Monday, February 6, 2012

Brewing Basics - Ingredients 101

So, yesterday I wrote post describing the mash portion of brewing.  I'm going to start to take some steps backwards over the next few days to describe some more basic aspects of brewing.  Today, we're going to concentrate on the four main ingredients that make up beer.

Just a couple of terms that show up that might need some explanation:
  • Fermentables: Smaller chain of carbohydrates (sugars).  Can be metabolized by yeast
  • Final Gravity: Specific gravity after fermentation has completed.  Number is used to calculate alcohol content when original gravity is known.  Shows the amount of starches and sugars not fermented.  Should never be able to reach 1.0
  • Original Gravity: Specific Gravity measured right before pitching yeast.  This number tells us potential alcohol.  Used in conjunction with final gravity to figure out actual alcohol content.  
  • Pitch\Pitching: The act of pouring yeast into wort.
  • Specific Gravity: The 'weight' of water.  When compounds are dissolved in water, the specific gravity goes up.  Distilled water has a SG 1.0.  High SG means more fermentables and starches in solution.  Usually measured with a Hydrometer or Refractometer.
  • Starch: Long chains of carbohydrates.  Cannot be metabolized by yeast.  
  • Wort: Pre-fermented beer.  A sweet, sticky liquid of fermentable sugars made usually from barley, water and hops.  Once yeast is added, the wort starts to turn to beer.

Brewing - Malt, Water, Hops and Yeast
While other ingredients can be used, the main four ingredients in beer are Malt, Water, Hops and Yeast.

Malt is the term we use when talking about the cereal grains used as the primary source of fermentable sugar.   When we talk about malt, we are almost always talking about malted barley. Malted barley contains two things that are really useful to us.  Starches and Diastatic enzymes.  We want to feed these starches to our yeast, but they are too large.  So, we activate the diastatic enzymes that naturally occur in malted barley (by heating).  I've gone deeper into these enzymes in my post Brew Basics - Mash

So, what makes the barley 'malted'?  Germination.  After barley is harvested, the malter moistens the barley to allow it to begin it's germination.

The level of germination is chosen by the malter.  Different types of malts can be malted to different levels.  The further along the malting process the grain is allowed to germinate, the more modified the starches become.  This is at the malters discretion - the further along the malting process (or the more modified) the barley is allowed to become, the more amino acids are available to be used later by yeast. The downside is that as the grain becomes modified, the total yield (kernel weight) drops.  The degree of modification is important when brewing all grain. Under-modified malt will require a protein rest during the beginning of the mash to help break down remaining proteins into usable amino acids.

After germination is completed, the malter next dries the malt in a kiln.  The temperature of the malt is slowly raised as the barley dries.  At this point the malt is ready for use.  Some malt will be kilned at higher temps and longer times to darken the color and caramelize sugars, some will be roasted. These are what are referred to as 'specialty malts' that are used in low total percentage of grain to impart body, color and flavor.

There are also two main types of malt, but I won't dive into the big differences here.  Just be aware that there is 2-row and 6-row varieties of barley and you should be aware of which you are using.  In general 2-row has a higher grain-to-convertible sugars ratio, while 6-row has more husk and is less likely to stick during a sparge. The other main (and important) difference is enzymatic power, but I'll leave that for another post

Malt needs to be crushed prior to use.  The level of crushing is important, we want the internal grain nice and crushed, but we need the husk of grain to be intact. If the grain isn't crushed enough, we won't get good conversion from starch to sugar.  Too much and we get stuck sparges. The husk helps keep water flowing through our grains. Try to get grains that are freshly crushed as they will begin to oxidize once crushed.

Beginner and intermediate (and sometimes advanced) brewers often use malt extract in place of malted grain.  This is a great way to get into brewing, and great beer can be made using extracts.  Essentially malt extract is malt that has been soaked to convert sugars and washed.  The result is a sweet, sticky syrup or dried powder.  When we make all grain brews, we are making this extract ourselves.  There is a huge selection of extracts out there, so most brew styles are possible.  Avoid pre-hopped extracts.  Also, using extract and small amounts of grain can create great beer by doing a partial mash.

