Big Mallow is a cabal that's been spreading disinformation. 240F is a big, fat, arbitrary lie.
(
tl;dr: Marshmallow Mania hit me, and I spent 20+ hours making marshmallows. My findings suggest that the texture of marshmallows is dependent on the sum total proportions of the marshmallow ingredients, not the degree of sugar syrup heating. 240F is an arbitrary syrup temperature, and is used across the board for relatively similar ingredient proportions.)
A short time ago, I was developing my "egg yolk-based marshmallow"/marshyellow recipe (still needs a bit of tweaking). I was doing some research, and noticed something kind of...odd about the information regarding a specific step.
Here's the Wikipedia entry for making marshmallows that gave me pause, courtesy of Chocolates and confections: Formula, theory, and technique for the artisan confectioner: Anything jump out at you? No? That might be because you haven't read a variety of marshmallow recipes.
Bruno aside, they ALL place marshmallows at 238F-240F. I've seen a lot of marshmallow recipes in my time, and I've NEVER seen Wikipedia's method of 227F. (And I was so confused by Bruno's recipe...265F was way higher than any I'd seen. But we'll come back to this.)
Wait, it gets even more confusing.
My confusion kept growing with every article I read. Everyone's telling me something different. Recipes that call for soft-ball! No, proclaim the sugar syrup stages, firm-ball or hard-ball! And for some reason, Wikipedia's telling me the THREAD stage is what you want. This was perturbing; if baking is a science, my impression of candy making is that of analytical chemistry. It's precise, exact, and demands strict adherence to the recipe beyond what baking asks and cajoles. I was under the impression that the sugar syrup's concentration is critical to somehow correctly forming marshmallows. So what's going on here? Why's everyone using the same temperature in their recipes, despite background info to the contrary?
Clearly, there's a conspiracy being perpetrated by Big Mallow. They're trying to keep us in the dark, to prevent us from tinkering with marshmallow recipes.
So I...um...made a ton of marshmallows to figure this out. (pictured: about 2/3 of every batch I made, along with some marshyellow variants) Marshmallow Mania reigned supreme, and I spent an ungodly amount of time making them for both this experiment, and for my marshyellow recipe improvement. I'll also note that I had to eat an ungodly number of the stupid clouds of sugar and fluff, and would gladly never consume another so long as I draw breath.
First, to determine if you can make marshmallows at all of the claimed stages.
I checked my thermometer in a pot of boiling water to ensure accurate readings. Then I made batches of marshmallows at varying sugar syrup temperatures.
Here's my recipe and methodology (base recipe is based on a scaled-down version of Migoya's 'mallows):
8g powdered gelatin
47g cold water
110g granulated, white sugar
120g corn syrup
50g water
3g salt
~2.5mL vanilla extract
In the bowl of a stand mixer, bloom the gelatin in the cold water. Combine sugar, corn syrup, and water in a saucepan. Heat to (VARIABLE) temperature, and slowly add to bloomed gelatin, while whipping on medium-low speed. Turn mixer speed to max, and whip for exactly five minutes, adding the salt and vanilla halfway through. Using a greased spatula, scoop as much batter as possible into a greased pan, and use a greased offset spatula to smooth the top. Let sit for a minimum of 8 hours to cure, then cut into cubes and coat in an equal mixture (w/w) of cornstarch and powdered sugar.
Between each batch, I scrupulously cleaned all utensils with hot water to avoid sugar crystal residue.
Left-to-right: 225F. 230F, 240F, 245F, 250F, 262F After coating, the marshmallows were stored at room temperature in ziploc bags to maintain freshness/moisture contents.
The most apparent conclusion is that, yes, you can ABSOLUTELY make marshmallows at varying sugar syrup stages. Well, in a sense. They're all "marshmallows", in the sense that they're masses of aerated, gelatinized sugar blobs. I'm sure plenty of people have their own personal textural notions of what a "marshmallow" should be. But here are the differences:
Volume: Due to what I imagine is increased viscosity (due to decreased water concentrations of the syrup), the volume of batter decreases proportionally to elevated sugar temps.
