Improving optical fruit sorting bynon-destructive determination of qualityparameters affecting wine quality

The scope of this project is finding suitable parameters
correlated with grape and wine composition to be implemented
as a quality criteria to sort harvested grapes. Grape quality is
not only defined by sugar concentration but by a complex equilibrium
of parameters depending on the type of wine to be produced.
Moreover, measuring berry composition is not always
linked to the amount that will finally be extracted into wine. Sorting
the berry according to their density and berry size showed
that measuring berry size could be another good tool to segregate
groups. It was possible to relate berry color with sugar accumulation
and anthocyanin accumulation until berry coloration
process (veraison). However, after veraison, berry color was not
a suitable parameter anymore to describe differences in maturity.
It was also possible to correlate berry color with aroma precursors
in Riesling white grapes, showing that VIS measurements in
white grapes could indeed be a possible way to sort the berries according
to quality. A multiparametric optical sensor, Multiplex®
(Force A, France) showed that change in simple fluorescence ratio
in green excitation was correlated to sugar concentration in
white berries. Two ratios showed promising results: Firstly, the
NBI G indicating amino acid in berries and juice then secondly
the ANTH G correlating red color pigments (anthocyanin) concentration.
This will have potential to determine quality parameters
and in combination with user-friendly interfaces will improve
grape sorting devices.