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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.

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