Usefully Useless

Go here to read about the story if you like. I’m not about to go into the event, but instead why it’s happened.

Why would anyone want to contaminate milk with melamine? What’s there to gain?

Usually milk is tested for concentration, to ensure it isn’t watered down or adulterated, and this is done by testing its protein content. Watered down milk, or milk powder cut with flour, will contain less protein as it contains less milk.

The standard test done is simply measuring nitrogen content, since in milk most of the nitrogen is in protein. Protein in milk is usually around 15% nitrogen by mass. However, melamine is 66% nitrogen by mass and so can be added in to watered down milk to make it appear to be undiluted.

Normally this would be almost undetectable, without specific reason to test for melamine. Melamine is about as toxic as normal table salt, you could drink melamine contaminated milk every day for your whole adult life and merely have a heightened risk of kidney stones, nobody would notice without specifically testing for it

It’s fraud, plainly and simply. By passing off the milk as undiluted and passing off animal feed as higher in protein than it is, the companies who buy the stuff to use it are being ripped off.

Melamine itself is harmless, but mix it with cyanuric acid (again totally harmless) and the two form melamine cyanurate, which is insoluble and forms crystals in the kidneys, kidney stones. An adult’s kidney is large enough to simply expel the crystals before they grow any larger, but a baby (or small animal) cannot.

If melamine contaminated milk finds its way into infant formula, then the problems start. A baby’s kidney will form melamine cyanurate itself, infants do not have the same kidney function or renal chemistry that adults (and older children) do, meaning melamine is much more harmful, rapidly forming kidney stones which can prove fatal in babies.

It’s not just milk formula, however. Other products tested and sold by protein content are also known to have been contaminated in the 2006-2008 timeframe, such as animal feed. This is harmless to humans, but did kill 1,500 raccoon dogs being bred for fur and can find its way into eggs produced from chickens fed with contaminated feed.

China already sentenced two people to death for their part in the 2008 scandal (which affected 300,000 children, hospitalised 50,000 of them and killed six) , it’s likely more will follow. China is very protective of its booming export trade and will deal very harshly with people or companies which threaten confidence in its exports.

Following right on from the post below, this one visits hydrogenated vegetable oil. I’ll be touching on the chemistry of it too, but nothing too scary.

The basic chemical structure of organic chemistry is the carbon chain, which is a line of carbon atoms all bonded to each other. Each carbon can be involved in four bonds, so it usually goes CH3, CH2, CH2 … CH2, CH3. This’d be a long chain alkane, quite similar to what fuels your car.

The longer the chain gets, the stronger it can interact with other molecules near it, which is an attractive force. This makes them boil at a higher temperature and melt at a higher temperature. Diesel is thicker than petrol for this reason.

In the chain, carbon can be double-bonded to another carbon (this is what makes an alkene) and this is quite special, because double bonds do not rotate. Normal single bonds are freely rotatable which means the molecules can pack more tightly. If we have a double bond, the molecule can’t rotate around it, so can’t pack as tightly. It’ll have a lower melting point so be more likely to exist as liquid at room temperature.

Vegetable oils have quite a few double bonds in their carbon chain, such as maleic acid. (For chemistry students, this is a but-2-ene chain with two carboxylic acid groups on either end) We consider it to be unsaturated, a chemical term meaning how well hydrogenated it is. Since a double bond can be broken to a single bond by adding two hydrogen atoms to one of the bonds (one either end), it is not saturated. A saturated fat has few to no double bonds and has a much higher melting point – This is desirable, as we’ll see below.

We hydrogenate the fatty acids, then, (maleic acid will become succinic acid, a butane chain with carboxylics on either end) to adjust their physical properties. Margarine goes well on bread, but sunflower oil likely will not. By hydrogenating the sunflower oil, we make it more solid and more appetising. Few would pour sunflower oil on their morning toast, but many spread margarine on it.

This brings us now to the tricky bit: trans-fats. In nature, biology favours cis-fats and trans-fats are very rare. This is all about the conformation around the double bond, it looks like either a bowl or a Z. The bowl shape, where the molecule continues off on the same side it entered the double bond is known as “cis” and the other, where the molecule continues on the opposite side is “trans”. Cis is less stable than trans, which is important for hydrogenation.

When we hydrogenate, we break the double bond and form a reaction intermediate. This intermediate can re-form the double bond, but it may form either cis or trans, which trans being favoured. We wanted to add hydrogen across it, but this doesn’t always happen.

The worry is because trans-fats are very rare in nature and don’t metabolise well. Most of them pass straight through the bowel. The usual scaremongers are out in force about it. Trans-fats are linked to heart disease and various obesity statistics, but let’s come back into perspective. People who’s diets are already high in fat are the ones most likely to be high in trans-fats! We already know a high fat diet causes heart disease and obesity so really, the scaremongers are pretty much stating the obvious.

We’ve been doing hydrogenation on a grand scale for almost two hundred years, the current scare is way out of proportion to the actual risks: Someone with a high fat diet who’s already a good bet for heart disease may have a 5% higher chance of it.

My advice here? Sit back, relax and don’t worry about it. It’s just another “fat craze” to add on to the “monounsaturated fat” panic of the 1980s and the “polyunsaturated fat” panic of the 1990s. Both of which were pretty much the same deal, “Fat’s bad for you but THIS ONE is worse!”

A “fat” is a carboxylic acid with none (saturated), one (monounsaturated) or more (polyunsaturated) carbon-carbon double bonds in its chain. The smallest fatty acid is butyric acid (four carbons long) while the smallest common in nature is octyric acid (eight carbons long) and go up to 28. Most of them are unbranched chains and we traditionally exclude methanoic acid, ethanoic acid (acetic acid) and propanoic acid but many chemists use “fatty acid” to mean any acyclic (no benzene rings), aliphatic (no substituents other than the carboxylic) caboxylic acids.