Nutrition analysis.
Nutrients - General information
Nutrients are food components that provide energy and/or are needed to sustain bodily functions and preserve the health of the organism. Referred to as the basic nutrients (major nutrients, macronutrients), carbohydrates, fats and proteins are primarily providers of energy, but they also perform important functions in the human body. The basic structural units of the proteins are amino acids, for example, which, among other things, constitute the base material for enzymes produced inside the body. As far as health is concerned, an ideal combination of the basic nutrients is made up of 50 - 60 % carbohydrates, 30 % fat and 10 - 15 % protein, measured against the energy required by the organism. Although the other nutrients, vitamins and minerals do not supply energy, they are essential for the preservation of health and to sustain many processes within the human organism.
Nutrients that are often not ingested in sufficient quantities in certain regions or among certain sections of the population are referred to as critical nutrients.
Nutrition labelling
The chemical composition of a foodstuff or its nutritive value can be determined by means of analysis and/or calculations based on the ingredients used or accepted nutrition tables. Labelling food with this data is basically voluntary. However, nutrition labelling is necessary if information relating to nutritive value is given on the packaging or used in advertising messages.
The scope of the information to be given is oriented to the nutrition-related claims. Where nutritive data is quoted on the packaging, such data must include calorific value, protein, carbohydrates and fat (the "big four").
If any value-related claims are made with respect to any other nutrients, such as fibre, then values must be given for the so-called "big eight". These are calorific value, protein, carbohydrates, of which sugar, fat, of which saturated fatty acids, fibre and sodium. The pertinent data must also be given with respect to claimed vitamins and minerals.
These stipulations are laid down in the German Ordinance on the nutrition labelling regulations for foodstuffs (YNKV) dated 25 November 1994. The German Ordinance constitutes the implementation of the European Council Directive on nutrition labelling for foodstuffs (90/496/EEC). Apart from regulations on nutrition labelling and advertising messages relating to nutritive value (e.g. information about saturated fatty acids), it contains the energy calculation factors and stipulations concerning low-calorie foods (reduced calorific value) and foods with a low sodium content.
Nutrition quantitation
Calorific value
The nutrient content values determined by analysis or calculation are converted into energy content (calorific value) in accordance with the NKV. The following energy values per g are assumed for the calculations:
| Fat | 37 kJ | (9 kcal) |
| Protein | 17 kJ | (4 kcal) |
| Carbohydrates (not including multivalent alcohols) |
17 kJ | (4 kcal) |
| Ethanol | 29 kJ | (7 kcal) |
| Organic acid | 13 kJ | (3 kcal) |
| Multivalent alcohols | 7 kJ | (2,4 kcal) |
| Vitamins, minerals, water | 0 kJ | (0 kcal) |
Total fat
Total fat quantitation (lipids, phospholipids) usually takes place in accordance with the official assay methods laid down in § 64 of the German Food and Feed Code (LFGB, formerly § 35 of the German Food and Commodity Goods Law LMBG). The pre-dried sample first undergoes hydrolysis to decompose any protein sheaths. The filtered and dried acid-free residue is extracted with petroleum benzin, the solvent is distilled out and the residue is determined gravimetrically and referred to the dry matter.
Total protein
The method laid down in § 64 of the German Food and Feed Code (LFGB) is used for quantitation. The organically combined nitrogen is transformed into ammonia sulphate by digesting the substance with concentrated sulphuric acid. The ammonia produced when excess base is added is carried over by distillation, collected in a saturated boric acid solution and subsequently titrated with 0.1 M hydrochloric acid (Kjeldahl determination). The raw protein content is given by multiplying the determined nitrogen content by 6.25.
Carbohydrates, sugar
According to the German Ordinance on the nutrition labelling regulations for foodstuffs (NKV), the term carbohydrate refers to every carbohydrate converted in the human body, including multivalent alcohols. Monosaccharides and disaccharides, on the other hand, are the only substances referred to as sugar.
The proportion of carbohydrates is not analysed directly, as a rule, but is calculated from the difference between the other nutrients (fats, proteins, minerals, water) and the total weight. The titrimetric method to determine carbohaydrates in meat products laid down in § 64 of the German Food and Feed Code [LFBG] may be applied and the content of reducing substances calculated as starch can be indicated. The starch contained in the sample is first hydrolysed by heating it with hydrochloric acid. The released glucose is subsequently determined by reductometric analysis. After adding a saline solution of copper II (Luff-Schoorl reagent), the consumed proportion of copper II ions is determined by titration with a sodium thiosulphate solution and the corresponding glucose or starch content is taken from a table.
The free sugars, indicated as glucose, are determined according to the same method, but without preliminary hydrolysis.
Fibre
The official assay procedure laid down in § 64 of the German Food and Feed Code (LFBG describes an enzymatic-gravimetric method of determining the total fibre content and the amount of soluble and insoluble fibre in foods.
In the context of the method described here, the fibre content refers to the measured proportion of organic constituents, which are not hydrolysed under the conditions of the analysis by the enzymes used. The total fibre content may be determined, or the soluble fibre and insoluble fibre may be determined separately.
These substances are predominantly soluble and insoluble non-starch polysaccharides (cellulose, hemicellulose, pectins, hydrocolloids), as well as resistant starch and lignin.
The fibre content is given in g per 100 g. The sample material is incubated with heat-stable α-amylase, which causes the starch to gelatinate and partially decompose. Proteins are then decomposed by adding a protease before decomposing the remaining starch by means of amyloglucosidase. The soluble fibre is precipitated with a multiple quantity of ethanol, the precipitate is filtered and washed in a suitable manner. The residue is subsequently dried and weighed. Each assay is carried out with two samples of very similar weight. The protein in the residue of the first sample is quantified by means of Kjeldahl nitrogen determination, while the minerals are quantified in the residue of the second sample. After subtracting the values for protein and minerals, the mean weight of the two residues obtained during the assay corresponds to the fibre content in the product.
Organic acids
Organic acids may be determined by means of titrimetric analysis or HPLC.
Minerals
The total mineral content is usually determined by means of ashing in the muffle furnace and is equivalent to the raw ash.
Special minerals, such as sodium, potassium, calcium and magnesium, as well as trace elements, such as selenium or iodine, are determined after digestion by means of AAS or ICP/MS.
Water
The loss on drying is usually determined by means of gravimetric analysis.
Vitamins
HPLC and HPTLC techniques, as well as tubidimetric microbiological and ELISA methods are usually applied to determine vitamins, such as thiamin (vitamin B1), riboflavin (vitamin B2), niacin (vitamin B3), pyridoxin (vitamin B6), cyanocobalamin (vitamin B12), ascorbic acid (vitamin C), biotin (vitamin H), folic acid and panthotenic acid.
Nutrient determination procedures can be performed properly and professionally by PhytoLab, the specialist laboratory. PhytoLab is Europe's leading external laboratory in the field of analysing plant constituents, such as the nutrients in food described above, as well as in the pharmaceutical sector.
Apart from the assays and analyses usually carried out in the food and pharmaceutical sectors, PhytoLab's scientists also specialise in the registration and market authorisation procedures for herbal medicinal products. Officially acknowledged in accordance with § 14 of the German Drug Law (AMG) and accredited in accordance with Directive 93/99/EEC, PhytoLab has ultra-modern equipment and highly qualified personnel at its disposal.
