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This may sound weird but could one 'zap' some liquid like milk with electricity of a certain voltage for a 'few' seconds hoping to kill any bacteria in it? I know some people suggested some type of radiation on meat ( I think) but could a small charge of electricity on liquid products kill any bacteria in them?

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Yes, this is a known phenomenon. It's a process called electroporation. Here's a paper talking about using it for sterilization. Basically, when you apply an electric field to a cell membrane, you can render it porous. At low field strength, the pores are small and can be closed by the cell, but if you apply a larger potential across the cell membrane, cell lysis is the result, killing the cell. It's actually used for killing cancerous tumour cells in humans.

Unfortunately the trick with doing it with something like milk is that, to get a large enough potential across the cells in the liquid, an enormous potential (up to 1 kV/mm) needs to be applied to electrodes immersed in the liquid, even though the cell membrane is only seeing a volt or two. For this to be manageable, you would probably need a thin flow cell or something. It could be a fair bit more expensive than pasteurization. Even though only a short pulse is used, electrolysis will occur, which could affect the taste. How well it works will also be affected by the electrical properties of the solution, which you can't necessarily play with too much in foods without changing the taste, so it might not be the best technique for foods, but there are certainly other areas where it's useful.

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  • $\begingroup$ Could electroporation be used on pop drinks ( or would the carbonation be a problem)? If so could this be done instead of their problematic preservatives? $\endgroup$ – user128932 Oct 5 '14 at 5:40
  • $\begingroup$ Most soft drinks don't contain preservatives anyways, though some contain sodium benzoate (which has been in and out of the news for the possibility of producing minute quantities of benzene below harmful levels). Sterilizing soft drinks and packaging them in a sterile environment is probably possible, but would add a fair bit of cost. I bet most soft drinks are conductive enough for electroporation, but it's probably not worth the effort. If one really wanted to sterilize them, other techniques may be better suited for the volumes required. $\endgroup$ – Michael DM Dryden Oct 5 '14 at 5:55
  • $\begingroup$ Sorry to disagree but all soft drinks in convenience stores and many in grocery stores contain preservatives. The only ones that don't are Orangina and some European style pop drinks. Would sterilizing POP drinks be LESS expensive than using preservatives? $\endgroup$ – user128932 Oct 5 '14 at 6:11
  • $\begingroup$ I really doubt it would be cheaper. Sodium or potassium benzoate is super cheap. I don't know where you are, but in North America, only a few of the major soft drinks contain it, normal Pepsi/Coke/etc. don't, though some of the diet versions do. I'm not sure whether some have higher risk of fungal or bacterial growth because of their composition. Soft drinks don't need to last for years so there's not really much motivation in making them totally sterile. $\endgroup$ – Michael DM Dryden Oct 5 '14 at 6:28
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    $\begingroup$ It'll help, but there are certainly bacteria that can grow at pretty low pH. $\endgroup$ – Michael DM Dryden Oct 5 '14 at 7:12

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