Sampling of Potatoes to Determine Representative Values for Nutrient Content in a National Food Composition Table

To update the Norwegian Food Composition Table (FCT), representative samples of 10 potato varieties — all domestically grown, were selected according to production and market statistics. The major varieties grown in different parts of the country were analysed separately, whereas less important potato varieties or analytes of less importance were analysed from one or more composite sample(s). A sample normally contained subsamples from five growers in the area. Potatoes to be stored for consumption during winter were sampled at harvest and after 4–6 months of storage. Of the 34 nutrients that were analysed, vitamin C is presented as an example of how the FCT values were derived from the analytical results. The content of vitamin C varied between 7 and 20 mg/100 g edible potato when analysed at different times during the year. The FCT-value of storage potatoes was set to 16 mg at harvest time. The different varieties and growing conditions may partly explain the apparent differences from other Nordic FCT-values, but “artificial” deviations due to different sampling and analytical methods may also be present.