Mad Food Science

Chemistry + Cupcakes

Soy lecithin

If you’re one of those people that likes to read the ingredients on the box, you’ve no doubt noticed that soy lecithin is in just about every processed food product and confection. It’s everywhere, and yet you’re probably not totally sure what it is or why it’s even there. Kind of like Jersey Shore.

Like many of the “unpronounceables” on food packaging, you probably feel vaguely negative towards it. After all, if you can’t pronounce it, it must be bad, right? Not this time. Soy lecithin is generally recognized as safe, and some studies have even shown that it can help lower LDL cholesterol and triglycerides (the bad ones) and raise HDL cholesterol (the good one!). Of course like most health claims related to food products, the results of studies have been inconsistent, so don’t get too excited.

Soy lecithin is a byproduct of manufacturing soy-based vegetable oils. Because it’s readily available from plentiful soy bean crops all over the world, it’s the cheapest and easiest type of lecithin to mass manufacture. Lecithins can also be made from animal sources, like eggs (where lecithin was first discovered), but it’s a lot more difficult and thus more expensive.

Lecithins belong to a family of molecules called “phospholipids.” As I’m sure you remember from high school biology, phospholipids are the molecules that make up cell membranes (walls). They have one end that likes to be near water (hydrophilic) and one end that doesn’t like to be near water (hydrophobic). So they naturally arrange themselves in such a way that all the water-lovin’ ends are touching water, and all the water-hatin’ ends are pointing inwards, creating millions of microscopic capsules.

Soy lecithin is generally used as an emulsifier – something that helps create an emulsion. An emulsion is made of two liquids like oil and water that don’t want to mingle, like exes at a cocktail party. Oh sure, you can shake things up (maybe serve some shooters?) to get them mixing, but they will very quickly separate again. Add an emulsifier like soy lecithin, and all of a sudden your emulsion will come together. That’s because those millions of phospholipid capsules package up the oil inside of them, and allow it to “mix” into the water because the outsides of the capsules are water-lovin’.

The other thing soy lecithin does is make emulsions more stable. This means those millions of tiny capsules stay together longer, and would need more energy to break apart. This makes it excellent for creating foams. When you go to a fancypants modern restaurant and have “seared Nova Scotia sea scallop with citrus foam,” the foam is made by whipping citrus juice with soy lecithin to create stable bubbles.

So if that’s the “what,” then here’s the “why”: baking and confection making involves bringing water (and water-based liquids) together with oil (and oil-based liquids). When you or I bake, we use eggs as an emulsifier. But when the good folks at Tootsie Roll Industries have to produce a staggering 15 million Junior Mints a day, they opt for cheap and plentiful soy lecithin.

As far as the what and why of Jersey Shore goes, you’re on your own.
Try a different blog.

  • 28 February 2011
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