13,600
edits
Changes
reworded beta glucan portion of Ropy/Sick Beer section
Some strains of ''P. damnosus'' can cause a beer (or wine) to go "ropy". This "ropiness" is actually caused by production of exopolysaccharides (EPS), specifically β-glucan. The gene known as Dps has been identified with the production of β-glucan/EPS. ''Pediococci'' that are ropy have been found to be more acid, alcohol, and SO2 tolerant than other ''Pediococci''. The thickness of the ropiness is increased with the presence of malic acid.
One study showed that the production of β-glucan coincided with the end of the growth phase of ''Pediococcus''. After 2 days of growth, β-glucan production increased as growth slowed. β-glucan production stopped when growth stopped. This would explain why beer containing ''Pedio'' often goes ropy shortly after naturally carbonating in the bottle. This study found that other variables were not factorsin the production of β-glucan, such as differing alcohol levels. The study also found that the lack of agitation increased the β-glucan production. A higher initial pH encourages higher growth (5.5+), which increases β-glucan production. A starting low pH decreases growth, and therefore decreases β-glucan production. Glocuse is needed for β-glucan production, while fructose is insufficient <ref name="ESP"></ref>.
===Other Metabolites===