Why is an ice cube rock solid whereas a scoop of Italian gelato is virtually liquid like? Even a ‘simple’ popsicle isn’t as hard as a pure water ice cube. Instead you have the right to bite some off fairly conveniently. Isn’t that interesting?

We’ve made fairly most ice creams already, fairly complicated ice creams including custards, a super easy ice cream through just two ingredientsor an Italian style semifredcarry out. In all cases we’ve sort of taken it for granted that the ice cream didn’t rotate out rock solid. Part of that is because of the advent of air. The ice cream was either made airy by incorporating whipped cream or many thanks to the constant stirring of the ice cream machine. But simply introducing air doesn’t execute the trick. Freezing pure whipped cream will still offer rather a solid icy framework.

You are watching: Does sugar lower the freezing point of water

In comes the prominence of sugar (or alcohol) and also a phenomenon called the freezing point depression!

What is freezing point depression?

The freezing suggest depression says that the freezing point of a mixture of two components is lower than that of individual components. It entails a solvent (e.g. water) and a solute which you’ll mix with the solvent.

A extremely widespread example of this phenomenon in everyday life is salting of the roadways in water. Pure water freezes at 0°C. However, by mixing in salt the freezing suggest of this mixture of water and salt will certainly drop well listed below zero. This is why salt is offered to store roads complimentary from ice. Even at temperatures listed below zero tbelow won’t be sheets of ice on the road.

So why is the freezing point of the solvent changed by disfixing somepoint else in it? Well, if you just have pure water (or any type of various other solvent) these water molecules have the right to organize themselves nice and also tight. When the temperature lowers and the water freezes they have the right to create a nice crystal among themselves (review even more around phase transitions). However, by mixing in a solute (e.g. salt or sugar) this nicely ordered structure is disturbed. Instead, they can only create these crystals at a reduced temperature. This is what happens bereason of the freezing suggest depression.

The freezing suggest depression in ice cream

In ice cream the freezing point of the water in the ice cream is modified. Water is the main components of most ice cream considering that it renders up the majority of of the milk or cream you could be using. The freezing suggest is mostly lowered through the addition of sugar. Sugar dissolves in the water and also this methods interferes through the crystal formation.

You might likewise expect the fat in ice cream to influence the freezing suggest. However before, that is not the instance. Water and oil carry out not mix rather bit bubbles of oil float about in the ice cream, but they never interfere in the very same method as sugar does.

Alcohol and also ice cream

In miscellaneous recipes alcohol is provided for making ice cream. Acomponent from the flavour and also alcohol it contributes to the ice cream it is likewise provided for lowering the freezing allude of water! Theoretically you could make ice cream without sugar and simply alcohol, yet, not certain whether that would taste as good…


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Ice cream via plenty of sugar

Calculating the freezing point depression

You deserve to calculate the readjust in freezing suggest of water in ice cream quite conveniently. The freezing allude depression is a so dubbed colligative residential or commercial property. This suggests that the temperature drop, so just how much the freezing suggest lowers, does not depend on the kind of component added, the solute. Instead, it just relies on the variety of pposts included as well as the original properties of the solvent to which they are added.

In other words, if we would certainly include 10.000 sugar molecules, this would certainly have the exact same effect on the freezing point as 10.000 salt particles. Only once the amount of solute becomes exceptionally high the form of solute becomes crucial.

Because of this straightforward partnership the freezing suggest depression can be calculated with a straightforward formula:

ΔTF= – KF· m ·i

Where:

ΔTF= The adjust in the freezing temperature in°CKF= the cryoscopic constant, this worth counts on the solvent you’re looking at, for 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 your pposts splits in 2 or 3 components after it’s been included to the solvent you need to take that into account, this is most widespread for salts. For sugars and the prefer which don’t break apart, this continuous is one, for sodium chloride (salt) it’s 2.Calculating the adjust in freezing suggest for ice creamVanilla ice cream

Let’s have a look at the readjust in freezing allude for a straightforward vanilla ice cream. This ice cream consists of around 600g (unstable assumption: 300 + 0.65* 300 + 4 * 25) of water and also 75g of sugar.

