Science – Ice Cream Calculator

How is PAC and POD calculated?

icecreamcalc — Tue, 22 Aug 2023 06:56:44 +0000

When adding ingredients most data is usually quite straightforward to calculate. You can use the Nutrition label information or the USDA database to input the data for an ingredient.
However calculating the PAC and the POD is a little more complicated.

First let’s recap what PAC and POD is.

PAC
PAC stands for ‘Potere Anti Congelante’ can also be called AFP-‘Anti Freezing Power’ or FDPF-‘Freezing Point Depression Factor’
This is a measure of how much the freezing point of the water is depressed. What it means is that the water freezes at a lower temperature. Different sugars affect the freezing point the most and salt and alcohol even more. The higher the PAC the softer the ice cream.

POD
POD ‘Potere Dolcificante’ is the relative sweetness of the ice cream. Another acronym is SP “Sweetening Power”.
The POD tells you how sweet the ice cream is.

For both PAC and POD sucrose (table sugar) is used as a reference with a PAC and POD of 100.
Other sugars and salts have different PACs and different PODs.
The smaller the molecule the more it will depress the freezing point and the PAC is higher.

To calculate the PAC you can use the molecular weight.
Sucrose has a molecular weight of 342.30 g/mol.
So, for example we calculate the PAC of Fructose. Fructose is a monosaccharide or simple sugar and it is smaller than sucrose (a disaccharide).
Fructose has a molecular weight of 180.156 g/mol
We just divide the molecular weight of sucrose with the molecular weight of fructose.
342.3/180.156=1.9
So, 100*1.9=190
The PAC of fructose is 190.

So, if you know the molecular weight of a sugar you can calculate the PAC.

To calculate the POD is a bit more complicated. The relative sweetness of a sugar compared to sucrose is not something we can actually calculate. Instead a panel will simply taste a solution of the sugar or sweetener and compare it to sucrose. So, all different sugars and sweeteners have been analyzed and tested and a relative sweetness has been defined.
Another problem is that the sweetness profile is different for different sugars, that is how fast and long the sweetness develops and lingers. Other sugars also does not taste the same as sucrose and some have side effects like off tastes or chilling sensations etc…

So why can it be hard to calculate the PAC and/or POD of an ingredient?
Well, the problem is that nutrition labels does not have to specify the exact carbohydrate profile of the ingredient. It only has to declare the total amount of sugars.
It also only have to declare mono- and disaccharides as sugars, higher order sugars are counted as carbohydrates.
So, if we read a nutrition label and it has 34g of sugars and 50g of carbs per 100g we don’t actually know what sugar or sugars it contains.
This is true for nutrition labels and in many of the ingredients in the USDA database.
If the sugar composition is not available the calculator assumes all the sugar is sucrose and calculates the PAC and POD for that.
(Unless you check the Dairy checkbox then all the sugar is assumed to be Lactose, the sugar in milk).
If you know the sugar composition you can use the PAC/POD tool and input the sugars for a better approximation.
If the USDA database ingredient has the sugar composition available that will also be used automatically. (Some ingredients have this info).

So, what do you do if you don’t know what sugar/sugars are used?
In the general case it can be hard, you can analyze the ingredient list of the item you like to add and see if it declares any specific sugars. If it does you can make an educated guess of the composition.
The best is if you can get a technical data sheet where the PAC and POD is declared or where the carbohydrate profile is declared. This is however usually not possible for normal supermarket ingredients. Even if you get a technical data sheet the PAC and POD is normally not declared unless the ingredient is specific for the ice cream market.

To summarize.
To calculate the PAC and POD of an ingredient without detailed information of the sugars it contains is not possible and the calculator will assume all the sugar is sucrose.

Glucose and Dextrose Explained

icecreamcalc — Tue, 11 Jul 2023 20:44:12 +0000

It can be a bit confusing when reading professional ice cream and gelato recipes the first time. They usually contain Dextrose or Glucose and then you might google a little and find out that Dextrose is in fact Glucose and you really don’t understand what is what and why different names are used. So in this post I will try to make this clear. The short version is that when you see Glucose in an ice cream recipe then that is some kind of Glucose Syrup or Glucose Powder and Dextrose is pure Glucose. The confusion is that in chemistry glucose is a sugar, a monosaccharide, but in the food industry glucose syrup refers to a sweetener made up of many glucose molecules derived from the breakdown of starch.

Glucose

So Glucose in chemistry is a monosaccharide. https://en.wikipedia.org/wiki/Glucose

Glucose syrup

Glucose syrup is made by breaking down the starch in corn (or sometimes wheat, potatoes, or rice) into simpler sugars, primarily glucose, through a process called hydrolysis. This process involves treating the starch with enzymes or acid, which breaks the large starch molecules into smaller glucose molecules. The resulting syrup is then filtered and purified to remove impurities.

Glucose syrup is often used in food manufacturing because it has several functional properties. It helps prevent crystallization of sugar, improves the texture and mouthfeel of products, enhances moisture retention, and acts as a bulking agent. It is commonly found in products like candies, desserts, baked goods, ice creams, beverages, and processed foods.

Glucose syrup is less sweet than pure glucose. This is because it contains other sugars, such as maltose and higher polysaccharides, which are not as sweet as glucose alone.

Atomized glucose, also known as powdered glucose or glucose powder, is a fine, white powder form of glucose syrup. It is derived from glucose syrup through a process called spray drying. In this process, a concentrated solution of glucose syrup is atomized into tiny droplets and then dried using hot air, resulting in the formation of fine glucose powder particles.

Glucose syrup usually comes in two variants DE40 or DE60 and Glucose Powder comes in many different variants defined by the DE value.

Dextrose Equivalent (DE)

Dextrose equivalence (DE) is a term used to measure the level of conversion of starch into glucose in glucose syrup. It is a numerical value that indicates the percentage of reducing sugars present in the syrup.

In the production of glucose syrup, starch is treated with enzymes or acids to break it down into smaller sugar molecules, primarily glucose. The degree of conversion determines the DE value of the syrup.

