While drinking and singing, don’t forget the little lives that create this wonderful wine. Who are they?

Wine has been with human beings for thousands of years and has greatly enriched people's lives. But few people have delved into it: where does this wine come from? On the surface, it is brewed by winemakers, but how can these winemakers turn ordinary grains that they eat every day into wine?

In fact, human beings have been accompanied by wine since ancient times. It is countless small lives that work loyally and busily day and night in the microscopic world that people cannot see to brew these wonderful liquids. It is these liquids that make people excited and confused, and make people feel a different world.

These little lives are bacteria. There are mainly two types of bacteria that have been involved in this work from generation to generation. Their names are mold and yeast. They have different divisions of labor in the winemaking process. The front part is mainly performed by mold, while the latter part is taken over by yeast, thus brewing these fine liquors for people to enjoy from generation to generation.

Today, let us learn about how these little lives work and express our gratitude for their efforts.

Let’s talk about wine koji first

Most people know that koji can make wine. But few people know what is in koji. Many people think that koji is yeast, and through yeast fermentation, grain becomes wine. In fact, koji mainly contains mold, and generally does not contain yeast.

The ancients did not know this when they invented koji, but they knew why, that is, they knew that koji could be used to make wine. As for why koji can be used to make wine, and why the same koji can be used to make different wines in different places, it is not clear.

Archaeological research shows that the earliest wine in China appeared in the Stone Age 9,000 years ago. Before the Xia Dynasty, the winemaking industry was already very developed. By the Shang and Zhou dynasties, wine had become an indispensable drink in social life, involved in all aspects of life from ordinary social life to various major family and national affairs.

Modern research believes that, in essence, wine is the result of yeast metabolism, which converts sugar into ethanol, also known as alcohol and carbon dioxide. However, yeast cannot directly use starch. Therefore, the early stage of winemaking is to use mold to saccharify starch, protein and other substances in crops such as grains.

The reason why mold has saccharification is that during its growth and reproduction, it produces a large number of enzymes, such as amylase, saccharifying enzyme, protease, etc. These enzymes accelerate the conversion of starch and protein in food crops into sugar and amino acids. Therefore, there is reason to believe that the earliest wine of mankind may have come naturally from moldy food. Smart people gradually formed the winemaking industry by thinking about the results of this mold.

Mold is also called moldy fungi. Its main feature is that its mycelium is well developed and its width is about 2~10μm. Mold can make moist objects moldy, make food rotten and deteriorate, produce toxins, and cause chronic poisoning, carcinogenicity, teratogenicity and other consequences, which are very harmful to human health. In this case, why can mold be used to make wine? This is because everything in nature has two sides. It depends on how people understand and treat it.

There are many types of molds, including Mucor, Rhizopus, Aspergillus, Penicillium, aflatoxin, ochratoxin, zearalenone, etc. Most of them are annoying, but there are also molds that can be used, and some have made great contributions to mankind. For example, lactic acid bacteria, catarrhal cocci, Bacillus subtilis, Staphylococcus aureus, etc. are all beneficial molds. People have also extracted drugs such as penicillin and streptomycin from molds, saving the lives of hundreds of millions of people.

Winemaking also makes use of its beneficial side, mainly by selecting molds that have strong saccharification effects on grains, such as Rhizopus, Monascus and Aspergillus (Aflatoxin, Black Aspergillus, and Oryzae). Winemaking is the process of making koji made from these molds, which are generally divided into wheat koji and rice koji. In the long history of practice, people have added traditional Chinese medicine or other substances such as beans to the koji to make a variety of koji, and thus a variety of wines can be made.

The appearance of koji has evolved from being loose and naturally moldy at first to being artificially made into blocks by people inoculating molds on purpose. Taking Daqu as an example, the production process is: wheat → moistening → piling → grinding → adding water and mixing → loading into koji molds → treading koji → entering koji making room for cultivation → turning koji → piling koji → removing koji → storing in warehouses → finished koji, etc.

The koji produced by this method is in the shape of bricks, circles, flat squares, etc., with moderate density. After being made into a rough shape, it is moved into the koji room and cultured at a temperature of about 50-60℃ for about 50 days to allow the bacteria to grow naturally. After leaving the koji room, it needs to be stored for 3 months before use.

The earliest primitive saccharification and fermentation agents are qu and jie. Moldy grains are called qu, and sprouted grains are called jie. Qu uses the mold contained in moldy grains to reproduce and produce a large amount of enzymes to saccharify the raw materials for brewing; jie uses the enzymes produced when the grains sprout to saccharify the raw materials themselves.

In modern times, alcoholic beverages are roughly divided into five categories, each of which is brewed with a different type of koji. Among them, wheat koji and red koji are mainly used to brew different types of yellow rice wine; small koji is mainly used to brew yellow rice wine and small koji white wine; large koji is mainly used to brew distilled alcoholic beverages, that is, the white wine series; bran koji is the main type of koji developed in modern times, replacing most of the small koji and large koji. More than 70% of Chinese white wine is brewed with bran koji.

Gluten koji is a major innovation in China's brewing industry, established and promoted in 1955. Its main features are that it uses bran as raw material, is inoculated with pure mold strains, and is cultivated under artificial temperature and humidity control. It is easy to mechanize, has a short production cycle, and has strong saccharification and fermentation capabilities. It increases the utilization rate of raw materials by 10-20% compared with traditional koji.

However, this method must be used in combination with yeast (starter) when brewing wine, and the brewed wine lacks aroma and flavor, which requires the use of other microbial fermentation methods to compensate.

