About beer through the eyes of a chemist. Part 1

Hello %username%.

As I promised earlier, I got a bit lost due to my business trip. No, it's not over yet, but it inspired some thoughts that I decided to share with you.

Let's talk about beer.

I’m not going to drown for certain varieties now, arguing which taste and color in the body changes less from the moment of consumption to the moment ... well, you understand - I just want to talk about how I see the production process, the differences and the influence of beer on our organism in terms of chemistry.

Many believe that beer is a drink of the common people - and they are very mistaken, many believe that beer is harmful - and they are also mistaken, however, like those who believe that beer is not harmful. And we'll figure it out

And unlike previous articles, I will try to get rid of long reads, but rather divide this story into several. And if at some stage there is no interest, then I will simply stop injuring the brain of the poor reader.

Let's go.

История вопроса

The history of beer in the world has several millennia. The first mention of it dates back to the early Neolithic. Already 6000 years ago, man used technology to turn bread into a fragrant drink - and beer is generally believed to be the oldest alcoholic drink in the world.

The history of the origin of beer began even before our era, and the laurels of the inventors belong to the Sumerians. Their cuneiform, discovered by E. Huber in Mesopotamia, contained about 15 recipes for this drink. Residents of Mesopotamia used spelled (spelt) to make beer. It was ground with barley, poured with water, herbs were added and left to ferment. A drink was made on the basis of the resulting wort. Pay attention: in fact, wheat beer was invented, but no one has yet said anything about hops, that is, in fact, gruit or herbal beer was brewed. At the same time, the malt was not germinated.

The next milestone in the history of the appearance of beer was the Babylonian civilization. It was the Babylonians who figured out how to improve the drink. They germinated the grain and then dried it to produce malt. Beer on grain and malt was stored for no more than a day. In order to make the drink more aromatic, spices, oak bark, tree leaves, honey were added to it - even then food additives were invented, of course, because before the Reinheitsgebot or, understandably, the German law on the purity of beer, there were still about 5000 years!

Gradually, beer spread in ancient Egypt, Persia, India, and the Caucasus. But in ancient Greece, it was not popular, because it was considered the drink of the poor. It was then that all these prejudices arose.

The history of the creation of beer developed with the beginning of the Middle Ages. This period is called the period of the second birth of beer. It is believed that it happened in Germany. The German name Bier comes from the Old German Peor or Bror. Although the same English Ale (ale) allegedly etymologically goes back to the Proto-Indo-European root, presumably with the meaning "intoxication". The Indo-European origin of the root is convincingly proved in comparison with modern Danish and Norwegian øl, as well as Icelandic öl (the Germanic group of languages, to which Old English also belonged) and Lithuanian and Latvian alus - beer (the Baltic group of the Indo-European family), North Russian ol (meaning intoxicated drink ), as well as Estonian õlu and Finnish olut. In short, no one knows how the words came out, because someone screwed up in Ancient Babylon - well, everyone now calls beer differently. However, they cook differently.

It was in the Middle Ages that hops began to be added to the drink. With its appearance, the taste of beer has improved, and its shelf life has become longer. Remember, %username%: hops were primarily a beer preservative. Now the drink could be transported, and it became a subject of trade. Hundreds of recipes and varieties of beer have emerged. Some scientists from some regions believe that the Slavs were the ancestor of hop cultivation, because in Rus' already in the XNUMXth century brewing was widespread.

By the way, in the Middle Ages, light ales were widely used in Europe instead of water. Even children could afford beer - and yes, it was specifically beer, and not kvass, as some people think. They drank not because the dark ones wanted to sleep, but because after tasting the water it was easy to make ends meet from a whole bunch of known and still unknown diseases. With the level of medicine at the level of a plantain and a midwife, it was too dangerous. In addition, the so-called table beer (“small ale”) was also nutritious and went great at the dinner table in enormous quantities, since there was about 1% alcohol there. The logical question is “what then killed all the infection?” we will also consider.

The 1876th century was marked by another breakthrough in the history of beer. Louis Pasteur first discovered the relationship between fermentation and yeast cells. He published the results of the study in 5, and 1881 years later, in XNUMX, the Danish scientist Emil Christian Hansen obtained a pure culture of brewer's yeast, which became the impetus for industrial brewing.

