South Korean scientists claim to have developed an effective, simple and inexpensive test to detect harmful levels of histamine in fish samples. Histamine can occur in spoiled food, such as fish, if left too long at room temperature.

The Chung-Ang University scientists, led by Professors Tae Jung Park and Jong Pil Park stated that, “We managed to accurately measure histamine concentrations ranging from 0.1 to 100 parts per million, with a limit of detection as low as 13 parts per billion.”

This was accomplished by using phage-display technology where external proteins of genetically modified viruses were used to check for chemical interactions. They established the best one to use as ‘Hisp3’. They then went on to produce carbon quantum dots and coated them in NAC (N-Acetyl-L-Cysteine) which naturally occurs and binds to ‘Hisp3’. The CQDs are fluorescent when exposed to irradiation with ultraviolet light but this is quenched when ‘Hisp3’ is added – this binds the NAC and coats the surface of the CQD.

The next stage is essential because when the sample, which contains histamine, is mixed with the CQD, the ‘Hisp3’ unbinds from the NAC and binds to the histamine which restores the fluorescent levels of the CQDS in direct proportion to the amount of histamine. By comparing the first and last levels of CQDs the scientists, using a handheld UV flashlight, or fluorescent detection equipment, were able to indirectly quantify the amount and intensity of histamine in the samples.

This strategy has been validated with samples of fish using known histamine concentrations and established techniques. Although the method is simpler it is proving to be more powerful than existing tests.

The detection of histamine is important and this new approach could further help to measure the quality, freshness of food and hence food safety for consumers.

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