There are many methods and theories for making wine yeast, so I won’t list them all here. In short, from a popular science perspective, winemaking requires wine yeast, which mainly contains molds. These molds continuously produce catalytic enzymes to convert starch in crops into sugars, providing raw materials for yeast to make wine.

Some winemaking raw materials, such as grapes, already contain sugar, so there is no need to use the mold saccharification step, and yeast fermentation can be used directly to make wine.

How does yeast turn sugar into wine?

Winemaking is a two-step process. The first step is to convert the starch and protein in the raw materials into sugar through the action of mold in the koji. The second step is to convert the sugar into wine and carbon dioxide through the action of yeast. After the carbon dioxide evaporates, only the wine remains.

However, these two steps are not strictly distinguished and are sometimes carried out together. In the ancient winemaking method, yeast does not need to be added, because yeast is everywhere in nature, in the air, water, soil, and in animals. It is a single-cell fungus, a microorganism with typical heterotrophic facultative anaerobic characteristics, and can survive in both aerobic and anaerobic conditions. It is a natural fermentation agent.

Saccharomyces cerevisiae belongs to the family Saccharomyces, and is a single cell, oval or spherical, with a size of about 2.5-10μm*4.5-21μm. Saccharomyces cerevisiae has a cell wall, a cytoplasmic membrane, a nucleus (very tiny, often difficult to see), a liquid spore, mitochondria, and various storage substances, such as oil droplets, glycogen, etc.

Although yeast can survive in aerobic conditions, it is only in anoxic or anaerobic conditions that it can better convert sugars into ethanol and carbon dioxide, and absorb the nutrients it needs in the process. Therefore, winemaking is roughly divided into two processes. In the early open period, it is mainly the mold in the koji that converts starch and other substances in the raw materials into sugars; in the later closed fermentation process, it is the time for yeast to show its skills.

Yeast can break down sugar into alcohol, but it cannot handle alcohol. As the alcohol content of the brewed wine increases, it will be killed by alcohol. Alcohol is the product of anaerobic metabolism of yeast. When yeast converts sugar in the environment into alcohol with a concentration of more than 12%, it becomes a little "drunk" and its growth is inhibited. When the alcohol concentration reaches 16-18%, yeast becomes "drunk" and its metabolic activity stops completely. When the alcohol concentration reaches 20%, yeast begins to die.

Therefore, fermented wine does not become thicker the longer it is fermented. The alcohol concentration of the raw liquor before distillation generally does not exceed 20%. Therefore, the production of liquor generally requires a distillation process, which is to evaporate and divert the alcohol and water according to the different boiling points of alcohol and water to obtain a higher alcohol content.

The boiling point of water is 100 degrees Celsius, and the boiling point of ethanol is 78 degrees Celsius. As long as special distillation equipment is used and the temperature is controlled, liquor of different degrees can be obtained.

In the winemaking process, molds and yeasts are the main agents, but there are many other microorganisms involved, and the degree of microbial involvement varies from place to place in winemaking companies and workshops, so different flavors of wine can be produced. For example, Moutai, the leader of China's liquor industry, announced that 1,946 microorganisms were found in the brewing environment, including 1,063 bacteria, and 883 yeast and filamentous fungi.

China has established the first brewing microbial strain resource library, which stores hundreds of strains and more than 13,000 strains.

Further reading: Several misunderstandings in the liquor market

1. It is unscientific and inaccurate to distinguish the quality of wine by blended wine and brewed wine.

Because all liquors need to be blended before they can be put on the market as commercial liquors. The alcohol concentration of edible alcohol is very high, generally above 95%, and of course it needs to be blended to reach the degree indicated on the product; but the original liquor (raw pulp) made from grains cannot be exactly the degree indicated on the bottled liquor, and it also needs to be blended with water to become a standard degree product on the market.

2. All liquors, whether edible alcohol or liquor brewed from grains, are safe to drink as long as they meet national standards.

Most edible alcohol is brewed from grains or sugars, such as corn, rice, sorghum and other cereals, or sweet potatoes, cassava, sugar, etc. The main difference between edible alcohol and specially brewed drinking liquor is that edible alcohol has a higher alcohol content before blending.

3. The difference between liquor blended with edible alcohol and specially brewed grain liquor lies mainly in aroma and taste.

The reasons why the flavor and taste of liquor blended with edible alcohol and liquor directly brewed from grains are different are mainly as follows:

Generally speaking, the raw materials for brewing edible alcohol are relatively simple, and due to multiple purifications, the water in the original wine is excluded, and the impurities contained in the water are also excluded; while directly brewed edible liquor has its own raw material formula, generally brewed with a variety of grains and ingredients, and contains a variety of impurities, which will form various flavors after purification.

Many companies or workshops that brew liquor have a long history. The fermentation sites or cellars, as well as the microorganisms, minerals and other trace elements contained in the water, grow special strains with local characteristics, so the flavors of the liquor brewed are different. No matter where the edible alcohol is brewed, due to its high alcohol content, the ingredients and flavors in it are very few.

In the blending process of liquor, the main focus is on adjusting the alcohol content and the aroma. Although the brewed liquor also needs to be scented, the main focus is on preserving the unique flavor, and a considerable part of it retains its natural aroma and fragrance. Liquor blended with edible alcohol generally has no natural flavor, so you can adjust it to any flavor you want, and it has a wider range of blending space.

Finally, a reminder: Although alcohol has enriched human life, the World Health Organization has classified it as a Class 1 carcinogen. Therefore, from a health perspective, it is better to drink less or not drink it. However, life is different, so just take your own course. What do you think about this? Welcome to discuss and comment.

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