How are nutrition facts calculated?

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I always imagine Karen’s machine from SpongeBob lol

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A couple of different ways but usually just a database. If Uncle Bob’s Chili has five pounds of beef, an onion, a can of beans, etc all of the nutritional information is added up from those separate ingredients. Larger companies use lab equipment to calculate. For example, the bomb calorimeter that pretty much burns food to see how much energy (Calories) is released.

What about protein drinks? Say a 330g drink has 33 grams of protein? How do they measure this? How do we know its 33 grams for sure? Could the amount vary?

There are many different chemical methods that are used for this. For macronutrients (water, fat, protein, carbohydrates, and ash) the specific method is dependent on the product.

Water has many different methods for being determined. One method that can be used to check a result is to simply dry a known quantity of a food. Any weight that is lost is water. There are other methods that are longer, but more accurate, but it’s been forever since I’ve worked with them. Google would likely be able to help with that.

Generally speaking, fat is determined by mashing the food, and soaking it in a solvent. Once it has had time to extract the fat, they take the weight of the solvent fat mixture. Since the amount of solvent added is known, the extra weight is fat.

Proteins are actually determined by figuring out the nitrogen content and multiplying by a factor that is dependent on the product. This works because proteins are usually the only naturally occurring nitrogen source in a food. If there is another source of nitrogen, say nitrates, that is a known quantity that is added and it can be subtracted out of the calculation.

Ash, or minerals, is calculated by simply burning the product. Whatever doesn’t burn is considered ash.

Carbohydrates are super fun. Legit, everything else is calculated, added together, and subtracted from 100. The chemical structure of carbohydrates is so vastly different there is no one test method to find all of them.

Calories are calculated because each group of macronutrients provides a known energy per unit of weight. Fats give nine calories per gram, proteins and carbohydrates give four calories per gram. Just take the results from above and add them all together to get the calories.

There are also rounding rules in place to give manufacturers some wiggle room for batch to batch variation.