I always wonder how “they” can know the exact amount of fiber, protein, carbs and sugars, etc when I’m reading ingredient labels.
PS: couldn’t decide between biology or chemistry flair since I guess my question relates to biochemistry! Haha
In: 527
[removed]
You can do this in a lab, but it’s expensive and slow so a food business will almost always just calculate calories etc based on the ingredients and a list of standard measurements, with an app of some sort ([like this one](https://www.food.gov.uk/business-guidance/menucal-calorie-and-allergen-tool)).
The list is made from actual lab measurements using a calorimeter to basically burn the ingredient and measure the energy released. They often include other facts like vitamin content and so on.
Here’s the one for the UK (the USDA and other agencies have similar ones ): https://www.gov.uk/government/publications/composition-of-foods-integrated-dataset-cofid.
(To help make these measurements repeatable, you can buy or prepare ISO-standard formulations of basic foods! They are made in a lab, quite expensive, and very plainly packaged)
Proteins are normally measured by determining the nitrogen content and multiplying it with 6.25 which is a very rough estimate of the weight of protein as compared to the weight of nitrogen.
Fibre, carbohydrates and sugars are all carbohydrates and can be measured crudely by subtracting the weight of water (evaporated at 105 deg C), ash (what remains after 550 deg C incineration) and protein. Alternatively carbohydrates can be quantified based on their ability to absorb light.
[removed]
When things are burned (lit on fire) they let off a certain amount of heat. A ‘calorie’ is defined as the amount of energy (heat) required to raise the temperature of 1 gram of water by 1 degree celcius.
In the lab, they literally combust the food items and use the heat put off to warm up water. By measuring how many degrees the water increases in temperature, they calculate how much energy or ‘calories’ were in the food.
If you burn a cracker and the resulting heat warms 1 gram of water up by 4 degrees, there were 4 calories in the cracker.
[removed]
[removed]
When I worked for the deli dept in a grocery that eventually became a Whole Foods, the following conversation was routine:
*Customer*: How many calories are in that salad?
*Me*: Well, we haven’t done a nutritional analysis, but that one has nuts, plus the dressing contains honey. I can recommend an alternative that likely has far fewer calories.
*Customer*: I’ll just have some chicken wings.
When things are burned (lit on fire) they let off a certain amount of heat. A ‘calorie’ is defined as the amount of energy (heat) required to raise the temperature of 1 gram of water by 1 degree celcius.
In the lab, they literally combust the food items and use the heat put off to warm up water. By measuring how many degrees the water increases in temperature, they calculate how much energy or ‘calories’ were in the food.
If you burn a cracker and the resulting heat warms 1 gram of water up by 4 degrees, there were 4 calories in the cracker.
When I worked for the deli dept in a grocery that eventually became a Whole Foods, the following conversation was routine:
*Customer*: How many calories are in that salad?
*Me*: Well, we haven’t done a nutritional analysis, but that one has nuts, plus the dressing contains honey. I can recommend an alternative that likely has far fewer calories.
*Customer*: I’ll just have some chicken wings.
Latest Answers