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Your mission, should you decide to accept it, is to describe how hydrocarbons can be stably mixed into a water-based liquid such as beer, as in this question. According to the usual textbook wisdom, hydrocarbons which are essentially nonpolar and have little or no hydrogen bonding with water, should be the classic hydrophobic material, surely repelled from water like, well, oil. How is a hydrocarbon such as humulene ($\ce{C_{15}H_{24}}$) stably incorporated into a liquid as watery as beer?

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    $\begingroup$ Humulene + detergent + beer. It's pretty much the recipe for Coors Light. $\endgroup$
    – Todd Minehardt
    Aug 8 '21 at 23:13
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    $\begingroup$ The question is how much humulene are you expecting in 5% ethanol-95% H2O? Everything dissolves in everything (again at a low level). The concentration of water in toluene is about 500 ppm. That is a lot and detectable by GC. Benzene dissolves about 1000 ppm water. Pure water dissolves about 0.17 % benzene. $\endgroup$
    – M. Farooq
    Aug 9 '21 at 0:01
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    $\begingroup$ A good starting point is the ampersand brew mentioned in the linked question. It's list of ingredients should hopefully contain a little more than 'stabilizing agents' $\endgroup$ Aug 9 '21 at 5:34
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    $\begingroup$ The more straightforward answer, similar to "is the dose that makes a poison" is in the comment by M. Farroq. It points to the relative amounts and this brings along that beer is a complex solution. Everyone knows the joke "what having sex on a kayak and Xoors have to do each other? “? Ans: fucking closed to water. The latter is OoT :)) $\endgroup$
    – Alchimista
    Aug 9 '21 at 9:39
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    $\begingroup$ @nilay because of the mixed voting record on this question I have only +44 rep from it, so I have to settle for accepting an answer and thus +15 for the winner. I have an answer but typically wait a few days to "shop around". $\endgroup$ Aug 10 '21 at 11:23
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There are many industrial problems similar where one would like to incorporate a hydrophobic ingredient into a hydrophilic matrix (or vice versa).

Luckily there are a few main strategies that can be used to incorporate dissimilar chemistries with each other.

The first is co-solvancy where you introduce a secondary solvent to help dissolve your target solute. This is a complex area of chemistry and is generally done empirically or semi-empirically in industry. The basic idea is that your solvent A is a bad solvent for your solute and solvent B is also a bad solvent for your solute. But a mixture of A+B is a good solvent. The chemical concept underpinning this is the Hansen Solubility Parameters.

In the case of beer, you have about 95% water, but you also have about 5% ethanol which acts as a co-solvent and will help dissolve more polar solutes. I can't say this is the dominant effect without doing some experiments, however.

What is much more likely is the second main strategy for mixing dissimilar chemistries: surfactants. Surfactants have a polar and non-polar end can dissolve organics in water (or vice versa). Your primary exposure to surfactants would be in cleaning as detergents are surfactants and they effectively 'dissolve' oil and dirt into water to take it away.

Beer is fermented which means it has all kinds of biomolecules in it that can act as a surfactant and dissolve the humulene. The most likely culprits will be metabolites from yeast or broken-up yeast cells. Yeast cells membranes (and all other cell membranes) are made up of a phospholipids bilayer and individual phospholipids are surfactants. There are likely to be plenty of phospholipids floating around the beer (in addition to proteins and nucliec acids) which will act as a surfactant and dissolve the humulene.

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