Beer 101: Fermentation

I know I’m skipping around a little bit (after all, there are several steps that come before fermentation in the brewing process), but it’s kind of because fermentation is my favorite. After all, it’s responsible for some of the best-tasting things in life: beer, wine, cheese, and chocolate to name a few. It’s a  crucial step, chemically, as it creates the alcohol that we all enjoy (presumably you enjoy alcohol – you are on a beer blog).

Beer 101 Fermentation

Photo from uncommoncaribbean.com

The Basics

Fermentation, at its very simplest, is the chemical process by which yeast converts the malts‘ sugar (glucose) into ethyl alcohol and C02 gas – this yields both the alcohol content and the carbonation that make beer, well, beer.

 

We’ve explained a little bit that temperature is important for this process, depending on the kind of yeast being used and the beer style that is being made – an ale needs to be kept at 68 degrees Fahrenheit for about two weeks and a lager needs to stay at 48 Fahrenheit for about six weeks. This process creates a lot of heat as a byproduct and so the container in which the fermentation happens generally needs to be carefully cooled.

To avoid contamination by stray, wild yeasts, fermentation tanks are generally sealed off from the air with only a small vent for the CO2 buildup to exit the tank.

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The Details

I’m no chemist, so I’m not going to go into that level of detail! However, there are some interesting things that go on during the fermentation process that need to be addressed. Yeast basically works in two stages during fermentation: the primary stage and the anaerobic phase.

In the primary stage, the yeast consumes all of the oxygen in the cooled and aerated wort mixture. During this stage, sterols (which are a type of cholesterol that make up part of the yeast’s cell wall) are produced. These sterols allow the cell wall to be permeable so sugar and alcohol can move in and out of the yeast cells; they also allow the yeast to survive in an increasingly alcoholic environment

Once that oxygen is gone, the yeast moves into the anaerobic phase, during which most of the sugars in the wort are turned into ethanol and CO2. Additionally, flavor compounds like esters (fruity notes) , diacetyl/ketones (butterscotch notes), fusel alcohols (responsible for a hot or burning sensation), and other chemicals that can make or break the flavor of a final beer.

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Other Uses for Fermentation

Cacao seeds must be fermented (often out in the sun, on large tarps) before being dried and then roasted in order to create the chocolate flavor that we know.

In winemaking, fermentation begins naturally when the skin of grapes is broken and the wild yeast on them and in the air begin the primary fermentation stage, turning sugar in to alcohol.

Fermentation happens several times along the journey from milk to cheese, developing flavors and even creating the famous holes in Swiss cheese.

The workhhorse of bread making, yeast-based fermentation creates the textures, flavors, and rise in bread doughs.

Pickles, sauerkraut, kimchee, and more can be fermented during the pickling process, allowing natural bacteria to create acids needed to preserve foods.

 

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Beer 101: Yeast

Yeast is one of the four main ingredients that go into making beer, beautiful beer. The others are hops, malt, and water (this post is next in my Beer 101 series). There are certainly other ingredients that can be added to the beer process, but these four are the core pillars that hold up the whole thing.

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These itty bitty single-celled microrganisms are technically classified as a fungi. They reproduce by an asymmetric division process called budding. Their job is to convert fermentable sugars from the malt into alcohol and other byproducts. There are hundreds of varieties and strains of yeast out there, some of which are commonly used to brew beer.

Yeasts are generally put into one of two categories: ale yeast (top fermenting) or lager yeast (bottom fermenting), depending on how they behave during the fermentation process. There’s also a nebulous third category, known as spontaneously fermenting yeasts, which result when beer is left exposed to the air and is literally infected with wild yeast strains as they wander by – this is what creates sour beers.

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Ale yeasts generally sit on top of the beer-to-be, fermenting away between temperatures of 10° to 25°C (though some yeasts won’t activate below 12°C). These guys rise up to the surface, forming a thick raft of a head as they bubble away. These yeasts tend to yield beers higher in esters, which are the chemicals that give fruits their characteristic flavors. In the case of Hefe Weizen beers, the yeast produces the ester iso-amyl acetate, the same one that is found in bananas. Other esters include ethyl acetate, which can be flowery, and ethyl caproate, which is kind of wine-like and fruity. Top-fermenting yeasts are used for brewing ales, porters, stouts, Kölsch, Altbier, and wheat beers.

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Lager yeasts create much less of a head and tend to settle at the bottom of the tank as fermentation nears completion. They grow less rapidly than the ale yeasts and don’t create that layer of thick foam on top of the beer. These yeasts work at lower temperatures, around 7° to 15°C.

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In addition to making beer the alcoholic beverage that we so enjoy, it also has a large impact on the flavor of the final beer. The flavor and aroma of beer is complex and is influenced by  many factors, including malt, hops, and the yeast strain. The synthesis of yeast creates many byproducts, including ethanol (alcohol), CO2 (carbon dioxide), and also some flavor compounds like clove, butterscotch, and green apple.

Yeast may be tiny and invisible to the naked eye, but it plays a huge role in making beer what it is.

 

 

Beer 101: Malt

This is the second installment of Beer 101 (the first being Hops) and we’re talking about another crucial ingredient: Malt. Malt is kind of a vague umbrella term that covers a number of grains added to beer for body and flavor as well as to create the chemical reactions needed for the fermentation process.