A glucose syrup with a DE of 100 means that it is fully converted, and all the starch has been transformed into glucose, resulting in a syrup that contains only glucose molecules. On the other hand, a glucose syrup with a lower DE, such as DE 40, indicates that only 40% of the starch has been converted, and the syrup contains a mixture of glucose, maltose, and higher polysaccharides.

DE values are used to classify different types of glucose syrups based on their sweetness and functional properties. Syrups with higher DE values tend to be sweeter and have a higher viscosity (thickness), while those with lower DE values are less sweet and more resistant to crystallization.

In summary, dextrose equivalence (DE) is a measurement used to describe the extent of starch conversion into glucose in glucose syrup. It indicates the percentage of reducing sugars in the syrup and helps classify syrups based on their sweetness and functional properties.

The higher the DE the sweeter the syrup or powder is. If the DE is between 5-20 the glucose syrup is called Maltodextrin and is used as a bulking agent in ice cream.

Dextrose

Dextrose is the old name for the glucose monosaccharide molecule. Dextrose has a DE of 100 meaning it is pure glucose.

The form of Dextrose used in ice cream is Dextrose Monohydrate. It is a specific form of dextrose that contains one molecule of water per molecule of dextrose. The presence of the water molecule gives it the “monohydrate” designation. Dextrose monohydrate is a form of glucose that is widely used in the food industry as a sweetener, flavor enhancer, texture modifier, fermentation agent, preservative, binder, and filler. Its versatile properties make it a valuable ingredient in various food products.

In ice cream Dextrose is very useful as it is less sweet than sucrose but has almost twice the freezing point depression. This makes it important for controlling the sweetness and hardness of the ice cream.

Eggs in ice cream

icecreamcalc — Thu, 06 Jan 2022 15:13:22 +0000

This post will explore eggs in ice cream. We will examine five different ice creams made with 0, 2, 4, 6 and 8 egg yolks. These ice creams has been balanced to have approximately the same Total Fat 15%, Total Solids 42%, Serving Temp -15C/5F, Sweetness POD 175 and MSNF/Water 15%. This means the ice creams are very similar. What is different is of course the fat composition, the 0-egg ice cream has all the fat from the milk and cream and the egg ice creams have some of the fat from the eggs. The eggs also contribute emulsifiers and stabilization. So for the 0-egg ice cream we add some emulsifier in the form of soy-lecithin. We also decrease the stabilizers as we use more eggs.

The recipe is a standard base recipe using Milk, Cream, Skim Milk Powder, Sucrose, Dextrose, Egg yolk and Stabilizer. This recipe is then balanced to have the same properties.

Emulsifiers

As egg yolks are the most common emulsifier in home made ice cream I will try to explain why we need emulsifiers in the first place.
An emulsion is a mixture of two liquids that normally does not mix. In the case of ice cream we have a fat in water emulsion. Milk and cream are already emulsions, milk fat is suspended in water and the protein (casein) in the milk acts as an emulsifier. Homogenized milk or cream are stable emulsions, this means they will not separate during storage. If the milk is not homogenized the fat will separate and create a layer on top.
When making ice cream the dasher in the ice cream machine will whip the mix to create a foam network of fat and proteins that traps air bubbles. What happens is that the fat droplets collide and join together and forms a network that holds the air.
Ice cream actually does not have enough fat to be whipped effectively. To whip cream, for example, the cream needs to have a fat content of at least 30%. If the fat content is lower it doesn’t work. Ice cream has a fat content much lower than 30%, so how can we whip air into our ice cream?
Milk and cream are actually too stable emulsions. So, we add an emulsifier to destabilize the milk fat emulsion. Some of the proteins in the milk will be displaced by the added emulsifier making the milk and cream a less stable emulsion. This destabilized emulsion can now partially coalesce in the ice cream machine and create the foam network needed to trap the air.
So, the bottom line is we add an emulsifier to our ice cream to weaken or destabilize the milk/cream emulsion in a controlled way to be able to whip it in the machine.

Adding an emulsifier to our ice cream will make the ice cream dryer and smoother. It will also make the ice cream melt slower and keep its shape better.

Here are three much more detailed posts on emulsifiers that you can read.
https://under-belly.org/ice-cream-emulsifiers/
https://www.dreamscoops.com/ice-cream-science/using-emulsifiers-ice-cream/
http://icecreamscience.com/why-are-emulsifiers-used-in-ice-cream/

Egg Science

Eggs yolks contain Lecithin that is a good emulsifier. Egg yolks can also work as a stabilizer thickening the ice cream mix. They also add fat, water and of course flavor.
One large egg yolk contains 1.5g Lecithin and to get emulsification we need 0.5-1% of the mix to be egg yolk. So, in a 1 Kg mix you will only need 1/4 to 1/2 egg yolk.
To get some of the thickening effect from the egg yolks you need 3-4%. So, 1.5 to 2 egg yolks per Kg mix. Also note that the mix has to be heated for the thickening to occur when using egg yolks.

I usually use two egg yolks as an emulsifier in my ice cream and maybe 4-6 if I want a custard ice cream. Using just 1-2 egg yolks will give you your emulsifier but you will not really be able to taste any eggy or custard flavor. For thickening I usually rely on other stabilizers.

Overrun

Overrun decreased with the number off egg yolks.
0-egg 46%
2-egg 42%
4-egg 40%
6-egg 36%
8-egg 34%

The viscosity of the mixes increased with the number of egg yolks. This is of course expected as the more egg yolks we add the more thickening we get.

Note! The ice creams has the same fat% and total solids so the overrun is most likely related to the amount of emulsifier and viscosity and not to total solids.

Melting

Here we can clearly see that the 0-egg ice cream melts much faster than the 8-egg ice cream. This is also expected. The images above are taken with ten minute intervals. It’s not clear if the melting relates to the egg yolks or the viscosity of the mix. Another experiment is needed where a 0-egg ice cream is compared to a 8-egg ice cream where the 0-egg mix is thickened to have the same viscosity as the 8-egg mix. In this experiment the viscosity increased with the number of egg yolks. The 0-egg and 2-egg mixes were quite watery and the 8-egg mix was quite thick.

