Why do some beers get "headache" when you drink them?
One. Definition of "headache" in beer
Sometimes, after drinking beer, people will experience the phenomenon of "headache", commonly known as "on the head", "on the head" is a physiological reaction of the human body, and cause after drinking "on the head" for many reasons, but the beer in the fermentation process produces a trace of by-products is an important reason.
Second. The main substances that cause "head"
The main substances that cause "head" after drinking are the advanced alcohols in beer, acetaldehyde, alcohol ester ratio and fermentation process contaminated bacteria. These substances enter the brain with the blood circulation, causing the brain nerve cells to contract and spasm, thus causing headaches and other discomfort ----- that is, "on the head".
1, the main senior alcohols in beer are isoamyl alcohol, active amyl alcohol, isobutanol, n-propanol and so on. The right amount of senior alcohol can make the body full and aroma coordination, but the following fermented beer in the senior alcohol content is too high (such as more than 120mg / L), especially isoamyl alcohol content of more than 50mg / L, isobutanol content of more than 10mg / L, will not only be drinking with a distinct odor, but also will cause beer "on the head The beer can also cause "headiness".
2, acetaldehyde in beer has a great impact on the flavor of beer, it is one of the main substances that constitute the taste of beer raw green. When the acetaldehyde content in beer exceeds this value of 10mg/L, the beer will show a pungent rotten grass flavor. Acetaldehyde is a strong irritant to humans. It can stimulate the vomiting nerve center of the human body, causing nausea and vomiting; it can prompt the brain nerve contraction and lead to headache, but also stimulate the human nerve endings blood vessels, especially easy to cause the face, eyes and ears capillary rapid congestion, and appear "red face and ears".
3, alcohol to ester ratio refers to the ratio of total alcohol to total esters in beer, alcohol to ester ratio is high, indicating a high content of senior alcohol, or low ester content; reduce the content of senior alcohol may reduce the alcohol to ester ratio, on the other hand is to increase the content of esters, may also reduce the alcohol to ester ratio. Ester is an indispensable flavor substance for beer flavor. Experts have found that the "headiness" of beer after drinking is not only related to the high alcohol content, but also related to the high or low "alcohol to ester ratio" in beer. Generally, after the beer is matured, the "alcohol to ester ratio" is controlled between 3.5 and 4.5:1, which is more suitable. Because the senior alcohol in the blood stimulates the brain nerve, making it contraction, while the ester in the blood makes the brain nerve stretch, so the "alcohol ester ratio" low wine, drinking is not easy to "on the head".
4, the fermentation process contamination corruption bacteria and wild yeast, will obviously increase the content of senior alcohols, especially isoamyl alcohols. Practice has proved that the fermentation process is seriously polluted beer, after drinking unpleasant, will be "on the head".
Three. How to prevent beer "on the head
1. Preferred brewer's yeast strain with low production of advanced alcohol (control a reasonable alcohol to ester ratio).
2. Control the appropriate wort pH.
3. Control the appropriate wort concentration.
4. Provide suitable wort alpha-amino nitrogen level and balance of other nutrients such as amino acids, magnesium ions, pantothenic acid and biotin.
5. Increase the yeast inoculum amount appropriately and lower the yeast inoculation temperature.
6. Lowering the fermentation temperature during the main fermentation period and controlling the yeast multiplication times <4 times.
7. Main fermentation with pressure of 0.04 to 0.08 MPa (to control a reasonable alcohol to ester ratio).
8. Proper control of beer fermentation degree.
9. Keeping beer freshness.
10. Strict control of microbial contamination during fermentation.