Froth! 

The Science of Beer

Mark Denny

2009, HB, 183pp
The Johns Hopkins University Press

£13.50 delivered from Amazon

Reviewed July 2012

Mark Denny is a homebrewer and a physicist. In the Introduction he sets out his stall: “My book is unique to the best of my knowledge, in that it unites brewing with accessible physics.” I imagine that at this point many of you will move along but I rather like the idea. After all pretty much everything is physics, even beer. But if mixing physics with beer isn't for you then it gets worse—there's mathematics too. (I'm not selling this well, am I?). But panic not, the maths can be bypassed—that's what I did most of the time.

Before getting to the science Denny outlines the history of beer and brewing. Maybe he should have stuck to the science. This chapter is riddled with inaccuracies and not-quite-accurate assertions. Did Balling introduce the hydrometer into brewing in 1843? That must have surprised Baverstock you was using one in 1770. Is porter really stronger than stout? Is stout usually dry? Guinness has been so only since the 1950s and London stouts never really were. This chapter is too long and a rather out of place. This is a book about “the science of beer”—get to the science! And I hated the stupid interlude inserted to break the chapter into two.

Next up is How to Make Good Beer at Home. Still no science then. This is a very basic introduction to homebrewing but at the same time idiosyncratic and opinionated. Certainly not for the homebrewing purists. Denny advocates natural cooling of wort, plastic bottles etc. Personally I don't have too much of a problem with that but like the previous chapter this seem a bit out of place in a book about the science of beer. Who is the book aimed at? The general reader? The beginner? Or the more advanced brewer? I would have thought it was the latter in which case a homebrewing primer is an unnecessary waste of space.

There are some odd mistakes for a scientist to make like stating that crystal malt is an adjunct: the clue is in the name, surely—it's a malt. And using the yeast from bottle conditioned beer: ”Don't throw away the gunk—feed it with yeast nutrient...and pitch it into your next brew. It will go like a rocket.” Probably not.

Finally, nearly halfway through the book we get to the science. The book gets much better from here.

Yeast Population Dynamics

Quite a lots of mathematical formulae from here on but these are explained and can be skimmed over and the text will still make sense.

This chapter contains one of the best description I have read of why yeast pitching rate is important. Clear, concise, and well explained both mathematically (by formulae) and in the text. The maths can be hard and is mostly beyond me but the explanations are good.

Brewing Thermodynamics

Sounds a laugh-a-minute, doesn't it?. But, of course, temperature control is a fundamentally important part of brewing so this is relevant stuff. The chapter covers a whole range of situations such as the heat produced by yeast during respiration, heating the mash, cooling the wort, temperature control etc. Lots of good stuff.

Now it has to be said that the design of the formulae and the associated explanations is a bit poor. New terms are introduced and the explanation of what they represent can be hard to find, sometimes hidden in the text of the next paragraph. Poor book design, in fact.

One thought provoking fact: enough heat is produced by the fermenting yeast in a standard wort to boil the whole batch. Lucky that heat is lost from the fermenter then.

Bubbles

Bubbles are everywhere in brewing. You might have noticed that. I found this chapter really stimulating. They is quite a lot of abstruse science, and I am sure some of it isn't that important, but most of it was absolutely fascinating. Fermentation is discussed in some detail and we learn that a typical homebrew fermentation might generate 35 billion bubbles. See what I mean? Not terribly useful but interesting and dead good for boring the guys down the pub. Denny points out that (for the US, I think) 0.5% of all carbon dioxide emissions are produced by beer production.

Beer froth and head production turn out to be more complex that you might think. Hey, one paper on the subject received an Ig Nobel Prize. The head on a beer is a surprisingly complex and dynamic system as Denny explains. He also discusses the background to the use of nitrogen/mixed gas and also shows why it isn't terribly beneficial to beer flavour. He gives a great explanation of how a widget works. They are surprisingly simple and are, in effect, a type of sparkler. Mention is made of disproportionation, which is another good one for use down the pub, and negative bubbles (a spherical layer of gas with liquid inside and outside of the sphere.

This chapter is probably the most successful of the book and is full of fascinating insight and some interesting science.