If we talk about the history of non-alcoholic beer, then the impetus for its appearance was the Volstead Act of 1919, which marked the beginning of the Prohibition era in the United States: the production, transportation and sale of alcoholic beverages stronger than 0,5% was actually banned. So it's not even "small ale" anymore. All brewing companies were involved in the release of such practically non-alcoholic drinks based on malt, however, by law, the drink had to be called "cereal drink", which the people immediately called the "rubber woman" "near beer" ("near beer"). In fact, in order to switch from the usual, forbidden, to the new “almost-beer”, it was enough to add only one additional stage to the production process (and we will definitely remember about it), which did not greatly increase the cost of the final product and allowed us to quickly to return to the production of a traditional drink: “I think it will be a glorious time for beer,” said US President Franklin Roosevelt, signing the Cullen-Harrison Act on March 22, 1933, which allowed ABV to be raised to 4%. The act came into force on April 7, and therefore since then this date has been National Beer Day in the USA! They say that already on April 6, Americans lined up in bars, and when the coveted midnight struck, then ... In short, statistics say that on April 7 alone, one and a half million barrels of beer were drunk in the United States. Did you have a glass of beer on April 7th, %username%?


By the way, if you are interested, in one of the following parts I will talk about an even more severe dry law - and this is not even the USSR, but Iceland.

At the moment, beer is not brewed except in Antarctica - although this is inaccurate. There are dozens of categories and hundreds of styles - and if you're interested, you can read their descriptions here. Beer is far from being as easy as it seems, the cost of a bottle can sometimes exceed the cost of a case of wine - and I'm not talking about Chateau de la Paquete wine.

Therefore, %username%, if you have opened a bottle of beer while reading, be respectful and continue reading further.

Ingredients

Before disassembling what beer consists of, let's briefly recall the production technology of this drink.

Beer - like so much in this world - is a product of incomplete combustion. In fact, fermentation - the process by which we taste this pleasure, as well as your ability to read these lines, %username% - is a product of incomplete combustion of sugars, only in the case of beer, sugars do not burn in your brain, but in yeast in metabolic chain.
As with any combustion, the products are carbon dioxide and water - but remember I said "incomplete"? And indeed: in the production of beer, yeast is not allowed to overeat (although this is not entirely correct, but it is good for a general understanding of the picture) - and therefore, in addition to carbon dioxide, alcohol is also formed.

Since the food is not pure sugar, but a mixture of various compounds, the product is not just carbon dioxide, water and alcohol, but a whole bunch, thanks to which these same beers exist. Now I will talk about some of the main ingredients, and along the way, I will debunk some myths about beer.

Water.

Remembering that after all I am a chemist, I will switch to boring chemical language.

Beer is an aqueous solution of malt extractives that have not undergone changes during the fermentation and post-fermentation of beer, ethyl alcohol and flavoring substances that are either secondary metabolites of yeast or originating from hops. The composition of extractive substances includes unfermented carbohydrates (α- and β-glucans), phenolic substances (anthocyanogens, oligo- and polyphenols), melanoidins and caramels. Their content in beer varies from 2,0 to 8,5 g/100 g of beer, depending on the mass fraction of solids in the initial wort, composition of the wort, technological modes of fermentation and strain characteristics of yeast. The same process parameters are associated with the content of alcohol, the mass fraction of which in beer can range from 0,05 to 8,6%, and flavoring substances (higher alcohols, esters, aldehydes, etc.), the synthesis of which depends both on the composition of the wort and, especially on the fermentation regimes and the nature of the yeast. As a rule, for bottom-fermented beers, the concentration of by-products of yeast metabolism does not exceed 200 mg/l, while for top-fermented beers their level exceeds 300 mg/l. An even smaller share in beer is made up of bitter substances of hops, the amount of which in beer does not exceed 45 mg/l.

All this is very boring, the numbers can actually differ up and down, but you get the point: there is very little of all this against the background of the water content in beer. Like you, %username%, beer is about 95% water. Not surprisingly, the quality of water affects beer in the most direct way. And by the way, this is one of the reasons why the same type of beer produced by different factories in different places can differ in taste. A specific and probably the most famous example is Pilsner Urquell, which they once tried to brew in Kaluga, but nothing came of it. Now this beer is produced only in the Czech Republic because of the special soft water.

No brewery will brew beer without first testing the water it has to work with - the quality of the water is too important to the final product. The main players in this regard are the same cations and anions that you see on a bottle of any soda - only the levels are not controlled in the range of "50-5000" mg / l, but much more precisely.

Let's figure out what the composition of water affects?

Well, first of all, the water must comply with SanPiN, and therefore we immediately discard heavy metals and other toxic ones - this rubbish should not be in the water at all. The main restrictions for water used directly in the production of beer (when mashing) relate to such indicators as the pH value, hardness, the ratio between the concentrations of calcium and magnesium ions, which is not regulated at all in drinking water. Significantly less water for brewing should contain ions of iron, silicon, copper, nitrates, chlorides, sulfates. The presence of nitrites in the water, which are strong toxins for yeast, is not allowed. Two times less in water should be mineral components (dry residue) and 2,5 times lower COD (chemical oxygen demand - oxidizability). When assessing the suitability of water for brewing, an indicator such as alkalinity was introduced, which is not included in the standards for drinking water.

