The Science of Beer: Yeast – Part 3

| November 1st, 2011 | No comments

Trying to explain yeast and what it does is much more difficult than trying to explain the other components of beer. Because of this, I have broken up my discussion of yeast into several posts. This is the third and last post in which I describe what affects fermentation.

As previously discussed, both species of beer yeast consume sugars and leave alcohol and carbon dioxide as waste products. I also mentioned previously that the process of fermentation was seen as a gift from god by early civilizations due to their lack of knowledge in unicellular microorganisms. Even today, with this understanding, it is also understood that brewers make wort, yeast make beer. Understanding what affects the yeast to do its job is what allows us today to successfully ferment at an expected level.

It is important to remember that yeast is a living organism, just like humans. While we have human civilizations living all across the world, there are certain conditions that must be met to allow us to survive and live in extreme conditions. If our body temperature gets too cold or too hot, we die. While humans can live and grow eating poor quality, empty calories, we can grow healthier and stronger with proper nutrition. It is also important that we are protected from bacteria and toxins which harm us, even one’s that our body produces.

Each strain of yeast has a temperature range in which it prefers to exist in. In general, lagers are known for their cold fermentation temperatures, in the 40’s-60’s (fahrenheit). Ales however, are known for their warmer temperature ranges, from the 60’s-70’s. The specific range that a given strain is meant to ferment at, ensures that the yeast remain healthy and actively consuming sugars. Should the temperature get too low, the yeast goes dormant and stops fermenting. Should the yeast get too hot, it will still ferment, however it will produce off-flavors that are not ideal to the flavor of the beer. To compare it in human terms, if you get too cold, you get hypothermia and go dormant (in a sense). Or compare doing housework inside your air-conditioned home as opposed to doing yard work in the middle of summer. You won’t die working outside, but you will smell a lot worse!

While yeast consumes sugar as it’s main diet, there are important other minerals that keep the yeast healthy enough to keep consuming sugar, much like us humans need adequate amounts of the appropriate vitamins and minerals in our diet. In the case of yeast, calcium, magnesium and zinc are important. Magnesium, for example, allows for better cellular metabolism, allowing the yeast to convert energy to continue consuming as well as reproduce. Some of these nutrients come from the malt and some come from the water. The water is an area that many people do no consider enough in beer making. Purified water is not ideal in brewing as it has been cleaned of all it’s minerals. Chlorinated water affects the yeasts ability to live and properly grow. Besides affecting the yeast, water chemistry also alters the mashes conversion of starch into sugar and the affect hops have in beer.

Lastly, while we may enjoy the alcohol and carbon dioxide in beer, remember that those are waste products to yeast. Imagine for a moment if you were trapped in a jail cell with no toilet. Yeah, exactly. Different yeast strains have difference tolerance levels for alcohol. If a particular strain doesn’t have a very high tolerance, than it won’t be ideal to use when making a barley wine. Instead of a high alcohol beer, the yeast will die off as the alcohol content rises leaving you a beer that has less alcohol and tastes rather sweet. Even commercial breweries like Dogfish Head have difficulty when making their 20% 120 Minute IPA. On the TV show Brewmasters, Dogfish Head was forced to dump an entire batch due to the yeast not finishing the fermentation.

Whether you are brewing a high alcohol beer, a lower session-style beer, it is important to consider all of these facts when it comes to brewing. Use a strain that’s best suited for the style being made. Ensure that you have the means to keep the yeast at the correct temperature specified for a given strain. Most people make a yeast starter, which is essentially a small batch of beer made for the same purpose that sports teams have pre-season games. It gets the yeast started fermenting and reproducing so it can be strong and ready for the main event. The higher the alcohol the beer will be, the more yeast will need to used. Consider trying to build a house by yourself as opposed to entire team of people. Sure you might be able to finish the house alone, but it’s going to take much longer and likely be of a lesser quality than one built by 10 people.

