Most of the factors which determine the variability of quality of draught beer drunk in pubs relate to the pub rather than the Brewer. How regularly does the publican clean his lines? Is the cooler working correctly? Are the first few pints pulled each day wasted so that you don't get a pint that's been slightly oxidised sitting in the line overnight? Does the publican have sufficient throughput of a particular beer so that it is relatively fresh and hasn't been sitting in a half full keg for weeks? Are the kegs stored in a relatively cool cellar?

Formerly, pulling a pint of Guinness was a bit of an art form as well, although modern dispense technology has reduced variability in this. I'm not an expert on the technical side of brewing but I would imagine beer coming out of microbreweries would be much more variable. Perhaps that is part of its charm and attraction.

Most large scale brewery produced beer - as far as I am aware - is pre-filtered and doesn't have the yeast floating issues discussed by Helen in relation to real or craft beers. Finings are used to settle or accelerate settling of sediments (yeasts and proteins) prior to bottling/kegging. Not all finings are vegetarian and so, technically, not all beers are vegetarian as trace elements may remain in beer.

Index of Frank's Diaries