Animals have been consuming alcohol for millions of years, and primates and humans have been digesting it for about 7 to 21 million years. Throughout human history, alcohol consumption and production has been a part of many different cultures. Experts on human societies, including anthropologists and indigenous peoples, have long known about the origins of rice wine (Miju) and beer (Lao Lee) has been part of ancient Chinese culture for 7,000 to 13,000 years. Similarly, people in the Andes region of South America have been brewing beer made from corn. Chicha It spans approximately 5,000 years.
Even though ancient methods of making alcohol have spread all over the world, people all brew drinks that contain the same amount of alcohol, a standard known as the “alcohol content.” Alcohol degree or ABV. Beverages can be brewed at a range of ABVs, but beer is preferred to be brewed at around 4% alcohol by volume, wine at 11%-16%, and stronger spirits at around 43%, 52%, 68%, and 75% alcohol by volume. However, scientists are yet to figure out the reason behind these universal ranges of ABV.
A team of Chinese researchers studied why people choose different alcohol strengths by looking at how water and ethanol molecules interact at different alcohol strengths. Alcoholic drinks contain a variety of molecules that add flavor, color and aroma, but the main molecules are water and ethanol. ethanolThese molecules are made of atoms such as hydrogen and oxygen. The atoms of the molecules are held together by electric forces, like two magnets, but the atoms between the two molecules also attract each other. Water and ethanol molecules are attracted to each other through their hydrogen and oxygen atoms. This process is called Hydrogen Bonding.
The team demonstrated how hydrogen bonds can hold water and ethanol in different orientations and Interaction AngleThey are devices that determine the structure of molecules, Hydrogen Nuclear Magnetic Resonance Spectrometer or H NMR. H NMR The machine can detect hydrogen atoms and determine what they are bonded to and what angle they form.
The research team created mixtures of water and ethanol ranging from 0% to 100% alcohol content and used H NMR to detect the change in the interaction angle between the two molecules. They found that as the alcohol content increased, the interaction angle decreased. It dropped from a 90° angle at 1% alcohol content to a 10° angle at 99% alcohol content. They noticed that this change was not smooth, but that the interaction angle decreased in stages. For example, the interaction angle was about 70° between 11% and 13% alcohol content, but suddenly dropped to 60° when the alcohol content reached 14% alcohol content. The research team noticed that these abrupt changes occurred across the preferred alcohol content ranges of alcoholic beverages around the world, as shown above.
The most common type of hydrogen bond that occurs between a hydrogen atom and an oxygen atom is Hydroxyl. Using 1 H NMR, the team found that these hydroxyl interactions produced a uniform 3D water molecular network at an interaction angle of 90°, forming tetrahedral structures. However, the hydroxyl interactions between ethanol molecules were nearly linear, and at an interaction angle of 0°, long chains were formed. As the alcohol content of the beverage increased, the tetrahedral structures and the long chain molecules competed with each other.
The team found that as the alcohol content increased, the number of hydroxyl interactions decreased stepwise, as did the interaction angle. The team concluded that alcoholic drinks with different alcohol content formed distinct mixtures of chain and tetrahedral interactions. Increasing the amount of ethanol molecules increased the number of chain interactions as the molecules found new preferred orientations.
Finally, the researchers investigated whether the amount of these chain and tetrahedral interactions altered the flavor when an alcoholic beverage was cooled or heated. When an 11% ABV beverage was cooled to 42°F (5°C), more hydroxyl interactions occurred. This cooling increased the number of chain interactions between water and ethanol molecules.
Next, the researchers hired professional and amateur beer tasters to test the flavor of cold and hot alcoholic beverages with 11% alcohol content. The tasters found that chilling low and high alcohol content beers produced even greater differences in the flavor of the alcohol, due to an increased number of chain reactions within these beverages.
On the other hand, when the researchers warmed the beverages to 104°F (40°C), the number of hydroxyl interactions remained consistently between 38% and 52% ABV. Professional and amateur beer tasters tasted the warmed alcoholic beverages at 38% and 52% ABV and could not detect any difference. The team concluded that warming these beverages resulted in similar amounts of chain interactions, so flavor was unaffected by the change in ABV. This difference in taste could explain why people prefer to drink warm sake and other alcoholic beverages at 38% ABV.
The team concluded that throughout human history, brewers and drinkers have relied on their tongues to find the right alcohol content and temperature needed to create beverages that involve water-ethanol polymer chain interactions. By learning the importance of hydrogen bonds and molecular interactions, the team hopes that future brewers and scientists will experiment with different ways to control these molecular interactions to create even more sophisticated and interesting flavors.
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Source: sciworthy.com