There is still much more to be said about yeast and it’s affects on beer making. As I mentioned a few times, while there are two main species of yeast, there are over a hundred strains within those two species, each with different levels of attenuation, flocculation and alcohol tolerance. All yeast give off different levels of the off-flavors that are a part of normal fermentation. In some strains of yeast it may be more of a particular flavor, that is best suited for one style of beer, but not another. In addition to these two species of yeast, there are other wild yeast strains that are used for the affects that they have on beer. For example the brettanomyces strains can consume even more polysaccharides than ale or lager yeast can, and it also produces some tart flavors. Some brewers will add this after completing a fermentation with an ale yeast, or some may completely ferment a beer using only this yeast. There are endless possibilities. To be a great brewer, you must truly understand how to use yeast.

The Science of Beer: Yeast – Part 2

| October 27th, 2011 | No comments

Trying to explain yeast and what it does is much more difficult than trying to explain the other components of beer. Because of this, I have broken up my discussion of yeast into several posts. This is the second post in which I describe what yeast does.

In the first post on yeast I described the two types of yeast, ale and lager yeast. To explain the differences, I first want to explain the purpose of yeast in the process of making beer, or any other alcohol for that matter.

Ethanol Fermentation: Ethanol is the type of alcohol found in alcoholic beverages. Yeast produce alcohol and carbon dioxide as a waste product of consuming sugar. Chemically, one part glucose (a simple sugar molecule) is broken up and converted into two parts ethanol and two parts carbon dioxide. The balanced chemical equation looks like this:

C6H12O6 —> 2C2H5OH + 2CO2

In the case of bread making, the carbon dioxide is what causes the dough to rise and the ethanol gets evaporated when baked. In beer making, the ethanol and carbon dioxide stay in the beer with the carbon dioxide being the source of carbonation.

While the above equation shows the fermentation process of a simple glucose molecule, not all sugars are that simple. The above glucose molecule is called a monosaccharide. More complex sugars form compounds called disaccharides or trisaccharides. Whereas all the monosaccharides and disaccharides will be fermented, the trisaccharides and larger polysaccharides are another story.

Prior to the beginning of fermentation, brewers measure the density of the wort. It’s the sugar within the liquid that causes the wort to be denser than pure water. As the yeast consume the sugars, the density drops, though never all the way down since the complex polysaccharides are more than the yeast can handle. The amount that a strain of yeast can decrease the density of the wort is called attenuation. Lager yeast typically has a higher attenuation than ale yeast, meaning that more of the larger polysaccharides get consumed into alcohol and carbon dioxide. The result of this is that lagers are known for their dry, crisp taste and feel whereas ales leave more residual sugar behind giving them a bit more of a complex taste that is typically described as fruity.

As the yeast is actively consuming sugar, they are simultaneously multiplying as well. The amount of yeast within the vessel increases. When using ale yeast strains, the yeast all rise to the top of the wort. Lager yeast, on the other hand, sink to the bottom of the vessel. For this reason, ale yeast is often called top fermenting yeast and lager yeast is called bottom fermenting yeast.

Once fermentation is complete, any yeast suspended in the beer clumps together and sinks to the bottom as it becomes dormant. The amount that the yeast will clump together and sink is called flocculation. Many beers have a relatively high flocculation rate however the yeast strains used in wheat beers have a low flocculation rate, which is why hefeweizens are cloudy looking.

This was a long article containing lots of big words and chemistry. The next yeast article will focus on the factors that affect fermentation, primarily temperature, which is the last main difference between ale and lager yeasts.

The Science of Beer: Yeast – Part 1

| October 26th, 2011 | No comments

Trying to explain yeast and what it does is much more difficult than trying to explain the other components of beer. Because of this, I have broken up my discussion of yeast into several posts. This is the first post in which I describe what yeast is.

Yeast is the unsung hero in beer making. An old brewing saying goes: “Brewers make wort, but yeast makes beer.” This quote stems from the fact that yeast has the most important job and without it, there is no fermentation and no alcohol. Prior to the discovery of what yeast is, ancient civilizations found the fermentation process to be a gift from the gods since the process was seemingly out of their control. You can’t force the yeast to ferment, it is a living organism and can at times be difficult to deal with.

