Wednesday, June 24, 2015

The "D" Word: Diacetyl

Remember when we were young and we were taught never to say bad words? I apologize in advance for all the obscene language I'm about to say.

In the beer world, there's no greater profanity than saying the "D" word. And even worse is putting that "D" in your mouth. (Get your mind out of the gutter! ...That's not what I meant!)

I am referring to Diacetyl.

Pronunciation aside (die-ASS-a-teel, DIE-a-see-till, or die-assa-TEEL), this compound causes a movie popcorn, almost rancid butter-like flavor and aroma in beer. Although Diacetyl is produced by all yeast strains during normal metabolism, its quantities are greatly affected by many factors. The main factor is the amino acid Valine and how much of it is present in the wort. Regardless of this, Diacetyl is always produced at some rate during the first few days of fermentation.

*Warning! Chemistry up-ahead!*

2, 3-Butanedione (AKA: Diacetyl)

During the initial stages of fermentation, the yeast cell creates Valine as part of its metabolism cycle. Along this pathway to create the amino acid, the compound α(Alpha)-Acetolactate is also produced. A non-enzymatic oxidative decarboxylation of α-Acetolactate (I know, right?) occurs outside the yeast cell and is converted to 2,3-Butanedione, the compound we know as "Diacetyl."

The presence of Valine is directly related to the amount of Diacetyl produced because the enzyme that produces α-Acetolactate is deactivated when the wort contains high quantities of Valine. We know Valine is an amino acid and amino acids are the building-blocks of proteins. In turn, we can assume the high concentration of proteins in wort should significantly reduce the amount of Diacetyl produced. High protein levels could cause some other problems in the finished beer, so large protein quantities is not a viable solution to control Diacetyl.

Another compound called 2,3-Pentanedione is created via an separate pathway. This compound is also sent outside the yeast cell and will end up in the finished beer if not properly reduced. 2,3-Pentanedione is believed to have similar buttery flavor and aroma properties (sometimes described as honey-like), however this compound is not produced in very high quantities as 2,3-Butanedione is.

For you chemist out there, these two compounds are Vicinal Diketones. "In chemistry-speak, 'vicinal' essentially means 'adjacent', and 'diketone' means that there are two ketone functional groups (a ketone is an oxygen double-bonded to a carbon in the middle of a carbon chain)." (Beer Sensory Science)

As fermentation wraps up, most of the previously produced 2,3-Butanedione and 2,3-Pentanedione is reabsorbed by the yeast into its cell. Through more enzymatic activity, they are converted into 2,3-Butanediol and 2,3-Pentanediol, which have a much higher threshold for us humans. In other words, Diacetyl is turned into something we can't taste.

For you brewers out there, this is typically referred to as a "Diacetyl Rest." Brewers usually aid the reabsorption of these compounds by raising the temperature during the last day or two of fermentation. This rise in temperature excites the yeast and can more easily and vigorously convert Diacetyl into the non-flavored compound.

If Diacetyl is detected in your beer, it is usually an indicator of rushed production or improper fermentation practices.

Another common contributor to Diacetyl is a bacterial infection. The most likely culprits are the little bugs called Pediococcus and/or Lactobacillus. Both of these lovely bacteria create lactic acid and can produce Diacetyl as part of their fermentation products. While they may be a welcome addition to some wild ales and artisanal sour beers, it is quite unpleasant when found in dirty draft lines that haven't been maintained or cleaned sufficiently. Infections can also occur in many stages of the fermentation process, but dirty draft lines seem to be the biggest contributor for Diacetyl via bugs.

One more discovery is Diacetyl production during beer aging. Although the levels of Diacetyl in aged beer may be undetectable because of low levels or hidden behind the veil of oxidation compounds, Diacetyl could be nonetheless present.

In very small quantities, Diacetyl can be a contributing factor to the overall flavor and aroma profile of certain styles. Most English and Irish beers tend to have some detectable levels of Diacetyl adding a pleasant buttery undertone. An interesting fact is Diacetyl is one of the differentiating characteristics between a German Pilsner and a Czech Pilsner (Czech Pilsners are expected/accepted to have low levels of Diacetyl). However, in high quantities this compound can impart a butterscotch, movie popcorn, or a rancid butter flavor and aroma.

