Introduction to Food Science and Food Constituents
Domain 1 tests how food is broken down into constituents and why their proportions matter. Expect definitions, classification, functions and simple energy calculations rather than brand names.
Core concepts
- Food science applies chemistry, microbiology, engineering and nutrition to food; food technology is the applied processing side.
- Proximate analysis reports moisture, ash (minerals), crude protein, crude fat, crude fibre and nitrogen-free extract (carbohydrate by difference).
- Macronutrients supply energy and structure; micronutrients (vitamins and minerals) enable metabolism but do not supply energy.
- Atwater factors: protein 4 kcal/g, fat 9, carbohydrate 4, alcohol 7. These are metabolisable energy values.
- Water is the largest component of most fresh foods and contributes 0 kcal.
Worked example
A 100 g snack has 10 g protein, 20 g fat, 60 g carbohydrate and 10 g water. Energy = (10×4)+(20×9)+(60×4)=40+180+240=460 kcal. Water adds nothing. If the label says 500 kcal, explain the gap by rounding, fibre or analytical variation; never count water as energy.
Traps
- Using 4 kcal/g for fat; the Atwater factor is 9.
- Calling ash organic matter; ash is the inorganic residue.
- Equating crude fibre with total dietary fibre; the methods and meanings differ.
- Treating every carbohydrate as 4 kcal/g; fibre is only partly fermented.