So what is yeast? Yeast is a unicellular microorganism in the fungus family. While there are 1,500 different species of yeast, brewers are concerned only with 2: Saccharomyces cerevisiae and Saccharomyces pastorianus. They are also known by their easier to pronounce nicknames: ale yeast and lager yeast.

All beers are either an ale or a lager. The differentiating factor between the two is determined by what species of yeast is used, saccharomyces cerevisiae being the ale yeast and saccharomyces pastorianus being the lager yeast. Within these two species are many strains of yeast.

To understand what the differences are between these two species of yeast are, it is best to understand what it is that yeast does to wort and what affects its ability to do so. In the next article, I’ll detail the purpose of yeast.

The Science Of Beer: Hops

| October 23rd, 2011 | No comments

This article was previously posted on the Examiner as part of my Science of Beer series.

This is part two of a multi-part article on the science behind making beer.

Beer is composed of only four ingredients: water, barley, hops, and yeast. Hops are the one ingredient that most people know the least of. Why are they added to beer? What is their purpose?

Hop plants are part of the hemp family Cannabinaceae. The Cannabinaceae family then breaks down into two genera: Cannabis, from which hemp fibers and marijuana come from, and Humulus. The Humulus genus is where hops come from. The Humulus genus breaks down into three different species, two of which are different Asian hop varieties and then there is Humulus lupulus, which containes the European and American hop varieties that are typically used in beer production.

Hop plants grow as a bine, similar to a vine however its method of climbing and attaching itself is different. The female hop plants create a flower cluster called a seed cone. This cone is similar in shape and purpose to other plant cones, like pine cones. However hop cones are green, soft and very leafy as opposed to the rigidness of the pine cone. These cones are the parts of the plant that are plucked and used in beer.

When brewing beer, malted barley is mashed in hot water to extract the sugars. The sugar water, called wort, is then drained where it moves to the next part of the process, the boil. Wort is boiled for about an hour for the purpose of both sanitizing it, and to boil off some of the water leaving the sugar concentration higher. It is during this boil that hops are added as well.

Hops serve three different purposes in beer: adding bitterness to balance out the sweetness in the wort, adding a pleasant aroma to the beer, and to prevent spoilage.

Hops contain an internal resin that contains both alpha and beta acids. Alpha acids contribute bitterness and beta acids contribute aroma. Thus the varieties of hops that contain high levels of alpha acids are called bittering hops and the varieties that contain higher levels of beta acids are called aroma hops. Bittering hops are added earlier in the boil because the alpha acids need heat to break down and be released. The earlier in the boil they are added, the more heat is added and thus the higher level of bitterness is added to the wort. Beta acids, on the otherhand, do not need heat to be released so aroma hops are added at the very end of the boil or even during the fermentation process. Adding hops during fermentation is called dry-hopping and is done regularly in many ale styles. Adding aroma hops during the end of the boil or during fermentation adds only more hop aroma without adding additional bitterness.

Lastly, hops help to prevent spoilage in beer. The alpha acids have a natural antibiotic and antibacterial quality to them. Prior to beer production, hops were used as a form of medicine because of these qualities. The antibacterialness of hops was realized when Britian began trading with India. Beer was produced and brought aboard ships for the sailers to drink during the voyage to India. By the end of the trip, most of the beer had been spoiled. However the beers that had hops used instead of other bittering herbs were not spoiled since any bacteria it came in contact with were killed by the alpha acids in the hops. Thus more hops were added to beer to ensure it would would not spoil during the trip to India; and with that the IPA, or India Pale Ale style was born!

Once the boil is complete and hops are added, the wort is then chilled and yeast is added to ferment. Yeast and fermentation will be discussed in a future article.

The Science of Beer: Malt

| October 23rd, 2011 | No comments

This article was previously posted on the Examiner as part of my Science of Beer series.

