Analysis of nuts and dried fruits
Dried fruits and nuts are produced and processed in many different countries. Recently more and more exotic fruit are making their way into German and European markets. As typical agricultural products, dried fruits and nuts can contain a variety of contaminants and harmful substances. Production, processing, transport and storage may result in contamination by pesticide residues, heavy metals, mycotoxins, or pest infestation. At the same time quality assessment, sensory analysis and the product quality class separation demand extensive experience and merchandise knowledge. European and German limit regulations, e.g. for pesticides, mycotoxins and SO2 require regular controls. Import controls on some contaminants and goods from non-EU countries are mandatory.
Currently in focus: Detection of bleaching in dried figs
Treatment with H2O2
Dried figs are a natural product and may exhibit different colours, ranging from almost white to brownish-dark. Brighter colors are considered more appealing by customers and vendors. A treatment with hydrogen peroxide (H2O2) – bleaching – can be performed to lighten darker fruits. This practice is not allowed in Turkey, the main producer of dried figs.
We have developed a method that can reliably detect the bleaching and discriminate between natural and bleached figs. The treatment is not easy to detect, and for a long time no analytical method was available to reliably identify bleached samples. In order to develop a method, we collected several authentic natural and bleached samples. The samples were analysed with 1H-NMR, which results in a profile of the compounds present in each sample. This profile can be thought of like a fingerprint, and it was found that the fingerprints of natural and bleached figs differ significantly. Thus a method was developed that can classify unknown samples into the two categories, natural and bleached, based on their NMR profiles. The test is performed under ISO 17025 accreditation.
Legal bases and guidelines
- Commission Regulation (EU) 2023/915 (Contaminants-Regulation)
- Regulation (EC) No 396/2005 of the European Parliament and of the Council (maximum residue levels of pesticides)
- Regulation (EU) No 1308/2013 of the European Parliament and of the Council
- Commission Implementing Regulation (EU) No 543/2011
- Commission Regulation (EC) No 401/2006 (Probenahmeverfahren und Analysemethoden Mykotoxine)
- Kontaminanten-Verordnung (KmV) (German)
Membership and approvals of individual Eurofins laboratories(*)
Other interesting pages
| Analyses Mycotoxins |
Industries Goji Berries |
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