Sunday, July 11, 2010

Back to basics - an aside on melting butters

I realized I didn't include this in the whipped butter or lotion bar posts, so I'll include it here...

Sometimes your mango or shea butters can get grainy (this can happen to cocoa butter, but not as often as the other butters). The reason for this is the fatty acid profile of the butters.

Let's look at the fatty acid profile of shea butter - 3 to 7% palmitic acid (C16), 35 to 45% stearic acid (C18), 40 to 55% oleic acid (C18:1), and 3 to 8% linoleic acid (C18:2). The palmitic and stearic acid have different melting and solidification points (the oleic and linoleic aren't solid fatty acids, so they aren't relevant for this situation). After melting, the palmitic and stearic acids will eventually turn solid again, but each does it at a different temperature. If they cool slowly, the fatty acids can crystallize into large clumps, which causes the graininess. If they cool quickly, they won't have time to crystallize and you'll have a smooth product.

If you are finding your mango or shea butter is always grainy no matter what you do, you can temper it the way you would temper chocolate. Melt your mango or shea butter completely, then pour into a mould or container of some kind and put it into the fridge or freezer to cool very quickly. Remove, store in a cool dark place, then use when you need it. This should eliminate the grains you're finding in your products. (The reasons you could be getting grains even when you've been cooling the product quickly could be due to the way you're storing it, the way your supplier is storing it, and possible melting and cooling while shipping from the supplier or from the manufacturer to the supplier.) This will increase the melting point of your mango or shea butter in future products, but it will eliminate the graininess so it's hooray time all around!

This is one of the reasons I suggest melting your butters slightly and to put your products into a fridge or freezer to cool: The less we melt the oils or the quicker we cool them, the less likely we are to see the grains!


Topcat said...

Thank you for this - and all your other amazing and informative posts!

p said...

Hi Susan!

I'm a bit confused about tempering. when you say we can temper butters like we temper chocolate, do you mean that the concept, not the procedure, is similar? The procedure for tempering chocolate is very different, no? Pretty fiddly compared to just melting fully & popping in the fridge. This has always confused me!

I've also always wondered about how best to avoid graininess in lotions that contain butters (especially w/o lotions, where the percentage of butter could actually be really high) - is it best to pop them in the fridge once they're made? (I've tried this before with beeswax and borax lotions and they've separated! Not sure if would have separated anyway, though, lol!)

One more question for you - if you wanted butter to go grainy, how would you do it? I've done some experiments with this just for fun - sometimes when I melt my shea and let it cool at warm room temp, say 75-80 F, it's slightly grainy but, strangely, there's a film of liquid oil on top! But if I pop the melted shea in the fridge, take it out and let it soften at warm room temp, then put it back in the fridge, repeating a few times - boom, graininess! Is what's happening that I'm melting the palmitic fatty acids but not the stearic, so stearic is forming clumpy grains suspended in the palmitic & liquid fatty acid base? Or do I have the chemistry all wrong?

The fact that I'm able to make shea go grainy by melting, cooling, warming, cooling, etc. makes me wonder whether it's a bad idea to use shea in lip balms, which often end up in pockets getting heated up to near body temp, then back to room temperature, over and over again. I've been wondering about this for a while!

Thanks for your insights, Susan! It's such a delight to be able to ask you these questions that have been bugging me!


p said...

Forgot to ask - most of the info I've read on tempering shea & mango butter (for example here: recommend heating and holding, 175 F for 20 minutes, then chilling in the fridge. Is holding for 20 minutes really necessary? Also, 175 F is way higher than the melting point of the butter - what's up with that?

kontakt said...

Very interesting post! Thanks. I just wonder: if I will melt the shea butter before using it, does it make any difference if it is grainy? It should be the cooling of that product that matters, right? But if I make whipped butters, then it makes perfect sense to first take the grains out of the fat.

I don't quite understand what the fatty acid profile has to do with it, though. Would a butter with several different fatty acid lengths and melting temperatures be more prone to graininess, or the other way around?

Susan Barclay-Nichols said...

Hi p. Yep, I mean the concept of tempering our butter is similar to that of tempering chocolate - the process is different. When I cool any creations I make containing butters, I pop them into the fridge or freezer (although sometimes it's cold enough in my workshop to ensure quick cooling!).

Stearic acid has a melting point of 69˚C to 72˚C; palmitic acid has a melting point of 63˚C or so. If you heat the shea butter to about 67˚C, you'll have melted all of the palmitic acid, and probably some of the stearic. Cooling it now would definitely get you some grains! Your chemistry is correct!

I've used mango and shea in lip balms and lip sticks with great success, but it is a personal choice. Cocoa butter is generally a safer choice given we can't predict the heat to which our users will expose the products.

As for heating the butter to 175˚F, that's about 79˚C, so it's not that far off the melting point of the two fatty acids. I wouldn't necessarily hold it for 20 minutes if I'm not planning to emulsify it with anything or if I'm just tempering it because getting to that temperature should ensure all the fatty acids are melted.

Susan Barclay-Nichols said...

Hi kontakt! I've used grainy butter and had it come out just fine in a melted product but you're right about using them in non-melted applications like a whipped butter - you'll definitely want to melt the grainy stuff first, then let it cool quickly, then melt it down slightly again to remove the grains.

