Prediction Of Grape Polyphenol Astringency By Means Of A Fluorimetric Micro-plate Assay

摘要

Previous works have demonstrated that astringency can be predicted on the basis of turbidity developed by polyphenol/mucin mixes.In the present study,a micro-plate assay,based on the ability of haze particles to screen the radiation emitted by a fluorescent compound (1%),is proposed for polyphenol/ mucin reactivity estimation.Grape seed extract (GSE) solutions prepared in a range of physiochemical active concentrations (0.0-2.9 g/L) were reacted with mucin.A significant linear relationship (r=0.99; p=0.000) was found between turbidity (NTU) and 1% values of GSE/mucin samples.Within the experimental range of phenolic samples,the CV value of 1% determinations was always lower than 10%.The relationship between sensory and instrumental responses,as a function of phenolic solution characteristics,was investigated.Variations in phenol concentration and pH induce similar modifications of both the intensity of perceived astringency and 1% values.A significant linear relationship (r=0.98; p=0.000) was found by relating sensory ratings to the relevant 1% values.