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Calculations in the NPC

​​Last updated: 17 September 2020

We describe how the Nutrition Panel Calculator (NPC) works out Nutrition Information Panels (NIP) with three steps:

Step 1 - Create recipe by adding ingredients and amounts

Calculations in Step 1 apply to the energy and nutrients of the individual ingredients.​

a) Locate nutrient profiles for ingredients

As you add ingredients to your recipe, the NPC retrieves the values for energy and nutrients per 100 g from the NPC database or from your custom ingredients. These values are displayed when you search for an ingredient to add to your recipe.

 

b) Convert all amounts and units to grams

Once you add ingredients to your recipe, you can choose to enter the amount of each ingredient as either:

  • grams
  • kilogram
  • millilitres
  • litres.

If any unit other than grams is selected, the NPC converts the amount into a gram equivalent.

Example: when entering 1 litre of chicken stock, the NPC uses the specific gravity to convert the 1 litre into grams.

1 litre of chicken stock = 1000 mL × specific gravity of chicken stock

= 1000 × 1.02

Total weight of 1 litre of chicken stock = 1020 g

The screen won’t display the individual ingredient conversion weights.

c) Calculate the nutrient contribution from each of the ingredients

The NPC will then:

  • add the total weight of all ingredients in grams
  • calculate how much each ingredient contributes to the overall nutrient values for 100 g of the recipe.

In the following example, the ingredients all use different units. So the system converts all amounts into gram weights, as in Step 1b. This adds up to a total weight of 1571 g.

The NPC then calculates how much each ingredient contributes to energy and nutrients if there was 100 g of ingredients. These values are determined by the following equation, using energy from stock as an example:

Energy from stock

= Energy per 100 g × Weight of stock in recipe ÷ Total weight of recipe

= 31 kJ × 1020 g ÷ 1571 g

= 20.13 kJ

The NPC then calculates energy for the remaining ingredients. It will repeat this process for the remaining nutrients.

NPC energy 

d) Sum all nutrient contributions

The values calculated in Step 1c are then added to give the total energy per 100 g of the recipe. The NPC repeats this process for the remaining nutrients and displays it in the 'Total per 100 g' row.

NPC total 

Step 2 - Enter recipe weights

The NPC uses values calculated in Step 1, and additional information entered in Step 2 (weight change) to calculate NIP values. Calculations from Step 2 onwards apply to the energy and nutrients of all ingredients when combined.

a) App​ly the weight change factor

The next step is to apply a weight change factor if the recipe’s weight changes in moisture content during cooking, which adjusts the energy and nutrient values. This is determined by the following equation, using the total energy calculated in Step 1c as an example:

Energy after weight change

= Energy per 100 g × 100 ÷ (100 + Weight change factor)

= 233.93 kJ × 100 ÷ (100 + -8)

= 254.27 kJ

NPC recipe weights 

The adjusted energy and nutrient values from this step are not shown on the screen.

Read more about how to determine weight change factors in the NPC user guide.

Step 3 - Generate Nutrition Information Panel

a) Convert from per 100 g to per 100 mL for liquids

If the final product is a liquid, the NPC will convert the values it generates up to this point from per 100 g to per 100 mL using the following equation. This example uses the total energy calculated in Step 2a:

Energy converted from per 100 g to per 100 mL

= Energy per 100 g ÷ 100 × (100 g × specific gravity of the final product)

= 254.27 kJ ÷ 100 × (100 × 1.01)

= 256.81 kJ

b) Calculate energy and nutrient values per serve

The values calculated to this point are per 100 g or 100 mL. The NPC will calculate the values per serve using the following equation:

Energy per 100 g or per 100 mL (depending on whether the final product is a solid or liquid)

= Energy per 100 g / 100 * (serve size in mL * specific gravity of the final product)

= 254.27 kJ / 100 * (250 * 1.01)

= 642.03 kJ

c) Determine number of significant figures and decimal places

Using the results from Steps 3a and 3b, the NPC applies the appropriate number of significant figures and decimal places to align with the requirements of Standard 1.2.8 as closely as possible.

The results display in the row with the name of your recipe as the title, and in the final NIP.

 

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