Another interesting fact to point out is while a great number of beer drinkers might be able to detect Diacetyl with ease, there are an equal amount of us that are completely blind to it. On that same note, some are very sensitive to Diacetyl while others will only find it detectable in extremely high quantities. Should you fall under any of these parameters, it is perfectly normal since it is simply genetics.

I think that's enough foul language for one lesson. I need to go wash my mouth out with some beer... Er, soap. And put a coin in the tip jar... Er, swear jar.

Class dismissed,

-Gilbert "Charlie" Perez, Certified Cicerone®

Photo Credits:
A big thank you to BeerAndBaking's Jessica Rice McNew for her amazing photography in this article!!

-Beer Sensory Science
-Janux Chemistry of Beer Course Materials
-White Labs
-Oxford Companion to Beer

Tuesday, May 19, 2015

*Beer Education - Ale vs. Lager*

Ale and lager. Which of the two is better? Before we can even begin to think about how to answer this question, we must first have a clear understanding on the differences between ales and lagers. The answer is not as clear-cut and dry as one would think.

Perhaps the question we should ask is: What is an ale and what is a lager?

The short answer is... nothing! Well, that is if we consider only the end product, which is still beer. But if we dissect this, there are only a few differences. The main few are yeast species, fermentation temperature, aging temperature & duration, and fruit character.


This is the only real physical difference between ales and lagers. There are two types of yeast that brewers choose from. Ale yeast (also known as "top-fermenting" yeast) is called Saccharomyces Cerevisiae. This species of yeast has many different strains. Lager yeast (also known as "bottom-fermenting" yeast) is called Saccharomyces Pastorianus. As with ale yeast, this species also has many different strains. They both act the same in terms of basic fermentation metabolism and end product. Reasoning for distinguishing them as bottom or top-fermenting seems to correlate with the amount of kräusen found at the top of the fermenter.

FYI: Kräusen is the fluffy stuff that develops at the top of the fermenter that is made up of yeast and proteins and other materials frothed up as a result of yeast metabolism.

Fermentation Temperature

In general, ale yeast is usually slated to ferment at higher temperatures (65°F to 70°F, on average with some strains reaching even higher) and thus results and a vigorous, relatively quick fermentation and development of a large cap of kräusen. Lager yeast typically ferment at cooler temperatures (48°F to 58°F, on average). Because of this cooler temperature, fermentation is less violent, takes much longer, and there is less kräusen.

Aging Temperature & Duration

Ales are generally not aged for very long and are usually cold crashed (significant drop in temperature to about +/-40°F) after fermentation to allow the yeast and proteins to drop out. Dry-hopping (adding hops into the fermenter after fermentation is complete) is done at this time. Typically, an average ale is ready in as little as two to four weeks.

Lagers ferment at cooler temperatures and therefore take longer to complete. Fermentation can last a few weeks and up to a couple months in some cases. Once fermentation has finished, lagering can start. The word "lager" is the verb "to store" or put away in German. Combined with cool fermentation, lagering at about 33°F helps to further clarify the beer and allows the flavors to round out. Lagers can take many months to complete, from brew-day to packaging. Depending on the beer, lagering alone can last upwards to 6 months to a year, although 3 months is average.

Fruit Character

The aforementioned items are production-based distinctions. All of those aspects result in the one piece of evidence we can detect in both flavor and aroma: Fruit character. Ale yeast produce many fruity esters due to the quick fermentation, generally higher temperatures, and short aging. This is acceptable and desirable. Lagers on the other hand, are clean and show no fruit character. The slow fermentation caused by low temperature and long lagering times result in a malt and hops focused beer.

There will be more explanation further below, but the same can be true with beers fermented cold with ale yeast strains, which will produce very little esters. Interestingly enough, lager strains used to ferment beers at ale temperatures will indeed produce more fruit esters than they would usually do if fermented cold.

