Information about the components  -  proximates

Energy

The energy content is indicated with the unit kJ (kilojoules) and is calculated from the foods' content of protein, fat, available carbohydrate, dietary fibre and alcohol using the energy factors:
 

This is one of the major differences from versions of the Danish Food Composition Databank which are prior to version 6.0. Earlier versions used the general Atwater factors 17, 38, 17 and 30 kJ/g for protein, fat, total carbohydrate and alcohol, respectively.

This procedure is recommended in the newest version of the Nordic Nutrition Recommendations NNR 2004 [3] and is described in FAO Food and Nutrition Paper, Food energy - methods of analysis and conversion factors [4]. Dividing up the total carbohydrate into available carbohydrate and dietary fibre and assigning a lower energy factor for dietary fibre takes into account the fact that not all dietary fibres are utilized in the human digestion.

The FAO report also mentions the energy factors
 

At present, the energy contributions from organic acids and polyols are not included in the energy calculations in this version 7 of the Danish Food Composition Databank as the data are not sufficiently covering. Furthermore, the energy contribution from these components only has an interest for a few foods.

The application of general energy factors for all foods is not necessarily correct. The correct calculation of the food's energy content includes the use of specific energy factors for protein, fat and carbohydrate for each food. On the other hand, in order to facilitate the energy calculation the Nordic recommendations concerning energy intakes are using these factors. Therefore, energy calculated with the general factors has been included in the Danish Food Composition Databank.

This energy calculation procedure must not be mistaken for the energy calculation procedures for nutrition labelling in the EU which is described elsewhere.

The energy values are only given as a guidance. The energy values are indicated as rounded integers.

Protein

The protein content is indicated as total nitrogen multiplied by a nitrogen-to-protein conversion factor, which is dependent on the protein composition and therefore dependent on a specific factor for each food.

The nitrogen-to-protein conversion factors used are specified in the following table 3 (unless otherwise indicated in the detailed description of each food).

The applied factor is indicated for each food in the detailed view of the food (e.g. 'NCF: 6.25'). The protein content is given with the unit and mode of expression g/100 g edible part.

The amino acid content for 18 amino acids are given in specific amino acid tables for each food. The indicated amino acids are isoleucine, leucine, lysine, methionine, cystine, phenylalanine, tyrosine, threonine, tryptophan, valine, arginine, histidin, alanine, asparagic acid, glutamic acid, glycine, proline and serine.

The amino acid content is given in mg/100 g and mg/g N, both edible part.
 

Carbohydrates

This version of the Danish Food Composition Databank distinguishes between two specifications of carbohydrate, total carbohydrate and available carbohydrate. This is due to the new energy calculation procedures introduced in the Nordic Nutrient Recommendations [2], which uses available carbohydrate and dietary fibre with different energy conversion factors in the calculation where previously total carbohydrate was used.

Generally, the total carbohydrate content has been calculated by difference, defining carbohydrate as

while available carbohydrate here is defined as

This calculation method introduces errors in the result as errors in the determinations of dry matter, protein, fat, ash - and for available carbohydrate also dietary fibre will influence the final total carbohydrate value. In many cases these errors are equalized though.

The total carbohydrate by difference value includes - apart from the components usually regarded as carbohydrates - also other carbon containing compounds like organic acids, lignins and tannins. It is with this carbohydrate definition Atwater has based his energy factor for carbohydrate.

All carbohydrate values are expressed as g/100 g edible part.

Other carbohydrate information

The Danish Food Composition Databank gives information about the following carbohydrate fractions:

• Starch, including dextrins and glycogen.
   
• Dietary fibre dependent on definition:
  The commonly most accepted definition is based on human physiology and defines that dietary fibre are plant polysaccharides and lignin which are not digested by the human enzymes in the digestive tract.
  Englyst and Cummings prefer a chemical definition of dietary fibre as non-starch polysaccharides (NSP) and they exclude lignin and every other form of non-digestible starch in this definition. Dietary fibre values are very dependent on the method of analysis used to determine the value. British values for dietary fibre has until recently been based on the Southgate method (sources 00802 and 02102).
  Danish values for dietary fibre have been determined by the AOAC method which gives slightly lower values than the Southgate method. The AOAC method is also the preferred method for declaration of dietary fibre in nutrition labelling.
  Older American values are based on the 'crude fibre' method (sources 00800 and 00804), which gives lower values than the AOAC method while newer American values are based on the AOAC method (source 02108).
  The predominant part of the dietary fibre values are based on new analysis of Danish foods with the AOAC method.
   
