Nutritional value of foods is calculated through lab analysis, databases, or recipe math, focusing on macros (protein, carbs, fats), micros (vitamins/minerals), and energy (calories).
Primary Methods
Lab testing uses chromatography/spectrometry for precise nutrient quantification (e.g., Kjeldahl for protein nitrogen, bomb calorimetry for calories).
Databases like USDA provide averaged values from thousands of samples; estimates borrow from similar foods or apply yield/retention factors for cooking losses.
Calculation Steps
For recipes: Weigh ingredients, multiply nutrient content per 100g by amount/portion, adjust for cooking (yield factor = cooked/raw weight; retention % for vitamins).
Energy: 4 kcal/g carbs/protein, 9 kcal/g fat, summed post-analysis.
Accuracy varies 5-20%; labels round per regs. Whole foods often exceed labels due to variability.
0 comments