Bonus: Myths About Ales and Lagers

"Lagers have lower alcohol than ales." ...FALSE!

Being an ale does not necessarily indicate a higher ABV. True, the high-alcohol beers are usually an ale of some kind, there are also lagers available that can reach ABV's above 10%. Eisbock is one example.

"Ales are dark." ...FALSE!

Cream Ales and American Blonde Ales are quite pale in color.

"Lagers are always light in color." ...FALSE!

Doppelbock, Dunkle, American Dark Lager, and Baltic Porter are examples of lager beers that are dark brown to almost black in color.

"Lagers have more carbonation." ...FALSE!

Have you ever popped opened a bottle of Duvel? That's a Belgian Golden Strong Ale. Try to pour it without a producing a foam head at least 3 fingers high. Just try it.


This is probably the most important part of this article. We have hybrid beers out there to throw us a off-course and shows off how far we have come in our understanding of what used to be a clear line between ale and lager. These hybrid beers are a blend of ale and lager, usually using lager yeasts fermented at the lower end of ale temperatures and/or often involve lagering for a period of time regardless of yeast strain or species. Examples of these hybrids include Cream Ale, California Common, Kölsch, and Altbier.

California Common and  Cream Ale use an adapted lager strain to ferment at the low-end of ale temperatures (too high for some lager strains) and results in clean lager characteristics. This is historically true for Cream Ale, but is currently not that common. Kölsch and Altbier are examples of an ale yeast strains fermenting at the high-end of lager temperatures (too low for some ale stains) used to produce lager characteristics. They also go through a period of cold conditioning although the duration varies by style. Those are some examples of styles which create clean, lager-like beers using non-traditional methods.

A word on lagering: It is not uncommon for a beer fermented with ale yeast to undergo a cold-conditioning phase or for a "bottom-fermented" beer to be aged at room temperature. The resulting beer may differ from the traditional expectations, but could still be enjoyable if done correctly.

Other cuveballs are beers fermented with other organisms and/or wild yeasts. These organisms and wild yeasts (such as wild Saccharomyces, Brettanomyces, Lactobacillus, Pediococcus, and Acetobacter) all have their own properties in regards to optimum fermentation temperatures. However, most of the beers we see inoculated with any type of "bug" or "wild" yeasts/organisms are typically kept at room temperature (68°-72°F) or higher. So, by the explanation above, these wild and sour beers are widely accepted as ales.

And there you have it!

To recap, ale yeast (Saccharomyces Cerevisiae) and lager yeast (Saccharomyces Pastorianus) is the only physical difference between them. The flavor differences between lagers and ales are small, but noticeable. Lagers are clean, little no no yeast character with and no fruity esters, fermented a cool temperatures, and are submitted to extended lagering. Ales tend to have fruit character, fermented at higher temperatures, and not aged as long by comparison. There are exceptions with hybrid's using lager strains at low ale temperatures or ale strains at high lager temperatures.

Hope you learned a thing or two. Thanks for reading!


Gilbert "Charlie" Perez, Certified Cicerone®

Tuesday, March 17, 2015

Vocabulary Lesson – Dimethyl Sulfide (DMS)

Dimethyl Sulfide, more well-known by its initials (DMS), is a compound causing flavors and aromas considered an unacceptable in most beer style. DMS causes a creamed corn or cooked vegetables flavor and aroma when found in beer at detectable levels. When present at high concentrations, DMS can cause more of a rotten vegetable aroma and taste. Although it is considered an off-flavor in most styles, DMS is actually a desirable trait and/or acceptable in small quantities (complementary and adding to complexity) in most pale lagers, such as a German Pils and Munich Helles, and some light-colored ales, like Cream Ale.

The most common way to form DMS is in the brew kettle. The precursor of DMS is the compound S-Methyl-Methionine (SMM), an amino acid formed in barley during the germination stage of malting. Once the germination (tricking barley into sprouting) is complete, the malt is then kilned (heated) to remove moisture then kilned even further depending on the type of malt that is being created. SMM is a thermally liable compound, which means that it reacts at a certain temperature and creates something else. Lightly kilned malts, such as Pilsner Malt, are not subjected to excessive heat for large periods of time and retain much of the SMM found within. Mashing (steeping malt in hot water) is usually done at a temperature that does not create DMS. However, it will release SMM into the wort (sweet liquid created in the mash) and is carried over into the kettle. When SMM is in the kettle and the wort is boiling, it create DMS.