Technique

All mixes were cooked to 85C/185F, chilled in ice water and aged for 6 hours. Churned in a Musso Stella 5030. Also, I don’t temper the egg yolks but instead just mix the milk, cream and egg yolks and add the well mixed dry ingredients using a hand blender to mix everything. This mix is then heated to 85C stirring all the time. I heated my mix in my Cecotec blender (Thermomix replica).

One thing I did this time was to remove the skin from the egg yolks before cooking. A comment on another of my posts suggested that some of the bad eggy taste was due to the egg yolk skin. So, this time I separated 20+ egg yolks and strained them through a fine sieve before adding the correct weight to each mix. I’m not sure this makes a huge difference but even the 8-egg yolk ice cream did not have a too eggy taste. I think it’s more important to not overcook the mix or cook it too long on high temperatures. But this is something you can test the next time you use egg yolks.

Conclusion

All ice creams have a good texture and taste. In a blind tasting the 6-egg ice cream was declared the winner, but it was very close. The 0-egg and 8-egg came in last.
There is no right answer how many egg yolks to use. It depends on the flavor you are making and personal taste. If using no eggs or very few eggs you should make sure you add some other emulsifier and that you add enough stabilizer/thickener to get the correct viscosity.

Recipes

The milk used is 3% fat and the cream 40% fat.

0-Egg
446.55g Milk
341.81g Cream
32.38g Skim milk powder
141.01g Sucrose
36.75g Dextrose
0.00g Egg yolk
3.00g Stabilizer
3.00g Lecithin

2-Egg
433.25g Milk
320.49g Cream
33.98g Skim milk powder
146.70g Sucrose
31.28g Dextrose
34.00g Egg yolk
2.30g Stabilizer

4-Egg
423.63g Milk
298.75g Cream
35.36g Skim milk powder
146.32g Sucrose
30.91g Dextrose
68.00g Egg yolk
2.00g Stabilizer

6-Egg
414.51g Milk
279.04g Cream
36.65g Skim milk powder
144.21g Sucrose
31.73g Dextrose
102.00g Egg yolk
1.50g Stabilizer

8-Egg
407.01g Milk
254.91g Cream
39.16g Skim milk powder
146.90g Sucrose
31.06g Dextrose
136.00g Egg yolk
1.00g Stabilizer

Stabilizer Experiment

icecreamcalc — Fri, 12 Nov 2021 16:07:00 +0000

In this experiment I did three identical ice creams with different amount of stabilizers. The idea was to figure out how they differ and what amount I liked best. Specifically I have looked at overrun, melting, texture, taste and mouthfeel.

The stabilizer used is Locust Bean Gum (LBG)

Recipe

The recipe used is a basic unflavored base with three egg yolks.

410g Milk (3%)
325g Cream (40%)
35g Skim milk powder
51g Egg yolk
143g Sucrose
35g Dextrose

The composition is like this

Samples

Three different samples was prepared.
Sample A
No LBG
Sample B
1.45g LBG corresponding to 0.25% of the water and 0.15% of total weight
Sample C
2.9g LBG corresponding to 0.50% of the water and 0.30% of total weight

All samples were prepared the same, heated to 85C/185F and aged for six hours then churned in my Musso Stella and extracted at around -8C/18F.

Mix after ageing

The viscosity of the samples was very different.
Sample A without stabilizer was watery.
Sample B with 1.45g LBG was thicker.
Sample C with 2.9g LBG was even thicker as you can see in the image.
Sample B clearly had the best viscosity. Sample A was too watery and Sample C was a little too thick.

Overrun

I measure the overrun for all three samples.
Sample A
36%
Sample B
42%
Sample C
36%

So a slightly higher overrun from Sample B but this is a little uncertain and could be measuring errors.

Taste

The actual taste was almost identical for the three samples. This tells us that the LBG itself does not change the flavor very much of the ice cream. The only noticeable difference was that Sample A tasted a little bit sweeter compared to the other two samples.

Texture and Mouthfeel

Now, here is when we start to notice quite big differences between the samples.
Sample A
The ice cream feels light and melts quickly in the mouth, there is almost no lingering flavor at all. This is not how I like my ice cream, the flavor disappears almost right away.
Sample B
A little denser compared to A and the flavor lingers in the mouth for a longer time. Much better compared to A.
Sample C
Maybe a little bit denser than B but not by much. The flavor also lingers even longer than B but you also get a slight cloying film in your mouth that is a little bit unpleasant. I’d still prefer C to A.

All samples are quite smooth but Sample B and C have a little less ice crystals and are a little smoother than A.

Melting

Images show the samples A, B and C at ten minute intervals.

One observation is that Sample A melts a little faster in the first ten minutes. After the first ten minutes the rate of melting is almost the same. The viscosity of the melted ice cream is very different between the samples and compares well to the mix before churning.

Conclusion

Adding Locust Bean Gum as stabilizer will greatly improve the ice cream compared to no stabilizer. The texture, consistency and melt of the ice cream is better. However adding too much will make the ice cream too viscous and can add a cloying film in the mouth that is a little unpleasant.

My personal preference is clearly Sample B with 0.25% LBG of the water weight. I think a little more would be even better maybe 0.30% to 0.35% of the water weight would be perfect.

Ice Cream Hardness

icecreamcalc — Mon, 31 May 2021 07:18:14 +0000

In this post I will try to explain how to calculate how hard your ice cream will be and what affects the hardness.

Ice Cream

First lets look at what ice cream really is. Ice cream is a mixture of water, air, fats, proteins, sweeteners, emulsifiers, flavors and sometimes stabilizers.
When calculating ice cream mixes we also need to explain solids.
Solids are everything that is not water and we can define a few different types of solids.
– Total solids is everything in the mix that is not water.
– Total solids not fat or TSNF is everything in the mix that is not water or fat
– Milks solids not fat or MSNF is the solids from milk and cream that is not fat. This includes lactose and milk proteins and minerals.

In a basic ice cream base of milk, cream, egg yolks and sugar the different ingredients contribute like this.
– Milk and Cream adds water, fats and MSNF
– Egg yolks adds water, fats, emulsifiers and solids
– Sugar adds solids

A typical ice cream will have 40%-50% solids and 50%-60% water. Gelato usually have 35-40% solids.

What affects hardness?

