Developing novel oenological tannins from 44 plants sources by assessing astringency and color in model wine

Abstract

BACKGROUND: Oenological tannins are commercial natural products extracted from different botanical sources, which were widely reported as prominent contributors to wine quality. Research on wine quality affected by tannins extracts promoted the development of new oenological products with low cost and high accessibility. In the present study, the structure and concentration of tannin in polyphenol extracts, as well as their correlation with astringency and the color of model wine, was investigated by UV spectrophotometer, HPLC, fluorescence quenching, sodium dodecylsulfate-polyacrylamide gel electrophoresis, colorimeter and sensory evaluation.RESULTS: Resource extracts from 16 of 44 plants were screened as wine oenological tannins, according to the total polyphenol and total flavanol, as well as the intensity of astringency and bitterness. Polyphenols extracted from grape seeds and green tea were more effective in increasing the wine astringency compared to other plant tannins.CONCLUSION: Total flavanol content and tannin activity showed a strong correlation with wine astringency. Condensed tannins with mean degree of polymerization also exhibited strong color stability, and the concentrations of (−)-epigallocatechin were associated with the a* value, a negative qualitative factor for wine color. The present study provides new clues regarding the development of low-cost and highly accessible sources of polyphenol extracts and lays a theoretical foundation for the development of the oenological product.

Targeted Removal of Galloylated Flavanols to Adjust Wine Astringency by Using Molecular Imprinting Technology

“…Model A was the pure gallotannin standard solution used to study the specific adsorption effect of MIPs. Three plant-derived tannins (green tea tannins, grape seed tannins, and grape skin tannins) were used to construct the wine model, and the extraction method was followed as reported by Cheng et al [ 25 ]. The model constructed with green tea was dominated by monomeric tannins and oligomeric tannins, with a low proportion of acylated tannins; grape seeds were dominated by oligomeric gallotannins; grape skin tannins were dominated by polymeric tannins.…”

“…Adsorption properties refer to the previous research method [24]. Samples of 30.0 mg of MIPs (N-MIPs, I-MIPs, II-MIPs) were weighed and mixed with 10.0 mL of EGCG (300 mg/L) solution separately and then shaken at 30 • C. EGCG was measured according to Cheng et al [25]. Reverse-phase HPLC (RP-HPLC) was performed using an Agilent 1260 HPLC system.…”