Brewing Science: A Multidisciplinary Approach

The first incarnation of the course described by the subjects in this text was aimed at the level of general studies. We also hope that this text will give you, the instructor, more details needed behind each of the processes in the brewery and give it an insight into the interrelationships between topics in brewing science.

Science and the Brewer

For example, a brewer may assume that the temperature of the water used in the process was too hot. In our example, the brewer can develop a theory that explains that the bacteria in the tap line is causing the off taste.

Fig. 1.1 The scienti ﬁ c method. A researcher makes observations, develops a hypothesis, and then tests the hypothesis with carefully designed experiments

What Is Beer?

For example, the Sumerians called it "ka". The Egyptians called it "bouza". Also in culture, there were several names for this drink, most likely due to many different recipes or due to different ways of using beer. In fact, the Egyptians referred to seventeen different types of beer, including one known as "bringer of joy" and another known as "heavenly". The ancient Babylonians called the drink "sikra".

Some Common Conventions

That temperature is close to, but not the same as, the liquid's boiling point. Fortunately, the freezing point of water is independent of atmospheric pressure (at pressure, we would experience in the brewery).

Yes Virginia, Beer Contains Alcohol

Thus, many states in the US have limits on the amount of alcohol that can be in one's body if that person plans to be in public, drive a car, or operate any machinery. Unfortunately, most of the statements we've heard about drinking are actually misconceptions and untruths.

Fig. 1.3 The US federal government requires that all bottles containing alcohol for sale be labeled to indicate the hazards of alcohol consumption

A Short History of Beer in the World

But similarities in the brewing processes of the two peoples at least reflected more than a casual interaction. As the alcohol content increased, overuse of the drink proved to be a problem in some places.

Fig. 1.4 Amphora as they might be stacked for transport in a ship. Image courtesy of Ad Meskens (https://

History of Beer in the USA

Apparently at least one person at the time wasn't a fan of the beer being produced at the brewery. The temperance movement stalled in the United States in the second half of the 19th century due to a number of different factors.

The Current Market for Beer

The American Lager style became the main style of beer produced in the United States after Prohibition. Use the mass of the malt and the difference in volume in the cylinder to determine the density of the malt.

Fig. 1.7 Breweries in the USA by year. Data are from the Beer Institute (https://www.

Judging Beer

The consumers knew what they liked, and over time they preferred the taste of the beer they could get. Today, many IPA-style beers sold on the west coast of the US are very expensive.

Parameters that Classify a Beer Style

The concentration of sugar in the original wort does not dictate the amount of alcohol that will be produced. FG Final weight (FG) is the density of the beer after fermentation.

Fig. 2.1 Distillation of sample to determine ABV. A sample of beer is distilled and the alcohol is collected in a separate vessel

Common Beer Styles

And in some cases, the beers mimic the flavors of the pilsners made in the Czech Republic. The basis of the beers comes from the use of pale malt (and sometimes from the use of large amounts of wheat).

Historical Beer Styles

For example, many different breweries in the US have produced imitations of the India Pale Ale style from England. Similarly, many other beer recipes have been identified in the literature and have been converted into beers.

How to Sample and Taste Beer

That's the glass the brewer envisioned when they constructed the recipe, and it's the glass that best accentuates the beer's style. The amount or thickness of the head often results in the perceived quality of the beer. There are multiple ways to inhale a sample of the beer's aroma.

One such way is to quickly draw small amounts of the beer into the nose with miniature exhalations.

Fig. 2.4 Glasses used in drinking beer. From left to right: pewter mug, chalice, fl ared top stang, goblet, pilsner, pub glass (cross between a weizen and a pint), stein, and pint (from the author ’ s own collection (MM))

The Atom

Unfortunately, it is rare to find one of the elements in the periodic table with the correct number of electrons around the atom. Note that although the ionic compound contains multiples of one of the ions, we do not indicate this in the name. Table 3.2 lists the names of the common polyatomic ions found in ionic compounds common in brewing.

Note that no space is placed between the parentheses and the name of the metal.

Table 3.2 lists the names of the common polyatomic ions found in ionic compounds common in the brewery.

Laws that Govern Atoms, Molecules, and Ionic CompoundsCompounds

Each of the compounds involved in a chemical reaction is represented by a separate formula consisting of atoms. On the left side of the equation, the compounds that react together are known as reactants. On the right side of the equation, the compounds formed in the reaction are known as products.

The difference in the two compounds results from the three-dimensional arrangement of the atoms.

Fig. 3.2 Examples of molecules with multiple bonds. The number of bonds between the two carbon atoms in each structure is represented with multiple lines

The World of Carbon-Containing Molecules

The result is the formation of the amide (pronounced "AM-id" in the US) functional group containing the C=O bond and a nitrogen atom at the C=O. If the functional group is not an alkane, we need to identify the carbon in the molecule containing the functional group. We then write the name for the longest carbon chain (pent) and add the end of the functional group to Table 3.5.

The functional group must always have the smallest number 5 Add the functional group to the end of the molecule name with its.

Fig. 3.4 The structure of some hydrocarbons, ethane, propane, and butane. Note that every carbon atom has 4 bonds and every hydrogen atom has 1 bond

Reactions of Organic Molecules

Any reaction that involves water and is the reverse of a condensation reaction is known as a hydrolysis reaction. The best example of an isomerization reaction is the conversion of humulone (also known as α-acid) to isohumulone (also known as iso-α-acid), as shown in Figure 3.20. A common example of a radical reaction is the formation of a skunk-like aroma in light beer, see fig.

In Figure 3.23, one of the compounds identified as a product of the reaction is a carboxylic acid.