Here, you can see the two extremes, 225F vs 262F. Weight: The lower temps allowed for increased aeration, which resulted in larger yields of 'mallow, and there's a downward trend corresponding to total batch weights and increased syrup temps. (225F->262F respectively, 249g, 242g, 222g, 211g, 203g, 165g)
Texture: The higher the syrup temp, the chewier and more "taffy-like" the marshmallow. Charybdis, my poor stand mixer, had a tough time whipping the 262F, that stuff was t h i c c. In contrast, the 225F melts in your mouth, with barely any chew. Far more pillowy, jiggly, etc.
Caramelization: The lower the syrup temp, the higher the final moisture content.
Held 10cm away from a torch, I noticed that it took slightly longer to caramelize the lower temp marshmallows. I wonder if there's also an aeration-based insulation factor at work (given the apparent increase in aeration in the lower-temp syrups).
So now I knew you can make marshmallows at most sugar syrup stages (I haven't tried soft-crack and upwards, I fear for my stand mixer's health after the 262F). Then I had a thought: what if the sugar syrup was a function of achieving a specific texture?
Enter the final experiment. Let's take the taffymallows of 262F and see if we can turn them into 230F squishmallows. At 262F, the sugar concentration is ~92%, and at 230F, it's ~80%. I calculated the amount of water lost at 262F, and added an amount of water to the gelatin that would correspond to the concentration at 230F. I figured it's easier to work "backwards", ie, make a higher temp identical to a lower temp. Going "forwards" might create an issue where reducing the water added to the gelatin leads to insufficient bloom. I don't thiiink you can "over-bloom" gelatin, so I doubt the reverse is true.
Well.
Here's the faux-230F with the real 230F::
[Compare the volume difference of the
faux-230F to the
262F and the 225F. By visual inspection, they were about double in volume to the original 262F!
And the texture was near-identical in nature to the 230F. The former were ever-so-slightly softer and "meltier", but they were also made a day or so after the latter, and I'm convinced that this accounts for the minor discrepancy. The final batch weights were identical too, suggesting similar aeration percentages.
(Note: The fact that they're
identical is a happy coincidence. There will be minor discrepancies due to unequal scooping of the batter into the pans, as well as additional mass from the sugacornstarch mixture. I cut all the batches into similar size cubes, so the surface areas would be similar, and they'd pick up similar quantities of the mixture.)
Suddenly, Bruno's aberrant 265F temperature made sense. His recipe uses egg whites in addition to gelatin, and egg whites are ~90% water. He heats his syrup to a much higher stage to compensate for the additional moisture content. I imagine that if you followed his recipe to a T, but stuck with good ol' 240F, the marshmallows would barely have much structure, and would be closer to the 225F squishmallows than what you'd typically want out of a marshmallow.
I did a repeat experiment with a different final hydration stage: 262F to 240F. The results were the same as before: I compared the product to my 262F and 240F marshmallows, and again, the faux-240F were no different than the real 240F (save, again, for a near-imperceptible difference for the same given reason as before).
Now, I refuse to say "I conclude X to be true", because my experiment isn't rigorous in the least. I didn't repeat each step numerous times, testing every possible extreme, I didn't test every potential example, etc. I would, but I think I'd go nuts, as I'd have an issue juggling this with my full-time job and other hobbies. I also nearly ran out of my 1lb tub of gelatin. So I'm going to leave it as "the data
suggests that..."
But the general idea this all suggests - aside from me being crazy - is that you can alter marshmallow recipes to achieve a texture
you prefer simply by changing either the syrup temperature, or the gelatin hydration. If you found a nice recipe for egg white marshmallows, but find them too soft for your liking, you can decrease the gelatin hydration within reason, and/or increase the sugar syrup temperature by some amount to make them chewier and more stable. If you don't mind the bit of math, you use this info to take more control of the marshmallow process.
I'm still not sure why people so unanimously use 240F as their temperature. I can imagine a scenario where Head Chef tells their underlings "Heat it to 240F, because [something something reasonable-yet-incorrect explanation]", and everyone follows HC's lead and reasoning. They move up the ranks, and proliferate HC's recipes, and if challenged about the reasoning, refer to HC's expertise to bolster their claims.
Look how many differing explanations people have about brownie skin/crust formation: It's easier to pull from your combined experience and instinct, and offer up a reasonable explanation, than to rigorously experiment your way to the answer. Or maybe there's actually a cult, I dunno.
But anyhow, thus concludes the week of the marshmallow. Please subject to peer review if you're also marshmallow-obsessed. I'd love additional insights and data!