Fluid Flow

The final “science” chapter uses its title rather liberally. Most of it is taken up with the mathematics of bulk beer distribution which is, just about, an example of fluid flow. This is the only section where I found my inability to understand the mathematics frustrating. It would have been helpful to have had the various formulae more fully explained and not to have taken so much on faith. Maybe an appendix for thickos like me could have been added?

A brief discussion of how beer is moved from cellar to bar and an appreciation of how complex the action of drinking a beer is in terms of physiology, completes the chapter.

There are a few odd assertions—are electric pumps replacing beer engines on the bars of English pubs? I'm not sure when I last saw an electric pump. I used to love watching a diaphragm pump dispensing a pint of Bank's mild when I were a lad. But then earlier in the book there was the assertion that the barrel (36 gallon) and the pin (4½ gallon) are the most common UK cask container size when the firkin (9) and the kilderkin (18) are, by far, the most common size encountered.

Final Thoughts

Not a lot to say about this chapter. Simply a summing up of what went before.

Throughout the book some of the graphs are poorly designed and sometimes inappropriate for the data they depict—line graphs where bar graphs would have been better, for example, which is rather odd for a book published by an university press.

The very simple brewing technique described is at odds with some of the science explained, especially in the thermodynamics section.

The book is a good quality hardcover, nicely printed, with a sown binding. In fact the cover is so substantial, for the size of book, that it may constitute a dangerous item. Don't try and take it onto an airplane.

Froth! is a brave attempt at a different homebrewing book. It contains some thought provoking information and certainly encourages the reader to look at things from a different perspective. But it is not a great book. Nearly half the book is not, in fact about “the science of beer”. Most of the beery science is interesting, some of it thought provoking, and some of it might even improve your brewing. Although the text is designed so that the mathematics can be missed out it is a pity that some space could not have been found to more fully explain how the formulae are derived. The mathematics is the backbone of several sections and not being able to understand it is very frustrating.

Froth! is not a book for everyone and newby brewers should avoid it if they don't want their head to explode. The more advanced and/or technical brewer will certainly get something from the book and it encourages the assessment of the brewing process from a new perspective.

So recommended (but with significant reservations) especially at £13.50 for a “proper” hardback.

Brewing With Wheat
The "Wit" and "Weizen" of world beer styles
Stan Hieronymus
Brewer's Publications 2010, PB, 216pp, 8 colour plates

£8.07 delivered from Amazon

Reviewed July 2010





I liked Stan's previous book "Brew Like a Monk", as you can see in my review on this blog, & I was pleased when I found out he was working on a book about wheat beers, a variety of beer I enjoy but don't know too much about.

BWW is similar in format to BLAM. It is not a "how to brew a wheat beer" guide and, although there are details of many beers discussed there are no recipes as such. I think this is one of the strengths of the book. Enough detail of the production of, and philosophy behind, named beers is given to inspire a brewer in recipe formulation with out getting bogged down with details of the brewing process that any reader is going to understand anyway.

The book starts by discussing wheat as an ingredient, both in bread and beer, from an historical perspective. Wheat has always been important in baking and has become increasingly so over the last two centuries whereas, on the other hand, wheat was in the past much more important in brewing than it currently is, although it is being more widely used these days.

A characteristic of most wheat beers is haziness and cloudiness. A very interesting chapter is devoted to this. A beer made from 20% wheat would probably have some haze but, as the proportion of wheat is increased the degree of haze will decrease. Yes you read that right. A 50-60% wheat beer will probably drop bright. Now, of course, this is the sort of proportion used in, say, a German hefeweizen which would not be bright. The brewers of hefeweizen overcome this inconvenient clarity in a number of ways such as removing the primary yeast, flash pasteurising to stabilise the protein in suspension, and then bottling with a non-flocculant yeast to prevent it settling and dragging down the protein with it. Draft hefeweizen containers are delivered upside down so that the yeast and protein is resuspended before dispense. Although that seems a lot of trouble, it must be better than the strategy adopted by some US brewers of using additives such as Tanal A or Biocloud, which sounds yummy.

