Formation of Polyphenol-Denatured Protein Flocs in Alcohol Beverages Sweetened with Refined Cane Sugars

Authors

Gillian Eggleston, USDA-ARSFollow
Alexa Triplett, USDA-ARSFollow

Date of this Version

2017

Citation

J. Agric. Food Chem., Just Accepted Manuscript, DOI: 10.1021/acs.jafc.7b03185

Comments

U.S. government work.

Abstract

The sporadic appearance of floc from refined, white cane sugars in alcohol beverages remains a technical problem for both beverage manufacturers and sugar refiners. Cane invert sugars mixed with 60% pure alcohol and water increased light scattering by up to ~1000-fold. Insoluble and soluble starch, fat, inorganic ash, oligosaccharides, Brix, and pH were not involved in the prevailing floc formation mechanism. Strong polynomial correlations existed between the haze floc and indicator values I.V. (color at 420 nm pH 9.0/color at pH 4.0 - an indirect measure of polyphenolic and flavonoid colorants) (R²=0.815) and protein (R² =0.819) content of the invert sugars. Ethanol induced denaturation of the protein exposed hydrophobic polyphenol binding sites that were further exposed when heated to 80 ˚C. A tentative mechanism for floc formation was advanced by molecular probing with a haze (floc) active protein and polyphenol as well as polar, non-polar, and ionic solvents.