Defending supermarkets as a whole, he added: “OK, you can say we haven’t been testing for horse – well, why would we?
“We don’t test for hedgehog either.”
That is a very interesting point actually.
This is analagous to testing for metals. For some metals you can do a simple test and just go “Yeah, that’s 99% iron” or whatever. Look, feel, shape, density, magnetism, a skilled scrap yeard worker can tell what most of the stuff coming through the yard is in seconds. Add a Geiger counter for radioactivity and you’re pretty much good to go.
But then there’s another end of the industry. Where you want and need to know not just what is the material basically, but what are all the trace elements in it? At which point you start to test for 72 elements (you can miss out the noble gasses and the transuranics etc). For example, we have one product where we need to make sure that Fe is below 5 ppm, Zr below 1 ppm. It’s a 99.995% purity and we don’t much care what the other 44 ppm of contaminants are. 999,950 parts Sc and O, 50 ppm allowable contaminants, but that Fe below 5, Zr below 1.
Given the way such measurements work you don’t actually count the Sc and the O. You count everything else and subtract from 1 million.
As you can imagine, this testing is rather more expensive that the glance and a feel that happens in the scrappie’s yard.
Now let’s turn to that meat problem. We’re going to test something to make sure that it is indeed what it says. Most of the time, usually, we’d go looking for beef DNA and on finding it say, yup, that’s beef.
But now we’re talking about trace amounts of other species. Some of this horse contamination is someone deliberately substituting, yes. But a lot of it, those trace amounts, is someone not cleaning the pipes between species being processed. Or the knives even. Which leads us to something of a problem.
How many species do we test for? Some minced beef…..or pink slime perhaps. Do we test for beef and horse? For beef, horse, mutton, pork, chicken, duck, goose? What about rat and mouse? For I’ll guarantee you that however much people try there will often be the odd molecule of either one of those in there. Sparrow? That’s more of a problem with grain processing but still.
For example, one lovely story about vegetarianism. Those (umm, OK, some) who have moved from the sub-continent to the UK. They carry on eating the (possibly Hindu caste based) vegetarian diet they are used to. And they start falling prey to all sorts of dietary deficiencies. Anaemia, there have even been reports of kwashikor (a protein deficiency). The grains and the pulses of the sub-continent have rather more insect and other residue in them than our more modern processing and storage systems provide.
People don’t test for hedgehog DNA in meat supplies, no. But how many species should they test for?
And there’s one other thing. Given the accuracy of today’s tests what are we actually meaning when we say “trace” amounts? Some modern water tests for example go down to parts per billion.
And one thing that I am absolutely certain about is that if we start testing food supplies down to ppb then absolutely everything is contaminated with something. At ppb you would, for example, find human DNA from the skin flakes of the human workers doing the processing. Does this make us all cannibals?