EXTRACTS FROM SELECTED TANNIN-RICH FOODS - A RELATION BETWEEN TANNINS CONTENT AND SENSORY ASTRINGENCY
 
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Pol. J. Food Nutr. Sci. 2007;57(3):329–334
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ABSTRACT
Extracts of polyphenols were obtained from black chokeberry, green tea, and walnut using acetone-water and ethanol-water system (8:2, v/v). The extracts were subjected to sensory evaluation using the method of sensory scaling and quantitative descriptive analysis (QDA). In sensory scaling a trained panel rated the samples for astringency which was expressed as Sensation of Astringency Coefficients (SAC). The QDA was applied for quantitative and qualitative characteristics of the extracts. To determine the content of tannins three spectrophotometric methods were used (n-butanol-HCl hydrolysis, BSA precipitation assay and PVP binding assay). The results proved that both the source of tannins and the type of solvent used for extraction had significant effects on the astringency and sensory profiles of the extracts. The analysis of multiple regression demonstrated that astringency of the extracts examined was affected to the greatest extent by tannins determined with the method of their binding on polyvinylpyrrolidone (PVP) sorbent.
ISSN:1230-0322