– Temperature
– Sugars
– Overrun
– Other factors

There are many factors that affects how hard the ice cream is at a certain temperature. How much air or overrun the ice cream has, how small the ice crystals are but the main factor is how much water and sugar is in the ice cream.

The amount of water in your ice cream and how much of the water that is frozen controls hardness.

Pure water freezes to ice so why doesn’t you ice cream do that?
The answer is sugar. When you add sugars to your ice cream the sugar will lower the freezing point of the water. This means that the water will start to freeze to ice at a lower temperature compared to pure water. And all water does not freeze instantly, it’s a dynamic process. When the water start to freeze the concentration of sugars will increase in the still unfrozen water. This means you will need a lower temperature to freeze the remaining unfrozen water. And so on.
So, just add more sugar and the ice cream will be softer? Yes.

Temperature

Homemade ice cream will usually be hard straight out of the freezer. This is also true for most premium brand ice creams like Häagen-Dazs etc. A domestic freezer should hold at least -18C/0F but your freezer might be even colder than that.
So, an ice cream designed to be scoopable at say -14C/6.8F will be hard out of the freezer and you need to temper the ice cream for a few minutes before serving.
The best method is to let it temper in a fridge for 15-30 minutes. How long depends on the ice creams hardness and the temperature of your freezer.

Sugars

Adding more sugar will make your ice cream softer. The problem is that your ice cream will also be sweeter. The trick is to use different kinds of sugars to be able to control both the hardness and the sweetness of your ice cream.

Sucrose
When we say sugar we usually mean sucrose. Sucrose is by far the most well known sugar and this is also the sugar that we will compare all the other sugars to. Sucrose is known as white sugar, table sugar, granulated sugar or regular sugar. Sucrose is a disaccharide composed of two monosaccharides glucose and fructose.

PAC and POD
We now have to introduce PAC and POD.
POD or relative sweetness is just how sweet a sugar is compared to sucrose.
Sucrose has a value of 100. If this value is lower it is less sweet and if it is higher it is more sweet.
PAC or Freezing Point Depression Factor FDPF is a measure of how much a sugar will affect the freezing point of water. Also here sucrose has a value of 100. If the PAC is lower it will have less effect and if it is higher it will depress the freezing point more. The science behind this has to do with the molecular weight of the sugar molecules. The smaller the molecule the more it will depress the freezing point. This is why the monosaccharides like dextrose and fructose have a higher PAC than sucrose. The molar mass of sucrose is 342 g/mol and the molar mass of for example fructose is 180 g/mol. If we take 342/180 we get 1.9. This means fructose has a PAC of 190 and it depresses the freezing point almost twice compared to sucrose.

Here is a short list of the most common sugars that is used when making ice cream.

Freezing Curve

The more water that is frozen the harder the ice cream will be. So, we need to figure out how much water is frozen. To do this we need to first figure out the freezing point of the ice cream. The freezing point is when the water in the ice cream starts to freeze to ice.
If we calculate the total PAC for our ice cream mix and divide that with the water we get what is called a Normalized PAC, you can think of this as the concentration of sugars in the water part of the mix. When we have this concentration we can use a table to calculate the initial freezing point of the mix. This table lists the freezing point of different concentrations of sucrose solutions, Ice Cream 7th Edititon by Goff, Hartel.
By using regression and simulating that more and more water is frozen we can calculate new freezing points. These freezing points will form a curve that is called a freezing curve. The freezing curve shows how much of the water is frozen at a certain temperature starting at 0% frozen water at the initial freezing point.

For hard ice cream we want to have approximately 70%-75% frozen water at our intended serving temperature.

A normal domestic freezer should have a temperature of at least -18C/0F. So, to have an ice cream that is scoopable directly out of the freezer we would need 75% frozen water at that temperature. Normally this is not the case, you usually have to leave the ice cream out for 10-15 minutes to soften up and reach a little higher temperature. I usually aim for -13C/9F to -16C/3F at 75% frozen water. You don’t want to suppress the freezing point too much because even if the ice cream will be softer it will also melt faster.

Example

Ok, lets show an example using only sucrose compared to using sucrose and dextrose.
Cream 300g
Milk 400g
Egg yolk 80g
Sucrose 155g
This recipe will have a sweetness of 170 and a serving temperature of -11C/12.2F when we have 75% frozen water.
To make this soft at -15C/5F we would have to add more sugar.
We would have to use 222g of sucrose and that would make the ice cream have a POD of 226. The sweetness would be far to high.

But we can add another sugar to solve this.
Cream 300g
Milk 400g
Egg yolk 80g
Sucrose 115g
Dextrose 61g
This recipe will have a sweetness of 170 and a serving temp of -15C/5F when we have 75% frozen water.

Since dextrose is less sweet than sugar but have almost twice the freezing point depression we can get an ice cream with the sweetness we want and the hardness we want at our serving temperature.

My best advice is to use sucrose and dextrose as your main sugars, if you also add fructose you have almost full control of sweetness and hardness of your ice cream.

Freeze Thaw Cycle

If you suppress the freezing point too much the ice cream might develop larger ice crystals over time. The problem is that most domestic freezers does not hold a constant temperature. They might have an automatic defrost cycle and also every time you open the freezer the temperature will change a little. This means that part of the water in the ice cream will melt and freeze. This is the so called freeze-thaw cycle. When the water freezes after it has melted larger ice crystals will form and the ice cream will become icier. This is also one of the reasons you want to consider using stabilizers in your ice cream to minimize this effect.

Alcohol and Salt

Both alcohol and salt depresses the freezing point very much.
Salt has a PAC of 585 and alcohol has a PAC of 740.
So, adding salt and/or alcohol will depress the freezing point a lot and make the ice cream softer.
The problem is that we really don’t want to add too much salt as it would make the ice cream too salty.
How about alcohol? One of the most common advice to make your ice cream softer is to add a little alcohol. Adding alcohol can be ok but it is usually not necessary if you know how to work with the different sugars. Alcohol will depress the freezing point but it does nothing for the texture and body of the ice cream. It can actually make you ice cream icier with larger ice crystals.
If you control the solids and water in your ice cream and use different sugars you do not need to add alcohol.