• Total sugars defines as all carbohydrates with the exception of tetramers and higher compounds of polyhydroxyaldehydes and polyhydroxyketones [1]. This definition includes monosaccharides (pentoses and hexoses), di- and trisaccharides and the values stated for total sugars in the tables are the sums of these saccharides.  As examples can be mentioned the sugars fructose and glucose present in especially plant foods, the disaccharides sucrose (saccharose) in plant and sweetened products, lactose (milk products) as well as maltose (dark bread products). The trisaccharide raffinose, the pentoses arabinose and xylose, and the monosaccharide mannose are rarely present in foods.
  The value for total sugars is the sum of all known sugars. Therefore, the values are not always equal to the sum of the sugars in the tables.
  This definition of sugars is different than the definition of total sugars in the European Directive on Nutrition Labelling, which only includes mono- and disaccharides in the definition of total sugars. As the trisaccharides are rarely found in food, the value for total sugars corresponds well to the value calculated according to the EU definition.
   
• Added sugar is defined as refined or industrially manufactured sucrose and other sugars, eventually in the form of an ingredient in a food. Naturally occurring sugars in fruits, vegetables and milk, etc. are not regarded as added sugars, whereas added glucose, glucose syrup, starch syrup and other hydrolysed starch products are regarded as added sugars [2].
  In the present Nordic Nutrition Recommendations 2004 [3], the term added sugar is represented by refined sugars (see [3], page 188).
  Normally, added sugar will be sucrose, which in acid environment will hydrolyse into fructose and glucose.
  The value for added sugar is not analysed but usually comes from information like the food label. Therefore, there are a few instances where the amount of 'added sugar' is not consistent with other carbohydrate information for the food.

All carbohydrate values are given as g/100 g edible part.

Fat and fatty acids

The total fat content is the total lipid content of the food. It is indicated together with the fatty acid conversion factor (FACF). This conversion factor is used for calculation from total fat to total fatty acid.

In general, the factors shown in table 4 are applied (from Paul and Southgate, 1991).

These fatty acid conversion factor should be taken only as indicative. Those wanting to work in detail with the fatty acid composition must be aware that the fatty acid conversion factors are determined experimentally and can vary substantially.

The fatty acid conversion factor is the ratio between the part of the lipids (fat), which is fatty acids, and the total amount of lipids (fat). All triglycerides contain a glycerol part that does not belong to the fatty acid part. The theoretical maximum for fatty acid C18 is 0.957, the rest is glycerol. In the case of phospholipids an even smaller amount of the lipid is fatty acids.

The total fat content is given as g/100 edible part.

The fatty acids are given as g/100 g edible part of the food as well as in percent of amount total fatty acid (g/100 g total fatty acid).

In table 5 below, the usual trivial names and the systematic names of the fatty acids are shown:
 

The value for 'Other fatty acids' is the sum of fatty acids that have not been identified during the analysis and eventual fatty acids not included specifically in the databank.

C18:3, n-6 (g -linolenic acid) is not included in the databank at present as it is very seldom found in foods.

The content of trans fatty acids is shown separately as a sum in this databank. A very large amount of the trans fatty acids occurring in foods is elaideic acid, which is included in C 18:1, n-9.
Other trans fatty acids are also present in foods, but their presence is not yet well documented. Trans fatty acids occur naturally in milk fat and meat from carnivores. They are also formed during hardening of oils, for example oils used in margarines. They are also formed by heating unsaturated fatty acids in oils for deep frying.

The trans fatty acids in margarine cover a broad spectrum of position isomers with the centre around n-7, n-8 and n-9, but other isomers are also represented. In milk fat the C 18:1, trans is dominated by the n-7 isomer (From Chow, C.K. (ed.), Fatty Acids in Foods and their Health Implications, 1992).

Content of fatty acids in milk products

The fatty acid content of dairy products is calculated on the basis of the products' content of milk fat. It is assumed that the fatty acid content of milk and milk products shows a constant and uniform distribution, this presumption is not completely right as the fatty acid distribution in milk has a clear seasonal variation and dependent on the feed and race of the cow.

Table 6 shows the average values used in the calculation of the fatty acids in dairy products. The values have been derived from results in reference no. 00324.
 

 Alcohol

The values for alcohol (ethanol) are given with the unit g/100 g. Note that this unit does not always correspond to vol. %. Vol. % is the usual unit stated on labels on alcohol containing beverages and it is typically higher than the unit g/100 g.

Water/moisture and ash

Values for water/moisture and ash are given partly because they are used in the calculation of 'carbohydrate by difference', partly because they may have common interest. Both values are given with the unit g/100 g edible part.

References