If sugar dissolves in water it will certainly not separation so i in the formula above is 1 and we also understand the worth for the cryoscopic consistent of water (1,853 °C·kg/mol).We then should recognize how many kind of sugar crystals we have actually. From literary works we uncovered that 1 mole of sugar molecules weighs 342,3g. Because of this 75g of sugar is 75 / 342,3 = 0,22 mol. Since we have 600g of water, the molality of the sugar is: 0,22 / 0,60 = 0,37 mol/kg.

Now it’s a issue of filling in the formula:

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

The freezing suggest dropped less than 1 level. This is actually really little, so this ice cream have the right to be made lot softer by including even more sugar.

Soft two-ingredient ice cream

Let’s execute one more instance to exercise these calculations, now looking at a super straightforward 2-ingredient ice cream. This ice cream includes 245g water (0,7 * 230 + 0,55 * 150) and also 70g sugar (0,45 * 150), for simplicity we’ve rounded of the numbers.

You have the right to usage the majority of the same numbers as in the previous calculation, but you’ll have to calculate the molality of sugar for this brand-new ice cream recipe. Using the exact same approach we uncover it is: 70 / 342,3 = 0,20 mol and also 0,02 / 0,245 = 0,83 mol/kg,

Let’s fill in the formula again:

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

Phase diagrams

Just this adjust of freezing allude doesn’t tell the complete ice cream story yet, it’s only the begin. Instead, as soon as you’ve obtained these new temperatures you need to have actually a look at a phase diagram. In a phase diagram you can watch precisely just how much ice and also liquid will certainly be existing at each different temperature. This is a little too much detailed for this article, however luckily there’s a sepaprice short article on the topic of phase diagrams for you.

A note on frozen fruits

Ever noticed that frozen fruits regularly aren’t rock solid? Acomponent from the impact of the fruit’s texture this is also because of the freezing suggest depression. The fruits contain fairly many sugar which prevent all the water from freezing!


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A video for even more explanation

A more standard explanation can be discovered in this great video from the Khan Academy.


Resources

An even more thorough explanation of the thermodynamics behind the freezing allude depression can be discovered on the websites of:UC Davis&Bristol College.


Great article.

You say “If you like you deserve to also calculate how a lot ice crystals have actually developed and you deserve to calculate what the new freezing temperature of your sugar solution is. If you prefer you deserve to also calculate how a lot ice crystals have actually created and also you deserve to calculate what the new freezing temperature of your sugar solution is.” Please tell me more. I guess, I might sindicate measure the temperature of some frozen ice cream to determine the freezing point.

For conmessage, I ‘m making residence low-calorie ice cream, frozen yogurts, and also sorbets. Over the months the batches are improving, but I am bedeviled by ice crystals, had actually texture after freezing, and also excess coldness on the tongue. Pure erythritol was good for calories and also taste, yet surrendered tough and also cold product. Presently, I am using a mixture of erythritol and also succlimbed (50% each). It’s much better, however still also hard and not creamy. I arrangement to attempt an additional fruit alcohol through even more freezing allude depression next.


Hello Mark,

Thank you for this fascinating comment and also question. It took me some time to come up via an appropriate answer, yet here it is, I hope it’s advantageous.

To start through your initially question, calculating the concentrations of ice crystals versus sugar solution. This question calls for a response much longer than just a comment so I determined to finish a blog article I had actually been functioning on which talks around this precise topic. Using so-dubbed phase diagrams deserve to tell you more around exactly how to calculate these values: https://jiyuushikan.org/phase-diagrams.There is also a way to calculate the freezing allude depression of a pure solution. It provides the molality of the sugar (or sugar substitute) to calculate the freezing suggest depression. This molality explains the number of molecules in a particular mass. Because of this the more molecules tright here are and thus the smaller they are, the even more effective they are. Aobtain, it’s a little bit also a lot for just a comment.

Then there’s your problem utilizing erythritol for ice cream. I should say that I have never before supplied erythritol yet I did some digging on the internet. Erythirtrol is a so called sugar alcohol as you might know. One of the attributes of erythritol is that it crystallizes more quickly than regular sugar, which could be one of the causes of your hard ice cream. This doesn’t necessarily have anything to carry out via the freezing suggest depression. At the very same time, erythritrol does have entirely various freezing point depression then regular sugar due to the different dimension of the molecule. Maybe this pdf file have the right to help you: http://www.jungbunzlauer.com/fileadmin/content/_PDF/JBL_AR_Erythritol_makes_a_difference_2015-104.pdf.

