Why is an ice cream cube rock solid vice versa, a scoop of Italian gelato is nearly liquid like? also a ‘simple’ popsicle isn’t as tough as a pure water ice cream cube. Instead you have the right to bite part off rather easily. Isn’t that interesting?

We’ve made rather a lot of ice creams already, quite facility ice creams including custards, a super an easy ice cream with only two ingredientsor an Italian style semifreddo. In all situations we’ve type of taken it because that granted that the ice cream didn’t rotate out absent solid. Component of the is because of the arrival of air. The ice cream cream to be either make airy by incorporating whipped cream or thanks to the constant stirring the the ice cream cream machine. However just introducing air doesn’t execute the trick. Freeze pure whipped cream will still provide quite a hard icy structure.

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In comes the prominence of street (or alcohol) and a phenomenon dubbed the freezing allude depression!

What is freezing allude depression?

The freezing suggest depression claims that the freezing suggest of a mixture that two materials is lower than that of separation, personal, instance components. It entails a solvent (e.g. Water) and also a solute which you’ll mix through the solvent.

A really common instance of this phenomenon in day-to-day life is salting the the roads in water. Pure water freezes at 0°C. However, by mix in salt the freezing point of this mixture of water and also salt will certainly drop well below zero. This is why salt is used to save roads totally free from ice. Also at temperatures below zero over there won’t be sheets of ice on the road.

So why is the freezing point of the solvent readjusted by dissolving something else in it? Well, if friend only have pure water (or any kind of other solvent) this water molecules have the right to organize us nice and tight. As soon as the temperature lowers and the water freezes castle can type a quite crystal amongst themselves (read more about step transitions). However, by mixing in a solute (e.g. Salt or sugar) this unique ordered structure is disturbed. Instead, they can only kind these crystals at a reduced temperature. This is what happens because of the freezing suggest depression.

The freezing allude depression in ice cream

In ice cream cream the freezing allude of the water in the ice cream cream is modified. Water is the main contents of many ice cream since it provides up most of the milk or cream you might be using. The freezing suggest is greatly lowered with the addition of sugar. Street dissolves in the water and also this means interferes v the crystal formation.

You might additionally expect the fat in ice cream cream to affect the freeze point. However, the is not the case. Water and oil carry out not mix instead little bubbles that oil float approximately in the ice cream cream, but they never interfere in the same way as street does.

Alcohol and ice cream

In various recipes alcohol is used for making ice cream. Except the flavour and alcohol it contributes to the ice cream the is also used because that lowering the freezing point of water! about theory you could make ice cream cream without sugar and also just alcohol, however, not sure whether that would taste together good…

Ice cream with plenty of sugar

Calculating the freezing suggest depression

You can calculate the change in freezing suggest of water in ice cream fairly easily. The freezing suggest depression is a so called colligative property. This means that the temperature drop, so just how much the freezing point lowers, walk not rely on the kind of component added, the solute. Instead, it only depends on the variety of particles added as well as the original properties the the solvent come which they room added.

In various other words, if we would add 10.000 sugar molecules, this would have actually the same impact on the freezing suggest as 10.000 salt particles. Only when the amount of solute becomes an extremely high the kind of solute i do not care important.

Because the this basic relationship the freezing suggest depression have the right to be calculated with a an easy formula:

ΔTF= – KF· m ·i


ΔTF= The readjust in the freeze temperature in°CKF= the cryoscopic constant, this value depends on the solvent you’re looking at, because that water it’s 1,853 °C·kg/molm = the molality of the solute, in various other words, the number of particles per kg of solvent, in mol/kgi = the van ‘t Hoff consistent if her particles splits in 2 or 3 parts after it’s been included to the solvent you have to take that right into account, this is most common for salts. Because that sugars and the prefer which don’t rest apart, this consistent is one, for salt chloride (salt) it’s two.Calculating the readjust in freezing point for ice creamVanilla ice cream

Let’s have actually a look in ~ the change in freezing suggest for a an easy vanilla ice cream. This ice cream cream contains approximately 600g (rough assumption: 300 + 0.65* 300 + 4 * 25) that water and also 75g the sugar.