So what is malt? Simply, it’s a grain that has been through the malting process. When it comes to beer, it is most commonly barley that is used. This “malting” means that the grains are wetted with water and allowed to germinate or bloom. This generates enzymes that break down sugar into simple sugar, which is used in the fermentation process (and eventually plays a role when the malt is put into the mash process).

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Germination is a determined sort of process and must be stopped by adding the malt to a kiln. Heating these grains up also toasts them slightly and creates flavors in the dried and cured malt. The malt can now be used as is, mostly in lighter-flavored beers like pilsners. The grain can also be roasted further, creating deeper, richer flavors, and turning it into specialty malts that are used to change the sweetness, color, body, and flavor of the final beer product.

Malt is then subjected to the mashing process, in which the malts are soaked in hot water. This process creates simple sugars like glucose, which are fermentable and create the alcohol in finished beer. It also creates unfermentable sugars like dextrine and melanoidins that flavor the beer. More interesting still, the mashing creates complex compounds that create nutty, roasted, toasted, and bitter flavors.

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While roasting does create flavor, it also destroys the starches that create fermentable sugars (the ones that become alcohol). Lightly roasted malts impart flavors like bread, biscuit, graham cracker, and some nuttiness. Medium malts will give flavors of molasses, toffee, brown sugar, or even burnt sugar. Dark roasted malts create coffee, chocolate, and some deep fruit flavors. While barley is usually the brewer’s choice of grain for malting, wheat, oat, rice, and rye can also be used. Each of these grains would create a unique flavor profile.

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Base malts, generally those grains which have only been very lightly toasted, can make up up to 100% of the malts used in a beer. This results in a light beer with a crisp, dry finish. Darker malts, which have been roasted for longer and at different temperatures, are called speciality malts. Crystal or caramel malts are the next rung up in the ladder, producing amber color and flavors like toffee and caramel. Toasted malts are next and bring, well, toasted flavors like bread and biscuit. Roasted malts are usually pretty dark and bring roasted, coffee, and chocolate flavors to the table.

Malts are a huge and widely varied ingredient in beer making. The kilning process can generate an incredible selection of colors and flavors from the basic grains that started out so plain. Beer is an art and a science, both at the same time. I suppose that all food and drink creation really is. Experimentation and research work together to help the brewer choose which malts and in what ratios to use them. The results of these experiments, it turns out, tend to be delicious and good for enjoying in a tall pint glass.

Beer 101: Hops

You’re going to hear me talk about a hops a lot in this blog. Partly because they’re a huge part of what makes beer, well… beer. But also because my tastes run toward IPAs right now and those tend to be hoppy by nature.

This first post in my Beer 101 series will take a look at what hops are, how they are used in the brewing process, and the effects they have on the flavor profile of a finished beer.

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Hops are one of the key pieces of beer brewing (the others being water, grains, and yeast) and are the flower of the female hops plant, Humulus lupus, which is related to the hemp family. Hops contain an essential oil that the tongue reads as being very bitter. This dry, bitterness can be used to balance out the sweetness that the malts in a beer create. Hops also act as a natural preservative and have antibacterial properties.

A beer made without hops can exist, but it would be cloyingly sweet and very one-note. Hops aren’t the only plant that can be used to flavor beer. Spruce, herbs, flowers and more can be used. But hops are the go-to if the brewer isn’t making anything too out there.

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Let us turn our attention to this helpful graphic! The parts of the hops flower are easily labelled here. The entire flower can be used as-is, though compressed pellets of hops exist and are used by some brewers to flavor their beer. Deep inside of these buds are little packets of resins and oils that lend that bitter flavor profile to beer.

Hops are actually kind of a newcomer in beer brewing, when you consider that beer has been made for around 9,000 years. Beer’s origins are more closely linked to the malt ingredients in the brew and were made with grains and yeast from bread making in its early years. Hops were first used in beer around 822 AD and even then, somewhat sparsely. Before the use of hops, beers were flavored and preserved using a mix of spices and fruits called “gruit” or “grut.”It’s really only in the last 200 years that hops have had their day.

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There are several steps in the brewing of beer and hops can be added into the mix at almost any of them, depending on what the flavor profile goal is. Hops can be added before or during the first boil of the beer, in the mash tun, or during tank or barrel conditioning. Each of these choices will affect the final beer product’s taste.

There are also a wide variety of hops available, each bringing its own unique flavor profile to the mix. There are several Continental or Noble Hops, which originated in central Europe and have a mild bitterness and spicy/floral aromas: Hallertau, Tettnang, Spalt, and Czech Saaz. English hops, which are herbal, grassy, and fruity: East Kent Goldings, Fuggle, Challenger, Target, and Progress. Bright, fruity, and resinous American hops: Cascade, Centennial, Chinook, Willamette, and Amarillo.

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Photo from menuinprogress.com

The above list is far from comprehensive. There are a large number of hops that I didn’t name in those little lists, many of which are American hops that are being hybridized, grown, studied, and analyzed even by Universities. There have been exciting new hops making their way into the market over the last decade.

So while hops aren’t truly necessary to brewing beer, what we think of as modern beer just wouldn’t be the same without them. So the next time you hear some know-it-all like me talking about “hoppiness” or “a hop-forward beer,” you can understand that I’m trying to find a way to describe the aromatic and bitter flavor profile that these plants bring to beer.