Cold Trub: Implications for Finished Beer, and Methods of Removal By Ron Barchet Republished from BrewingTechniques' March/April 1994. In the November/ December 1993 issue of BrewingTechniques, Ron Barchet described the importance of removing hot trub. In this issue, he discusses cold trub and its implications for brewers. Although brewers' opinions vary as to cold trub's ultimate impact on finished beer, certain facts are generally agreed upon. The presentation in this article is descriptive, not prescriptive. Cold trub consists of proteins, protein-polyphenol complexes, and carbohydrates (Table I). The protein component of cold trub consists of by-products from the breakdown of hordein (prolamin) and globulin. These by-products are soluble in hot wort but precipitate as the wort cools. Approximately 15-25% of these proteins bind to polyphenols, forming protein-polyphenol complexes. Higher molecular weight carbohydrates, called beta- glucans, make up 20-30% of cold trub (2). As Table I shows, the composition of cold trub produced varies with the percent difference between fine and coarse grist extract and the degree of malt modification. Highly modified malts, for example, yield a higher percentage of polyphenols in cold trub than do less-modified malts. Undermodified malts yield more protein and relatively fewer polyphenols (3). Cold trub proteins and polyphenols begin to bind at lower temperatures, especially when cooled to <170 °F. Consequently, as wort cools, cold trub precipitates (see Table II) . If conditioned beer or wort is reheated, cold trub will go back into solution. Chill haze in finished beer is, essentially, cold trub. Most beers that exhibit chill haze clarify as they are brought to room temperature (the cold trub goes back into solution). FACTORS AFFECTING QUANTITY OF COLD TRUB PRODUCED
Cold Trub:Implications for Finished Beer, and Methods of Removal
By Ron Barchet Republished from BrewingTechniques' March/April
1994. In the November/ December 1993 issue of BrewingTechniques,
Ron Barchet described the importance of removing hot trub. In this
issue, he discusses cold trub and its implications for brewers.
Although brewers' opinions vary as to cold trub's ultimate impact
on finished beer, certain facts are generally agreed upon. The
presentation in this article is descriptive, not prescriptive. Cold
trub consists of proteins, protein-polyphenol complexes, and
carbohydrates (Table I). The protein component of cold trub
consists of by-products from the breakdown of hordein (prolamin)
and globulin. These by-products are soluble in hot wort but
precipitate as the wort cools. Approximately 15-25% of these
proteins bind to polyphenols, forming protein-polyphenol complexes.
Higher molecular weight carbohydrates, called beta-glucans, make up
20-30% of cold trub (2). As Table I shows, the composition of cold
trub produced varies with the percent difference between fine and
coarse grist extract and the degree of malt modification. Highly
modified malts, for example, yield a higher percentage of
polyphenols in cold trub than do less-modified malts. Undermodified
malts yield more protein and relatively fewer polyphenols (3). Cold
trub proteins and polyphenols begin to bind at lower temperatures,
especially when cooled to