Along with SMM, there is another compound is responsible for DMS. Dimethyl Sulfoxide (DMSO) is created when DMS gets oxidized and this can happen either in the kettle or already be present in the malt. DMSO is not as volatile as DMS and is not heat sensitive, therefore, it would remain dissolved in the wort even after boiling. DMSO is then reduced into DMS in the fermenter by yeast during fermentation. Since top-fermenting (ale) yeast tends preform more vigorous fermentations, the production of Carbon Dioxide (Co2) can literally scrubs away some of the DMS compounds out of the fermenter via the blow-off valve. Conversely, bottom-fermenting (lager) yeasts preform much slower so more of the DMS created from DMSO during fermentation can remain in the beer because the Co2 production is not as energetic. This is yet another reason why pale lagers tend to have higher levels of DMS compared to other styles.

DMS is quite volatile and generally escapes the brew kettle as steam with no issue. Homebrewers will encounter this as a problem if they cover the pot of boiling wort or before it has cooled down. The condensation collected on the cover is full of DMS and simply falls back into the wort. Other major contributors are a the use of high-protein malt such as those made from 6-row barley, lack of a vigorous boil, not cooling down the wort quickly enough, or bacterial infections from bacteria such as Enterobacter.

Thanks for reading. I hope you enjoyed it and learned a thing or two. Class dismissed!


Gilbert “Charlie” Perez, Certified Cicerone®

"Beer: Quality, Safety and Nutritional Aspects" by by Paul S Hughes (Author), E Denise Baxter
"Malts and Malting" by D.E. Briggs

Wednesday, March 11, 2015

Doppelbock: Liquid Bread

Paulaner's Salvator Doppelbock

We've all heard beer referred to as “liquid bread” once or twice before. This analogy can fit many styles such as a Bavarian Weissbier or Belgian Quad. But, there is one beer style with greater affinity to "liquid bread" than any other: Doppelbock.

This beer style has a strong footing in Munich as a place of origin and monks are credited for its creation. Although that may be (somewhat) true, the actual origin story begins in northern Germany and the monks were from another neighboring country. Puzzling, to say the least. Let’s explore where this style came from and see if we can bring these two puzzle pieces together, shall we?

The story of Doppelbock begins in the city of Einbeck, located in northern Germany, in the mid 1500s. Einbeck was a thriving trade city and its specialty trade item was beer. This ale was made with lightly kilned barley & wheat and was generously hopped. Einbeck's beer made its way into many cities and that included Munich. The ruling family of Bavaria were particularly fond of the Einbeck brew. Plenty of money was being spent on this beer. Some brewmasters from Einbeck were brought to Munich in 1540 to teach the Munich brewers a thing or two.

In 1612, Duke Maximillian I(the first) convinced well-regarded Einbeck brewer Elias Pichler to move down to Munich and improve the Einbecker clones that were available. Pichler refined the brew to fit the parameters he had. This meant the Einbecker no longer contained wheat malt as this was reserved for special beers made for the royal family and employed the lagering tactics that were already well established by Munich brewers. The resulting beer was released at the famous Hofbräuhaus in 1614 and it was referred to as brewed the “Einbeck way.” We now have the birth of what eventually evolved to what we know as the traditional bock, or Bockbier. One puzzle piece down.

Now to discuss the he second puzzle piece: the monks. In 1627, they came marching in from Italy over the Alps and took home near Munich. Wait... Italy?! That's right, Italy. These monks were from the order of St. Francis of Paula. They wasted no time and began brewing shortly after arriving. These Franciscan monks established the Paulaner Brewery in 1634 and lay claim to the Doppelbock style. However, it went by another, more divine name. More on that later.

