|
Nach oben
| |
Journal
of the American Society of Brewing Chemists
Volume 55: Number 2 (Spring 1997) Publication no.
J-1997-0420-02R
| Evaluation of Rapid Colloidal Stabilization
with Polyvinylpolypyrrolidone (PVPP). I.
McMurrough (1), D. Madigan, and R. J. Kelly, Guinness Brewing Worldwide Research Centre,
St. James's Gate, Dublin 8, Ireland. (1) Present address: 28 Longcliffe Dr., Ainsdale,
Southport, England PR8 3PR. Phone: (01704) 571406. J. Am. Soc. Brew. Chem. 55(2):38-43.
Accepted March 3, 1997. Copyright 1997 by the American Society of Brewing Chemists, Inc. [english] [espagnol] |
| Several colorimetric, chromatographic, and
nephelometric tests were compared as tools for monitoring the rapid (<3 days) colloidal
stabilization of lager beers by a combination of cold filtration at -1°C and treatments
with polyvinylpolypyrrolidone (PVPP). No significant changes in composition were detected
during storage of beer for seven days at -1°C prior to filtration on a bench scale. The effects of dosage on a pilot-scale with different amounts of
recoverable PVPP (10-50 g/hl) or single-use PVPP (10-20 g/hl) on total polyphenols, total
flavanols, simple flavanoids, protein sensitivity, alcohol-cooling
haze, and tannoids were compared with concomitant
changes in colloidal stability, as revealed by accelerated aging at both 37 and 60°C. Close
correlations were found between the results of the haze forcing tests and all tests
other than the tannoid measurement made on freshly bottled beers.
Although decreases in the contents of the simple
flavanoids related most closely to improvements in colloidal stability, the alcohol-cooling
test was also a useful indicator of stabilization effectiveness. The colloidal
stabilities of beers aged at 37°C were related to both the amounts of simple flavanoids
that were oxidized during aging and also to the contents of tannoids in the aged beers.
Treatment with recoverable PVPP at the highest rate
effectively stabilized the sample beer by adsorbing both the simple flavanoid precursors
of chill haze and the tannoid components of protein-polyphenol complexes. |
| Keywords: Alcohol-cooling haze, Haze stabilization,
Polyphenols, Polyvinylpolypyrrolidone, Simple flavanoids, Tannoids. |
[ Tannometer Methoden ] [ Tannometer Literatur ] [ TannoLab 2.0 Software ]
| [english]
[espagnol] Varias pruebas colorimétricas,
cromatográficas y nefelométricas fueron comparadas como herramientas para monitorear la
rápida (<3 dias) estabilización coloidal de cervezas lager con una combinación de
filtración en frio a -1°C y tratamientos con polivinilpolipirrolidona (PVPP). No fueron
detectados cambios significativos en la composición durante el almacenamiento de cerveza
por 7 días a -1°C previo a filtración a escala de laboratorio.
Los efectos de dosificar a escala piloto con diferentes
cantidades de PVPP recuperable (10-50 g/hl) o PVPP no recuperado (10-20 g/hl) sobre
polifenoles totales, flavanoles totales, flavanoides simples, sensibilidad
protéica, turbiedad por alcohol en frio y tanoides,
fueron comparados con cambios asociados en estabilidad coloidal, como se revela por
envejecimiento acelerado a ambas temperaturas de 37°C y 60°C. Fueron encontradas correlaciones
muy cercanas entre los resultados de las pruebas de turbiedad forzada y todas las pruebas
excepto las mediciones de tanoide hechas en cervezas recien envasadas.
Aunque el decremento en los contenidos de los
flavanoides simples se relaciona mas estrechamente a mejorias en la estabilidad coloidal, la
prueba de alcohol en frio fue tambien un indicador util de la efectividad de la
estabilización. Las estabilidades coloidales de cervezas envejecidas a 37°C
fueron relacionadas tanto a la cantidad de flavanoides simples que fueron oxidados durante
el envejecimiento como a los contenidos de tanoides en cervezas envejecidas.
Tratamiento con PVPP recuperable a la dosis mas alta
estabilizo efectivamente la muestra de cerveza al adsorber los flavanoides simples
precursores de turbiedad en frio, y los componentes tanoides de los complejos
protéina-polifenol. |
[ Tannometer Methoden ] [ Tannometer Literatur ] [ TannoLab 2.0 Software ]
|
