Cheers! : Science at Work in Beer Brewing

Beer has been a beverage with a history that dates back to the 6th millennium BC. Beer finds its place in most ancient civilizations and has become a part of popular culture  – one that brings together people over a pint. Until about 2 centuries back, there was no set process for beer brewing and it was more of trial and error method. Things changed as the science of the process improved and beer brewing became an industry. 

While the bubbly beer traverses down the throat, does it occur to you that there is a lot of art and science that goes into making it the pleasant drink it is?

Read on for more! Cheers!

by Swati Sinha
1 year, 5 months ago
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Beer is judged on four parameters- taste, aroma, colour and density. And the ingredients that create this wondrous golden concoction include barley, hops, yeast and water. 

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Amongst the various cereal grains such as Rice, Corn, Wheat, Oats etc., Barley stands out for the desirable flavor that it renders to the malt. Barley is the ideal choice for brewing, as its enzyme system converts starch to sugars quickly. Barley’s chemical composition is such that it has a balanced amount of starch and proteins, without excessive oils or other undesirable flavor-rendering substances. Barley’s husk is also rigid and does not get broken during harvesting or malting, thus conserving its taste while being processed. 

There are three major types of barley differentiated by the number of kernels on the
plant stem. Barley seeds grow in two, four and six rows along the central stem. European brewers traditionally prefer the two-row barley because its malt is best and has a higher starch/husk ratio than four or six-row barley. Brewers in the US traditionally prefer six-row barley because it can be grown economically and has a higher concentration of enzymes that help in better fermentation.

An important aspect of barley is its protein content which contributes to the taste as also foam formation of the finished product. The protein level in the barley depends on the agricultural conditions for growth of barley such as soil conditions, fertilization and moisture levels to which the crop has been subjected.
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Hops are a flowering vine belonging to the Cannabis family, whose flowers are used as a preservative and for their essential oils that add flavor and aroma. Each variety of hops has its own distinct flavor/aroma profiles. The cultivation of hops is known to have started between 5th and 7th century in Europe. During the medieval times, various additives were added to beer to develop a different flavor. Hops became an accepted ingredient as their preservative qualities were understood.  

Hops require specific growth conditions such as generous soil moisture, and a warm, dry climate. Hops are generally classified into two types – aromatic and bitter. Though there are more than 100 varieties of hops grown worldwide, about 50 varieties are used in beer-making. They can be categorized into 6 major types – Saaz, Hallertau, Fuggle, Goldings, Brewers Gold and Others. The Lupulin glands present in hops contain alpha acid which determine the bitterness, flavor and consistency of the beer. All hops contain alpha acids. However,the quantity of alpha acids is below the norm in aroma hops.
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Brewer's yeast is made from a unicellular fungus of the species Saccharomyces. This type of yeast reproduces by a vegetative process called budding when an exact replica of the unicellular organism is formed.

The yeast produced during brewing is mainly classified into two types: top-fermenting a.k.a. ale yeast- which ferments and settles on the froth formed in the top during the fermentation process; bottom-fermenting a.k.a. lagers yeast- which settles at the bottom of the vessel.  
Lager yeast is used at lower temperatures and grows slower than ale yeast. As a result, they produce less surface foam and typically settle to the bottom of the fermenter. Pilsner beer is amongst the common lager beers produced. With increased usage of bio-technology, many of the original top fermenting strains have been modified to be bottom fermenters.

Brewer's yeast is a rich source of minerals -- particularly chromium, an essential trace mineral that helps the body maintain normal blood sugar levels; selenium; protein; and
the B-complex vitamins. Brewer's yeast ferments carbohydrates, forming a froth of carbon dioxide which can ferment grains into beer. It grows readily as long as conditions are warm and moist, emitting carbon dioxide and alcohol as by-products of metabolism, a process called fermentation. Brewer's yeast is easily available in a dried, 'ready-to-be activated' form, for brewing beer.
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Approximately 92% of beer consists of water, which makes it necessary that the brewery has abundant access to clean, colourless and odourless water. The water then needs to be filtered to obtain the optimum mineral composition. There are different types of filtration employed for this purpose- carbon filtration removes chlorine and organic residue; ion-exchange and line treatment method result in softer water; and reverse osmosis removes unwanted minerals & contaminants. 



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These are used as a supplement to the barley malt in order to give a lighter color
and density to the finished product. The role of adjuncts is to enhance one or another characteristic that the four essential ingredients contribute to beer. Adjuncts which may be used are grains, chocolate, coffee, fruits and vegetables, additional sugar, herbs and spices. Corn grits and milled rice are often used as adjuncts in the brewing process. Corn-based adjuncts are used by most American breweries. It is available in various forms such as grits, flakes, refined starch and dextrose. Rice is high in starch content and gives the beer a dry flavor when used as an adjunct.