If sugar dissolves in water it will certainly not split so ns in the formula over is 1 and also we likewise know the value for the cryoscopic continuous of water (1,853 °C·kg/mol).We then need to understand how numerous sugar crystals us have. From literature we discovered that 1 mole of sugar molecules weighs 342,3g. Because of this 75g of sugar is 75 / 342,3 = 0,22 mol. Because we have 600g the water, the molality that the sugar is: 0,22 / 0,60 = 0,37 mol/kg.

Now it’s a matter of pour it until it is full in the formula:

ΔTF= – KF· m ·i = -1,853· 0,37· 1 = -0,68°C

The freezing point dropped less than 1 degree. This is actually really little, therefore this ice cream cream can be made lot softer by adding more sugar.

Soft two-ingredient ice cream cream

Let’s do an additional example to practice these calculations, now looking at a super an easy 2-ingredient ice cream. This ice cream cream contains 245g water (0,7 * 230 + 0,55 * 150) and 70g street (0,45 * 150), because that simplicity we’ve rounded the the numbers.

You deserve to use a the majority of the exact same numbers together in the ahead calculation, however you’ll should calculate the molality of sugar because that this brand-new ice cream recipe. Using the same technique we discover it is: 70 / 342,3 = 0,20 mol and 0,02 / 0,245 = 0,83 mol/kg,

Let’s to fill in the formula again:

ΔTF= -KF· m ·i = -1,853· 0,83 · 1 = -1,55°C

Phase diagrams

Just this change of freezing point doesn’t phone call the complete ice cream story yet, it’s only the start. Instead, once you’ve gained these new temperatures friend should have a look at a phase diagram. In a phase diagram you have the right to see precisely how lot ice and also liquid will be current at each various temperature. This is a bit too much in-depth for this post, yet luckily there’s a separate write-up on the topic of phase diagrams for you.

A keep in mind on frozen fruits

Ever noticed the frozen fruits often aren’t absent solid? except the influence of the fruit’s texture this is also due come the freezing suggest depression. The fruit contain quite a many sugar which stop all the water indigenous freezing!


A video for more explanation

A more basic explanation have the right to be discovered in this good video native the khan Academy.


A more detailed explanation the the thermodynamics behind the freezing suggest depression can be discovered on the website of:UC Davis&Bristol University.

Great post.

You speak “If you prefer you can even calculate just how much ice cream crystals have formed and you have the right to calculate what the brand-new freezing temperature of your sugar systems is. If you choose you can also calculate just how much ice cream crystals have formed and you can calculate what the new freezing temperature of your sugar systems is.” please tell me more. I guess, I can simply measure the temperature of some frozen ice cream cream to recognize the freeze point.

For context, i ‘m making residence low-calorie ice cream cream, frozen yogurts, and also sorbets. Over the months the batches are improving, yet I to be bedeviled by ice crystals, had actually texture after ~ freezing, and also excess coldness ~ above the tongue. Pure erythritol was great for calories and also taste, but yielded hard and also cold product. Presently, i am utilizing a mixture the erythritol and sucrose (50% each). It’s better, however still too hard and also not creamy. I arrangement to shot another fruit alcohol with an ext freezing suggest depression next.

Hello Mark,

Thank you for this fascinating comment and also question. It take it me part time come come up v an appropriate answer, but here that is, i hope it’s useful.

To begin with your very first question, calculating the concentrations of ice cream crystals versus street solution. This question requires an answer longer than simply a comment for this reason I made decision to end up a blog short article I had actually been functioning on which talks about this exact topic. Using so-called phase diagrams have the right to tell you much more about just how to calculate these values: https://stillproud.org/phase-diagrams.There is likewise a method to calculate the freezing suggest depression the a pure solution. It uses the molality of the sugar (or street substitute) to calculate the freezing allude depression. This molality defines the number of molecules in a details mass. Therefore the much more molecules there are and also thus the smaller they are, the much more effective they are. Again, it’s a little bit too much for just a comment.

Then there’s your problem using erythritol for ice cream. I must say that I have never used erythritol yet I did some digging ~ above the internet. Erythirtrol is a so dubbed sugar alcohol as you can know. Among the features of erythritol is the it crystallizes much more easily than regular sugar, which could be among the causes of your difficult ice cream. This doesn’t necessarily have anything to carry out with the freezing suggest depression. In ~ the very same time, erythritrol does have fully different freezing suggest depression then consistent sugar as result of the various size of the molecule. Possibly this pdf paper can help you: http://www.jungbunzlauer.com/fileadmin/content/_PDF/JBL_AR_Erythritol_makes_a_difference_2015-104.pdf.