Chocolate and Nuts

Some ingredients affect the hardness of the ice cream in other ways. The fat and fiber in chocolate and nuts will make your ice cream harder. When calculating hardness this has to be taken into account. You can modify the PAC (like Corvitto) to account for this by setting lower or even negative PAC values for these ingredients. The problem with this is that you will not get a correct initial freezing point calculation. Another way is to calculate the freezing curve using the non-modified PAC values and to adjust the hardness calculation. This is done by a Hardening Factor. The HF acts like a negative PAC and a separate curve can be calculated taking the HF into account. The serving temperature is then approximated using both the freezing curve and the HF curve.

Freezing Curve Revisited

There are other ways to calculate the freezing curve. One popular method is to use this formula from Tchigeov (1979). https://www.researchgate.net/publication/233303640_Evaluation_of_Thermophysical_Property_Models_for_Foods

The blue curve is the freezing curve using the regression method. The green curve is the Tchigeov formula. I know some calculators use this but I don’t find it correct for the type of ice cream I am making.

Ice Cream Process

icecreamcalc — Mon, 23 Nov 2020 21:12:38 +0000

Introduction

In this post I have collected the methods I usually use when making my ice cream.

Mixing
When mixing the dry ingredients it is important to mix well. Stabilizers are used in very small quantities and to get good dispersion and avoid clumping they need to be mixed with the sugar and other dry ingredients for best effect.
It is also important to mix well when adding the dry ingredients to the milk and cream. Preferably using a high-speed blender or at least a stick blender.

Temperature
Many recipes call for cooking the milk and cream to almost boiling, then temper the egg yolks and finally slowly heating the mix to everything between 72C/167F to 85C/185F.
If using stabilizers that need over 85C/185F to hydrate this is the way to go, for example when using cornstarch you need to reach almost boiling.
If using stabilizers that hydrates at lower temperatures this is an unnecessary step. Just add the egg yolks at the beginning and bring everything slowly to temp.
I’m using 82C/180F for the stovetop method. For the sous-vide method I use 80C/176F but for a longer time.

Homogenizing
This is an extra step that you can perform on the mix when it is hot. Run it in a high-speed blender for 60 seconds to break up the fat globules into smaller pieces. This will improve the smoothness of the ice cream.

Chilling
My favourite method is using zip-lock bags in very cold water or ice water. The large surface area will chill the mix very fast. It’s also super convenient, just pop the bag in the fridge afterwards.

Aging
Aging is when you rest the mix in the fridge. This is to partially crystallize the fat making it easier to whip. This takes at least four hours at 3c/38F.

Classic stovetop method

Combine all dry ingredients in a bowl and mix well.
Add milk, cream and egg yolks to a pan.
Whisk in the dry ingredients.
Slowly heat to 82C/180F while stirring.
Transfer to a zip-lock bag and chill in ice-water.
Age in fridge for at least four hours or best overnight.
Churn in ice cream machine.

Stovetop using a blender

Combine all dry ingredients in a bowl and mix well.
Add milk and cream to a blender.
On low speed add the dry ingredients.
Run on high for 30 seconds to combine.
Turn speed to low and add the egg yolks and run for a short time to combine.
Transfer to a pan and slowly heat to 82C/180F while stirring.
Optional. After heating you can run the mix in the blender again on high for one minute to homogenize.
Transfer to a zip-lock bag and chill in ice-water.
Age in fridge for at least four hours or best overnight.
Churn in ice cream machine.

Sous-Vide method

Combine all dry ingredients in a bowl and mix well.
Add milk and cream to a blender.
On low speed add the dry ingredients.
Run on high for 30 seconds to combine.
Turn speed to low and add the egg yolks and run for a short time to combine.
Transfer to a zip-lock bag and sous-vide at 80C/176F for 45 minutes. Add some weights to the bag.
Optional. After heating you can run the mix in the blender again on high for one minute to homogenize.
Transfer back to the zip-lock bag and chill in ice-water.
Age in fridge for at least four hours or best overnight.
Churn in ice cream machine.

No-cook method

Combine all dry ingredients in a bowl and mix well. Make sure you only use stabilizers that hydrates cold.
Add milk and cream to a blender.
On low speed add the dry ingredients.
Run on high for 30 seconds to combine.
Turn speed to low and add the egg yolks if using and run for a short time to combine.
Age in fridge for at least four hours. I usually age for a shorter time than this with ok results. It’s kind of the whole point when using this method to make ice cream quickly.
Churn in ice cream machine.

Getting started

icecreamcalc — Sun, 11 Oct 2020 09:19:14 +0000

Table Of Contents

Getting started
What do you need?
Ratios
Stabilizer
Egg yolks
Milk and Cream
SMP
Sugars
Total solids
Example
Final words

Getting started

Do you want to be able to create ice cream recipes that are predictable and have the texture, softness, body and sweetness that you like?
Do you want to be able to tweak and change a recipe and not have it fail on you?

All good ice cream recipes are well balanced meaning that all the ingredients are there for a reason. So you can not just change it without consequence. You can not reduce the sugar and expect the consistency to be the same. You can not replace the cream with something else. Ice cream is chemistry and to modify or create a recipe you need to understand some of the basics of ice cream science.

This is my take on how to get started.

What do you need?

You need a compressor style ice cream machine. It will be much more fun and the ice cream will be much better. Ok, you actually don’t need this but it is highly recommended.

You need a scale to be able to weigh your ingredients. Forget the volume measurements start weighing your ingredients.

You need the following ingredients for your ice cream base. With this mix of ingredients you have great control over sweetness and consistency.
Milk
Cream
Skim milk powder (SMP)
Sugar (Sucrose)
Dextrose
Egg yolks
Stabilizer

Ratios

So, what do these ingredients do and how can you change the relative amounts to produce different results.
First we need to look at the ratios of your ice cream. The most important are.
Butterfat
MSNF
Total Solids
PAC
POD

Butterfat – This is the fat content from your milk and cream.
MSNF – This is the proteins in the milk, cream and SMP. It has great water controlling properties.
Total solids – This is everything that is not water.
PAC – This is the freezing point depression factor. This basically controls the softness of your ice cream at a certain temperature.
POD – This is the relative sweetness. Basically how sweet your ice cream is.

