On Sun, 31 May 2009 12:09 Kathryn wrote:

>From the New Zealand Food Safety Authority:   (this has some interesting
>information that doesn't really answer my question)
>
>Does freezing kill all pathogens and parasites?
>
>No. A common misunderstanding is that freezing makes food sterile (ie, it
>kills all microbes including bacteria, yeasts and moulds) - this is NOT the
>case. The best way to kill pathogens and parasites in food is to cook food
>thoroughly.
>
>Although pathogens don't multiply in the freezer, certain species can
>survive the freezing process by going into 'hibernation' or forming
>resistant cells (eg, spores2) and up to 70% may 'come back to life' again as
>the food begins to thaw.3 Salmonella have been known to survive for 7 years
>at -23°C in ice cream and Campylobacter can survive freezing if the initial
>contamination levels are high. Also, freezing does not affect toxins left by
>certain bacteria (eg, staphylococcal enterotoxin and botulinum toxins).
>
For parasites, if you don't know what to look for yourself,
rely on your butcher. That is, a real butcher - don't shop
in a supermarket, which may have its meat prepared
by people with superficial training in all-round food 
hygiene. This is because a trained butcher will know what 
to look for. Organ meats, particularly liver, are most likely 
sites for parasites and a butcher will recognise a parasite 
(like a worm) or their cysts.

In the economic recession, we will be localizing and the oil-
based just-in-time distribution will collapse. To protect yourself
get to know a local butcher. If there are none nearby and you 
are relocating, take advantage of your shift to go to where 
there is a local butcher (preferably organic or biodynamic), 
a CSA farm etc.

Different species have different parasites that live in different
sites. For example, the kangaroo I eat has a particular
parasite that finds its home in the knee joint - this parasite
can infect humans.

Another source of generally reliable information, particularly 
in respect of game meat, is hunters. But many of these have
no formal training in food microbiology and rely on chance 
rather than informed prudence. On the other hand, some
hunters have made a study of all aspects of meat hygiene
and know as much - if not more - than a qualified butcher.

The advice quoted above is worth remembering: it's not
just parasites, it is toxins left behind by bacteria in the food,
as well as the toxins produced by these unwanted bacteria in 
your own gut. You won't see any sign of them.

Nor will you see any sign of 'mad cow disease' or many other
animal illnesses. We heard about 18m ago of cattle being
slaughtered in the US for human consumption that were so 
sick they could not stand. And we know that only a small 
proportion of animals and carcases are randomly selected 
for inspection.

Most bacteria are picked up by the meat in the slaughter
and butchering process from contaminated surfaces. If you
buy supermarket meat (or any meat not butchered by
experienced butchers on the premises), ALWAYS wash the
meat. Botulism can be fatal. Therefore, if you are eating
raw, don't choose mince, which can't, of course be washed. 
If you are cooking mince make sure you cook it right through. 
But remember, cooking won't protect you from botulism 
[see above] - it's simpler and reliable to just rinse off 
parasites and bacteria from the meat's surface - which is 
where most of them are. Muscle meat (like steak) is far 
less likely to have parasites or bacteria inside it (though 
this is not impossible).

Talk to a local food hygiene inspector for more information
about the sorts of contamination most frequently found in
your area.

Keith.