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16.03.2018 - Foods
Nitrate testing in lettuce and spinach
In 2017, a total of 44 samples of various fresh salads and spinach were tested for their nitrate content at the State Office for Agriculture, Food Safety, and Fisheries (LALLF) in Rostock. They mostly originated from Germany (33 samples) but also from Italy (7), France, and the Netherlands.
The samples were collected from producers and various trading companies in Mecklenburg-Vorpommern for examination. Only two samples – a spinach and an arugula salad, both from Italy – were rejected due to exceeding the EU-wide maximum limits for nitrate.
Plant-based foods are a major source of nitrate intake for humans. Nitrate itself does not pose an immediate danger, but it can be converted into nitrite through microbiological or enzymatic actions – nitrite, in turn, is involved in the formation of nitrosamines, which are considered carcinogenic. Possible causes of nitrite formation can be improper transport and incorrect storage. For example, if salad is hermetically sealed in a plastic bag, microorganisms can reduce nitrate to nitrite.
In heavily chopped foods stored for a long time in a closed container, the reduction of nitrate to nitrite is favored because the reaction surface for microorganisms is significantly larger in the chopped state. For instance, spinach should not be left standing for too long and should preferably be consumed all at once. Consumers should not eat less vegetables due to these circumstances, but rather focus on a diverse selection of vegetables.
In contrast to tomatoes, cucumbers, or beans, some types of vegetables, such as field salad, lettuce, spinach, or arugula, can have comparatively high nitrate levels. Therefore, they are regularly tested for nitrate.
Nitrates are nitrogen compounds that occur in the soil but are also absorbed by plants through chemical fertilization. This depends on the type of plant itself, the intensity of fertilization, as well as light, water, and temperature influences.
The arugula contained a nitrate content of 7,400 mg/kg. According to Regulation (EC) No. 1881/2006 setting maximum levels for certain contaminants in foodstuffs, a nitrate maximum level of 6,000 mg/kg applies to arugula harvested from April 1 to September 30. The spinach contained 4,713 mg/kg of nitrate, with a maximum allowed of 3,500 mg/kg.
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Source: LALLF / food-monitor.de (01/25/2018)