Food composition values are usually based on chemical analyses which are carried out in analytical laboratories. In some cases, however, values for composite foods are derived from the nutrient composition of its individual ingredients. An overview of the process for the chemical analysis of food is detailed below:

Step 1            Collect food samples to be analysed

                        A number of samples of the same food item will be analysed to

                        derive an end value.

Step 2            Treatment of samples before analysis

Foods may need to be washed, peeled and waster material discarded.

Foods may also need to be cooked and stored before they are sampled.

Step 3            Analysis of samples

Each nutrient within a food will be analysed using a specialised method. Today much of this analysis is undertaken using specialised technology.

The different samples of food may be ‘pooled’ for the analysis, so that an average value can be obtained. Otherwise each sample of the food under investigation will be analysed separately.

Step 4            Expression of results

Some statistical calculations may be needed to ensure the reliability of some of the values derived from the analysis.

The database should detail how many samples were analysed, and provide details of the treatment of the sample, such as if it was cooked or whether only edible material was analysed.