In addition, additional requirements are imposed on water, which is used to adjust the mass fraction of solids and alcohol in high-gravity brewing. This water must be, firstly, microbiologically pure, and secondly, deaerated (i.e. practically free of water-soluble oxygen) and contain even less calcium and bicarbonate ions compared to water recommended for brewing in general. What is High Gravity Brewing?If you didn’t know, then the technology of high-density brewing is that in order to increase the productivity of the brewhouse, wort is brewed with a mass fraction of solids that is 4 ... 6% higher than the mass fraction of solids of the finished beer. Further, this wort is diluted with water to the desired mass fraction of solids, either before fermentation, or already finished beer (yes, beer is diluted - but this is only at the factory, and I will also talk about this later). At the same time, in order to obtain beer that does not differ in taste from beer obtained by classical technology, it is not recommended to increase the extract content of the initial wort by more than 15%.

It is extremely important to maintain the correct pH in the water - I'm not talking about the taste of the finished beer at all, but about the process of wort fermentation (by the way, as it was found - this just doesn't affect the taste - you just won't feel such a subtle difference). The fact is that the activity of enzymes that yeast uses to eat depends on pH. The optimal value is 5,2..5,4, but sometimes this value is shifted to a higher side to increase bitterness. The pH value affects the intensity of metabolic processes in yeast cells, which is reflected in the biomass growth rate, cell growth rate and the synthesis of secondary metabolites. So, in an acidic environment, ethyl alcohol is mainly formed, while in an alkaline environment, the synthesis of glycerol and acetic acid is intensified. Acetic acid adversely affects the process of yeast reproduction, and therefore it must be neutralized by adjusting the pH during fermentation. For different "foods" there may be a different value of the optimal pH: for example, 4,6 is needed for the metabolism of sucrose, and 4,8 for maltose. pH is one of the main factors in the formation of esters, which we will talk about later, and which create those very fruity smells of beer.

pH adjustment is always a balance of carbonates and bicarbonates in a solution, they determine this value. But even here everything is not so simple, because in addition to anions there are also cations.

In brewing, the mineral cations that make up water are divided into chemically active and chemically inactive. All salts of calcium and magnesium are chemically active cations: for example, the presence of calcium and magnesium (and, by the way, sodium with potassium) against the background of a high content of carbonates increases pH, while calcium and magnesium (sodium and potassium are already in the span) - but in commonwealth with sulfates and chlorides lower the pH. Playing with the concentrations of cations and anions, you can achieve the optimal value of the acidity of the medium. At the same time, brewers like calcium more than magnesium: firstly, such a phenomenon as yeast flocculation is associated with the calcium ion, and secondly, when temporary hardness is eliminated by boiling (it’s like in a kettle), calcium carbonate precipitates and can be removed , while magnesium carbonate precipitates slowly and partially dissolves again when the water is cooled.

But in fact, calcium and magnesium are still flowers. In order not to overload the article, I will simply bring together some of the effects of ion impurities in water on various factors in the production and quality of beer.

Impact on the brewing process

• Calcium ions - Stabilize alpha-amylase and increase its activity, resulting in increased extract yield. They increase the activity of proteolytic enzymes, due to this, the content of total and α-amine nitrogen in the wort increases.
• Determine the level of decrease in the pH of the wort during mashing, boiling the wort with hops and fermentation. Yeast flocculation is determined. The optimal concentration of ions is 45-55 mg/l of wort.
• Magnesium ions - They are part of glycolysis enzymes, i.e. necessary for both fermentation and yeast propagation.
• Potassium ions - Stimulate the reproduction of yeast, are part of enzyme systems and ribosomes.
• Iron ions - Negative effect on mashing processes. At a concentration of more than 0,2 mg / l can cause yeast degeneration.
• Manganese ions - Included as a cofactor in yeast enzymes. The content should not exceed 0,2 mg/l.
• Ammonium ions - Can only be present in wastewater. Absolutely unacceptable.
• Copper ions - At concentrations of more than 10 mg / l - toxic to yeast. May be mutagenic for yeast.
• Zinc ions - At a concentration of 0,1 - 0,2 mg / l, they stimulate the reproduction of yeast. At high concentrations, α-amylase activity is inhibited.
• Chlorides - Reduce yeast flocculation. At a concentration of more than 500 mg / l, the fermentation process is slowed down.
• Bicarbonates - At high concentrations, they lead to an increase in pH, and consequently to a decrease in the activity of amylolytic and proteolytic enzymes, and reduce the yield of the extract. and enhance the color of the wort. The concentration should not exceed 20 mg/l.
• Nitrates - At concentrations above 10 mg/l, they are found in effluents. In the presence of bacteria of the Enterbacteriaceae family, a toxic nitrite ion is formed.
• Silicates - Reduce the activity of fermentation at a concentration of more than 10 mg / l. Silicates come mostly from malt, but sometimes, especially in spring, water can be the reason for their rise in beer.
• Fluorides - Up to 10 mg/l has no effect.