The same chapter includes a section on the production of the clove flavour found in weizen and wit beers. The flavour compound is 4-vinyl guaiacol (how the hell do you pronounce that!). Wheat contains the precursor of this in the form of ferulic acid. Ferulic acid is released from barley at a mash temp of around 45 °C and a temperature step or decoction mash may include a ferulic acid rest. Once the ferulic acid is released from the wheat it can be converted to 4-vinyl guaiacol by a suitable (Phenolic Off-flavour Positive) yeast. POF+ yeasts are characteristic of weizen production, less so for wit beers.

We then move onto a description of wheat beer by region: Belgium, Germany, and the USA. For many Hoegaarden is the definitive Belgian wheat beer but, as Hieronymous points out, Wit beer as a species had died out before Pierre Celis revived it in Hoegaarden and compared with historical examples it is atypical. In 1948 the great brewing scientist Jean De Clerk found that Hoegaarden, Peeterman, and Leuven Wit were all infected with Lactobacilli and sometimes Pediococci. He described Hoegaarden as very sour. It is not surprising that these beers were infected in this way because the brewers used white "wind" malt, short boil times (and may not have boiled the wort at all, merely heating it near to boiling), and very low hopping rates. The beers were cloudy and white from microbiological and protein haze and because the beers were drunk while still fermenting. Plenty of detail of old production methods for many types of wheat beer is given illustrating many various unique or just plain weird production methods.

A whole chapter is devoted, quite properly, to Pierre Celis who has had a role in the popularisation of spiced wheat beers, in the Belgian style, both in his home country but also the USA. Without Celis wheat beers, in particular Wit, would be no where near as popular as they currently are. His influence in the US has been phenomenal and he provides a direct link between Belgium and the USA. Mind you this chapter includes a section on Coor's Blue Moon. I recently had the misfortune to try this. It is a peculiar looking beer with an odd orange hue and a weird haze which doesn't look quite right. I wonder if this is Biocloud in action? Things got worse on tasting it. It is without doubt one of the most horrid beers I have sampled in the last few years. Mind you it could be worse. The next chapter describes a wheat beer with bloody Cascade hops in it. Wrong, wrong, wrong.

Anyway back to the book. Off to Germany next, so put the spices away and forget about Pierre Celis. First off, Bavaria for Weizen. Unlike Belgium, and often the USA  the spiciness evident in these beers  comes from the distinctive POF+ yeast. One of the great Bavarian Weizens is Schneider. This is produced  using an odd mix of techniques: a decoction mash (with ferulic acid rest) followed by top fermentation in open fermenters. The brewery believe the open fermenters, and the aeration they lead to, are essential in developing the clove-like flavours they want in their beers. Wheat beer nearly disappeared in Germany as it did in Belgian. It returned from the verge of oblivion when it became popular and trendy because of its perceived healthy appearance. Bless "the young", I knew they would be useful for something.

From Germany we move on to the USA. Wheat beer in all its varieties has been a big success in the USA. Some microbreweries find their cloudy wheat beers are their biggest sellers. It is hard to imagine that happening in the UK. I have to say I didn't enjoy this section, not that there is anything wrong with it. Its just that I get irritated with so many aspects of the US micro scene especially when they start messing around with things like Weizen which is just fine as it is. That's just me. A reactionary old fart.

Leaving the US behind we return to Europe for a discussion of various historical and less important wheat beer species. Things like Berliner Weisse (which is uncomfortably close to extinction), Gose, Lichtenhainer and the like. We are back to bacterial infections again.

The book concludes with a chapter on style guidelines and beer judging. The US style guidelines for some of these beers are, like several of the European styles, highly dodgy and apparently the standard of judging leaves something to be desired. I have little interest in style guidelines and not much more in judging but there is quite a lot of thought provoking stuff in this chapter and a lot of sensible advice on making  good wheat beer.

I didn't enjoy this book as much as BLAM but it does have plenty of interesting things to say. It is certainly worth the price and will be a useful book to have on the shelf for future reference. If you want to make a wheat beer it would be well worth reading BWW before starting.

Radical Brewing
Recipes,Tales & World-altering Meditations in a Glass
Randy Mosher
Brewers Publications, 2004
PB, 324pp
£9.88 delivered from Amazon

Reviewed January 2010


Randy Mosher is clearly a clever bugger. He not only wrote this book but designed it as well. More of which later.

