Flavour Compound of the Week - H2S

This week we are looking at H2S or hydrogen sulphide. This is my least favourite natural flavour compound in beer. Its aroma is the disgusting smell you will remember from the playground after someone let off a stink bomb or when your grandmother has been on the spouts at Christmas. At lower concentrations it has a sweet eggy smell like your lunchbox when you didn’t get around to eating your egg sandwiches.

I can’t understand how at any level, flatus and rotten eggs is a welcome component of beer flavour but some drinkers welcome it as a quirk of the brew. It would be interesting to see if they missed it if it was removed.

H2S is produced during fermentation by yeast from various sources. The most significant source is through yeast metabolism of amino acids. The amount of H2S is influenced by sulphate levels in water and the availability of sulphur containing amino acids so the brewer has some control over levels by ensuring that these are correct. The most significant factor in the production of H2S is the yeast strain. Some yeasts pump the stuff out like a fart machine while others need extreme conditions to produce any. H2S is also produced prodigiously by certain bacteria and wild yeast so may indicate an infection especially in bottled beer.

Tip Beer in Mouth and then Swallow

Before I became a commercial brewer I used to love tasting beer. Don’t get me wrong, it’s still a real perk of the job and finding a new gem of a brew at a festival or in a pub is still exciting, but now brewing is my living tasting is an entirely different proposition. When tasting beer commercial brewers aren’t doing it for fun. If it’s their own stuff they are looking for faults or for where things have gone well but most importantly for trueness to type. If it’s other beers they will probably be rating them in their head judging it like the panel on Strictly Come Dancing, comparing it to their own stuff and to the model of a good beer in that style in their brain.

I taste beer according to this hierarchy listed from most important to least important

1. Evidence of off flavours (DMS, H2S, Diacetyl, bacterial, wild yeast etc)
2. Technical merit (how difficult the beer is to brew)
3. Balance of flavours
4. ‘Commerciability’ (will the average drinker like it?)
5. Character (will the beer enthusiast like it?)
6. Do I like it (this is strongly influenced by the 3 above)

Most drinkers are only concerned with the last point. Rate beer reviewers and beer enthusiasts are probably only concerned with the last two points along with another which is individuality. The more you understand about beer the more complex tasting beer becomes. For a brewer the machine (his/her palate and brain) measuring the beer has a great deal more functions, whistles and bells.

Next time you are enjoying your beer spare a thought for the poor commercial brewer for whom beer will never be as much as fun again!

Flavour Compound of the Week

Welcome to flavour compound of the week. In this ‘feature’ of my blog I will introduce you to (bore you to death with) a different flavour compound each week, describing its sensation, origins and some of its chemistry.

Flavour in the most important part of beer. That goes without saying. Rather irritatingly for brewers it is also the most complicated. This is why global brands are low in flavour. It is easier to control flavour when there is very little there in the first place. There are thousands of known flavours in beer and probably more unknown ones. All have thresholds and act additively, synergistically and or antagonistically to each other. That is some can promote the detection of other flavours and some can mask them.

In truth, with regard to a lot of flavour compounds we don’t know exactly where they come from.

I am starting with a compound that I know more about than most because I studied it for my thesis at university. It is the wonderfully-named 2,5-dimethyl-4-hydroxy-3(2H)-furanone or DMHF for short.

DMHF smells like candyfloss and strawberry jam. As with most flavour compounds it smells differently at different concentrations and in different contexts. At high concentrations it has been described as having a rotten note. Interestingly (or not) DMHF is not only formed by non enzymic browning of malt sugars during malting and wort boiling but is also produced by yeast during fermentation. It is likely that the yeast transforms a precursor molecule which has been formed during a stage of the brewing process involving heat.

Stronger beers with more dark malts will have higher levels of DHMF than pale weaker beers, although a beer with less back ground flavours (hops, fruit, roast) may exhibit more than beers 'with a lot going on'. Look out for it in less hoppy barley wines, dubbels and strong German lagers.

Next time you're in the company of a beer nerd and they are reeling off a list of abscure chemicals that s/he has picked up in the beer, just mention that a whiff of 2,5-dimethy-4-hydroxy-3(2H)-furanone has just danced like a zephyr across your olfactory epithelium and that should keep them quite for a few seconds.

It's just not the same

Have you ever had a beer and thought that it’s different to how you remember it?

As a brewer very occasionally you are faced with having to defend the job you do against a customer who has had just this experience. The main problem with all things taste-related is that all the information is processed by the most fallible piece of equipment in existence, the human brain. Take for example the statement “I remember it as being hoppier than it is now.”. Hoppy being a qualitative thing is subject to change due to changes in the frame of reference. Hoppy in 2009 is a golden ale made with American high-oil hops with an overwhelming citrus character. Hoppy in 1999 was a late hopped session bitter with resinous hop notes.

From time to time customers have even alleged that my beers are darker or lighter than they used to be. Of all beer attributes, colour is the one that any brewer can measure and control so colour will only change if change is desired.

Another source of distortion in the chain of information between tastebuds and memory is the halo effect. When you discover a gem of a beer which no one else knows about in a small country pub on holiday this beer can be close to god. If you try the same beer, probably faithfully reproduced by the brewer in a packed ‘spoons at 7PM on a rainy Wednesday, after a pint of 300EBU Faceache Stout it is unlikely to rate as highly in your estimation. Halo well and truly removed.

