Hi Yasaman,

each gramm of macronutrients in your 100 g of your plant foodstuff counts as follows:

-digestible carbohydrates: ~4 kcal/g

-digestible proteins: ~4 kcal/g

-digestible fats: ~9 kcal/g 

This means, according to the given percentages 100 g of your plant foodstuff has the following calories:  37*4 + 10*4 + 9*0.03 = 188 kcal/100 g.

You can find loads of online tools who can calculate this values  for you also automatically i.e.: http://fnae.org/carbcalorie.html

Good luck!

Dear Josef

Thank you very much.

Experimental calculations of calories can also be done using Bomb calorimeter.

Agree with Josef and Faiz. These calculations and measurements are also valid for animal and microbial derived foods.

The calculation Jozef has given, does (rightly) take into account only the digestible nutrients; so it is a calculation not a measurement.

The bomcalorimeter approach  gives the combustion value ( a measurement), but does not take digestibility into account, which can make quite an important difference in the case of plant or microbial derived foods.

Dear Kan

Thanks

Now if total carbohydrate in a plant such as brown seaweed that had been measured by chemical methods was 33.16%

Protein 10.39%

Fat 0.03%

Fiber 5.8

Ash 33.18

Moisture 13.25

How can I calculate the digestible carbohydrate? I when calculate according Josef method, the count of digestible carbohydrate will be high! And also the count of calorie will be high! But in fact brown seaweed should be low calorie!

Can you calculate for me that how I can obtain a right amount?

Dear Yasaman

Calculating the digestibility is - to the best of my knowledge - not possible.

You have either to determine it or rely on data from tables (from the literature)  on similar products (eg for poultry see the attached old European Table)

Be aware that digestibility will not only differ between ruminants and monogastrics, but also between different monogastrics and between ages within a species.

Also the age of the (plant) feedstuff will influence its composition and digestibility.

Thus very rough figures are easy to obtain, but very specific ones certainly not.

Thanks

Best regards; Yasaman

Dear Yasaman

It is very useful to calculate the calories of each food meal to save many people from the obesity and over weight.

First you should have a proximate composition of food especially carbohydrates, fats and crude proteins.

Then you can calculate the calories by multiplying the carbohydrate in 4, the proteins in 4 and the fats in 9 and make summation for all results.    

In the tables of composition of food appears that data, nevertheless each food is constituted by macronutrients and they have precise values of energetic contribution, if it is known the amount in grams can obtain the general contribution. It is necessary to know the correction values according to the edible part

Hi: this link can help you  https://www.healthstatus.com.

A pleasant greeting, determines the weight of the food, its edible content and then the content of macronutrients according to the procycles it provides. Multiply grams of protein and carbohydrates by 4, while grams of lipids by 9, and you get the amount of calories. Then add everything and have the grand total. The nondigestible part, if incorporated into the intake, is a fiber and micronutrient, and functions as caloric. Successes

I agree with Ricardo, 1 gram of protein or carbohydrate= 4 kcal, so you can calculate the amount of protein and or carbohydrate (in grams) multiply by 4. while 1 gram of lipid= 9 kcal. In the end, you can sum up the total calorie provided by fat, protein, and carbohydrate.

Regards, I apparently made a writing error and rectified that micronutrients and fiber do not contribute calories. sorry

Bomb colorimetric method is more accurate for measuring the calorific value of any food. If the instrument is not available, we can use the formula (Multiplying value with 4 for protein and carbohydrate, and with 9 for lipids) that gives approximate calorific value of the respective sample.