CHARACTERISATION OF BEER PARTICLE CHARGES AND THE ROLE OF PARTICLE CHARGE IN BEER PROCESSING

Streaming current measurement has been shown to be an effective tool in measuring the net charge of beer particles. Using this method, it was demonstrated that non-microbiological particles of a number of beers could be either positively or negatively charged. Copper fining has been shown to significantly affect the net charge of the NMP in the resultant beer. Increasing the copper fining rate enhances the negative net charge of the NMP to a limiting value at which the addition of further copper finings has no effect. This is believed to correspond to the complete removal of all of the positively charged NMP by copper fining. The reduction in pH during fermentation results in the production of further positively charged NMP. The presence of positively charged NMP has been shown to have an adverse effect on isinglass fining performance. These results suggest that choice of raw materials and process conditions play as much of a role in defining fining performance as does careful consideration of fining rates .