Nutritional Analysis
Food Preparation & Nutrition: AQA GCSE, topic 2.3.4
Macronutrients
Nutritional analysis involves working out different foods' nutritional content.
Units of energy
- We either talk about energy in terms of kilojoules (kJ) or kilocalories (kcal).
Energy values of macronutrients
- The three main macronutrients - fat, protein and carbohydrate - will give the following energy values (approximately):
- 1g of fat = 9 kcal.
- 1g of protein = 4 kcal.
- 1g of carbohydrate = 4 kcal.
Total energy value
- To calculate the total energy value of a particular food, multiply the energy value (kcal) for 1g by the number of grams of each macronutrient in the food.
Total energy value example
- A small bag of carrots contains: 0.9g protein, 0.2g fat and 9.6g carbohydrate.
- Energy value of each macronutrient:
- Protein = 0.9 × 4 = 3.6 kcal.
- Fat = 0.2 × 9 = 1.8 kcal.
- Carbohydrate = 9.6 × 4 = 38.4 kcal.
- Total energy value = 3.6 + 1.8 + 38.4 = 43.8 kcal.
Sourcing Nutritional Data
There are reference tables and software available to help you find out nutritional data.
Reference tables
- Available in print (e.g. books) and online.
- Reference tables are usually ordered by food group or alphabetically.
- The nutritional values given are normally per portion or per 100g.
Nutritional labels
- Legally, packaged foods must have nutritional labels.
Nutritional analysis software
- By inputting the ingredients of a particular dish and the weight of each ingredient into nutritional analysis software on a computer, you can find out the amount of nutrients and energy in the entire dish or portions of the dish.
- Advanced software analysis may have additional features.
- E.g. showing how the nutritional values of a meal compare with recommended daily intake.
Test yourself on Nutritional Analysis
What are the main units of energy?
Which of the following is NOT a unit of energy?
Which macronutrient has the greatest energy value?
How are reference tables of nutritional data usually ordered?