COMPARATIVE STUDY ON THE USE OF A NON-DESTRUCTIVE OPTICAL SENSOR (MULTIPLEX3®) FOR THE MONITORING OF THE ANTHOCYANINS CONTENT IN RED BERRY FRUITS

The preliminary results of a comparative study on the determination
of the anthocyanins content in red berry fruits by a portable fluorescence-
based optical sensor (Multiplex 3®) are reported. Commercially
available Multiplex 3® was used to measure the “Fluorescence
Excitation Ratio Anthocyanin Relative Index” (FERARI index) in red
plums (Prunus domestica, L., cv Nero Sardo, Dore A., Stanley) and red
grapes (Vitis vinifera, L., cv Monica and Cagnulari). In both species the
FERARI index was related to the total anthocyanins content, such variable
was determined by UV-Vis spectrophotometry and was expressed
as mg/100 g of peel of malvidin 3-glucoside, and as mg/100 g of peel of
cyanidin 3-glucoside, for grapes and plums, respectively. A good correlation
between fluorescence index and peel anthocyanins content in all
the plum cultivars was observed. On the contrary, only for one grape
cultivar (Cagnulari) was found a correlation. Moreover, FERARI index
and anthocyanins content showed a linear relationship in plums,
whereas it was logarithmic in grapes. Finally, the Multiplex 3® allowed
to detect a larger range of anthocyanins content in plums than in grape.
Preliminary results showed that the fluorimetric-based optical sensor
Multiplex 3® can be an effective tool for monitoring anthocyanins content
in the peel of red plums. Moreover, a marked difference in its use
depending on the species observed.