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What's the difference between *76 & *92 ?


Sharon in KY

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76 degree coconut oil begins to melt at 76 degrees F. 92 degree coconut oil begins to melt at 92 degrees F.

Looking around online, I've found various answers for this. Some manufacturers will claim that the difference in temperature depends on how the oil was extracted and processed. Others claim that the 92F coconut oil has steric acid added, or at least a higher percentage of steric acid than the 76F. I've also seen other waxes added to bring up the melt temp, but don't recall which waxes off the top of my head.

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Coconut oil is a mixture of triacylglycerols, which in turn, are three fatty acids linked to a glycerol backbone. This is how the plant stores fats for metabolic use. Now, those three fatty acids can be saturated or unsaturated. Saturated means that all of the carbons in the fatty acid chain are hydrogenated (as CareBear mentioned above). Unsaturated means that the carbons do not have the maximum number of hydrogens linked to them. If the maximum number of hydrogens are not present, that means that some of the carbons have double bonds to other carbons (instead of single bonds to hydrogen).

The presence of double bonds is what actually changes the melting point of a fatty acid, or collection of fatty acids.

A fully hydrogenated fatty acid (saturated) is an extended molecule with no double bonds in the carbon chain. Extended molecules tend to pack together very well. A consequence of close packing is a higher melting point (it takes more energy - higher temp - to "unpack" the extended chains). The more saturated fatty acids, the higher the melting point.

On the other hand, an unsaturated fatty acid has one or more double bonds. This no longer allows the chains to take on the extended conformation; the double bond puts a kink in the chain. The kink pushes fatty acids away from one another, so they cannot pack together as well, and thus have a lower melting point. The more unsaturated fatty acids, the lower the melting point.

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76 degree coconut oil begins to melt at 76 degrees F. 92 degree coconut oil begins to melt at 92 degrees F.

Looking around online, I've found various answers for this. Some manufacturers will claim that the difference in temperature depends on how the oil was extracted and processed. Others claim that the 92F coconut oil has steric acid added, or at least a higher percentage of steric acid than the 76F. I've also seen other waxes added to bring up the melt temp, but don't recall which waxes off the top of my head.

This makes sense. Stearate is a saturated fatty acid. It is a chain of 18 carbons, all of which are completely hydrogenated. Its melting point is 71 C.

Compare stearate to oleic acid, linoleic acid and linolenic acid. All are chains of 18 carbons. Oleic acid has one double bond, and its melting point is 16 C. Linoleic acid has two double bonds (polyunsaturated) and its melting point is -5 C. Linolenic acid has three double bonds, and its melting point is -11 C.

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Functionally, yes, the melt point is the only difference. In soap it can be a wee bit harder. I've tried both and sought out 105F or 109F as well, can't remember which it was. I'd say that between the 76F and 92F you may notice a bit of a difference in hardness, but nothing MAJOR. Just my experience. I get super hard bars using 76F, so don't bother looking for paying for the 92F.

Honestly, if you think the 76F isn't giving you hard enough soap, there are things you can do. Increase the amount of oils that produce a hard bar of soap (coconut, pko, etc.) or use a bit of beeswax or stearic acid, add some salt to your lye water (1 tsp to 1 tblsp.)

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I made some soap with 100% CO 76, 0% superfat for use as laundry soap. You could have killed people with those bars! Within an hour of cooling off from gel, they were plenty hard enough to cut. If I had waited 24 hours, I'd have had to use a SawzAll.

The MP doesn't seem to make an appreciable difference in the hardness. SoapCalc doesn't show any difference in the numbers for the two oils.

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