Another common de-haloing factor is popularity. The beer can’t be that good if it’s popular because it’s ‘mass produced’. This is of course complete bullshit. Knocking well-balanced, well-brewed beers just because lots of people like them is not uncommon amongst some self-appointed beer experts. If someone tells you something is wrong with your pint you are unlikely to like it as much.

I’ve brewed some brands in previous roles where significant changes have been made to the process for one reason or another and there has been a change in the product. I know of a few of my favourites which have been subject to change and are lesser products for it. I am fortunate enough to be completely in charge of how Sharp’s make beer so no changes are made other than those needed to maintain consistency.

Maintaining consistency without reducing appeal is the true test of a brewer’s capability. All the inputs to the brewing process are in a state of continual change so brewers must use all the art and science at their disposal to maintain consistency.

Below is a list of changes which have fairly profound effects on the character of a beer.

· Malt – variety change, change of maltster, seasonal shifts
· Hops - variety change, change from whole hops, bad year for key variety
· Yeast - strain change, strain shift, Saccharomyces contamination
· Milling and mashing - new plant, plant optimisation
· Boil - new copper, new calandria, change in regime
· Fermentation – new vessels, FV shape change, temperature optimisation
· Conditioning – throughput optimisation
· Other - centrifuge, processing aids

Brewing is a complicated thing even for a brewer! I always drink with an open mind

The Panel Has Spoken

The results are in from the flavour panel Christmas tasting. Here’s how the individual beers were rated.

Sierra Nevada Kellerweis 6/10
Comments: Good attempt at Heffeweizen. Light and refreshing. Saccharine sweetness lacked bitterness and moreishness.

Abbaye Des Rocs Blanche de Honelles 7/10
Comments: Dry grainy aroma with spices not especially inviting, very complex taste. Feels much more alive and natural than the Kellerweis.

Belgium 1 – USA 0

Sierra Nevada Pale 5.1/10

Comments: Hops and not much else. Very and quick to finish and too bitter for the lady panellists.

Orval 6.1/10
Comments: Smells like cider incontinence pants.
Promising aroma let down by taste. Finish not good with saccharine and puckering bitterness. Unusual!

Belgium 2 – USA 0

Odell St Lupulin 5.9/10
Comments: Stunning hop rub aroma. Flavour lets the beer down. Harsh metallic middle and very little in finish. One dimensional.

Dupont Avec les Bon Voeux 8.7/10
Comments: Universally loved. Complex, alive, balanced dangerously moreish. Accomplished beer.

Belgium 3 – USA 0

Flying Dog Kerberos Tripel 6.9/10
Comments: Nice aroma of hops and grains. Good balance in the mouth. Pleasant bittersweet finish. A sound beer but nothing special.

Maredsous Tripel 8/10
Comments: Lovely fruit and alcohol aroma. Rich but balanced in the mouth. Wonderfully warming finish. Very good.

Belgium 4 – USA 0

Struise Pannepeut 6.9/10
Comments: Dark oxidised aroma. Thick earthy flavour. Dirty finish. Tastes like an ok homebrew. Cloying

Stone Double Bastard 7.6/10
Comments: Stunning hop and roast aroma. Tons of flavour. Too bitter and flavoursome for some of the panel.

Belgium 4 – USA 1

Dog Fish Head Palo Santa Marron 8.1/10
Comments: Smells like Parma Violets. Stunning aroma. Wine like body. Loads of flavour . Like drinking perfume

Dubuisson Bush Ambree 8.6/10
Comments: This is special! Far too drinkable for a 12% beer. Lovely hop flavour without the bitterness. Smashing!

Result

Belgium 5 – USA 1

Summary of findings

US beers seemed more synthetic and the flavours were too brash. They almost seemed to be trying too hard to impress. The very highly hopped beers divided opinion some loved them, some hated them none of the panel were on the fence. The Belgian beers were more subtle and refined. The Belgian brewers seemed to be trying to make strong beer easier to enjoy whereas the US brewers seem to be engaged in a race to squeeze as much flavour into the beer as possible. The analogy used was Belgian beers were like eating a good homemade soup where as the US beers were like eating a stock cube.

Vin de Cereale

I wanted to resist the temptation to turn the blog into a beers I have tasted and liked blog because that is selfish. I will however just mention that during my Belgian trip I tasted the most exciting beer I have tried this year. I’m not going to go into detail about it. Rodenbach Vin de Cereale is just blindingly wonderful.

Oooooh yes!

Winter Berry Ale

I have just spent a very enjoyable day with the charming, interesting and debonair Adrian Tierney Jones making Sharp’s latest seasonal, Winter Berry Ale. Winter Berry Ale is so called because it’s matured with rose hip, hawthorn berries and sloes before racking. Adrian was treated to the full brewery experience. Lapsang in the lab, stories about the brewer’s I have maimed and a guided tour of the holes I have punched in my office wall.

The brew went very well and the wort tastes very promising. I had always presumed that beer writers would be strange creatures, Oscar Wilde-like bohemians, full of their own importance and deft prose. After spending the day with a few now I can honestly say they are just like you and I but just a little bit nicer!

I have promised to update Adrian on the progress of the brew. I’ll try to update my blog with the same.