How zmrzka calculates the composition of the mix

With every recipe on zmrzka you’ll see a table showing the composition of the mix: fat, milk solids, sugars, total solids, PAC, POD and, for sorbets, Brix. Nobody typed these numbers in by hand. The app calculates them from the weights of the ingredients — the same way for recipes from our content and for recipes you adapt or create yourself. Here’s how it works and where the calculation has its limits.

What the calculation is based on

Every ingredient in the zmrzka database has its composition per 100 g: water, fat, protein, fibre, starch, sugars broken down by type (sucrose, glucose, fructose, lactose, maltose, galactose and dextrins), polyols (erythritol, xylitol), alcohol, salt, milk solids non-fat and energy.

The values come from two public databases:

• USDA FoodData Central — the US food composition database (the SR Legacy and FNDDS datasets),
• NutriDatabáze.cz — the Czech database maintained by the Institute of Agricultural Economics and Information (ÚZEI) (version 11.26).

The values are rounded averages. For products that vary by brand (cream, yogurt, quark, chocolate), they represent a typical product on the Slovak and Czech market. The Slovak food composition database could not be loaded during our research, so it wasn’t used.

Milk solids non-fat (MSNF) are calculated for dairy ingredients as 100 − water − fat. For dairy products with added sugar (such as condensed milk), they are estimated from the protein, which makes up about 38 % of MSNF.

What the individual numbers mean

Everything is in per cent by weight of the mix. The method is always the same: for each ingredient, the composition per 100 g is multiplied by its weight, everything is added up and divided by the total weight of the mix.

• Fat — all fat from the ingredients (dairy and vegetable, from nuts, chocolate or yolks).
• MSNF — milk solids non-fat: protein, lactose and minerals from milk.
• Sugars — all sugars except lactose, including sugars from fruit and dextrins from syrups, plus polyols. Lactose is shown separately because it is already part of MSNF.
• Total solids — everything except water and alcohol.
• PAC — anti-freezing power in grams of sucrose per 100 g of mix, including lactose. The higher it is, the softer the ice cream at a given temperature.
• POD — sweetening power in grams of sucrose per 100 g of mix.
• Brix — the proportion of all dissolved sugars and polyols, including lactose. It is shown for sorbets and granitas.

PAC and POD are calculated by multiplying each type of sugar by a coefficient and dividing the sum by 100. They are explained in detail in the article PAC and POD.

Coefficients

Sucrose has a value of 100. The coefficients for common sugars come from the sweetener table in Goff and Hartel’s book (Ice Cream, 7th edition). For polyols and alcohol they are calculated from molar mass, and for dextrins they are an estimate.

The coefficient for dextrins is set so that DE 40 glucose syrup comes out close to the table value for DE 42 (PAC around 80 on a dry basis), and DE 18 maltodextrin around 35. Exact figures depend on the syrup manufacturer.

Example: egg-free vanilla ice cream

The egg-free vanilla ice cream recipe has 450 g of whole milk, 400 g of 33 % cream, 35 g of skimmed milk powder, 140 g of sugar, 30 g of dextrose and 3 g of vanilla — 1,058 g in total.

• Fat: 450 × 3.5 % + 400 × 33 % + 35 × 0.8 % ≈ 148 g, i.e. 14.0 %.
• MSNF: 450 × 8.7 % + 400 × 6 % + 35 × 95.7 % ≈ 97 g, i.e. 9.1 %.
• Lactose: about 52 g (4.9 %). Added sugars: 140 g of sucrose and 27 g of glucose from dextrose, together 15.9 %.
• PAC: (140 × 100 + 27.5 × 190 + 51.8 × 100) / 100 ≈ 244 g of sucrose equivalent, per 100 g of mix 23.1.
• POD: (140 × 100 + 27.5 × 74 + 51.8 × 16) / 100 ≈ 169 g, per 100 g of mix 16.

Balance from the mix, nutrition from the whole recipe

The composition table (fat, sugars, PAC…) is calculated only from the mix that goes into the machine. Toppings, sauces and pieces added at the end (marked as toppings in the recipe) aren’t included — they don’t freeze together with the mix in the machine and have no effect on the hardness of the ice cream.

Nutritional values, allergens and suitability for diets, on the other hand, are calculated from the whole recipe including toppings, because you eat all of it. Optional ingredients aren’t included in the calculation; their allergens are shown separately.

If a machine needs different quantities (for example the CREAMi or the no-machine method), the recipe has its own ingredient list for that machine and the composition is calculated separately.

Target ranges for each type

For each number, the app shows whether it is within the range for the given type. The ranges are based on the technical literature (mainly Goff) and adjusted for a home freezer at around −15 to −18 °C.

Limits of the calculation

• Fruit varies. The sugar in fruit depends on the variety and ripeness. For banana, NutriDatabáze gives 19 g of sugars per 100 g, USDA only 12 g. For sorbets it’s worth measuring the purée with a refractometer.
• Syrups are an estimate. Glucose syrups differ by DE and manufacturer. Dextrins are estimated in zmrzka.
• Custom ingredients without a composition count only towards the weight. The app then shows what share of the mix it doesn’t know, and the numbers are only indicative.
• Missing data. Mascarpone or Greek-style yogurt with 10 % fat aren’t in the verified databases; in such cases you need the manufacturer’s label.
• PAC is a model. It is based on ideal-solution theory. Milk salts are not counted, and the actual hardness also depends on the stabiliser, the overrun and the freezer.

So the calculation won’t replace experience, but it will reliably show whether a recipe has gone off balance — for example when you cut the sugar by a third or add too much rum.