Butters containing more shorter chain saturated fatty acids - like lauric, myristic, palmitic, and stearic acids - are more prone to graininess than something like apricot kernel oil with 4% to 7% palmitic and 1% stearic acid would be. It has a lot to do with the types of fatty acids and their melting and solidification points.

If you had a butter that had only one type of fatty acid in it (can't find one to suit this example), then you probably wouldn't have a lot of problems with graininess as the product would melt and solidify at the same temperature. Let's call it fatty acid X with a melting point of 30˚C. You could heat it to 35˚C, see it melted, then let it cool.

But if we add fatty acid Y to the mix with a melting temperature of 40˚C, we've changed how much we have to heat the mixture to get a liquid and how much we have to cool down the mixture to get a solid. Now let's throw in fatty acid Z with a melting point of 50˚C. We heat the entire mixture up to 55˚C and allow it to cool.

If we leave this to cool at room temperature, Z will cool first as the temperature drops to 50˚C. As it cools, it will form little fatty acid crystals to which the other Z fatty acids are attracted. This is normal, but it can also entice fatty acids X and Y over because they are not yet cooled. This is how you get a grain.

If you cool it very quickly, Z will start to solidify at 50˚C, Y at 40˚C, and X at 30˚C, and there won't be time for the fatty acids to form crystals with the other types of fatty acids as they're too busy forming crystals with their own types as the temperature plummets.

You can see this in chocolate making. If you make chocolate and leave it at room temperature to cool, you get a matte finish. If you put it in the fridge or freezer, you get a shiny chocolate because all the fatty acids cooled quickly and didn't form bigger crystals or grains to mess up our lovely shine.

p said...

Wow, thank you! I get what's going on with graininess far better than I did before - yay! :)

I'm really confused about one thing, though - the melting point of stearic acid is pretty high, 69 C, or so. So how can the melting point of a butter that contains stearic acid be lower than 69 C? Cocoa butter is about a third stearic acid and its melting point is 38 C. Voyageur lists the melting point of shea, which is almost half stearic acid, as 29 to 32 C (and this jibes with my experience of it melting in my pocket!). Deeply confused, help!! :)

kontakt said...

That was a good explanation, thanks.

Susan Barclay-Nichols said...

Hi p. What a fantastic question! I hope I've answered it in this post!

Pam said...

Hi Susan,

I thought I read somewhere that butters can be frozen and then thawed for future use? If so is this true for all butter? How long can they remain frozen? What is the effect on graininess?

Susan Barclay-Nichols said...

Hi Pam. I freeze my butters regularly, and I haven't seen any difference in the graininess or non-graininess when I melt them. (Having said that, I tend to use refined or ultra refined versions of most things.) The big key is the melting and re-solidification of the butter when you're using them in a product!

Pam said...

How long can the butters remain frozen? How do you package them for freezing. Tks

Susan Barclay-Nichols said...

I've left my butters for months on end during the hot season around here, and they've melted without issue. I'd say 6 months is a safe period of time. I tend to package them in the container in which they came - which could be a plastic bag or jar - or I'll put them in a freezer bag to ensure they stay closed (I'm not a fan of the twist tie!). Just make sure they are closed well and you'll be fine. (As a note, you can do this with oils as well - just put the plastic - not glass!!! - bottle into the freezer!)

kki said...

Wow this thread of Q & A has been amazingly helpful! Thank you! My question is, if I were to temper my grainy butters to eliminate the graininess would I 1) temper all the grainy butters together or each separately, and then mix as I remelt them? 2) if I temper the grainy butters, would I still have to bring it to 70*C and hold for 20 minutes?

My other question pertains to butters in salves: I had made some salves and noticed that that particular batch started blooming (cauliflowering--developing clumps of lighter patches). The product also shrank so there was a gap between the salve and the tin. I was told to let the mixture cool at room temp the next time. So when I made the next batch, that's what I did. The product didn't "shrink" and it was beautifully uniform. BUT 1-2 months later, it started to form the cauliflowers again--the lighter color clumps. So upsetting! So I was wondering, after reading your tempering technique, if I should treat these this as a tempering process where the finished product (salve) can be treated as the "melt-and- quickly-cool phase (the temper phase?)" and then the remelting of the product could be the second part of the tempering process. Would that work? I really want to save this batch.

Thank you so much!

Susan Barclay-Nichols said...

HI Kki. I would temper them separately unless you want them to be combined. Then temper them together. (Sorry, not really sure about this question you're asking...) No, you don't need to hold them for 20 minutes. You want to bring them to the higher temperatures, then put them in the freezer.

Is your salve in a place where it could melt slightly and reform, because that sounds like what is happening. Do you have butters like babassu or coconut oil that melt at low temperatures? I'm afraid I can't really help without the recipe.

Susan said...

Hi Susan,

One question I've wonderered about solid lotions. I make a solid lotion bar with shea butter, cocoa butter, coconut oil -76, vitamin E, beeswax and some essential oil (usually lavender). They never seem to have grainyness to them HOWEVER I do find that after stored for a few months, they have some weird film on them... any ideas what that might be? Seems like oxidation, but I wrap them in wax paper and put them in an aluminum tin for storage.

Thanks, from another Susan :)