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Listen to this siteWednesday 2 August 2006
This research project aims to select and critically evaluate published methods for the determination of histamine in food.
Study Duration : September 2001 to March 2002.
Histamine is a biogenic amine. It is produced post mortem in the muscle of Scombroid fish such as tuna and by bacterialogical decarboxylation of the amino acid L-histidine, found in the fish muscle. Fish species that are particularly vulnerable to the development of histamine are those with high levels of free L-histidine in their muscle tissues. Additional histidine may be released during decomposition and spoilage by proteolysis, whereby the protein is degraded and amino acids are liberated. The level of histamine produced in Scombroid or other histidine containing fish by these processes can therefore indicate how much decomposition has occurred.
When present at higher levels, histamine can be a health hazard. It can cause nausea, vomiting, cramps, burning sensation in mouth, itching, uticaria, facial swelling and intense headache. Other biogenic amines such as tyramine, cadaverine and putrescine, often formed in a similar manner in foods, may possibly enhance this toxicity.
Food legislators, consumers and manufacturers have, therefore, a common interest in monitoring levels of histamine in foods. For this reason, the EU has set maximum levels of this substance in bivalve shellfish and fishery products. These limits are taken into UK law through the Food Safety (Fishery Products and Live Shellfish) Hygiene Regulations 1998. The Regulations state that histamine determinations must be carried out in accordance with reliable, scientifically recognised methods, such as high-performance liquid chromatography (HPLC).
The decarboxylation of histidine can also be related to fermentation processes involved in production of foods such as meat and meat products, wines, alcoholic beverages, sauerkraut, yoghurt and cheese. For example, cheese has also been documented as a food borne source of histamine poisoning.
The development of universally accepted or harmonised methods of analysis is essential for the enforcement of food and animal feeding stuffs law under both EU and UK legislation. The variety of existing methods of analysis for histamine may give incomparable results, may not be suitable for all samples types and may not be rugged. Research is needed, to establish the equivalence, accuracy, precision and suitability (including ruggedness) of these methods, and if necessary to refine existing techniques.
The approach used was as follows:
All of the methods evaluated were found to be satisfactory for the determination of histamine in fish, when properly controlled and used by experienced operators. However, results indicated that HPLC based methodology was superior to the other procedures examined, in terms of both the percentage recovery obtainable, and the applicability to a range of food matrices.
The HPLC methods have the advantage of being able to quantify other biogenic amines that are also present in fish, which may enable a more reliable assessment of the fish quality. Such data can be used to calculate a Quality Index for fish, which may be a more reliable indicator of freshness than histamine alone. The HPLC results investigated demonstrate that there is little difference between data derived from either trichloroacetic acid or perchloric acid extraction. Chromatograms from both were free from interference.
For fish samples, the fluorometric method gave results that agreed well with those obtained by way of HPLC, although the use of fluorimetry will only determine histamine, unlike HPLC which can detect a range of biogenic amines.
The ELISA method gave acceptable results for histamine in cheese, pork and fish but had a tendency to over recover and a high variability. Again, the ELISA method only determines histamine.
The colorimetric method gave unacceptable high, therefore other sample components must be interfering with the measurements made using this technique. Such non-specific methods are not recommended.
Variability between analytical procedures does not seem to be a significant problem when methods are under analytical control, but it is apparent from the FAPAS data that some laboratories still have difficulties in this area. Analytical errors, lack of experience with the method used and incorrect selection of the appropriate methods are all likely factors in this variability.
Any of these methods may be perfectly satisfactory for specific use in experienced hands, especially where variables are limited (e.g. product control of one fish type, etc.). However, for ease of use, precision, reliability and general applicability to a range of foods, HPLC with ion pairing, gradient elution and post column detection using o-phthaldialdehyde is recommended.
The final report is available from the FSA Library and Information centre.
To obtain a copy, please contact the Enquiry Desk, Information Services, Food Standards Agency (020 7276 8181/8182 or at
library&info@foodstandards.gsi.gov.uk
).
Contact
: For any enquiries concerning this research project, please contact the relevant Programme contact or email
science@foodstandards.gsi.gov.uk
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