When I first heard that the suspected cause of the pet food deaths was melamine, I knew instantly what had happened. One of my previous careers was in food science, and I knew instantly that if you detected melamine in vegetable protein, the reason had been to forge the certificate of analysis.
Most people are blissfully unaware of how the nutritional content of food is analyzed- I assume many people, blinded by shows like CSI, assume that you pop a sample in the mass spec and out spits the carbohydrate, fat, protein content. In reality, nutritional content is largely computed through a series of assumptions- if you make 200g of a mixture which contains 1% oil, then it is given a fat content of 2g. Standardized tables are used- avocadoes are expected to contain 8% fat, so 100g of avocado into a guacamole mix is 8g of fat. No measurement is typically made. In some cases, things like carbohydrate content have never been measured- it was routine practice to determine protein, fat, moisture, etc, determine total calories and estimated caloric content of the pieces measured, and then the difference was "carbohydates" because no good test existed.
When using a manufactured ingredient, such as vegetable protein, there must be a certificate of analysis made to confirm what the nutritional content in the end product. Protein is not measured directly- there really isn't a test for it. Rather, elemental nitrogen is analyzed (because all protein contains nitrogen, but so do non-protein things like caffeine, too) by decomposing a small sample, and that number is multiplied by a conversion factor, ~6 (because protein is about 16% nitrogen, 100/16=6.25), which is then used to compute protein and calories. Any contaminating substance which is rich in elemental nitrogen, as melamine (which is 66% nitogen) is, will boost apparent protein content- each gram of melamine translates into four grams of computed protein.
There's a couple responses that I've heard to all this, and I have very mixed feelings about the tone and tenor of the responses.
First- nutritional analysis is important, but compliance with strict metrics such as "protein content" is not the total answer. Measurement is an important part of the assurance of "purity"- but blind adherance to protocol is also a danger to "safety". It's tough to do the science, and expensive, and so we tend to accept figures as given. The FDA does what it can to prohibit this. Much of my career lately has been spent on keeping systems and procedures for measurement and testing honest AND efficient. That's a tough problem- maybe not as interesting as rocket science, but requiring just as much intelligence.
Second- xenophobia is not the answer. Too often the response voiced, like at the bottom of the news story here, is to blame the Chinese or to blame our outsourcing and big business. During my visit to China a couple of years ago, it was abundantly clear that I had taken a journey in time back to how life was 100 years or so ago. They have cellphones and technology but as a culture, they haven't gone fully through the period we now look back upon and call "modern"- the industrial revolution. Lessons we have learned- such as those we have learned from The horse named Jim, Quackery, and Elixir Sulfanilamide, are important lessons which have taught us to demand purity, safety, and efficacy. Trust is harder at a huge distance, but just because something comes from far away doesn't mean it's less safe. Trust is important, but so is verification. If you have both- a history of reliability and good verification practices, you can source from anywhere. Without both, and you can be deceived by close friends- even unwittingly and without malice.
Third- education is the answer, not atavism. Part of the problem is not that we live in an industrial age, but that we don't want to take enough responsibility to know what we need to know to have a clear idea of what we put into our bodies. Even if you are a strict local-grown-only vegetarian: how do you insure you've eaten enough protein, carbs, vitamins, minerals? Abysmally, many people I know believe they can simply take a handful of vitamins to balance the equation, but thise vitamins are also chemicals, often sourced from the same places (like China) that many of them object to be "poisoning" us with unnatural gums and preservatives and industrial byproducts. We can't simply look at an "organic" tomato on the shelf of a local farmer's market, and trust that the organic-certified fertilizer used is free of bacterial contamination without scientific testing for microbiologial purity. We can't simply look at a sack of grain, and be assured that it was grown under sufficiently vigorous conditions that we'll get the calories and the protein from it that we need to be healthy and grow, without scientific testing to assure that growth and nutrition happened.
Fear and withdrawal are not the answer. We need to be genuinely curious about what we put into our mouths and what we feed to the ones we love. "Growing your own" is a good learning step, but it's not a total answer- one bad season, one drought or fire, one illness or accident, and you starve. Worldwide, there are a lot of mouths to feed. Science can provide some of the answers, but with power and industrialization come huge responsibilities. Everyone worldwide deserves safe food, effective medicines, pure water. Making sure that happens means not simply pulling into your shell- it means coming up with global solutions and ethical systems that benefit everyone.