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The chain of events in brewing starts with the malting process. This is a preparatory phase when the barley is processed to make it ready for the advanced porcessing it has to undergo at the brewery. This process can be broken down into a series of steps which can be summarized as follows:

Barley cleaning and grading: All undesirable materials need to be removed from barley and it needs to be sorted into grains of uniform size. Also, each variety of barley needs to be malted separately as various factors have varying impacts on the malting process.

Steeping: This process is required to initiate germination of the grains and can be
considered as one of the most important steps in the brewing process. Any mistakes during this process may not be undone in any of the later steps. Barley which contains about 12% water is immersed in water at temperature of 55-62 degree Fahrenheit to increase its moisture content to 45%. To further promote germination, barley is exposed to alternate periods of immersion in water and resting out in the air.

Germination: Following the steeping process, the barley is transferred to a germination compartment. The kernels develop small roots and the young barley plant inside begins to grow. The enzyme system in the kernel thus gets activated- this is crucial for the brewing process. The barley is carefully exposed to controlled temperature, moisture and oxygen conditions until it is fully modified into the beginnings of a plant.

Kilning: This process is meant to gently slow down the enzymatic activity and reduce the moisture content to a level suitable for storage and milling (4%). This step ends with the cooling and cleaning of malt over a cleaner that removes the roots to get rid of the grassy or sprout flavors in the malt, so it can then develop a nutty or roasted taste. The time and temperature of kilning determine the color of the malt.

The malted grain has a starch conversion system in place and the remaining starch gets utilized for production of wort in the brewery. The overall malting process takes about 8-9 days post which the malt is transported to the brewery for the beer making process.

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The malt mill separates the husk from the kernel and then grinds the kernel. the process begins with cracking the grain so that it can easily absorb the water which will be added to the malt in the next step- mashing. The milling process needs to be delicately balanced as the starchy interior of the kernels should get finely ground. This is so that the conversion to sugar is easy while keeping the hull intact- as it acts as a natural filter in the later processing. 

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A large quantity of heated, purified water is added to the malt. The malt enzymes which had been activated during malting, restart the process of breakdown of starch to sugar. The other set of enzymes act on the complex proteins to convert them into simple amino acids. The time and temperature schedules are critical in determining the composition of the wort sugars and impact the performance of yeast during fermentation.

Mashing takes place in a large, round tank called a "mash mixer" or "mash tun". A single mash system may be sufficient for all-malt beers. A double mash system may be used for boiling the malt mash in small fractions for the decoction process of select all-malt beers. For beers made with the addition of adjunct, a double mash system is required- mash tank for the malt mash and cooker for the adjuncts.

The mashing process prepares the malt mash to become an ideal nutrition medium for the growth of yeast once added. The various elements like- pH, thickness of the mash and temperature need to be carefully controlled. The temperature is gradually increased during the mashing process with intermittent periods in between where enzymes are active. The hottest temperature is enough to deactivate the enzymes and stop their activity.

There are various types of temperature rests in the process:

Protein rest period: During which the protein gets converted to simpler amino acids which is important for yeast nourishment in later stages and also results in flavor
development and foam formation in the beer.

Conversion rest period: During which the mash temperature is raised for conversion of malt into fermentable sugars. For more conversion, the temperature can be low and the process can be for a longer duration and vice-versa for less conversion. A greater amount of conversion results in lighter, less sweet tasting beer with lower calories and carbohydrates and a wort with higher potential alcohol. 

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The word lautering finds its origins in the German word lauter which means "to clean". In this process, the mash is separated into clear liquid wort and residual grain. During mashout, the temperature of the mash is raised to 177 degree Fahrenheit to minimize remaining enzymatic action and slowly stabilize the wort composition. This straining process takes place in a lauter tun which has slotted openings to hold back the grain husks, thus, forming a natural filtration bed. When the wort passes through this filter bed to the brew kettle, the filter bed is flooded with clean water at a temp of 170 degree Fahrenheit in a process called as sparging.  The water is added gradually to be in tandem with the rate of the wort outflow. The sparge water flows through the grains, extracting fermentable sugars as it passes into the kettle, decreasing the overall density of the wort.

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The wort is boiled in the kettle and through evaporation it is reduced to a desirable density. This process also inactivates any enzymes left post the mashing process and stabilizes the wort composition. Additionally, it helps to get rid of any natural volatile compounds which may have been formed in the processing. During boiling, an important biochemical reaction takes place – protein from the malt combines with the polyphenols from the malt and hops to form flakes or 'hot break'. The quality of hot break determines the brightness, clarity and stability of the beer. At this stage hops are added to the wort. During this process, the wort absorbs the aroma and flavor of the hops. The hops if boiled for a long duration, increase the bitter taste and the beer loses its aroma. Hence they need to be added in batches to carefully retain the desirable properties.

For obtaining clear wort, it needs to be subjected to centrifugal action in a whirlpool. The hot break or flakes settle in the bottom of the kettle in a conical shape due to the centrifugal action. The clear wort is then distilled from the top of the kettle.

