Letters to the Editor

Thomas B Halpin

Dr. Anderson's paper - Microbes and the Origins of Porter (BHS Number 113) - has made me cast my mind back to my early years in the brewing industry.

There are two expressions which come immediately to mind namely the perfect secondary fermentation and OBS Vats.

The former of course is the Brett effect of giving beer a pronounced vinous character some might call it matured, aged or whatever. Suffice to say that some higher alcohols and alliphatic esters are no doubt responsible. Brewing Science however at this juncture (1952) had not yet embarked upon the notions of flavour chemistry. Indeed one could honestly say that the analysis of beer was really a measure of its wholesomeness in line with its Original Gravity.

The latter however in the more longhand meant Old Brewery Stock Vats. These contained a miscellany of tank and line residues from all over the brewery together with some recovered beers (barm beers) which of course were pasteurized before being blended off into Racking Vats.

The impact of not only a yeast organism but also a rod and perhaps tetrads of spherical bacteria are vital to the cause of porter's flavour. Sadly the oak vessels are now of generations past these were the warehouses of the micro-organisms responsible. Brewing has moved on. There are few places now in which to store old beer recovered in both brewery and trade for future blending. Science however has provided all the answers necessary to produce good porter in a modern stainless steel fabricated brewery tank farm.

Just for the record I feel it essential to draw all our readers' attention to the issue of beer flavour. There are three easily measurable parameters that have a primary impact upon the flavour of beer i.e. alcohol, carbon dioxide and acidity. The measurement of bitterness did not become a routine laboratory analysis until circa 1960. I can recall myself working on the measurement of isohumulones (bitterness) in 1958. Like most analytical tests it took time to resolve the minor conflicts associated with different methods that were put forward. As far as bitterness measurement is concerned in the opinion of this writer all credit must go to two great Canadians. In passing also let us not forget two other famous pairs of Canadians who (a) discovered insulin (b) developed the caloric value of food factors. Just a little food for thought as I arrest my case.

Terry Foster

I would like to comment on the articles on Porter by Martyn Cornell (BHJ Summer 2003), and Ray Anderson (BHJ Autumn/Winter 2003). Both were excellent, especially Cornell's debunking of the Harwood myth. However, both state that it was necessary to store porter for long periods in order to reduce the smoky flavour it had initially. My experience; and that of many brewers here in the US, is that if beers brewed with smoked malts are stored any length of time, then the smoke flavour becomes more "forward", and therefore more pronounced on the palate. Further, in looking at the literature, it would seem that brown, or "blown" malt was dried extremely rapidly (in 2-3 hours), using a very hot fire in the latter stages of the process. That suggests there may, in fact, have been little smoking of the malt at all!

Ray Anderson's comments on Brettanomyces are too sweeping. Certainly, Brettanomyces species could have been present in porter storage vats as he correctly suggests, but that is only an inference; it cannot be definitely stated, from 20th century analyses, that porter contained fatty acids and their ethyl esters, as Anderson does state. Indeed, one of the biggest porter brewers, Whitbread, in his "new" 1760 brewery did not use wooden storage vats for porter. Instead, he used cisterns lined with special glazed tiles, which may well have been a much less suitable environment for Brettanomyces than wood. If that were the case, then the beer would have tasted very different to that which

Whitbread had previously been brewing, which seems unlikely, given the success of his business.

There are still many questions about porter's flavour, and why it became so popular. For example, why was it cheap compared to other beers, when it needed to be stored for such a long period before sale? Surely storage space must have been at a premium in a crowded London, and the capital tied up in the beer kept for as much as a year before sale, must have been enormous? Or was porter malt so much cheaper than other pale and other malts?

I should be particularly interested in hearing other people's comments on the price question. Perhaps I'll come up with some answers myself in the next year or so!