Now is the season of grape ripening, many people prefer to brew grape wine, but there’s an article on the internet, that home-brewed grape wine may contains methanol, seriously can cause blindness, even death. Is that a truth?
Home-brewed wine are mostly safe
“Generally speaking, most of home-brewed wine are safe”, a dietician said, “As long as to make sure brewed in the right way, and there is no problem with the hygiene conditions.”
Methanol has strong toxicity to human body, mistaking swallowed more than 4 ml will appear the symptom of poisoning, more than 10 ml may be blind, 30 ml can lead to death. The dietician said, it does have some methanol during fermenting. However, most of the methanol content in brewed grape wine is in the safety scope. Unless particularly high temperature when fermenting, or using the serious rotten grapes, can lead wine alcohol content exceeded from the standard.
Not only the home-brewed wine, all wines contain trace methanol. Methanol is generated in grape fermenting process, such as hydrolysis of pectic substances in raw materials, amino acid deamination, mildew of fermentation materials etc. At the time of fermenting, few of methanol will be produced, generally can be ignored. As long as note on carefully select raw materials, clean, keep clean in brewing, control the fermentation conditions properly, keep the low temperature fermentation, methanol cannot be exceeded.
These details should be noticed when brewing
The dietician said there’s a common problem in home-brewed wine is apt to deteriorate, mildew, this is related to limitation of home-brewing. She reminded us that we should repeatedly rinse the grape raw material and vessel, if the fermentation container has not been rinsed, are likely to lead to bacterial infections.
The fermentation process in brewing would produce a large amount of gas, so don’t use plastic bottles, iron and aluminum vessel, had better use glass or ceramic containers, lest produce chemical reaction, generate toxic substances.
Another risk is pesticide residues in brewed wine. In addition, in the process of brewed wine, try and keep low temperature fermentation, prevent enzyme mutation caused by the excessively high temperature, lest produce toxic substances. The alcohol concentration have not reached a certain degree, yeast can live, as well as bacteria. Once the sugar remained, could lead to secondary fermentation or bacterial growth.
Thus, keep in mind that those above tips are very important when home-brewing.
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