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Improved fluorescence‐based evaluation of flavonoid in red and white winegrape cultivars
Author(s) -
Ferrandino A.,
Pagliarani C.,
Carlomagno A.,
Novello V.,
Schubert A.,
Agati G.
Publication year - 2017
Publication title -
australian journal of grape and wine research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.65
H-Index - 77
eISSN - 1755-0238
pISSN - 1322-7130
DOI - 10.1111/ajgw.12276
Subject(s) - anthocyanin , cultivar , flavonoid , chemistry , vitis vinifera , bathochromic shift , berry , botany , absorbance , flavonols , fluorescence , horticulture , food science , chromatography , biology , biochemistry , physics , quantum mechanics , antioxidant
Background and Aims Modern viticulture requires robust, fast, non‐destructive methods to assess berry composition. We tested a chlorophyll fluorescence screening method to estimate berry phenolic substances. Methods and Results We focused on anthocyanin and flavonol in red and white cultivars. The ANTH_RG index was dependent on the cultivar anthocyanin profile. In Nebbiolo, in which dihydroxylated anthocyanins prevail, ANTH_RG was 2.4 times higher than in Barbera, in which trihydroxylated anthocyanins prevail. Considering the profiles of the two cultivars at similar anthocyanin concentration and their relative in vitro absorbance, a bathochromic shift of 10 nm emerged, which can explain the different screening effect exerted by anthocyanin on chlorophyll fluorescence. As to flavanols, we propose the calibration of a new spectroscopic index, the FLAV_UV, in coloured and white berries, finding good correlation with flavonol concentration determined analytically ( R 2 higher than 0.7). Conclusions Spectroscopic indices can estimate the concentration of anthocyanin and flavonol in grape berries. Significance of the Study A calibration curve for Nebbiolo, which has a distinctive anthocyanin profile, and the calibration of a new index, the FLAV_UV, able to estimate flavonol concentration in both red and white cultivars, are described for the first time. These indices can effectively be applied for non‐destructive assessment of grape flavonoid.