PAC and POD are mostly controlled by the sugars you add to the ice cream. And by using two types of sugars, sucrose and dextrose that have different properties, you can easily control the PAC and POD.

Stabilizer

Ok, this is somewhat optional but using a stabilizer will make your ice cream smoother and it will store better in the freezer. A stabilizer will thicken the water part of the ice cream and slow down the formation and size of ice crystals. Common stabilizers are egg custard, gelatin, starches and gums. I suggest you buy a commercial ice cream stabilizer OR that you use gelatin by adding one sheet of gelatin per 1000g of ice cream mix.
And when you want to learn more you should read the definite guide to stabilizers.
https://under-belly.org/ice-cream-stabilizers/

Egg yolks

When making ice cream the egg yolks will act as an emulsifier and a stabilizer. Here you can experiment and I suggest you use between 2-6 egg yolks per 1000g (3% – 10%). I don’t like egg yolks you say! Ok, many people want to make egg free ice cream for different reasons. Egg yolks can dampen flavours and has its own taste. If you don’t like to use egg yolks I suggest you try to use just 1 or 2, you will still get the texture benefits from the eggs but not much of the flavour. If you really really don’t want any eggs just get lecithin and use that instead. Use 1.5g of lecithin per egg yolk.

Milk and Cream

Milk and cream is of course the base of your mix, usually between 70-80% of the total weight. The milk and cream adds butterfat, and MSNF. What you want to do is to change the ratio between the milk and cream to get the butterfat amount that you aim for. There are great tools in the software to calculate what ratio of milk and cream you should use to reach a certain butterfat amount. Because the milk and cream fat content is a bit different in different countries you want to make sure you use the correct fat% for your milk and cream. So a simple example. If you use 400g of milk(2%) and 300g of cream(40%) in a 1000g mix you will get 13.2% butterfat. If your aim was 15% butterfat you would change this to 351g milk and 349g cream.

SMP

The skim milk powder is very important, it binds water and adds body to your ice cream. You will use this to balance the MSNF and the Total solids of your ice cream. I usually aim for about 8-10% MSNF. Just add SMP until you reach this.
Try to not add more than 10% SMP. Because the SMP can absorb a lot of water it can give your ice cream a sandy texture if you add too much.

Sugars

You will work with two different sugars. Normal table sugar sucrose and the sugar dextrose. Dextrose is only 70% as sweet as sugar but it has almost twice the freezing point depression. So, by combining these two sugars in different ratios you can control the sweetness and the softness of your ice cream. Follow these rules to manipulate the sugars.

Sweetness ok but consistency too hard
Increase dextrose and decrease sucrose, maintain POD and increase PAC

Sweetness ok but consistency too soft
Increase sucrose and decrease dextrose, maintain POD and decrease PAC

Consistency ok but too sweet
Decrease sucrose and increase dextrose, maintain PAC and decrease POD

Consistency ok but not sweet enough
Decrease dextrose and increase sucrose, maintain PAC and increase POD

And when you want to learn more read this very good post.
https://under-belly.org/sugars-in-ice-cream/

Total solids

Finally a note on total solids. The total solids is everything in your ice cream that is not water. Making smooth ice cream that is not icy means you need to control the amount of free water in the mix. When making ice cream at home we are at a disadvantage to commercial ice cream making because our ice cream machines are not as good. We can not freeze our ice cream fast enough and we can not freeze our ice cream fast enough after churning. The faster you can churn your ice cream the smoother it will become and the ice crystals will be smaller. To handle this at home we can make sure we chill our base properly before churning and that we pre-freeze our ice cream machine before churning. All to minimize the time it takes to churn our mix.
We can also aim for a high total solids amount. I suggest you aim for 42%-50% total solids.

Example

This can be a good starting point. This will make an ice cream with.
Butterfat 15.1%
MSNF 8.8%
Total solids 46.3%
PAC 283.8
POD 195.5
The freezing point is -3.7 C, 25.3 F meaning it will be quite soft out of the freezer.

Ingredient	Weight (g)	Amount (%)
Milk(2%)	350.0	34.97
Cream(40%)	350.0	34.97
Skim milk powder	40.0	4.00
Sucrose	160.0	15.98
Dextrose	40.0	4.00
Egg yolk	60.0	5.99
Stabilizer	1.0	0.10

Makes 1001g

Final words

Ok, this ice cream has no flavour ingredients. This is an ice cream base and to this base you can add different flavours. Use a base like this to add flavours like vanilla, coffee, spices and herbs. It is also perfect as a base for different add-ins.

Fruit and berries ice creams
If you want to make for example strawberry ice cream you need to modify this base quite a lot. Strawberry is 90% water so just adding strawberry will drastically change the ratios and you will get a very hard and icy ice cream. My best advice when making ice cream with fruit and berries is to replace the milk with the fruit. Milk also has approx 90% water. You also need to increase the SMP a little to account for the MSNF in the milk.

Chocolate ice creams
When making chocolate ice cream you need to skip the eggs and reduce the cream. Chocolate has a lot of fat and to avoid a too fatty ice cream we need to balance this by removing the eggs and reducing the cream. We also need to use more dextrose because the fats in chocolate freezes really hard and without using more dextrose the ice cream will be too hard.

Calculations

icecreamcalc — Sun, 09 Aug 2020 10:25:23 +0000

NOTE! Some of the information in here is not correct anymore. Please read the documentation

Ingredient

An ingredient has the following properties. Internally these properties is a value between 0-1. So if an ingredient has 10% sugar the value for Sugar is 0.1.
ButterFat
Fat
Sugar
MSNF
OtherSolids
Alcohol
Salt
PAC
POD

From these properties we can calculate the following.
TotalFat = ButterFat+Fat
TotalSolids = TotalFat + MSNF + OtherSolids + Sugar + Salt + Alcohol
Water = 1.0 – TotalSolids
PACtotal = PAC+PACsalt+PACalcohol

POD – relative sweetness. The POD value is not automatically connected to the Sugar property for a couple of reasons. First the Sugar property is the total amount of any sugar and different sugars have different sweetness. The other reason is that the POD can be modified to handle bitter ingredients (like cacao powder) by setting it to a negative value.

