Sugar isn’t very good for our health, but it does taste fantastic. In fact, sugar is one of the staple ingredients of many modern foods and it is completely ubiquitous in most homes. But are we taking another less understood risk with our health, by having so much sugar around us? Is sugar a fire hazard or worse, could it explode in the right circumstances?
Common table sugar (sucrose) can catch fire at 662 degrees Fahrenheit (350 Celsius), which means that it is not technically flammable. However, powdered sugar, due to its smaller particle size and greater surface area, can be flammable and even explosive in certain situations.
So, here’s what you need to know about sugar and making sure that your family stays safe around it. Let’s take a look.
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Also read: What Makes Something Flammable?
What Is Sugar? (Chemically)
Sugar is a catch-all term for various different compounds which taste sweet to us.
The five most common types are:
- Fructose (found in fruit)
- Lactose (in milk products)
- Maltose (also in milk)
- Dextrose (a synthesized sugar that athletes often use)
- Sucrose (table sugar)
However, for the purposes of this article, we are going to be talking about sucrose. This is the most common form of sugar and it’s the sugar that most of us will have some quantities of in our homes.
Sugars are hydrocarbons with some oxygen in them too. The simplest sugar is glucose – C6H12O6 which contains 6 carbon atoms, 12 hydrogen atoms, and 6 oxygen atoms. All other sugars are slightly more complex but made up of similar atoms.
As with all hydrocarbons, the raw ingredients are very easy to burn.
Hydrogen is explosively flammable. Oxygen will burn in conjunction with nearly any other element (as an oxidizer), and even Carbon (think coal here) will easily burn to form Carbon Dioxide or Carbon Monoxide.
However, the more complex the hydrocarbon, the harder it is for them to burn as all the chemical bonds within the compound must be broken before they can burn.
This is good news when it comes to the flammability of ordinary table sugar because it’s just complex enough and in just big enough quantities that it won’t burn that easily.
Also read: Is Baking Soda Flammable? What About Baking Powder?
What Happens If You Put It In A Fire?
We regularly put sugar in fires because when you heat sugar, it melts and then it burns, ever so slightly, to form a substance that we know as caramel.
Caramel can be used to coat toffee apples, to form the crust on a crème Brulee, and even be eaten on its own because it’s delicious.
It is worth noting that you don’t want to leave sugar melting for too long.
Eventually, the molten sugar burns more than just a little and you get a sort of burned flavor throughout the mix – it’s not very nice at that point.
Sugar melts around 366 degrees Fahrenheit, that’s at about 186 degrees Celsius and it will caramelize at heats just above this. (although it technically doesn’t melt the many other things do, check this out).
Sucrose won’t ignite, however, until it reaches 662 degrees Fahrenheit or 350 degrees Celsius, though it can still burn at temperatures lower than this (hence the caution when making caramel).
Also read: Is Salt Flammable? Will it Catch on Fire?
What About Powdered Sugar?
Sugar dust or powdered sugar/icing sugar, on the other hand, is a whole different discussion to table sugar.
Powdered sugar is a highly flammable dust and it can even lead to explosions.
But why? It’s made out of exactly the same sugar (sucrose) as the table sugar.
Surely, the chemistry hasn’t changed? What makes this burn easily and explode?
Well, the chemistry hasn’t changed, but it is affected by the physical properties of the sugar.
Powder or dust contains much, much smaller particles than the crystals (or cubes) of table sugar.
When they are scattered in the air (for example by dropping the box, breathing over it, or shaking it vigorously – all things we are likely to do when using this kind of sugar), the ratio of oxygen to sugar is very different from the ratio of oxygen to sugar over a bowl of sugar on a table.
This leads to a greater surface area of the sugar.
It is the extra available oxygen in this mix that facilitates much easier burning. This is enough even to trigger an explosion in a cloud of sugar dust or powdered sugar.
Not only does powdered sugar explode easily, but so does that other staple of baking – flour and for much the same reason, the powder makes it much easier to ignite due to extra oxygen.
Also read: Is Dust Flammable? When To Worry… and Is Flour Flammable? Can it Explode?
You can see this in action in the video below:
This means that bakers need to be very careful in the kitchen with naked flames.
Powdered sugar has even caused explosions that have killed people!
“On February 7, 2008, at about 7:15 p.m., a series of sugar dust explosions at the Imperial Sugar manufacturing facility in Port Wentworth, Georgia, resulted in 14 worker fatalities.”
https://www.csb.gov/assets/1/20/imperial_sugar_report_final_updated.pdf?13902
This video goes into more detail about this tragic incident:
Also read: Is Honey Flammable? Will it Catch Fire?
Liquid Sugar?
Liquid sugar is a sugar suspension that contains juice and sugar syrup. Liquid sugar is not flammable and has an auto-ignition temperature of 932 degrees Fahrenheit (500 degrees Celsius).
According to this safety sheet, it is not considered to be flammable and while, again, it will burn if you heat it enough – there’s nothing to be concerned about in ordinary usage.
We suspect that it’s less flammable than table sugar because it will have higher water content.
Also read: Is Mayonnaise Flammable? Will it Burn?
At What Temperature Does It Burn?
Sugar (sucrose) will ignite at a temperature of 662 degrees Fahrenheit (350 Celsius).
That’s very hot and you’re not likely to encounter temperatures like that outside of the kitchen and even in a kitchen, you’re not likely to have raw sugar in contact with this kind of temperature.
This is good news because it means that table sugar is no real fire risk but you should be careful with powdered sugar and sugar dust as we’ve already noted.
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