Hope that helps and also thanks because that the questions!

Thank you very much. I look front to analysis your fascinating post and learning. It might be a little of a difficulty as i didn’t pay enough attention in high school chemistry and was tossed out after I set off a potassium permanganate and sugar bomb. I guess ns can constantly forget my pride and also ask my high college kids.

Nonetheless, I prospered to it is in an epidemiologist and also one job was challenged by a hospital where the water mechanism was contaminated with ethylene glycol antifreeze because of a cross link in the pipes. The contamination had happened at night and we required to decide quickly if the water was safe to drink and also for the hemodialysis equipments (one patient had died during the night as the molecule of ethylene glycol pass the semipermeable membrane.

My team visited the chemistry laboratory where we learned they to be unable to measure up levels of ethylene glycol. The head tech had actually an idea. The filled a beaker with distilled water and also another through ethylene glycol. He placed both in an ice cream bath and we watched in fascination as the water began to ice over and he put a thermometer and also it verified 0 C. Shortly afterword, the contaminated madness water froze well listed below 0. Hence, we didn’t enable people to drink the water.

the hospital toxicologist told us that that air conditioning liquid was significant with uridene environment-friendly so human being would understand if there was contamination. Alas, he explained that uridene green is a relatively huge molecule so it didn’t pass the dialysis semipermeable membrane so nobody thought the liquid was contaminated until the patient slipped off into a deep sleep and also died.

This to be in brand-new York City, wherein the city lab could test for anything and they detailed us with hourly tests as we flushed out the building, which took around 12 hours.

Forgive an old guy for his stories. Based upon the write-up you attached ns have adhered to its reference to usage 1/3 erythritol to 2 parts sucrose. Erythritol is great stuff. It is took in into the body, so the doesn’t reason osmotic diarrhea like various other sugar alcohols. Also, is cannot be metabolized through the body, so the is excreted unmodified in the urine and also contributes 0 calories to the body. Also, the can’t be metabolized by oral bacteria, so that is not connected with dentist caries.

Since my score is create the lowest feasible calorie ice cream cream, erythritol seems good for the job.

If i may, I’ll let girlfriend know how my freezing point determinations ~ above commercial commodities works out and also use this together a target for my house brew ice cream cream. If ns can number out how to use the formula in your posting, I’ll compare this v my experimental results.

Best Wishes,Mark

Hi Paing,

Thank you because that coming by! In stimulate to calculation the freezing allude of milk you should use the cryoscopic continuous for water and also then usage the formula to calculation the new freezing point. However, this isn’t directly forward because there are both salts and also sugars in milk. Friend would have to know the concentrations of all solutes in her milk and this varies per breed type and the diet that the cow.That said, there is fairly a lot of published data ~ above the freezing suggest of milk. Generally, the freezing allude depression that milk is a little much more than 0,5C (so the brand-new freezing point is -0.5c). Milk is mostly water with only some salts and sugar, therefore the lowering of the freezing suggest is no that much. This article might assist you further.

Thanks you and please price what’s tha van ‘hof constant for milk? Is that 1 or other else. And also you should stated this formual result of freezing allude depression need to be in minus,i’m totally confused v the 0.62 degree celsius the freezing point depression the water added with sugar while original water freezing allude is 0 level celsius.should be Tfi – Tfs = Kf*m*i

Hi Paing,

I included some clarification in the write-up that will hopefully help you. Adding sugar come water lowers the freezing point by 0.62C. So the brand-new freezing point is -0.62C.

There exist no van ‘t Hoff continuous for milk. Instead, check out milk as water with solutes such as sugar and salts dispersed throughout. Usage the cryoscopic constant for water and also then uncover the molality and Van ‘t Hoff continuous for the solutes the are current in the milk.

Hope that helps!


I to be assuming sucrose, but not milk fat, lowers the freezing point of ice cream (about minus 20 levels C) .

What portion of sucrose (or dextrose?) would have to be included to otherwise level milk to protect against it freezing at minus 22 degrees C.Are there various other food grade additive which have a comparable effect?

