Sort of problematic is the "at a whim" part. Just a brief search to wikipedia on electric organs, here, we see that the electrocytes are controlled by a nucleus of pacemaker neurons. This is all unique to electric fish, and you'd have to express that whole system in a human being to elicit the same effect. You'd also have to consider how your organism is engineered to withstand the actual electric shock emitted by the electric organ.

We can already tag molecules with luciferase to emit light as a mode of bio-luminescence. To get an appreciable reaction, or rather an appreciably bright light, I can imagine we'd need a ridiculous amount of luciferin in vivo, though. We also get stuck at the part about it being on a whim. The control mechanisms/structures for the light-emitting reaction simply aren't present.

Can a portion of human skin cells be modified in some way to generate light?
I'm wanting to do a follow up to this Q&amp;A in the cooking stack regarding browning avocados. I specifically want to expand my experiment to to include the options in Wayfaring Stranger's Answer. Unfortunately, I managed to get the wrong stuff, and shipping rules make exchanging it problematic.

I am the proud owner of $500~\mathrm{g}$ of sodium bisulfate ($\ce{NaHSO4}$), instead of sodium bisulfite ($\ce{NaHSO3}$).

Dammit Jim! I'm a cook not a chemist!

What I have learned is that that both compounds are used as food additives towards the same end, and that my stuff has a slightly higher LD50. That's it.

Can anyone advise as to substituting my compound for the other? I'm not interested in tasty guacamole at this point, I'm really only looking at browning. If I'm trying to more or less duplicate the more successful experiments of the University of Florida, should I start with the same ratios? Or more or less of the additive? I can get sodium metabisulfite (also an anti-oxidant food additive) locally, if that would be a better option.

EDIT: So far, answers have all been consistent in that I have a half-kilo of white powder that is useless to me. I will make a trip to the wine-making shop and acquire some sodium metabisulfite. That still leaves me with the question of how much? The University of Florida got the results I'd like to duplicate with $30~\mathrm{mg}$ of sodium bisulfite per $100~\mathrm{g}$ of avocado. Should I start with the same ratio of sodium metabisulfite?
