How do you calculate ‘total carbohydrates’ values using the results of proximate analysis? Total carbohydrates =

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One way to determine carbohydrates is by difference. This approach is based on Weende’s proximate method of analysis where major compounds ( in g/100g) in a food are identified based on the chemical properties of the compounds (see scheme). Thus minor constituents (present in mg or m g per 100 g) are ignored. Originally this approach was developed for the analysis of animal feeds but is also applied to food analysis. The scheme below shows that for carbohydrate calculation, the other major constituents in the food are determined individually, summed and subtracted from the total weight of the food.

Proximate analysis.

* the compounds in green are determined quantitatively

** Note that carbohydrates calculated by difference also contain some non-carbohydrate components, like organic acids.

100 – (fat + protein + Inorganic matter)

100 – (moisture + protein+ fat + fibre)

100 – (moisture + protein + fat + fibre + ash)

100 – (moisture + protein + fat + ash)

100 – fat contents

100 – fibre contents

100 – (fat + fibre contents)

Not right. Total carbohydrates can be calculated by subtracting the weight of ALL major non carbohydrates components from the total weight of a food. Study the scheme to learn what are the major components in food.

Not right. Although FCDB are sometimes inconsistent in the definition of total carbohydrates, it is recommended to use the term ‘total carbohydrates’ only if you refer to both available carbohydrates AND fibres. Thus total carbohydrates can be calculated by subtracting the weight of all major NON carbohydrates components from the total weight of a food. In the option you selected, also fibre values are subtracted from the total weight of the food. This results in a value for ‘AVAILABLE carbohydrate’. Although some FCDB (like the former Australian database) calculate ‘total carbohydrates’ this way, this is certainly not recommended.

Right. It is recommended to use the term ‘total carbohydrates’ only if you refer to both available carbohydrates AND fibres. Thus total carbohydrates can be calculated by subtracting the weight of all major NON carbohydrates components from the total weight of a food. If also fibre values are subtracted from the total weight of the food, this will result in a value for ‘AVAILABLE carbohydrate’ and not for ‘total carbohydrates’. Please note that FCDB are not consistent in the use of the term‘total carbohydrates. For example the former Australian database excluded fibre from ‘total carbohydrates’ values. However, this is certainly not recommended.

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