Markings such as "mit Konservierungsstoff …", "Schale nicht zum Verzehr geeignet", "konserviert mit … – gewachst", "konserviert mit …" ("with preservative …", "peel not for human consumption", "preserved with … - waxed", "preserved with …"), ortho-phenylphenol, thiabendazole or enilconazole (imazalil or chloramizole) are commonly found on the packaging or labels of oranges, mandarin oranges, clementines, limes and grapefruits.
These substances are fungicides and are used as preservatives and for the post-harvest treatment (surface preservation) of the fruit to avoid the formation of moulds and, thus, premature spoilage.
The substances applied to the fruit’s peel via dipping or spraying remain almost completely on or in the peel and only very minute traces are found in the inner, edible areas.
The peels of citrus fruit treated with orthophylphenol, thiabendazole or enilconazole are not fit for consumption. Surface-treated citrus fruit could contain high levels of surface treatment substances on or inside the peel. Thus, the peel is not fit for consumption. Following harvesting, the fruit are usually washed industrially, which removes the fruits’ thin, natural wax layer. Subsequently, the peel can be waxed artificially with bees wax (E 901), candelilla wax (E902), carnauba wax (E 903) to avoid any loss of moisture.
It is recommended to use fruit untreated after harvest or organic produce for all recipes that use the entire fruit or the peel, such as baked goods, duck à l’orange, marmalade, punch, but also summer drinks, such as sangria and caipirinha.
Tips for Consumers
Washing the fruit using lukewarm water and patting it dry with a cloth can also help remove most preservatives from the peel’s surface. Consumers should always wash their hands thoroughly after peeling citrus fruit and eat the fruit afterwards, as post-harvest treatment substances are transferred to the hands during peeling.
Always purchase produce that is marked as "nach der Ernte unbehandelt" (untreated after harvest) when you have to use the peel or the entire fruit for cooking. If you want to avoid any synthetic pesticide residues, make sure you pick organic produce. Citrus fruit from organic cultivation must not be treated with surface preservatives after harvesting.