Radical has a couple of distinct meanings which can be applied to the title of this book. First, going to the root or basics and secondly, far-out, wild or unusual, This is apt because the book does contain both elements.

This is not a book for the neophyte brewer but for someone who has a few brews under the belt and wants to find out more or expand their horizons and it will certainly do this well. Although all the information is there it is not organised in a way that would be easy for the starting brewer but of course there are plenty of other books or web sites which will fulfill this need.

The first half of the book deals with the brewing process and theory behind it: radical in the first sense. A lot of the information is seen from an historical perspective which I like because it accords with my outlook on brewing. Although this is quite detailed and in-depth Mosher's style is light and breezy and he gets his point across easily. He also, clearly, knows his beer history and has read and researched much more deeply the authors of some other, supposedly authoritative books (and yes, I am thinking of the Classic Beer Styles Series). For instance his brief description of the history of porter which, let's be honest, is a pretty contentious area is well balanced and thought out and avoids all the usual dodgy information. Mosher's views on brewing are always well reasoned and I rarely took issue with his suggestions. For instance in the hops section Mosher suggests there is no homebrew justification for high alpha hops and that pellets give an inferior flavour to whole flowers. That seems pretty much bang on to me. You might argue that the flavor of pellets is not "inferior" but it is well established that it is different.

There are some sections that work really well. I particularly liked the section on off flavours and how to mimic them. Not, I hasten to add, so that you may add them to your beer but so you can detect them and eradicate them! I also appreciated his approval of the use of sugars. Now I know to some brewers this is spawn-of-the-Devil stuff but, having overcome my CAMRA inspired aversion to sugar, I have come to appreciate it is often a useful, and sometimes a necessary, ingredient in beer. Annoyingly our US brethren seem to have, as always, relatively easy access to a greater range of this product than we do. Damn their eyes.

In the second half of the book there is more concentration on beers from around the world mainly, again, from an historical perspective. This is very wide ranging and there are some interesting beers to try or at least think about and perhaps inspire you. But there is also a element of that annoying (to me anyway) American habit of just chucking anything in willy-nilly and assuming it will be marvelous. Well it might be, but usually getting the quantities of flavouring additives (spices etc) right is pretty difficult and without considerable thought, and usually a bit of trial and error, the results are less than stellar. It is the US "can do" thing, I think. And why do you need to put mint in stout? It's not exactly lacking in flavour is it? And if you think of the difference between a Guinness clone and an imperial stout there is one hell of a lot of variety as well.

There are some odd errors, especially since it is obvious that Mosher is very well read in the brewing literature and well traveled. For instance a british beer barrel doesn't hold 31.5 gallons (although oddly the volumes of the kilderkin and firkin are correct) and Dorset isn't a short hop south of London. I was born in one and lived in the other. Dorset is definitely to the west of London. OK I might give you southwest.

I do have, however, severe issues with the design of the book, which was undertaken by Mosher himself. I don't know, but would hazard a guess, that he is a designer rather than typographer. The design looks modern and attractive at first look but it is a right royal pain to use. For instance on the facing pages 98 and 99 there is one illustration, two recipes in full page width tables and two small tables inserted into the text blocks. In all there are only eleven lines of type on the two pages. This sort of design is repeated throughout the book. So what's the problem? Well reading the text is repeatedly and frequently interrupted by the extra matter on the pages. The text is not allowed to flow, which is a pity because it is actually very good. You either have to stop reading to consult the tables, recipes, sidebars etc or ignore the extraneous matter on concentrate on reading the text through before returning to the other matter. This is what I did, which is not ideal, but I found the whole experience of using the book incredibly frustrating if I didn't. A pity: there is a much better book in there trying to get out.

So not a perfect book then. But certainly a useful, stimulating, and informative one. I am glad I added this book to my library. If you are looking to expand you knowledge of the history of beer and brewing or want to expand your brewing horizons to include a wider palate of beer styles, types, and flavours you could do much worse than Radical Brewing. Recommended.

Practical Brewing
E R Southby,3rd Edition, ed C H Jolliffe
The Brewing Trade Review, 1895
HB, 391pp, 11 pages of trade adverts
Long out of print, this book is sometimes available from the usual second hand sources. Also now as a PoD paperback for about £20.

