The nature of floc problems in alcoholic beverages sweetened with cane sugars and how to remove them

Authors: Eggleston, Gillian; Triplett, Alexa

Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 3/13/2019
Publication Date: 11/6/2019
Citation: Eggleston, G., Triplett, A. 2019. The nature of floc problems in alcoholic beverages sweetened with cane sugars and how to remove them. In: Proceedings of the Advances in Sugar Crop Processing and Conversion 2018 Conference, May 15-18, 2018, New Orleans, Louisiana. 2:122-133.

Interpretive Summary: The sporadic appearance of floc from refined, white cane sugars in alcohol beverages is 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. 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 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. Amylase and dextranase, added as processing aids during sugar manufacture, were both shown to form flocs with haze active polyphenol. This was not surprising as both these industrial enzymes contain proline, which is a key amino acid component of floc forming proteins, as well as arginine that has also been reported to interact with polyphenol flavonoids but to a lesser extent than proline. Thus, it is important that sugar refiners remove any residuals of these enzyme proteins. Powdered activated carbon is known to remove both protein and polyphenolic colorants.

Technical Abstract: The sporadic appearance of floc from refined, white cane sugars in alcohol beverages is 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. 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 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. Amylase and dextranase, added as processing aids during sugar manufacture, were both shown to form flocs with haze active polyphenol. This was not surprising as both these industrial enzymes contain proline, which is a key amino acid component of floc forming proteins, as well as arginine that has also been reported to interact with polyphenol flavonoids but to a lesser extent than proline. Thus, it is important that sugar refiners remove any residuals of these enzyme proteins. Powdered activated carbon is known to remove both protein and polyphenolic colorants.