Before we move on, a quick note on how “Bockbier” got its name. It is widely believed and accepted that it is a manipulation of the word “Einbeck” in the Bavarian dialect. This would make the word sound like “Ayn pock” and eventually evolving to “ein bock” (one bock). “Bock” is also the word for “buck” or “goat” in German, explaining why so many versions of Bockbier display goats on their labels. That is quite ironic when you think about it. We consider the development of the Doppelbock style was a by-product of a testament of faith, yet the goat has some satanic symbolism.

(So metal! \m/)

Ahem... Moving on...

As with most devout Catholics, Lent was taken very seriously. During this time, the monks would not eat solid food and only liquid was allowed to be ingested. With Lent being the longest period of fasting for them, plenty of liquid would be consumed, most of which was the bockbier they were already experts at producing. Over time, and after receiving blessing from the Pope himself to consume such a wonderful beverage during Lent, the bockbiers got stronger. This was literally liquid bread for the Paulaner monks. It was only natural the beer was referred to as “Salvator,” as in “The Saviour,” for obvious reasons. In 1780, Paulaner was finally granted permission to brew commercially.

After the brewery came under Napoleon’s control in 1799, it lay in shambles until 1806 when it was rented a brewer by the name Franz Zacheri, ultimately purchasing it by 1813. Following a stretch of legal battles, in 1837 Zacheri finally was given permission by King Ludwig I(the first) to brew “Salvator” without obstruction. Clones were soon being produced by other breweries. The Schmederer brothers, Zacheri’s heirs, wisely trademarked “Salvator” in 1896. Paulaner is now the only one that can use the name “Salvator” for its Doppelbock. This is why we see other Doppelbocks with names such as Celebrator or Optimator keeping the “-ator” suffix since they cannot use the original name.

Ayinger's Celebrator

If you are not the fasting type, pair your Doppelbock with game meats such a venison or wild boar. Fruit sauces are great complements to both the meat and the sweet malt character of the beer. For an interesting combination, try Doppelbock with earthy, smoky Mexican dishes such as Oaxacan Mole. Don’t stop with the main course and try a caramel flan for dessert with a Ayiger's Celebrator (pictured above). If you are looking to pair with cheese, reach for Swiss Gruyère.

Doppelbocks are quite amazing and flavorful, but be cautious at that seemingly gentle touch. These beers are made for sippin’ as they span from about 7.0% to 10.0% ABV. Colors range from mahogany to deep garnet to almost black in some examples. Aromas are almost like rising bread in the oven. On the palate, you’ll get toasty and bready notes, slight caramel and toffee sweetness, finishing off with a moderate bitterness and a clean lager character. The darker versions have some chocolate flavors, too. Silky, full, and round on the tongue and finishes malty and clean. Serve in a traditional dimpled mug at 40°F, take your time, and enjoy what the monks gave us.


-Gilbert "Charlie" Perez, Certified Cicerone®

The German Beer Institute
The Brewmaster's Table: Discovering the Pleasures of Real Beer with Real Food by Garrett Oliver

Monday, February 9, 2015

*Presenting: Chocolate Milk*

Chocolate Milk by Tustin Brewing Company

What’s sweeter than a box of chocolates on Valentine's Day? A Sweet Stout made with real chocolate, of course! Our local Orange County Brew-Pub, Tustin Brewing Company has made something special for us. Behold this glass of creamy, chocolaty goodness (pictured above). You can almost hear her asking, “Will you be my Valentine?”

Chocolate Milk is Milk/Sweet Stout brewed with lactose sugar, cocoa nibs and vanilla beans. Milk/Sweet Stouts differ from Dry Stouts with their addition of lactose (milk) sugar. Lactose is disaccharide (a two-sugar-molecule carbohydrate) composed of a galactose sugar and a glucose sugar. The bond holding those two sugars together cannot be broken by typical beer yeast (unless additional external enzymes are added) and therefore is not fermented. In other words, the lactose sugar ends up in the finished beer contributing texture and sweetness.