Hope that helps and many thanks for the questions!


Thank you very much. I look forward to analysis your fascinating article and finding out. It may be a little of a challenge as I didn’t pay sufficient attention in high school chemistry and was tossed out after I collection off a potassium permanganate and also sugar bomb. I guess I can always forgain my pride and also ask my high school kids.

Nonethemuch less, I prospered to be an epidemiologist and someday was faced by a hospital wbelow the water system was contaminated through ethylene glycol antifreeze due to a cross connection in the pipes. the contamicountry had happened at night and we necessary to decide conveniently if the water was safe to drink and for the hemodialysis machines (one patient had passed away in the time of the night as the molecules of ethylene glycol passed the semipermeable membrane.

My team saw the chemisattempt laboratory wbelow we learned they were unable to measure levels of ethylene glycol. the head technology had actually an concept. He filled a beaker with distilled water and one more with ethylene glycol. He put both in an ice bath and we watched in fascicountry as the water started to ice over and also he put a thermometer and also it verified 0 C. Soon afterword, the contaminated tap water froze well listed below 0. Hence, we didn’t enable people to drink the water.

the hospital toxicologist told us that he air conditioning liquid was marked via uridene green so world would know if there was contamination. Alas, he described that uridene green is a relatively large molecule so it didn’t pass the dialysis semipermeable membrane so nobody thought the fluid was contaminated till the patient slipped off right into a deep sleep and also passed away.

This was in New York City, wbelow the city lab can test for anything and they gave us via hourly tests as we fluburned out the building, which took around 12 hrs.

Forgive an old male for his stories. Based on the post you attached I have actually complied with its recommendation to use 1/3 erythritol to 2 parts sucincreased. Erythritol is good stuff. It is soaked up right into the body, so it doesn’t reason osmotic diarrhea prefer other sugar alcohols. Also, is cannot be metabolized by the body, so it is excreted unreadjusted in the urine and contributes 0 calories to the body. Also, it can’t be metabolized by dental bacteria, so it is not linked with dental caries.

Due to the fact that my goal is create the lowest feasible calorie ice cream, erythritol seems good for the project.

If I might, I’ll let you recognize exactly how my freezing suggest determinations on commercial commodities works out and also use this as a targain for my residence brew ice cream. If I deserve to number out how to usage the formula in your posting, I’ll compare this via my speculative results.

Best Wishes,Mark


Hi Paing,

Thank you for coming by! In order to calculate the freezing suggest of milk you should usage the cryoscopic constant for water and also then usage the formula to calculate the brand-new freezing point. However before, this isn’t right forward because there are both salts and sugars in milk. You would need to recognize the concentrations of all solutes in your milk and this varies per breed type and the diet of the cow.That shelp, there is rather many publimelted information on the freezing allude of milk. Generally, the freezing suggest depression of milk is a small even more than 0,5C (so the new freezing point is -0.5c). Milk is mainly water with only some salts and also sugar, so the lowering of the freezing allude is not that much. This post can aid you even more.


Thanks you and please answer what’s tha van ‘hof continuous for milk? Is that 1 or something else. and you must pointed out this formual result of freezing point depression should be in minus,i’m entirely perplexed via the 0.62 level celsius of freezing suggest depression of water added via sugar while original water freezing allude is 0 degree celsius.should be Tfi – Tfs = Kf*m*i


Hi Paing,

I included some clarification in the short article that will hopetotally aid you. Adding sugar to water lowers the freezing point by 0.62C. So the brand-new freezing allude is -0.62C.

Tbelow exist no van ‘t Hoff consistent for milk. Instead, check out milk as water with solutes such as sugar and also salts spread throughout. Use the cryoscopic continuous for water and then find the molality and Van ‘t Hoff consistent for the solutes that are existing in the milk.

Hope that helps!


Hello,

I am assuming succlimbed, yet not milk fat, lowers the freezing suggest of ice cream (around minus 20 levels C) .

What percent of sucincreased (or dextrose?) would certainly must be included to otherwise plain milk to proccasion it freezing at minus 22 levels C.Are there other food grade additives which have a similar effect?


