Views: 2 Author: Site Editor Publish Time: 2022-05-23 Origin: Site
How is Methanol Produced?
Also known as methyl alcohol or wood spirit, methanol is the simplest (shortest chain) of alcohols which is one-part carbon, one-part oxygen and four parts hydrogen.
Methanol is commonly produced commercially from coal, natural gas, and other renewable sources such as recycled carbon dioxide, biomass, and municipal waste. Initially, it was produced by performing a destructive distillation of wood, but nowadays it’s produced from synthesis gas by combining hydrogen and carbon monoxide with the help of a catalyst.
Apart from that, methanol is also produced in small amounts during the process of alcohol distillation. It is produced at the initial stages of the process and is tossed out by the distillers. This biodegradable form of alcohol is an organic water-soluble chemical.
How to Minimize Methanol in Fermentation?
When making alcohol at home, it’s the fermentation stage that produces methanol.
The amount produced will vary with different conditions, including the temperature, the type of yeast and other bacterial in the solution, the type of food you provide to them, the minerals, and more.
Normal fermentation of starch-derived sugars from corn, wheat, and barley will only contain very small amounts of compounds that will turn into methanol during fermentation.
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Can you Test for Methanol in Alcohol?
Yes! You can test for the presence of methanol in an alcoholic beverage by performing some quick tests.
The Smell Test
Smelling the beverage is the easiest methanol test yet one that takes a lot of practice to hone your senses. If you sense an unpleasant chemical odor from the solution, the drink is not safe for consumption.
Methanol has a sharp, stinging scent that is quite potent and can be easily recognized as ‘the smell of alcohol’
Ethanol will smell much milder by contrast. It’s softer, less stingy, and almost has a ‘creamy’ aroma. Ethanol won’t smell as potent as methanol of the same concentration.
Compared to methanol, ethanol will smell very pleasant – but it’s very hard to tell if you’re not comparing the two side by side.
The Flame Test
Take a small sample of the alcohol solution and light it on fire – if you witness a yellow fire instead of a blue flame, the solution contains methanol.
Again, this test is good in theory, but in practice you’ll seldom be comparing two solutions that are entirely methanol or ethanol. They will be blended and of varying proportions.
Also, be very careful setting things on fire as distilling is a potentially explosive process. Keep any open flame well away from a running still.
The Chemical Test
A more effective test for methanol in alcohol is to apply sodium dichromate to a small sample of the solution.
All you need to do is mix 8 mL of a sodium dichromate with 4 mL of sulfuric acid, further swirling the mix and adding 10 drops of the same to a small container or a test tube containing the alcohol to be tested.
Gently swirl test tube, followed by using your hand to fan the air from the opening of the test tube towards your nose while you hold the tube 10-12 inches from your nose. Notice the smell – if it’s unpleasant and pungent, then the alcohol contains methanol. However, if it seems fruity, the beverage contains only ethanol and is safe for consumption.
How to Avoid Methanol in Distilling by Making ‘Cuts’?
This is where the magic happens.
Depending on the varying boiling points of different chemicals involved in distillation, the process allows you to collect those chemicals separately.
Lighter compounds with lower boiling points will boil off first. Heavier compounds with higher boiling points evaporate last.
Regular distillation (or pot distillation) allows this to happen very crudely.
Fractional distillation using a reflux still lets you separate the compounds much more accurately.
Making ‘Cuts’ is the process of collecting the take-off from your still in discrete containers. Changing between the containers at regular intervals (say every 200ml) while collecting the distillate in order to separate the output into four stages – foreshots, heads, hearts and tails.
At the time of distilling, you must collect into many separate glass containers as the flavor and contents of the alcohol solution undergo changes throughout the entire distilling.
Before the vapor temperature hits 175 degrees Fahrenheit the first to come out of the distill are the foreshots and this is the harmful stuff that contains mainly acetone (ethyl acetate), methanol and several other poisonous elements.
This part is highly toxic and tastes awful, which is why it must be separated out as methanol can lead to blindness and even death. The foreshots contain almost zero ethanol and must always be discarded.
It’s recommended to collect and discard around 4 ounces of foreshots per 5 gallons that are being distilled. However, this is the minimum recommendation, and you can always discard a little extra. If using a reflux still, it’s best to discard the initial 50 mL you collect, while throwing away 100-200 mL when using a pot still. This ensures that you get rid of all the methanol and other harmful foreshots.
The next stage is the heads, which come out at 175-185 degrees Fahrenheit. The heads are set aside but can be recycled, as they can contain substances that can affect the flavor of the final beverage. Heads will have a small amount of methanol, mixed with ethanol as the delineation is very gradual.
The hearts evaporate at 173 degrees Fahrenheit (78.3 degrees Celsius) and mainly contain ethanol. The majority of your take off will be heads.
If not cut on time, the unwanted bitterness and oily aroma from the tails could dominate. The tails come off at approximately 203°F (95°C) and should be removed from the distillate.
These can be collected and recycled to get a bit more ethanol in your next run.