calories on food packets is it true
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Derek Goffin
(Derekoak)

Locale: North of England
calories on food packets is it true on 05/29/2008 07:35:05 MDT Print View

When you read a food packet you get a breakdown of what is in the food. There is a line giving calories for 100 grams of the packet or the equivalent.
I may be wrong but I think laboratories get this figure with a bomb calorimeter. Basically they burn the food and measure the heat put out.
If this is how it is done the lab burns any roughage in a way that the body cannot. Therefore the body sees things like muesli as less energy dense than the packet shows.
Any views?

Lyan Jordan
(redmonk)

Locale: Greater Yellowstone Ecosystem
calories on food packets is it true on 05/29/2008 11:33:30 MDT Print View

It's been my experience that for the basic nutritional information label, the lab experimentally determines the moisture content, fatty acids, cholesterol, simple sugars, complex carbohydrates, fiber, protein, and basic vitamins values of the sample. Caloric content is not determined directly, but is calculated with basic addition using the 9-4-4 method for digestible fat,carbs, and protein.

Without knowing if the assays to get a nutritional label are standardized, I can't say what the calorie value would mean on any label other than the ones I was looking to use. My guess would be, if the label lists the fiber, the lab went through the trouble to measure it in order to provide a more accurate calorie count in the context of human nutrition.

Charles G.
(Rincon) - M

Locale: Desert Southwest
calories on food packets is it true on 05/29/2008 12:22:40 MDT Print View

They wouldn't be able to give values for carbohydrates, proteins, fats and fiber if all they did was bomb calorimetry. Total calories are calculated after having determined the amounts of carbohydrate, fat and protein etc in a set of, presumably, randomly obtained samples.

Derek Goffin
(Derekoak)

Locale: North of England
calores on food packs on 05/29/2008 14:00:17 MDT Print View

thanks for that,I am reassured