Fig. 3.18 The formation of an ester via a condensation reaction. Note the formation of water as one of the products

Overview of the Process

We now know that the necessary sugars are packed in the endosperm of the seed as starch. This step causes the starch in the endosperm of the grain to be released into the mixture. Again, the brewer has many options that determine the final hop profile in the beer.

The purpose of the yeast from the perspective of the brewer is to digest the sugars in the bitter wort and leave alcohol behind.

Fig. 4.1 2-Row and 6-row barley. Photograph by Xianmin Chang (xianmin.

Cleaning and Sterilizing

It is at the packaging site where the process differs based on the size of the brewery. The length of shelf life is very dependent on the style and strength of the beer. Instead of sterilizing, we clean the brewery and equipment as best we can and clean with a chemical agent, which removes most of the unwanted microorganisms.

Outline at least three things the brewer could adjust during the conditioning phase of the beer.

Inputs and Outputs

The result is that enzymes in the grain are activated and convert malt starch into sugars. The brewer has had time to adjust the color, taste and clarity of the product in the conditioning tank. This pouring method allows most of the beer to be added to the glass without a large loss of carbonation.

One of the more important indicators of good beer handling is how the beer is served.

Fig. 4.9 Schema for producing a wide variety of malts from a single type of grain

Biology of Barley

There are many different cultivars of the barley plant that are used to make beer. The black arrows show the flow of barley into the dryer and along the conveyor to the post at the bottom of the machine. This step is very important to ensure that the barley used in the brewing process (or at least in the malting stage) is of the same size.

Sorting takes place when a sample of barley is placed in a hopper and then discharged into a set of vibrating sieves (Fig. 5.5).

Malting Barley

The effects of the kiln reduce the humidity in the malt and inhibit the further growth of the barley seed. If the malt is dried and stored cool, most of the enzymes that are in the seed will remain "alive". The drop in humidity indicates that the moisture in the outermost part of the malt has evaporated.

In addition to the flavor of the smoke, what would you predict would also exist in the malt.

Fig. 5.6 Water movement as a barley seed hydrates. The dotted blue circle is the last place to become hydrated

Maillard Reactions

The initial addition of the amine functional group of an amino acid or protein to a carbohydrate is relatively unstable and removes water to form glucosamine (or maltosamine or etc.). It involves re-opening the ring and then rearranging the double bond to a more stable carbonyl (C=O). The product of the initial dehydration then undergoes Strecker decomposition (named after the German chemist Adolf Strecker who discovered it in the 1860s).

The product of the Strecker decomposition is an aldehyde (known as the Strecker aldehyde) and an amino ketone.

Fig. 5.15 Dehydration gives rise to dicarbonyls that can make compounds with caramel flavors

Water — The Most Important Ingredient

Contamination of the aquifer in these areas can be a problem due to the flow of the water. The pH of the water will likely be at or above 7.0 due to the high levels of carbonate ions. So, the water delivered to a brewery is very dependent on the location of the brewery.

The composition of cations and anions in the water is a result of the source of the water and any added pollution.

Fig. 5.18 Formation of bicarbonate and carbonate from dissolution of CO 2 . The second reaction predominates in water

Purpose of Mashing

Equipment Used in Mashing

The heated and mixed mash is then transferred back to the mash mixer, the addition of which increases the temperature of the mash. The temperature is kept constant for some time, after which about one-third of the total mash is removed to the mash boiler. After returning this to the mash boiler, the temperature of the whole mixture rises again to 63 °C.

This results in the dilution of the mash (for easier transfer) and the destruction of further enzyme activity.

Table 6.1 Gelatinization temperatures of unmodi ﬁ ed cereals

Enzymes and What They Are

The alkalinity or acidity (pH) of the solution with the enzyme is also important in the reactivity of the enzyme. If the pH is too low (too acidic solution), enzyme activity is reduced. If the pH is too high (too alkaline solution), the activity of the enzyme decreases.

Shear forces are the last of the damaging factors that can affect enzyme activity.

Fig. 6.5 Enzymes are active based on the pH and temperature of the solution. Note that enzymes do not denature below their optimum temperature, and that the pH must deviate a lot from the optimum before the enzyme denatures

Chemistry While Resting

Note that the position of the OH in the aldehyde that was not attacked is not reported in this nomenclature. No, on the contrary, we find that enzyme activity decreases as we move away from the optimal pH. The water used between the two glasses should be as close to the temperature of the mash as possible.

Addition of hot water to the pan should be made periodically to maintain the temperature of the mash.

Fig. 6.6 The ﬁ ve forms of glucose found in water. Their relative percentages are <1% open-chain glucose, trace amounts of α-glucofuranose and β-glucofuranose, * 62% α-glucopyranose, and

Introduction

Alternatively, the brewer can slowly drain the lauter tun and continuously feed fresh sprinkling water to the top of the grain bed at the same rate as the grain. In both cases, the first grain was often returned to the top of the lauter tun to be filtered through the grain again. At first the straw dripped from the grain bed, loaded with insoluble proteins, cellulose, small amounts of insoluble starch that was not crushed, and even small grain particles.

By passing it through the system again, the grain bed will act like a ﬁlter and help remove the insoluble material.

Fluid Physics: Static Case

The question then is: What is the difference in water level,x, on both sides of the pipe. We can use Pascal's law to calculate the pressure difference between the top of the water and the location of the valve. In the example above, keep in mind that we ignored the atmospheric pressure pressing on the top of the water in the container.

Calculate the total force on the bottom of the barrel after the pipe is filled with water.

Fig. 7.1 Example illustrating Pascal ’ s principle. The pressure at each piston must be the same

Fluid Physics: Dynamic Case