Comparison Between Chilling and Crossflow Membrane Filtration in Beer Clarification
MBAA TQ doi:10.1094/TQ-48-1-0120-01 |
VIEW ARTICLE
Sunny E. Iyuke, Clarence S. Yah,
Molefe Mahlabegoane,
M. D. Thulo, and Anton Erasmus. School of Chemical and Metallurgical
Engineering, Faculty of Engineering and the Built Environment,
University of the Witwatersrand, Wits 2050 Johannesburg, South Africa.
Abstract
With the desire to improve the quality of beer acceptable to
consumers, two clarification methods were compared: the chilling method
and crossflow microfiltration method. The beer samples for this study were
produced at the University of Witwatersrand Microbrewery and evaluated
according to the European Brewing Convention (EBC) standards. Using the
microfiltration technique, it was observed that higher temperatures
increase the total flux, head retention value (HRV) and haze. The
filtration temperature was conducted at less than 4�C (39�F) to bring the
haze level to an acceptable standard. There was a linear correlation
between flux and haze, where the higher the flux, the higher the haze.
Cleaning of the membrane by backwashing with water effectively opened up
the membrane pores. The chilling technique showed that haze decreased
significantly from 3.1 to <0.8 to meet the EBC requirements. The
mouthfeel, measured by the real degree of fermentation (% RDF), increased
slightly with time, while the specific gravity, pH, color and bitterness
remained relatively constant because of the exhaustion of the sugars. The
findings also showed that membranes may reduces alcohol percentage, haze,
HRV and % RDF increases slightly, while chilling on the other hand,
increases the alcohol percentage, HRV and % RDF. Chilling decreases haze
but not as much as microfiltration. Although there were slight
differences, both methods were satisfactory in terms of EBC standards.
Keywords: beer, biotechnology, chilling, clarification,
cross-flow microfiltration, microbrewery.
S�ntesis
Se compararon dos m�todos de
clarificaci�n de cerveza con el objetivo de mejorar la calidad de la
cerveza: El m�todo de enfriamiento y el m�todo de microfiltraci�n
transversal. Las muestras estudiadas fueron elaboradas en la micro
cervecer�a de la Universidad Witherstand; fueron evaluadas seg�n los
est�ndares de la European Brewing Convention (EBC). Usando la
microfiltraci�n se not� que mayores temperaturas aumentan el flujo, la
estabilidad de la espuma (EE) y la turbidez. La temperatura de la
filtraci�n fue menor de 4�C (39�F) para que los valores de turbidez fuesen
aceptables. Se encontr� una correlaci�n lineal
entre el flujo y la turbidez; mientras mayor el flujo, mayor la turbidez.
La limpieza de la membrana mediante un flujo contrario
efectivamente abri� los poros. La t�cnica de
enfriamiento pudo reducir la turbidez de 3,1 a <0,8, cumpliendo as� con la
normativa EBC. El grado real de fermentabilidad (% GRF), afectando
la sensaci�n bucal, aument� con el tiempo, mientras que la densidad, el
pH, color y amargor se mantuvieron relativamente constantes debido a la
reducci�n de los azucares presentes. Tambi�n se
not� que las membranas pueden reducir el porcentaje de alcohol, la
turbidez, el EE y el % GRF. El enfriamiento reduce la turbidez,
pero no tanto como la microfiltraci�n. Aunque se
notaron peque�as diferencias, ambos m�todos cumpl�an satisfactoriamente
con los est�ndares de la EBC.
Palabras claves: biotecnolog�a, cerveza, clarificaci�n,
enfriamiento, microfiltraci�n transversal, micro cervecer�a.
