Stronger brews by osmosis

The Homebrew Forum

Help Support The Homebrew Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

kelper

Old Salt
Joined
Mar 4, 2019
Messages
2,998
Reaction score
1,189
Location
Highlands
Is it possible to concentrate an alcoholic beverage by a cold process? I don't think freezing works very well.

There must be some chemical or mineral that absorbs water?

Would reverse osmosis work? It might need high pressure; making fresh water from seawater needs about 60bar (900psi).

Please remember forum rules and don't discuss any process that may be illegal.
 
I did quite a bit of research years ago trying to get together a business plan for a combined fuel plant from waste materials. This was when waste veg oil was just being discussed and a few homebrew fuel producers were trying biodiesel - which needs the addition of methanol.
So the plant would take in veg oil, new timber, old timber, cardboard, jiffy bags (that have plastic inside), mixed paper waste, weed cut round bales and round straw bales, and fresh cut grass from the council.
The plan was to shred the timber, and all cellulose materials, put it through high/low pressure system to explode the cell walls, then ferment it in a two stage process, which first produced methanol and then biobutanol.
The fibres were then compressed, dried and combined with the plastic/paper, with the addition of the waste veg carbon residue and made into pellets to be burnt as fuel. The methanol gets used to produce biodiesel, and the only waste is ash from the boilers that are burning the straw bales, so that goes to forestry as a dressing.

One of the bits of research was the filter material used to separate out the biobutanol from the methanol water mix, and yes it is a membrane on a molecular level...which is expensive and gets clogged easily which was a stumbling block.
Another block was that the EPA & SEPA didn't like plastics going into the pellet mix to be burned, or the print on the paper which may be toxic, and the Fuel pellet standards for this country are so high they can't even include bark in the mix, plus uptake for pellet heating is so slow we would need to start another company giving away the burners just to increase demand for pellets on a contract basis. (Free burner if you sign up to buy pellets from us for 12 months). That was a clusterfck of problems so I shelved the plan.
At the moment the UK buys it's ECO wood pellets from Norway....They have a lot of trees and not much else.
 
Yes it's a molecular filter that will only allow the alcohol through it at pressure and high temperature. It gets clogged easily so needs back flushing like a RO system.

Find the right filter media and you can extract alcohols using Reverse Osmosis, but that is all you would get.

You may get smaller molecules than your target product, so you may get methanol and ethanol together, and as there is no heat involved you would then need to either filter again or heat it to distil it.

Would it be classed as distilling though? It is just filtration.
 
Reverse osmosis is used to make low aclohol beer. Normally fermented beer is sujected to high pressures across a membrane, the smallest molecules such as water, CO2 and ethanol would pass through the membrane, leaving a concentrated solution of larger molecules, including the flavour and colour components. The water / alcohol mix is then separated and the selected portion is added back to the beer (water for L.A. beer, alcohol for high alcohol beer). The trouble is that this separation of the water and alcohol would probably be done using 'the technique that darest not speak its name'.

A far easier technique is to use freeze distillation (completely legal). Make beer as normal, partially freeze, pour liquid off the ice (pure H2O), then drink, or refreeze and repeat. Brew Dog used this method to make its mental brews (penquin etc.). I have tried it inadvertently by putting a french stubby in the freezer for slightly too long, open it and pour quickly, the water rapidly freezes as the pressure increases, leaving a beer slush puppy in the glass.
 
If you freeze an alcohol-water mix, the solid that forms is not pure water. But the remaining liquid will have more alcohol than before. And the 'ice' will contain less alcohol than the original mix.
 
I think Brewdog used it for their Tactical Nuclear Penguin Stout at 32% ABV.
beer_1532191c.jpg

https://www.brewdog.com/blog/the-worlds-strongest-beer-tactical-nuclear-penguin
 
The freezing point of water is 0*C. The freezing point of ethanol is -114.5*C.

The two liquids are miscible and form what is known as an "azeotropic mixture" which is:

"A mixture of two or more liquids whose proportions cannot be altered or changed by simple distillation. This happens because when an azeotrope is boiled, the vapour has the same proportions of constituents as the unboiled mixture."

In "freeze distillation", as the water solidifies, it will trap some of the liquid ethanol molecules within itself; in the same way that a bucket full of tennis balls could still hold a large amount of ballbearings in the gaps between them.
 
'Distillation has been used for centuries to make high alcohol Bock beer. In addition to their strength anecdotal evidence suggests have two key attributes. First they tend to have remarkable flavour stability, far greater than standard Bock beers. Second, they tend to be very smooth because all the 'rough edges' in their precursors have been removed by the freezing process' (Kunze 1996)
The Labatt group uses an ice stabilisation method which does not involve distillation. (George Fix Principles of Brewing Science.)
 

Latest posts

Back
Top