Hi Pete,

Sucrose undoubtedly lowers the freezing point, however, that does not lower the freezing allude of all the water to listed below -22C in the quantities that you’d usage in ice cream. Component of the water will still freeze, just not all of it (so the freezing point of the remaining part is indeed really low). I would certainly not recognize the specific concentration of sugar compelled to prevent any type of of the milk native freezing, generally, at this allude the mixture becomes really viscous and also other contents in milk (such as the lactose) also influence freezing so it’s not simple calculation. I would certainly say you’d require >60w% of sugar (so of 100g of ice cream, much more than 60% must be sugar), possibilities are her ice cream won’t taste good anymore and you might start having worries dissolving every the sugar in her ice cream mix.Propylene glycol (which is also used in antifreeze, for the same reason) is also a solid freezing point depressor and is enabled to usage in ice cream, despite it counts by location how much, certainly at much lower concentrations then sugar.

I think our course on ice cream cream, specifically the section on freezing point depression might help you out as well, it contains a few more details than discussed in this post.

Hope the helps!Alcohol additionally lowers the freeze point, again, it won’t stop all freezing, only component of it.

Thanks kindly for the response. Ns am mainly interested in save milk (or sweetened milk if requirements be) at minus 22 C. Such the it stays both palatable and also liquid. .However, 60% w/w sucrose is most likely to be more thick syrup fairly than liquid. More than likely attempting to perform the impossible.

This is for this reason interesting. Just how do you regulate to come up with the water content in each. For example, in the vanilla. I would have just presume it to be 300mL x 2 from the milk and the cream. Where did the extra 50g come from and also how can I calculate this for my own batches?

Thanks very much! Gonna be nerding out on your site for the longest time.

Hi Tiffany,

Great inquiry (and ns did an alert there was a slight error which ns adjusted)! The water in the vanilla ice cream recipe originates from three sources: milk (which we’re suspect is 100% water here), cream (65% water) and egg yolks (we’re presume 25g water each). Do notification that whether you use 600g the water of 650g the difference in freezing suggest is pretty small.

If you’re interested in digging deeper, I’d imply you have a look in ~ our totally free ice cream course too where we describe this in even more detail!

Thanks for her reply and also clarification. I actually am enrolled in the course. I did desire to twin check however. If I get one inquiry wrong on the quiz it commonly doesn’t allow me relocate on and also it seems as despite I have to redo the whole thing until I can gain to the next section.

I’m not sure if this is the case or if i’m just having trouble navigating.

Another inquiry though to clarify. Is the true that many ice creams have about 20% sucrose and some kind of glucose syrup and also thus the freezing allude depression of commercial items room usually -18 deg C? does this average that up until -18 deg C the icecream will certainly not frozen rock tough like water?

Thanks again!

Hi Tiffany,

Thanks for flagging her quiz issue! the shouldn’t execute that and enable you to progress also if you didn’t get whatever correct. We’ve updated part settings and also it must now job-related fine.

For your second question, good question and one that needs a long answer!:The freezing suggest of her ice cream mix will normally not it is in -18C. For it to it is in so low, you’d have to add means too lot sugar. What happens despite is that when you freeze ice cream cream, few of the water in the mix will certainly freeze and turn right into ice. Together a outcomes you’re left through ice + sugar systems (aka water + sugar). Because there’s less water in the systems now, the concentration of sugar has actually increased. As a result, the freezing point will be lower. Again, part water will certainly freeze right into ice and also you’re left v an even more concentrated sugar equipment with an even lower freeze point.In reality, this doesn’t walk in steps however is a smooth transition. It method that in ~ the finish you’ve got ice crystals + sugar solution. The sugar solution provides sure the ice cream is tho soft. The ice cream harden the ice cream. Balancing the concentration that sugar will certainly ensure you’ve gained your right texture in ~ the end and remember the this deserve to be affected by other ingredients in the ice cream cream too (e.g. Alcohol or salt).

Hope that clarifies!

When i was a son …if you put ice cream right into a freezer it came to be gard together a rock.

Modern ice cream never ever gets hard….

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Why that?

Hi Tomi,

Ice cream manufacturing has developed a lot of in the previous several decades, as has cold chain storage. Few of the distinctions I’d i think play a duty are:

Better temperature control through the logistics chain. Once ice cream has molten and sets again it becomes tough as a absent (it loser air).Better equipment for making ice cream cream, e.g. Better aeration of the ice cream which provides it easier to scoop.

Do those make sense? any thoughts on her end?