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The clear wort needs to be cooled to a temperature of 68 - 78 degree Fahrenheit before proceeding with the addition of yeast. During cooling, secondary coagulation of protein happens, which results in the formation of 'cold break'. The 'cold break' particles are smaller than the 'hot break' particles formed earlier, during the boiling. Most of the cold break particles are removed during an additional settling step and some of the cold break particles if retained, help in better nutrition of the yeast during fermentation.

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This is where the microbes come into action. There are two basic types of yeast used both hailing from the Saccharomyces family – Saccharomyces cerevisae and Saccharomyces uvarum. During fermentation, the fermentable sugars are converted to alcohol, carbon dioxide and other compounds that determine the characteristic flavour of the beer. Brewing yeast strains have a slow action, but tend to produce minimal unwanted flavours and display higher toleration to alcohol concentration. Majority of the yeast used for pitching is obtained from previous fermentations. As the quantity of fermentable sugars decrease, the yeast growth decreases and it settles down towards the bottom of the tank. This settling called flocculation can be increased by lowering the temperature of the fermenter tank. The yeast is then harvested from the bottom of the tank carefully so that it can be reused.



Warm-fermenting: Saccharomyces cerevisae is used for the production of ale beers. Production of ale beer is completed after primary fermentation which takes place at approximately 58 – 67 degree Fahrenheit. This type of yeast rises to the top of the fermenter during the primary fermentation process. They are responsible for the fruity taste of ale beers.

Cool-fermenting: Saccharomyces uvarum (earlier known as Saccharomyces Carlsbergensis) is used for the production of Lager beers in which the temperature is maintained at about 50 degree Fahrenheit. The production of Lager beer involves primary as well as secondary fermentation. The yeast activity is maximum during the primary fermentation when the wort sugars are converted to alcohol and carbon dioxide. Secondary fermentation takes place when the beer is stored for 30 days or more.

The yeast is introduced into the wort stream during the pitching process. Often after
cooling, oxygen is dissolved into the wort to help the yeast in budding. The yeast replicates and form similar yeast during budding and are responsible for the rapid fermentation. The yeast activity depends on various factors such as type and concentration of wort, oxygen level, temperatures etc. There are important factors in the beer making recipe such as oxygen addition rate, pitching rate, cooling temperature etc. Though most of the fermentable sugars are converted during primary fermentation, the full flavour of the beer is yet to be developed. The “green beer” produced in the primary fermentation is subjected to secondary fermentation or aging.

During the secondary fermentation also called as lagering, the beer is subjected to high pressure to naturally carbonate the beer and to keep it free from oxygen which may hamper its taste. The less quantity of fermentable sugars ensures that the yeast activity decreases. There are several compounds which are produced during primary fermentation which gives an unbalanced or unfinished taste to the beer. Secondary fermentation substantially decreases such compounds thus, making the beer clear in colour and making it fully mature.

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Clarity is an important and much sought after aspect of beer. Protein particles and polyphenols give it a hazy murky look called as chill haze. However, neither the protein particles nor the polyphenols can be completely removed for the sake of clarity. Presence of  protein is important for foam stabilization and flavor, whereas that of polyphenols is important for the desired bitterness of the beer and its role in prevention of undesirable aging effects. The process of chill-proofing involves removal of most, but not all, of these protein particles and polyphenols.

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To obtain the finished product, the beer needs to undergo filtration after the process of chill-proofing. Filtration helps in removing protein and suspended yeast particle. The filter is generally coated with Diatomaceous Earth( fossil remains of single-celled organisms called diatoms). To compensate for the insoluble material coming with the beer, DE needs to be continuously added. The addition of DE is important for optimum sedimentation of the insoluble materials, resulting in greater clarity of the beer. 

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To protect the beer against harmful bacterial action, the beer needs to be pasteurized. In this type of pasteurization, the beer is gently heated and rapidly cooled. Adequate pasteurization for a necessary time period is a must for the flavor stability of the beer. Pasteurization allows bottled beer to be stored at room temperature without any effect on its original and characteristic flavor. 

The beer is finally ready to be bottled and shipped.

Have you ever wondered how beer is actually made? Well check out this video featuring ...
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Now that you know all the steps in the beer brewing process, I am sure that you will better appreciate each sip that you take, of this refreshing and bitter-sweet beverage. 

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17
Sections
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1. Ingredients
2. Ingredient 1 - Barley
3. Ingredient 2 - Hops
4. Ingredient 3 - Brewer's Yeast
5. Ingredient 4 - Water
6. Ingredient 5 - Adjuncts
7. Step 1 - Malting
8. Step 2 - Milling
9. Step 3 - Mashing
10. Step 4 - Lautering
11. Step 5 : Boiling & Hopping
12. Step 6 - Cooling
13. Step 7 - Fermentation
14. Step 8 - Chillproofing
15. Step 9 - Filtration
16. Step 10 - Pasteurization
17. Conclusion
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