Water makes up a good 92% of beer.  The quality of water used is important for brewing.  Mineral content is an important factor, and certain brews call for specific mineral contents.  This will be covered in a post on it's own in the future, but know it's important.  Use a charcoal filter when using a municipal water source as chlorine can impart a flavor on your beer.

Hops haven't always been used in brewing beer.  Prior to hops many other herbs were used to add flavor characteristics (usually bittering) to beer.  But since they arrived on the scene, they pretty much have taken over the duties provided by other herbs.  Hops are an annual vine plant that produce small green leafy cones that are used in the production of beer.

What do hops do for beer, exactly?  Hops contain organic oils produced by the plants lupulin glands.  These are commonly reffered to as alpha and beta acids; adhumulone (alpha), cohumulon (alpha), lupulone(beta), colupulone (beta) and adlupulone (beta).

Each of these acids imparts some character on the beer when the hops are boiled in the wort.  Different hops will have different levels of each bittering compound, as well as other compounds that can have unique flavor profiles (such as the citrus aroma of cascade hops).  When purchasing hops, it's good to know the AAU % (Alpha-Acid Utilization) as well as the BAU% (Beta-Acid utilization).  This percentage gives us a barometer for figuring how much bitterness a hop will impart on our final product.  The length of time in the boil, and how vigorous the boil will affect the end product.

For hops that are used for bittering, an hour boil time is used, this will get our Alpha Acids.  I often do another addition that will last about 20 minutes.  These hops will add bittering through Alpha Acids, but will also impart some beta acids and floral aroma.  A final addition is usually done at the last five minutes for aroma.  Be aware of what the type of hop you are using is best used for.  Usually you can find a hop type described as bittering, aroma or both.  Use the appropriate type of hop for the appropriate use.

Hops come in a variety of forms.  Pellets, Plugs, Whole, and Oil (extract).  While it may seem that whole hops are the best, that is actually not the case.  More often than not, pellet or plug hops are going to be better.  They keep longer, and their oils don't become oxidized as quickly due to the lower surface-to-volume ratio.  Don't get me wrong, whole hops are great.  They are best used closer to harvest season if being used for bittering hops.  Older whole hops work great for aroma as the oxidation of the acids actually help mellow out the flavor in short boil times.  Avoid hop oils at all costs.  These oils only add harsh bittering effects that are unnatural to the palate. Also, hops add much more to beer than just those bittering oils.

So hops add flavor, that's it, right?  Wrong.  Hops also help stabilize the finished product.  Hops have mild antibiotic properties and stunts the growth of bacteria.  Hops act as a preservative that helps keep nasty wild organisms at bay, yet have no negative effect on brewers yeast.  This is where IPA's are said to get their name- large amounts of high AAU hops were used in brews that were to be on board the trip from England to India.  Extra hops were added to increase the life of the brew.  Hence, India Pale Ales are very hoppy.

In future posts I'll go over some more technical items regarding hops.  Just know that IBU is "international bittering units" and we can estimate this number, although it's probably not as accurate as breweries.  There is also the "HBU" scale which is "Homebrew Bittering Units", which we can accurately calculate to compare to other homebrewers.  To compare homebrew to brewery beer, we'll have to use an IBU estimation.

Yeast is a wonderful little single cell organism.  It lives everywhere, floating in the air, on your skin and on surfaces all around you.  Yeast loves sugar.  When yeast metabolize sugars, the main by-products are alcohol and CO2.  So, we utilize these little buggers to take our sugary, hopped and hopefully sterilized wort and turn it into a fizzy alcoholic beverage.

