Diverse interaction of commercial enological tannins with the protein fraction of saliva. Association with astringency

Abstract

Commercial enological tannins (CETs) are wine additives that are mostly aimed at modulating astringency. This study aims at comparing the effects of eleven CETs (supplied by 4 companies) extracted either from grapes (n = 2) or oak wood (n = 9) on the salivary protein fraction and on the astringency they provoke. Phenolic compounds were characterized by spectrophotometry and HPLC methods. Interaction of CETs with the salivary protein was assessed by diffusion on cellulose membranes and precipitation assays. Astringency was measured by a trained sensory panel. The study showed major differences among CETs in both phenolic composition, strength of the interaction with the salivary protein fraction and ability to provoke astringency. Those differences were observed even among products that are marketed under common designations. Altogether, functional characterization of CETs is recommended as a preliminary necessary step to decide on which CET could be more appropriate to modulate wine style.