This is part one of what will become a multi-article study into the science behind making beer.

Apart from water, barley is the main ingredient in beer. The barley is what determines the color and primary taste as well as dictates how much alcohol will be present within the beer in the end.

To create malt, barley grains combine with just enough water that they begin to germinate as though they are being planted into the ground. When barley begins to germinate, it releases an enzyme called amylase. The purpose of amylase is to break down the starches within the barley into smaller carbohydrates that can be used as an energy source for the sprouting plantlet. Human saliva also contains amylase to begin breaking down the food we eat before entering the stomach. Without amylase to break down the carbohydrates, sugars cannot be extracted from the barley to later be converted into alcohol.

In order to stop the germination process, heat is applied to the barley to completely dry it out. This process can be done in a number of different ways and is what differentiates one type of malt from another. Either the heat can be slowly and gradually added to the malt, leaving the color pale with no noticeable roasted characteristics, or it can be left heated long enough that the barley darkens and turns various shades of brown or even becomes blackened. Another common method is to add a very high heat very quickly to caramelize the outer edge into a reddish color. Depending on the combination of malts used in a brewing recipe, the flavor and color of the beer can be determined.

Breweries typically purchase barley already malted and will then begin the first step of creating beer, mashing. Mashing involves milling the grain and letting it soak in hot water, typically around 150 degrees Fahrenheit, for about an hour. The ultimate goal in mashing is to release the sugars from the malt into the water creating a sweet liquid called wort. Wort is simply unfermented beer. Later when yeast is added to the wort, sugars are converted in alcohol and thus wort becomes beer.

The amount of malt used in a beer will vary from one recipe to the next. Since the purpose of malt is to release sugars that later get converted into alcohol, you would typically add more malt if you want more sugars, and in turn, more alcohol. For 5% alcohol by volume beer, you would use about one pound of malt for four pints. If this beer were to be one 15 gallon keg of beer, about 30 pounds of barley would need to be mashed.

Once the malt is mashed, the wort is drained from the grains and moved on to be boiled and have the hops added. This will be discussed further in a future article on hops.

Types of beers

| January 23rd, 2011 | No comments

Last night at the bar it was mentioned that many people don’t realize how many different types of beer there are. I thought I’d give a brief overview:
To simplify things, there are primarily two different types of beer: Ales and Lagers. At the most basic level, the difference between the two is the type of yeast used to ferment the beer. Lager yeast ferments at colder temperatures and ale yeast ferments at higher temperatures. Lagers and ales break down even further into different types of beers.
This is the most prominent type of beer simply because this is the kind of beer that Budweiser, Miller and Coors are. Other common lagers are the popular Mexican beers: Corona, Dos Equis, Pacifico etc. These beers are best served at ice cold temperature and as such have a lighter more “refreshing” taste. Or as I think of it, kind of watered down taste. The predominant lager beers are American lagers and pilsners. Again simply because this is what the big 3 companies make. The good lagers are the kind that Germany makes: marzen, bock and dunkel. These beers are typically darker colored and have a much more complex taste than the common American lager. However these beers are still lighter in flavor and feel than most ales and don’t have a predominant hop taste.
These are the more complex beers with a wider range of style. These range from the wheaty Hefeweizen and white beers (like Pyramid Hefeweizen or Blue Moon) to the dark stouts (like Guinness). Pale ales and India pale ales sit in the middle of the spectrum. IPAs and pale ales are recognized by their hoppy bite. Ales are the predominant type of beer everywhere except North America. I couldn’t begin to try and explain every type of ale because there is just so many kinds!
Ales are by far, my favorite kind of beer just because there are so many different kinds. The few beers that ive blogged about here have all been ales. I’ll try to continue to review different beers and use that opportunity to describe the beer type and it’s common characteristics.

How To Make “Big Beer”

| January 13th, 2011 | No comments

The term “big beer” typically refers to beers that have a higher gravity, or alcohol content, than most other beers. I will soon be reviewing Dogfish Head’s “World Wide Stout” and I thought I’d take the time to explain what it is that makes these beers so unique.