Man has been breeding brewers yeast for a long time.  There are two types of yeast usually used in the brewing process (although some odd ball brews call for unique types):

  1. Saccharomyces cerevisiae - Often referred to as "top fermenting" yeast, or ale yeast.  This is the most common yeast used with homebrewers as it ferments best at temperatures that don't require heating or refrigeration. If the beer is too cold, fermentation will be slow and will not complete.  Too hot and the yeast produces off flavors not desirable in most beer styles. Preferred temperature range is about 60-75 F, but depends on strain.  Used for ales and stouts.
  2. Saccharomyces uvarum -  Called "bottom fermenting" yeast or lagering yeast. This yeast type is common with commercial breweries that make light colored brews, though dark lagers do exist. Creates a more mellow flavored brew.  Fermentation takes longer as preferred fermentation temperature is 35F-55F.  Too hot will result in undesirable flavors.  Too cold and fermentation will stop.    

Within each type of yeast, there are different strains.  Each strain will have it's own characteristics during fermentation and in the resulting brew.  Flavor, fermentability, and body are all effected by the strain of yeast used, as well as the enviroment during fermentation.  Some important charecteristics of yeast are:

  1. Attenuation: Expressed as a percentage. The expected percentage of fermentable sugars that the yeast will metabolize.  Higher number results in a thinner, more alcoholic brew
  2. Flocculation: Usually express as low, medium, high or very high.  This is how well the yeast cells clump together and drop out of solution.  If flocculation happens early, attenuation will be lower, resulting in a malty, sweeter beer. Usually a high flocculation is preferred, and has been selected for by brewers.  More flocculation means easier transfers and clearer beer.  Common exception would be a Heffwiezn where flocculation is low
  3. Optimum Fermentation Temperature:  Expressed as a temperature range. The temperature range best suited for selected strain
  4. Alcohol Tolerence: Expressed as low, medium or high.  Alcohol will kill off the yeast when the ABV% gets to a certain level.  High tolerance yeasts (like high gravity yeasts) can get up close to 20% ABV 

There are other characteristics to look at when choosing a yeast strain.  Things like Diacetyl and Pentanedione production levels are useful for matching styles.  Luckily, most yeast strains are named after the beers they are designed to brew.

Yeast is commonly available in two forms - dried and liquid cultures.  Historically dried varieties have been lower quality.  Dry forms usually require re-hydration with sterile water prior to pitching.  Also, dry forms usually require creating a starter the day prior to brewing.  Dry cultures are also known to contain a small percentage of wild yeast.  Liquid yeast cultures are 100% pure, active, ready to pitch and work great.  I suggest using liquid yeast cultures over dried, or culture your own.  I have heard that many of the issues with dried cultures have been mediated by the yeast producers.  Still, if you can afford it, go with White Labs or Wyeast liquid cultures.

Finally, somethings about making yeast happy.  If you give your yeast the right environment, everything will be all good.  The keys are

  1. Pitch Temperature: If your wort temperature is too far from the yeast, you'll shock the yeast and it will not take off
  2. Oxygen:  When boiling the wort, pretty much all oxygen gets boiled out.  Yeast needs oxygen to store energy during it's first cycles in the wort. So we need to introduce oxygen after cooling the wort.   Vigorous sharking can achieve this.  Once yeast consumes all the oxygen, we do not want to introduce any more as the fermentation process is anaerobic (does not require oxygen).  The lack of remaining oxygen will help keep wild yeast and bacteria from colonizing your brew
  3. Available Amino Acids - Depending on the modification of the malt used, one may need to be  concerned getting the proper amino acids in the wort. 
  4. Available Sugars - Yeast needs sugars to eat, and we need to be sure we've converted enough starches into fermentables.
  5. Original Gravity: If the original gravity is too high or too low, your yeast will have problems.  This goes with fermentable sugars.  The needed OG range is defined by the yeast strain used.
  6. Give them the upper hand:  Keep things sanitary throughout the brew process, especially once boiling is finished.  The less wild yeast and bacteria that make it into your wort (it's impossible for us to be perfect) the better off your yeast is.  It's a competition for space, oxygen and sugars from the get go.  Make sure you are using fresh, active yeast cultures.

So that's the basics when it comes to ingredients.  Stay tuned for more basic brewing, as well as more on ingredients!

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