PAC – Freezing Point Depression Factor. For the same reasons as for POD the PAC is not connected directly to the Sugar property. For the ingredient category of “milk or cream” the PAC is automatically calculated.

Milk or Cream – If an ingredient is categorized as milk or cream you can only change the ButterFat content, all other properties are automatically calculated. This is how the other properties are calculated.
MSNF = (1.0-ButterFat) * 0.09
PAC = MSNF * 0.545
POD = PAC * 0.16
The MSNF also contain salts that I don’t include in any of the PAC properties. But the salts from MSNF are accounted for when calculating the freezing point.
Note on lactose. The MSNF contains lactose, this is the 0.545 factor (54.5%). Lactose is only 16% as sweet as sucrose and this explains the POD formula. The lactose from milk and cream is not listed in the sugars column in the software. The problem is that lactose is already accounted for in the MSNF so if adding it to the sugars it would be counted twice. The total solids calculations would be off.

Recipe

In a recipe we have a list of ingredients each with a weight. We also have an evaporation factor for how much water is evaporated when cooking the mix. This will give us a Total weight and a Final weight. The Total weight is just the sum of all the ingredients weights. The Final weight is the weight after evaporation. Since evaporation only removes water the different solids gets more concentrated. This affects the percentage of each data property and it of course affects the actual weight of the water property.
Weight = Sum of all the ingredients weights
Final = Weight * (1.0-Evaporation)
So, why complicate things with evaporation. Well evaporation is approximately 4-5% when cooking the mix in a normal way on the stove. Some people even cook for longer times to take advantage of the evaporation to increase the solids. But we will also utilize this when calculating the freezing point curve of the mix.

Freezing Point Calculations

Using PAC we can calculate the freezing point of our ice cream. In my software I calculate the freezing point separately for Sugars, Salt, Alcohol and the salts in MSNF. The freezing points are then summed to present the final freezing point (FP). The freezing point calculations are in Celcius or Kelvin (same scale) If you need them in Fahrenheit you need to convert them using F=C * 1.8 + 32

Normalized PAC
Before showing the actual calculations we must explain Normalized PAC. Normalized PAC is the PAC in relation to the total water in a recipe. So, if we divide PAC with the total water we get Normalized PAC. This is more useful because it accounts for the amount of water that needs to be controlled and without this we can not calculate the freezing curve.

Freezing point depression formula used for salt and alcohol (from Wikipedia)
If the solution is treated as an ideal solution, the extent of freezing-point depression depends only on the solute concentration that can be estimated by a simple linear relationship with the cryoscopic constant (“Blagden‘s Law”):
ΔT_F = K_F · b · i,
where:
ΔT_F, the freezing-point depression, is defined as T_{F (pure solvent)} − T_{F (solution)}.
K_F, the cryoscopic constant, which is dependent on the properties of the solvent, not the solute. (Note: When conducting experiments, a higher K_F value makes it easier to observe larger drops in the freezing point. For water, K_F = 1.853 K·kg/mol.^[8])
b is the molality (moles solute per kilogram of solvent)
i is the van ‘t Hoff factor (number of ion particles per individual molecule of solute, e.g. i = 2 for NaCl, 3 for BaCl₂).

Freezing point for salts
FPsalt = -2.0 * 1.86 * (PACnsalt / 58.44)
PACnsalt is the normalized PAC for salt

Freezing point for alcohol
FPal = -1.0 * 1.86 * (PACnalcohol / 46.0684)
PACnalcohol is the normalized PAC for alcohol

Freezing point from the salts in MSNF
Here I use the formula from “Ice Cream 7th edition” by Goff and Hartel.
FPmsnf = -(MSNF * 2.37) / Water

Freezing point from sugars
By using experimental data from sucrose solutions we can fit a polynomial equation.
FPse = -(0.0000000018 * x4 – 0.0000015486 * x3 + 0.0004066439 * x2 + 0.0429570733 * x + 0.1564927407)
where
x = PACn*0.1;
x2 = x*x;
x3 = x*x*x;
x4 = x*x*x*x;

Final freezing point
Just sum the freezing points to get the final freezing point of the mix.
FP = FPse + FPsalt + FPal + FPmsnf

Freezing Curve

Freezing Curve or Ice Curve is a curve showing the relationship between temperature and the amount of frozen water.

The Freezing Point FP of a mix is when the water starts to freeze. When the temperature drops, more water freezes. When more water freezes the concentration of the solids increases in the remaining unfrozen water. This means you need lower temperatures to freeze more water and so on.

I calculate this by simulating more and more water being frozen starting at the FP with 0% frozen water. Simulate that some of the water gets frozen and run the freezing point calculations again and so on. In my code I calculate the FP from 0% to 85% of the water being frozen. This curve can then be used to predict the hardness of the ice cream at a certain temperature.

More info on freezing point calculations in this post.

Adjusting the recipe

icecreamcalc — Mon, 27 Jul 2020 07:26:05 +0000

Adjusting the recipe

Let’s assume you have prepared the mix properly and your ice cream still is not perfect. Here are some pointers on how to adjust the recipe.

TOO ICY

Probably the most common problem with homemade ice cream. Iciness usually means you have too much free water and too little total solids. You should add more solids like milk powder, fat or sugars. You can also cook the mix longer to evaporate water. Also make sure you prepare the mix properly, let it rest in the fridge and that everything is as cold as possible when churning. The shorter time the ice cream spend in the machine the smaller ice crystals you will have. Smaller ice crystals gives you a less icy and smoother ice cream. Commercial machines can make a batch of ice cream in under 10 minutes, many home ice cream machines needs 30-40 minutes, so it is important to make sure you chill the mix and the bowl before churning. If you have a compressor machine you should start it 10-15 minutes before to let it cool down before adding the mix.

TOO SOFT

This is usually not a problem. The mix will freeze in the freezer after you have churned it. If it still too soft the recipe probably has a too low freezing point due to too much sugar, salt or alcohol.

