture practice to detect the ripening progress and
determining the ideal harvest time effective, simple, and nondestructively.