Haze and Foam Chemistry & Perception
Response surface model of haze formation
Proteins in beverages can interact with small molecules to influence physical properties. The amino acid composition of proteins plays a major role in these effects. Proteins that combine with polyphenols to form haze (turbidity) are rich in proline, while peptides that lack proline do not form haze. This appears to be the case in beer, wine, and fruit juices. The ratio of protein to polyphenol influences the amount of haze formed (see above); this can be explained by the conceptual model shown below. This finding has major implications for turbidimetric analytical methods and for beverage stabilization by adsorption or fining.
Beer foam involves interactions between basic amino acids in proteins and hop bitter resins. Other interactions between proteins and small molecules that influence functional properties are studied.
Program Activities and Outputs
K.J. Siebert, L.E. Stenroos, and D.S. Reid. 1981. Characterization of amorphous-particle haze. J. Amer. Soc. Brew. Chem. 39(1): 1-11. abstract
K.J. Siebert and E.J. Knudson. 1989. The relationship of beer high molecular weight protein and foam. Tech. Q. Master Brew. Assoc. Am. 26: 139-146. abstract
K.J. Siebert, N.V. Troukhanova, and P.Y. Lynn. 1996. The nature of polyphenol-protein interactions. J. Agric. Food Chem. 44: 80-85. abstract
K.J. Siebert, A. Carrasco, and P.Y. Lynn. 1996. Formation of protein-polyphenol haze in beverages. J. Agric. Food Chem. 44: 1997-2005. abstract
Karl J. Siebert, P.Y. Lynn and Aurea Carrasco. 1996. Analysis of haze-active polyphenols and haze-active proteins in grape juices and wines. Proceedings, 4th International Cool Climate Symposium on Viticulture and Enology, Rochester, NY. pp. VII-18 – VII-21. abstract
K.J. Siebert & P.Y. Lynn. 1997. Haze-active protein and polyphenols in apple juice assessed by turbidimetry. J. Food Sci. 62: 79-84. abstract
K.J. Siebert & P.Y. Lynn. 1997. Mechanisms of beer colloidal stabilization. J. Amer. Soc. Brew. Chem. 55: 73-78. abstract
K.J. Siebert & P.Y. Lynn. 1997. Mechanisms of adsorbent action in beverage stabilization. J. Agric. Food Chem. 45 (11): 4275-4280. abstract
A. Carrasco & K.J. Siebert. 1999. Human visual perception of haze and relationships with instrumental measurements of turbidity. Thresholds, magnitude estimation and sensory descriptive analysis of haze in model systems. Food Qual. & Pref. 10 (6): 421-436. abstract
K.J. Siebert & P.Y. Lynn. 1998. Comparison of polyphenol interactions with PVPP and haze-active protein. J. Amer. Soc. Brew. Chem. 56 (2): 24-31. abstract
K.J. Siebert. 1999. The effects of protein-polyphenol interactions on beverage haze, stabilization, and analysis. J. Agric. Food Chem. 47 (2): 353-362. abstract
K.J. Siebert and Lynn, P.Y. 2000. Apple cultivar and maturity affect haze-active protein and haze-active polyphenol concentrations in juice. J. Food Sci. 65 (8): 1386-1390. abstract
K.J. Siebert. 2000. Relationship of particle size to light scattering. J. Amer. Soc. Brew. Chem. 58 (3): 97-100. abstract
K.J. Siebert and P.Y. Lynn. 2000. The effect of protein/polyphenol ratio on the size of haze particles. J. Amer. Soc. Brew. Chem. 58 (3): 117-123. abstract
L.-C. Wu and K.J. Siebert. 2002. Characterization of haze-active proteins in apple juice. J. Agric. Food Chem. 50 (13): 3828-3834. abstract
K.J. Siebert and P.Y. Lynn. 2003. Effects of alcohol and pH on protein-polyphenol haze intensity and particle size. J. Amer. Soc. Brew. Chem. 61 (2): 88-98. abstract
Fleet, C.F. and Siebert, K.J. 2005. Effect of illumination intensity on visual perception of turbidity. Food Qual. & Pref. 16 (6): 536-544. abstract
Siebert, K.J. Effect of pH on beer colloidal stability Cerevisia – Belgian J. Brew. & Biotech. 30 (3): 189-194, 2005. abstract
Fleet, C.F. and Siebert, K.J. Effect of viewing background on visual perception of turbidity. J. Sens. Stud. 21 (1): 34-53, 2006. abstract
Siebert, K.J. and Lynn, P.Y. The effect of beer pH on colloidal stabilization with adsorbents. J. Amer. Soc. Brew. Chem. 65 (1): 52-58, 2007. abstract
Siebert, K.J. and Lynn, P.Y. On the mechanisms of adsorbent interactions with haze-active proteins and polyphenols. J. Amer. Soc. Brew. Chem. 66 (1): 48-54, 2008. abstract
Siebert K.J. Haze in Beverages. In: Advances in Food & Nutrition Research Vol. 57, Taylor, S., Ed. Elsevier, 2009, 53-86. abstract