Tins/Cans question - one for Baccyman - anyone?

[Hyacinth]

.....in Olden Days, once a 'tin' was dented there was too much risk of poisoning (or at best, spoiling) from the tin to the food.....even if there wasn't a 'blowing' of the tin, one binned it.....

Nowadays? 'Tins' (cans) are routinely reduced in price but still sold - presumably still, in these highly litigious days, safe to eat.....so what's the change, if any, in the chemistry of our current 'cans' please that makes them safe to sell/consume?

[Hyacinth]

[Baccy Man]

Changes in tin can manufature from 1795-2000 listed here:
http://www.cancentral.com/hist_timeline.cfm

Products in slightly dented cans can be consumed as long as the product appears wholesome. Products from severely dented, leaking, rusty, or swollen cans should never be consumed.

[tim]

Olden Days?? Remember them well!!

[shirlton]

By the look of that photo Tim you were quite  a catch in the olden days.lol

[katynewbie]

 :-\

See? There's the thing Baccy "..severely dented cans should not be consumed" But that's exactly what the supermarkets have in their bargain bins! Could one sue if the product was inedible? God preserve us from the American habit of litigation, but there could be a case?

???

[Baccy Man]

If anything you bought from a supermarket made you ill you could sue. If you bought a severely dented tin and when you opened it you found the contents had gone off you could return it & get a refund.

[Rhubarb Thrasher]

we had a tin of gog food that had blown. It looked OK til I opened it, when the can exploded and covered the kitchen with gunk. The smell was appalling. the proteins had started to decompose into things like cadaverine and putrescine. We got a voucher for about £100 from Mr Dog Inc or whoever it was

[Melbourne12]

.....in Olden Days, once a 'tin' was dented there was too much risk of poisoning (or at best, spoiling) from the tin to the food.....even if there wasn't a 'blowing' of the tin, one binned it.....

Nowadays? 'Tins' (cans) are routinely reduced in price but still sold - presumably still, in these highly litigious days, safe to eat.....so what's the change, if any, in the chemistry of our current 'cans' please that makes them safe to sell/consume?

It's a while since I worked in the food industry, so I'm not full up to date, but as I understand it, the key change has been the introduction of plastic linings to cans.  The old-fashioned cans were made out of roled and pressed tinplate.  The outside was mild steel, and the plating inside the can was a tin alloy of some sort, which was inert to attack from the acids in food.

If the can was dented, the danger points would be the creases at the edge of the dents.  The tinplate lining could crack, allowing the juice in the can to come into contact with the steel.  This would erode until eventually a pinhole would appear allowing bacteria to get into the can and spoil the food.  Worst of all, the pinholes could seal up temporarily with rust, and so encourage the growth of anaerobic bacteria which produce poisons that lead to botulism.

Some cans (such as sweetcorn cans) had an enamel lining, but the same risks apply.

In recent times, steel cans have had a liner made of plastic resin.  This is not only inert, but has the advantage of being flexible, so it won't be fractured if the outer steel can is dented.

What I don't know is the extent that the old technology is still used.  I did a quick search to see if I could readily find out.  I didn't, but my search did turn up an amusing food scare put about by the loony tunes brigade, that plastic can liners contain something called Bisphenol A which is said to call down the wrath of the Earth Goddess on anyone who consumes it.

[Rhubarb Thrasher]

the bisphenol A surprised me a bit, and the looney tunes include the Canadian Government and Walmart
sometimes there's something in all these scares. They changed the formulation of clingfilm on the quiet some time back I remember

[Hyacinth]

Thanks to Baccy and all...I took the point that Katy had made too ....but Special Thanks to Melbourne who's given the most comprehensive answer which I'll print out...

Q was asked because yesterday lunchtime a client attempted to feed her young daughter a can of soup - which had a small dent in it. Child refused to have it because "teacher said....." I suspected that teacher's knowledge was about as comprehensive as mine (was! ;)) and that things have moved on over the years to make canned foods safer...

Would love to be a fly on the classromm wall on Monday ;D

PS I'm omitting the bisphenol last para....let b. teacher come back with that one... :D