No-Fills CrustaStun

[Matthew Millar]

I trap crayfish and frequently and at present use a knife to dispatch the crustaceans before cooking them.

However, due to crustaceans having a distributed neural network rather than a cerebral cortex as in mammals, whether cutting through the head actually kills the crustacean or simply disables it is heavily debated, and so it is still unknown whether this is a humane practice.

A PETA award winning design for humanely killing crustaceans before cooking is the CrustaStun, and various industrial competitors, but retailing at £2,000 places this amongst the restaurant kitchen equipment, rather than domestic.

However, the technology in my mind seems simple.
Deliver an 5amp AC between cathode and anode (top and bottom of the crustacean) for 10 seconds. The crustacean is unconscious within 0.5 seconds and dead after 10.

So this is a two part question.

Firstly, I live on a boat with plenty of 12v DC, but AC isn't plentiful (I would need to invest in a new inverter to deliver 1.2kW). So firstly, does anyone know whether DC would be an effective alternative in a DIY setup? Are there any "electric shock" factors, in the sense of how do I deliver a deadly DC charge? (If I stick my fingers on both terminals of a 90Ah DC battery, I don't get a shock - but I have experienced a shock from a 500W computer PSU in the past).

Secondly, could the cathode and anode be re-implemented in the form of burying an metal plate anode into the base of a plastic bucket, pouring saltwater and crayfish into the bucket and then placing a metal colander cathode into the water on-top of the crayfish? How could this be implemented with DC? What would I need to protect the battery from a short circuit (e.g. resisters)?

If I'm missing questions or need to consider other factors, please bring them to my attention.

 

[telectrix]

that post causes me grave concerns about whether or not my treatment of food is humane. question is " does SPAM have nerves?"

 

[Lucien Nunes]

Both AC and DC can kill / stun / give shocks. What is important is the current, and to get a certain current through an organism of a certain resistance, needs a certain voltage. I haven't measured the resistance of a crayfish but I am fairly sure 12V isn't enough to achieve a high enough current density in the appropriate places to stun it. You would have to find out what voltage the commercial machine uses - one report mentions 110V - in which case a step-up converter is necessary, along with some kind of regulating / limiting system. If you have to step up, it is better to leave it as AC because passing DC through conductive solutions (rather than metallic conductors) causes electrolysis, gradually dissolving one of your electrodes into the organisms it contacts and possibly causing small chemical changes in the organism too due to the high current. With AC over a period of many cycles there is no net anode or cathode so the electrolysis is much less marked.

The electrified bucket will probably expend 90% of your electrical power heating the water and only 10% in the crustacean. I think the idea of the 'press' arrangement of the commercial unit is to ensure that the sponge electrodes are mainly in contact with the crustaceans rather than with each other, so that hardly any current bypasses it as it would in a bucket of water. There is also a very high chance of accidentally electrocuting yourself instead of the seafood! I would stick with the real machine instead of a Heath Robinson style lashup.

BTW the reason you got a tingle from a PC PSU was probably nothing to do with the low voltage DC output, but mains earth leakage of low current derived from the 230V side.

 

[rolyberkin]

I think your attempts to DIY electric shock the crayfish would probably be worse welfare wise than normal methods, aren't you meant to chill them prior to dispatch?

 

[uksrevivor]

Big pan of Boiling hot water chuck em in job done.