Pours black in color with a rich, thick off-white head. Aromas of milk chocolate, whipped cream, vanilla and roasted cereal grains. The chocolate flavors from the cocoa nibs playfully dances with the milk sugar. Vanilla beans add an extra layer of lavishness to an already lush character, holding hands with the light roasted coffee notes. Fluffy texture with a silky mouthfeel. The finish is long and sweet, just as a kiss from your beloved should be. 

So, will you be her Valentine?

-Gilbert "Charlie" Perez, Certified Cicerone®

Wednesday, January 7, 2015

I Like Your Style

It’s no secret that I am a big fan of beers crafted to a defined style. Be it a classic style like a Helles or lesser known styles like an American Strong Pale Ale (no, it’s not an IPA). Within a short drive of either my residence or place of work, I feel lucky to have several breweries producing beers that are stylistically solid.

Although several may happen to be one-off's or special/seasonal releases, the fact that these breweries are making beers to style is worth mentioning. I appreciate and admire the hard-working brewers that created these amazing beverages.

Currently, at the time of this article’s publication, these are my current stand-outs…

Bottle Logic – Anaheim, CA
Heliosphere (Helles Lager)
Availability: Please check with the brewery

Like father, like son. Yup, that's my pops enjoying his beer. Recently made available on draught at the tasting room, this Helles Lager is amazing! Soft, subtle, and elegant. One of the most difficult styles to create because it is so gentle on the senses, Bottle Logic took the challenge and recreated this old-world beauty perfectly.

Bootlegger’s Brewery – Fullerton, CA
Rocco Red (American Amber/Red Ale)
Availability: Year Round

Bootlegger’s make some unique beers and plenty of one-off’s which are all great in their own right, but nothing stands out more than Rocco Red. This American Amber is layered with citrusy and piny hops on top of a sweet and bready malt backbone. If you’ve ever had their popular Knuckle Sandwich IIPA, it’s as if Rocco Red is a baby version of it. Not as aggressive, but quite flavorful. I like to call it a “juicy” beer.

Tustin Brewing Company – Tustin, CA
Galaxy Hopper (American Strong Pale Ale)
Availability: Specialty every few months

Tustin Brewing Company continues to impress me and I find it disheartening to know that many still do not consider them a great beer producer. Galaxy Hopper is a great example of how remarkable the beers are there. This American Strong Pale Ale showcases Galaxy Hops out of Australia. The best of both IPA and APA (American Pale Ale) -IPA aromatics of immature tropical fruits, an earthy white grape trait, and grassiness; Pale drinkability with a stiff, yet not too sweet, maltiness- all in one satisfying pint.

The Bruery – Placentia, CA
Saison Rue (Saison/Farmhouse Ale)
Availability: Year Round

What can be said about The Bruery that has not been mentioned before? They make some of the most unique and eccentric beers you will ever find in this ever-expanding beer world. Yet behind the veil of powerful spirit barrel-aged beers, puckering wild ales and sours, and unusual creations lays one of their original gems. Saison Rue is a near perfect example of the Saison style. Light tart and funkiness, pepper and spice flavors, refreshing bitterness, plenty of explosive carbonation, and dry. I’ve heard many suggest that this Saison might still fall short of being a proper representation of the style. In my opinion, it’s spot on!

Noble Ale Works – Anaheim, CA
English Bitters
Availability: Please check with the brewery

Noble has established itself as creating some the best IPA’s around with the likes of Tongue Tickles DIPA and I love It! IPA (both are award winners, mind you). However, they are the only brewery around me that constantly makes English style ales accurately. At the moment you can find a few English Bitters in their line-up with The River Thames being especially good.

TAPS Fish House & Brewery – Brea, CA
Dortmunder (Exportbier)
Availability: Please check with the brewery

TAPS has always been known for making solid stylistically accurate beers, and the Dortmunder is no exception. Basically a super-charged Helles, this golden bright beer has just enough malt character to draw you in while the pleasant bitterness keeps you coming back for another sip.

I will focus on other breweries that are not so near me at a later time. For now, check these out when you have a chance! Please visit the brewery’s social media outlets and/or websites for availability.


-Gilbert “Charlie” Perez, Certified Cicerone®

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