TOO HARD

For homemade ice cream you usually have to take it out of the freezer and let it warm up in room temperature or in the fridge before serving. Normal serving temp should be -12C to -18C. If it is still too hard you have a too high freezing point usually due to too little sugar or milk fat. You can also have to much other fats from chocolate or nuts. This fat freeze really hard and should be accounted for. To fix you can add more sugars, salt or a little alcohol.

WRONG SWEETNESS

Well add or remove sugar. For best control you can use different sugars like sucrose, dextrose and fructose or glucose syrup etc. The different sugars have different sweetness and affect the freezing point differently.

TOO GREASY

To much fat. Try to decrease the amount of cream and add more milk. If adding ingredients with fat like chocolate or nuts you also need to decrease the cream.

NOT SMOOTH

If your ice cream has a sandy texture you have to much lactose from skim milk powder that has crystalized. SMP should not be added to more than 10%.
If your ice cream has buttery lumps referred to as buttering you either have to much fat or run the mix too long in the ice cream machine. Try to reduce the fat and make sure everything is as cold as possible to reduce the time the ice cream spends in the machine. If adding acidic ingredients to you ice cream (PH below 5) they should be added when the mix has cooled to avoid the milk from curdling.

MELTS TO QUICKLY

If your ice cream melts to quickly you might have too little fat, air, solids, emulsifiers or stabilizers. Homemade ice cream contains less air (overrun) than commercial ice cream, and ice cream with more air melts slower. An ice cream with more fat and emulsifier (egg yolks) can hold more air. More solids also makes the ice cream melt slower. So to improve melting you can add more eggs, more fat, more solids from skim milk powder and more stabilizer.

TO CHEWY

Probably too much stabilizer

Freezing point depression

icecreamcalc — Fri, 24 Jul 2020 16:19:36 +0000

Table Of Contents

Freezing point depression
Science
Implementation details
Sugars
Example
Freezing point
Freezing curve

Freezing point depression

Freezing point depression FPDF or Anti Freezing Power AFP or Potere Anti-Congelante PAC is the lowering of the freezing point of water. When making ice cream this can be used to predict the softness or scoopability at a certain serving temperature. This is especially important in ice cream display cabinets where all the different flavored ice creams must have the same softness. The main ingredients that suppresses the freezing point is SUGAR, SALT and ALCOHOL. You have probably seen in many recipes that you can add a splash of alcohol or a little salt to make the ice cream softer. But the most important ingredient is sugar. By using different types of sugars you can control the sweetness and freezing point of your ice cream. If your ice cream is too hard but has the correct sweetness you can’t just add more sucrose to make it softer you have to use a mix of different sugars.
The freezing point depression in itself is a hint of how soft the ice cream will be, there are other factors to consider as well. If everything else is equal the ice cream with the highest PAC value will be softer. When we calculate the PAC in relation to the water content and look at the freezing curve we get a better measurement of softness.

Science

The science behind freezing point depression is related to the molecular weight of an ingredient. Normal table sugar SUCROSE has a molecular weight of 342 and is used as a reference when calculating PAC.
100g of sucrose in 1000g of water has a PAC of 100
Other types of sugars have different molecular weights and thus affects the freezing point differently. What we do is to calculate the Sucrose Equivalent of any other sugar.

Implementation details

This section is an explanation of how PAC is implemented in the software. There is not a standard way of calculating this. Different sources calculate the PAC and FP in different ways and in different detail. My approach is like this. I calculate the PAC for sugars (PACse or PAC sucrose Equivalent) and use experimental data tables for sucrose solutions to calculate the FP. I then separately calculate the FP for salt, alcohol and for the salts in MSNF. These FPs are then added together to find the final FP. Alternative ways would be to sum the PAC from sugars, salts, alcohol and salts in MSNF to get one final PAC and either use the sucrose table to find the FP or use the linear formula for freezing point depression. So, if you look at other calculators or sources for PAC and freezing point calculations be aware that they might differ from my software both due to different calculations and also of course how the PAC is defined for the ingredients.

Sugars

The most useful sugars in home ice cream making are sucrose, dextrose and fructose. These are all in powder form and is easy to measure and work with. Honey, glucose syrup and other syrups are also common. Lactose is the sugar in milk and also affects the freezing point.

Sugar	PAC	Relative sweetness POD
Sucrose	100	100
Dextrose	190	70
Fructose	190	170
Glucose syrup (DE42)	80	50
Honey	146	94
Lactose	100	16
Salt*	585	0
Alcohol*	740	0

* Not sugars, just added for comparison

Example

To illustrate assume we have the following ingredients.
Water 800g
Sucrose 200g
PAC 200
POD 200
The PAC will be 200 and the POD (relative sweetness) will also be 200. Now we want to keep the relative sweetness and raise the PAC. We can replace some of the sugar with dextrose to accomplish this. Since dextrose only have 70% sweetness compared to sucrose we also need to reduce the water to get the same sweetness.
Water 784g
Sucrose 162g
Dextrose 54g
PAC 265
POD 200
So, by replacing some of the sucrose with dextrose we have kept the sweetness the same but increased the PAC making the ice cream softer.
If we use fructose as well we can use dextrose+fructose to get the same sweetness as sucrose.
Water 800g
Sucrose 150g
Dextrose 35g
Fructose 15g
PAC 245
POD 200
So, we can use a blend of sugars to manipulate the sweetness and the freezing point depression of our ice cream.

Freezing point

All water does not freeze at the same time. Using the PAC we can calculate when the water starts to freeze. This is called the freezing point or FP. So at the FP we have 0% frozen water. When water starts to freeze the concentration of the sugars increases resulting in a higher PAC for the remaining water. Thus we need lower temperatures to freeze more water and so on. This is also the reason why your ice cream machine can not freeze your ice cream completely.
To calculate the freezing point for sugars I use a table of experimental data of sucrose solutions. For salt and alcohol I use a linear formula based on the molality of salt and alcohol.

Freezing curve

Adding the freezing point for the sugars, salt and alcohol we get the initial freezing point of the ice cream. By simulating more and more water being frozen we can plot a freezing curve. This curve can then be used to calculate the serving temperature of the ice cream or indicate how much water is frozen at a certain temperature. I try to aim for approx 75% frozen water at -14C.