Hi Pete,

Sucrose indeed lowers the freezing suggest, yet, it does not reduced the freezing suggest of all the water to listed below -22C in the amounts that you’d use in ice cream. Part of the water will still freeze, just not all of it (so the freezing allude of that remaining portion is indeed exceptionally low). I would not understand the precise concentration of sugar required to proccasion any kind of of the milk from freezing, generally, at this suggest the mixture becomes very viscous and various other components in milk (such as the lactose) likewise affect freezing so it’s not an easy calculation. I would certainly say you’d require >60w% of sugar (so of 100g of ice cream, more than 60% need to be sugar), possibilities are your ice cream won’t taste great anymore and also you could start having concerns disresolving all the sugar in your ice cream mix.Propylene glycol (which is additionally supplied in antifreeze, for the exact same reason) is also a solid freezing point depressor and also is allowed to use in ice cream, though it counts by place how a lot, absolutely at much reduced concentrations then sugar.

I think our course on ice cream, especially the area on freezing allude depression could help you out too, it has a couple of even more details than disputed in this write-up.

Hope that helps!Alcohol also lowers the freezing suggest, aacquire, it won’t proccasion all freezing, just part of it.


Thanks kindly for the response. I am largely interested in storing milk (or sweetened milk if requirements be) at minus 22 C. Such that it continues to be both palatable and liquid. .However before, 60% w/w sucrose is likely to be even more thick syrup quite than liquid. Probably attempting to do the difficult.


This is so interesting. How execute you regulate to come up with the water content in each. For instance, in the vanilla. I would have actually just assumed it was 300mL x 2 from the milk and also the cream. Where did the added 50g come from and just how can I calculate this for my own batches?

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


Hi Tiffany type of,

Great question (and I did alert tbelow was a slight error which I adjusted)! The water in the vanilla ice cream recipe comes from three sources: milk (which we’re assuming is 100% water here), cream (65% water) and also egg yolks (we’re assuming 25g water each). Do notice that whether you usage 600g of water of 650g the difference in freezing suggest is pretty tiny.

If you’re interested in digging deeper, I’d indicate you have actually a look at our complimentary ice cream course also wbelow we explain this in even even more detail!


Thanks for your reply and also clarification. I actually am enrolled in the course. I did desire to double examine but. If I get one question wrong on the quiz it typically doesn’t let me relocate on and it seems as though I have to reexecute the whole thing until I have the right to acquire to the following area.

I’m not certain if this is the instance or if I’m just having actually trouble navigating.

Another question though to clarify. Is it true that a lot of ice creams have around 20% sucincreased and some sort of glucose syrup and for this reason the freezing point depression of commercial items are commonly -18 deg C? Does this mean that up till -18 deg C the icecream will certainly not freeze rock difficult prefer water?

Thanks again!


Hi Tiffany type of,

Thanks for flagging your quiz issue! It shouldn’t carry out that and also allow you to development also if you didn’t gain whatever correct. We’ve updated some settings and it have to currently occupational fine.

For your second question, good question and one that calls for a long answer!:The freezing point of your ice cream mix will certainly primarily not be -18C. For it to be so low, you’d need to add means also much sugar. What happens though is that when you freeze ice cream, some of the water in the mix will freeze and also rotate right into ice. As a results you’re left with ice + sugar solution (aka water + sugar). Because there’s less water in the solution now, the concentration of sugar has raised. As a result, the freezing allude will be lower. Aacquire, some water will certainly freeze into ice and also you’re left through an even more focused sugar solution with an also lower freezing allude.In truth, this doesn’t go in steps but is a smooth transition. It indicates that at the end you’ve acquired ice crystals + sugar solution. The sugar solution provides certain the ice cream is still soft. The ice cream harden the ice cream. Balancing the concentration of sugar will encertain you’ve obtained your right texture at the finish and also remember that this deserve to be affected by other ingredients in the ice cream also (e.g. alcohol or salt).

Hope that clarifies!


When I was a kid …if you put ice cream right into a freezer it became gard as a rock.

Modern ice cream never gets hard….

See more: Everything Is Not Always What It Seems Quotes, Not Everything Is As It Seems

Why that?


Hi Tomi,

Ice cream manufacturing has developed a lot in the previous numerous decades, as has cold chain storage. Some of the distinctions I’d assume play a duty are:

Better temperature regulate via the logistics chain. Once ice cream has molten and sets again it becomes tough as a rock (it loses air).Better tools for making ice cream, e.g. better aeration of the ice cream which renders it easier to scoop.

Do those make sense? Any thoughts on your end?