Influence on the taste of beer

• Calcium ions - Reduce the extraction of tannins, which give the beer a rough bitterness and astringency. Reduce the utilization of bitter hop substances.
• Magnesium ions - Give a bitter taste to beer, which is felt at a concentration of more than 15 mg / l.
• Sodium ions - At concentrations of more than 150 mg / l, they cause a salty taste. At concentrations of 75 ... 150 mg / l - reduce the fullness of taste.
• Sulfates - Give beer astringency and bitterness, cause aftertaste. At concentrations over 400 mg/l, they give the beer a "dry taste" (hello, Guiness Draft!). May precede the formation of sulphurous tastes and odors associated with the vital activity of infecting microorganisms and yeasts.
• Silicates - Influence the taste indirectly.
• Nitrates - Negatively affect the fermentation process at a concentration of more than 25 mg / l. Possibility of formation of toxic nitrosamines.
• Chlorides - Gives beer a more subtle and sweet taste (yes, but if there is no sodium). At an ion concentration of about 300 mg/l, they increase the fullness of the taste of beer and give it a melon taste and aroma.
• Iron ions - When the content in beer is more than 0,5 mg / l, the color of the beer increases, brown foam appears. They give the beer a metallic taste.
• Manganese ions - Similar to iron ions, but much stronger.
• Copper ions - Negatively affect the stability of taste. Soften the sulphurous taste of the beer.

Effect on colloidal stability (haze)

• Calcium ions - Precipitate oxalates, thereby reducing the possibility of oxalate haze in beer. They increase the coagulation of proteins when boiling the wort with hops. Reduce the extraction of silicon, which favorably affects the colloidal stability of beer.
• Silicates - Reduce the colloidal stability of beer due to the formation of insoluble compounds with calcium and magnesium ions.
• Iron ions - Accelerate oxidative processes, cause colloidal turbidity.
• Copper ions - Negatively affect the colloidal stability of beer, acting as a catalyst for the oxidation of polyphenols.
• Chlorides - Improve colloidal stability.

Well, what's it like? In fact, different styles of beer were formed in different parts of the world thanks to different types of water. Brewers from one area produced successful beers with a pronounced malt flavor and aroma, while brewers from another came out with a wonderful drink with a noticeable hop profile - all because in different regions there were different waters, on the basis of which one beer turned out better than another. Now, for example, the composition of water for beer is considered optimal in this form:

However, it is clear that there are always deviations - and these deviations often lead to the fact that Baltika 3 from St. Petersburg is not Baltika 3 from Zaporozhye at all.

It is quite logical that any water used to make beer goes through several stages of preparation, including analysis, filtration and, if necessary, composition adjustment. Very often the brewery carries out the process of water treatment: the water obtained in one way or another is subjected to the removal of chlorine, a change in the mineral composition and the adjustment of hardness and alkalinity. You don’t have to bother with all this, but then - and even then, if you are lucky with the nominal composition of the water - the brewery will be able to brew only a couple of varieties. Therefore, water control and preparation is ALWAYS performed.

Modern technologies, with sufficient funds, make it possible to obtain water with almost any desired characteristics. At the same time, even city tap water, even extracted directly from an artesian source, can serve as a base. There are also exotic cases: one Swedish brewery, for example, brewed beer from treated wastewater, and Chilean craftsmen make beer with water collected from fog in the desert. But it is clear that in mass production, an expensive water treatment process affects the final cost - and, perhaps, that is why the already mentioned Pilsner Urquell is not produced anywhere else, except at home in the Czech Republic.

I think that's enough for the first part. If my story turns out to be interesting, in the next part we will talk about two more essential ingredients of beer, and perhaps one optional, why beer smells differently, whether there are “light” and “dark”, and also touch on strange letters OG, FG, IBU, ABV, EBC. Maybe there will be something else, or maybe something will not happen, but will appear in the third part, in which I plan to briefly go through the technology, and then deal with the myths and misconceptions about beer, including that it is “diluted” and “strengthen”, we will also talk about whether it is possible to drink expired beer.

Or maybe there will be a fourth part... The choice is yours, %username%!

Source: www.habr.com