I have added pieces of 24 carat gold to a bottle of water and they stay at the top rather than sink to the bottom which makes the water unpresentable. How I can make edible gold leaves sink in spring water? I need it to still be safe for drinking, so I can’t include any additives.
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15$\begingroup$ Perhaps better asked here: cooking.stackexchange.com $\endgroup$– CDCMCommented Jun 10, 2017 at 13:07
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1$\begingroup$ @CDCM and others who upvoted that comment: perhaps so, but there seems to be very little support (i.e. flags and close votes) for the position that this question is off topic here. We will not be migrating it unless that changes. $\endgroup$– David ZCommented Jun 11, 2017 at 1:16
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1$\begingroup$ Does the "spring water" contain dissolved gas, which might be forming bubbles attached to the gold leaf and floating it to the surface where surface tension can take over and keep it there? See if using boiled water makes any difference - boiling will expel the gas. $\endgroup$– alephzeroCommented Jun 11, 2017 at 1:44
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$\begingroup$ It isn't off topic here. But it is also on topic in the cooking site. There is a surprising number of physics-of-cooking questions asked there. $\endgroup$– mmesser314Commented Jun 11, 2017 at 3:57
2 Answers
It's floating because of surface tension, so your options are: reduce the surface tension with an edible surfactant (frequently used surfactants in cooking include: egg yolk, soy lecithin, and mustard), or add water on top of the gold leaf to get it below the surface (eg: spray them with a spray bottle until they sink).
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7$\begingroup$ Yes, it's almost certainly the surface tension to blame. You could try adding alcohol to reduce the surface tension :-) $\endgroup$ Commented Jun 10, 2017 at 14:14
Take a look at this post about the same problem with gold flakes in honey. I blamed air bubbles.
If air bubbles is the problem, you might try stirring or shaking the container.
Another thought might be a layer of oil on the gold. You could try adding soap to disolve the oil. That would not be edible, but it would tell you something about the problem.
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$\begingroup$ Soap would also make the gold flakes sink in case surface tension is the culprit, so it won't definitively identify the problem. $\endgroup$– PranabCommented Jun 11, 2017 at 9:31