For reference, most beer ranges from 4-6% alcohol. Usually, the higher stuff, IPA’s and Belgian ales, will range from 7-12% alcohol. The big beers will range from 12-20% alcohol. Any higher is practically impossible using traditional methods. World Wide Stout is 18% alcohol.

Below is a very brief overview of how beer is made:

– Malted barley is boiled in water. This releases, among other things, sugar into the water creating what is called “wort.”

– Because of the sweetness of the wort, hops are added to tone down the sweetness and add some bitterness and flavor. Hops are responsible for the “bite” that some beers have.

– Finally, the most important ingredient, yeast. Yeast determines whether a beer is a lager or an ale and, for purposes of this discussion, how much alcohol is in a beer.

Yeast is a living organism and, much like you and I, consume and create waste. The waste that yeast expels however, unlike you and I, is actually useful. Yeast consumes the sugar in the wort and expels CO2 and ethanol (alcohol) in it’s place. Thus, a carbonated, alcoholic drink! Once the yeast is added, it’s left to do it’s thing for about 2 weeks on average.

So how do you increase the alcohol content of a beer? The obvious answer is add more sugar and yeast. So, more malts = more sugar +  more hops to balance out the sugars + more yeast to eat up all the sugar = more alcohol!

So how much more malts and hops are needed for the big beers? Dogfish Head’s 120 Minute IPA has the highest alcohol content of any other IPA at 18%. Dogfish has explained that for them to brew 120 Minute, they need “over 7 times the volume of malt and over 30 times the volume of hops than your average light lager.” Not only that, it is also “aged over 5 times longer than the average ale.”

To make these beers, it’s not just as simple as adding more ingredients either. It’s also very difficult to do so as well. Remember, ethanol is a waste product of yeast. Much like how neither you or I could live in a house of our own waste, ethanol is toxic to yeast. Meaning in high alcohol environments, yeast dies off rather than eating more sugar and creating more alcohol. This is why creating a beer thats over 20% alcohol is nearly impossible using traditional methods. There has to be a balance between the sugar, yeast, and alcohol.

More ingredients, higher difficulty level and longer time to complete the fermentation period mean that these are very expensive beers to make. For Dogfish Head to produce 120 Minute IPA it costs them half a million dollars! It is likely the same cost for their other big beers. For the single 12 oz bottle of World Wide Stout, Ho Foods (Whole Foods) charged me $10. Compare that to the usual $10-12 it’s costs for any other micro-brewed six pack.

That is why the big beers are so rare, expensive and unique. Few breweries can afford to take the risk of producing something of this caliber. Last year, Dogfish Head had to dump their productions of 2 of their big beers due to the lack of continued fermentation. This cost the company almost a million dollars in lost profits.

I’ve never personally tried any of Dogfish Heads big beers so I am very excited to try out the World Wide Stout that I purchased!

Alcohol And Your Health

| January 8th, 2011 | No comments


I read several articles today relating alcohol to health: – Beer contains nutrients that make bones stronger and it is suggested that moderate drinking will reduce the risk of osteoporosis and other diseases – Red wine prevents cavities.

The above articles are related to the chemistry of alcohol. The below articles are a bit more vague: – People who drink more, are more likely to exercise longer and more intensely. – Women were monitored for 13 years. The non drinkers gained the most weight, the moderate drinkers gained the least weight

These articles, on their own don’t offer much of an answer. But then there’s this article: – People with higher intelligence drink more than those with a lower intelligence. 

I think that because those that drink typically have a higher intelligence, they are also more likely to have the knowledge to want to keep themselves healthy and in shape. But then the real question is, why is there a correlation between intelligence and alcohol consumption? 

“An intelligent man is sometimes forced to be drunk to spend time with fools.”
—Ernest Hemingway 

Or, it could just be that those with intelligence have a taste for the finer things in life, like a glass of red wine or a pint of craft beer!