Tuesday, November 30, 2010

Titer points!

The recent cold snap we've been enjoying in southwestern  B.C. had me thinking a lot about the effects of cold on our products, especially given that most of the ingredients in my workshop have either frozen or become so cold they won't pour out of the bottles. I got to thinking about why oils cloud when they get cold, so here's your chemistry lesson for the day! 

The titer point for fats is the temperature at which said fat will solidify. Our oils and butters all have titer points, which is considered the "temperature at which the lowest melting material becomes hazy". Our oils and butters are not composed of just one fatty acid - they tend to have quite a few, so it's important to know which of the fatty acids will solidify or melt first. "As a product is cooled, often there will be a cloudiness that forms as the least soluble material begins to crystallize. This cloudiness is called the cloud point or titer point..." (If you want more in-depth information on this topic, visit Melt Point vs. Titer Point on Cosmetics & Toiletries.) This titer point is the point at which our oils will go cloudy when you've stored them in a cool place or put them in the fridge or freezer.

If an animal fat solidifies at higher than 40˚C, it's a tallow. If it solidifies at lower than 40˚C, it's a grease. With non-animal fats, anything with a titer point over 40.5˚C is a fat and anything under 40.5˚C is an oil. Butters are over 20˚C but under 40.5˚C.

So why do we care? There are a few reasons - we can figure out if a product will melt on our skin on contact, we can figure out how cool we have to make a product before it solidifies, and we can figure out just by looking at the titer point if a fat is a liquid or solid.

Side question: Does it help to make our oils and other ingredients cool or frozen? Yes. It slows down rancidity, so our oils stay better longer. (Chemical reactions tend to speed up when we apply heat. When we apply cold, they tend to slow down.) If we put our oils in a cool, dark place - and I'm sure you've seen that recommendation a hundred times before - we can retard rancidity better than if we put them on a high, sunny shelf! We also slow down the growth of any possible bacteria or other nasties.

Click here for the primer on rancidity and here for the mechanisms of rancidity

If you've been storing your oils and butters in a cool, dark, or frozen place, you can heat them up slowly in a double boiler until you see you've passed the cloud point.

So now you know all about the fun of titer points. Let's take a look at iodine values tomorrow.

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