Reviewed July 2009

Southby was a consulting brewer of experience and certainly believed himself to be an authority on all aspects of his trade. He was no shrinking violet and his character comes over very strongly through his writing style.

This was, arguably, the glory days of british brewing. Porter was still a significant style, stock ale was widely available and running beers were considered a necessary evil. Yeast and it's role in fermentation was well understood, although Pasteur's work was sufficiently recent that it has to be briefly discussed in the text rather than being taken as read.

This is a thoroughly scientific, detailed text and many of the methods that are described have recognisably been modified into those that small scale brewers use today. All aspect of the brewing process are covered, both theoretically and practically.

For me the book really comes alive when Southby describes the brewing process. I was intrigued to read that Southby is not a great lover of the tower brewery but advocates the use a horizontal arrangement with the extensive use of pumps (and I didn't realise there where so many types of pump). There is plenty of in-depth information on mashing including temperature stepping, decoction, the Pigeon converter and what we would now call RIMS. Fermentation is similarly covered in detail with cleansing, skimming and stone squares fully explained. Puncheons & Burton unions are described. All through this section I kept thinking, "I reckon I could build one of those". Oh! the curse of the craft brewing tinker.

There are a few areas that seem surprisingly outmoded in this scientifically based work. Some of the materials used, especially the extensive use of wood to fabricate various brewing vessels, seem very old fashioned compared to much of the rest of the descriptions of the brewery and brewing process. Southby is very strong on the importance of cleanliness which was clearly a significant problem in a brewery that utilised a lot of wooden equipment. He is very keen on the use of hot water and, especially, steam to clean and disinfect equipment and pipework, along with a long list of unpleasant chemicals for other uses.

Noticeable by its absence is the term pH. Of course this is because Sørensen did not introduce the concept until 1909. This makes the descriptions of how to control mash acidity rather clumsy and long winded. Mash acidity is one of those topics that can be rather confusing but, trust me, brewing is far easier to describe using the concept of pH!

Another area that seems at odds with modern thinking is the oxygenation of hot wort in the copper. Southby is insistent that there should be full ebullition during the boil so that oxygen is taken up as much as possible. Hot side aeration not withstanding, although we would agree that a full rolling boil (and them some) is a necessity it is now recommended to encourage various chemical reactions such as isomerisation of hop components rather than to increase the uptake of air. Still we are back on track with the aeration of cold bitter wort which is much more in line with the modern concept.

I may have given the impression that this book is totally out of date, which it is in some ways but it was written at the time when the "mystery and art of brewing" had become the "science of brewing". A surprising amount of the advice given is totally in agreement with our current understanding of the brewing process. I am sure that much of this information, especially that on mashing and fermentation, could be adapted to our use with interesting results.

One area struck a discordant note with me. Southby is not adverse to utilising surprisingly large proportions of non-malted adjuncts and is clearly very taken with the, then quite new, Pigeon convertor which I find a little odd because most the work is a directed at improving quality. I suppose we are seeing the seeds of the accountant led, commercial brewing process that we are "enjoying" today. A pint of InBev corn syrup and maize extract anyone?

This book often amuses me. I have mentioned the writing style already but I also love the way Southby isn't quite sure if he wants in insure something or ensure it and, frankly I don't think he cares—after all Shakespeare couldn't even spell his name and he did OK. Southby clearly enjoys the word ebullition and uses it whenever possible. And I have learnt never to place one vessel above another ever again. From now on I am going to place it so that it commands the lower vessel. As I mentioned above Southby is not slow in coming forward. Several times throughout the book whilst describing a crucial stage in the process our hero tells us that the best device to use is use is "Southby's patent widget". But to be fair it isn't always his device. Oh no, on occasion it is his brother's patent widget. Keep it in the family.

My copy of the book is very well bound in the Victorian manner and printed on high quality paper. The typography and printing are good.

If you can get hold of this book I thoroughly recommend it, especially if you are interested in the history of UK brewing or want an insight into the beer of our great-grandfathers. It certainly isn't a dull, dusty text book. Actually it's a rather good read. And hopefully it will encourage you to brew some historically informed beer using some new (or rather, old) techniques.

July 2012 update. This book is now available as a POD paperback facsimile for about £20.