Freezing Curve Dialog

The freezing curve dialog plots several curves showing how much water is frozen at a certain temperature. These curves are used to calculate the hardness of the ice cream and the recommended serving temperatures.

Freezing point depression

Freezing point depression, also known as FPDF, AFP, or PAC (Potere Anti-Congelante), refers to the phenomenon of reducing the freezing point of water. In the context of making ice cream, this concept becomes crucial in predicting the softness or scoopability of the ice cream at specific serving temperatures. Particularly, it plays a vital role in maintaining consistent softness among various flavored ice creams showcased in ice cream display cabinets.

The primary components responsible for lowering the freezing point are sugars, salt, and alcohol. You may have come across recipes suggesting the addition of a small amount of alcohol to achieve a softer ice cream texture. However, among these ingredients, sugar holds the utmost importance. By utilizing different types of sugars, you can effectively 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, because it would make the ice cream too sweet, you have to use a mix of different sugars.

While freezing point depression provides an indication of ice cream softness, other factors also influence the outcome. If everything else is equal the ice cream with the highest PAC will be softer but when we calculate the PAC in relation to the water content and look at the freezing curve we get a better measurement of softness.

The science behind freezing point depression is related to the molecular weight of an ingredient. The smaller the molecule the more it lowers the freezing point of water. 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.

Not all water freezes simultaneously. Utilizing PAC, we can determine the onset of water freezing, known as the freezing point (FP). At this point, no water is frozen (0% frozen). As freezing initiates, the sugar concentration in the unfrozen water increases, resulting in a higher PAC value for the remaining liquid. Lower temperatures are necessary to freeze additional water, which explains why ice cream machines cannot freeze ice cream completely.

To calculate the freezing point for sugars, we refer to a table containing experimental data on sucrose solutions. This table provides freezing point data for various sucrose concentrations.

Frozen water (%FW)

This curve shows the percentage of water frozen in relation to the total water. So, the amount of frozen water or ice can be presented in two ways. Either as a percentage of the total weight of the mix or as a percentage of the total water in the mix. This is the curve used for serving temp calculations.

Hardness

This is a similar curve to Frozen water and is the curve adjusted with the hardening factor HF in the ingredients (used for chocolate and nuts) where it acts as a negative PAC value.

Ice

The Ice curve is exactly the same as the Frozen water curve except it shows the frozen water as a percentage of the total weight. (Some other calculators or other resources might display this curve instead of the Frozen water curve so it is available here as well.)

Free water

The free water curve is the inverse of the Ice curve showing free water as a percentage of total weight.

% Ice cream and Serving temp

The ice cream serving temp is the temperature when ‘% Ice cream’ water is frozen and is by default 75%. So, at the temperature when 75% of the water is frozen we have an ice cream with a hardness that is suitable to be scooped with an ice cream scoop. You can modify this percentage slightly if you like but I recommend keeping it at 75%.

% Gelato and Serving temp

The Gelato serving temp is the temperature when ‘% Gelato’ water is frozen and is by default 69%. So, at the temperature when 69% of the water is frozen we have a Gelato with a hardness that is suitable to be scooped with a Gelato paddle. You can modify this percentage slightly if you like but I recommend keeping it at 69%.

Excel, CSV, EMF

Exports the data to different formats.

Checkboxes

Check/uncheck the checkboxes to show/hide curves in the graph.

Show freezing curve panel

Check this to show the freezing curves in the main dialog.