Major new insights into the cause of floc formation in alcohol beverages sweetened with refined cane sugars

Authors: Eggleston, Gillian; Triplett, Alexa

Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 6/2/2017
Publication Date: 9/1/2017
Citation: Eggleston, G., Triplett, A. 2017. Major new insights into the cause of floc formation in alcohol beverages sweetened with refined cane sugars. In: Proceedings of the Sugar Industry Technologists Conference, May 7-11, 2017, Tainan, Taiwan. p. 1-17.

Interpretive Summary: The sporadic appearance of floc from refined, white sugar in alcoholic beverages is a large concern to both beverage manufacturers and sugar refiners. For cane sugars, no definite cause for floc formation has been attributed to any one quality parameter. In this study, sugarcane sugar mixed with 60% pure alcohol and water increased light scattering by up to ~1000-fold. There were strong correlations between haze floc and the color indicator value I.V. and protein values of the sugars, indicating that polyphenol colorants and protein are involved in the floc formation mechanism. Much lower levels of I.V. ratios and protein are involved with alcohol flocs than those reported for acid beverage flocs sweetened with sugar. More haze formed when select 60% ABV samples were heated to 80 °C because partial or full denaturation of protein exposed hydrophobic polyphenol binding sites.

Technical Abstract: The sporadic appearance of floc from refined, white sugar in alcoholic beverages is a large concern to both beverage manufacturers and sugar refiners. With the declining use of high fructose corn syrup as a beverage sweetener in recent years, floc from cane sugars remains a technical problem that is not easily managed. For cane sugars, no definite cause for floc formation has been attributed to any one quality parameter. Silica, polysaccharides, protein, waxes, and color indicator values I.V. (color at pH 9.0/color at pH 3.0) have all been previously implicated, especially with acid beverage flocs. In this study, cane invert sugar mixed with pure alcohol and water to a 60% ABV target) increased light scattering by up to ~1000-fold, i.e., 11.3 to 20.5 NTU, greater than the initial invert sugars (0.018 to 0.024 NTU). Both insoluble and soluble starch, fat, inorganic ash, oligosaccharides, Brix, and pH were found not be involved in the prevailing floc formation mechanism. There were strong correlations between haze floc and the I.V. (R2=0.994) and protein (R2=0.837) values of the invert sugars, indicating that polyphenol colorants and protein are involved in the floc formation mechanism. Polyphenolic-protein flocs are known to combine and cause floc formation in other alcohol beverages including beers, ciders, and wines. Much lower levels of I.V. ratios and protein are involved with alcohol flocs than those reported for acid beverage flocs sweetened with sugar. More haze formed when select 60% ABV samples were heated to 80 °C because partial or full denaturation of protein exposed hydrophobic polyphenol binding sites. Heating to increase floc formation is consistent with a greater role for hydrophobic rather than hydrogen bonding. By probing the floc formation with nephelometry and a haze (floc) active protein and polyphenol, as well as polar, non-polar, and ionic solvents, major new insights into floc formation caused by refined cane sugars were observed and are discussed.