New Sensor allows for fast and accurate check for Fish Rottenness
Researchers from Iowa State University have developed a new sensor that can detect if fish is rotten. This sensor determines is fish is rotten by checking for a for a molecule called histamine in the fish. Histamine is produced in seafood that has not been properly stored and refrigerated. Consumption of seafood with high histamine levels can lead to food poisoning.
In the past, the World Health Organisation has implicated histamine as being responsible for several food poisoning outbreaks. Also, the FDA prohibits the interstate sale of rotten fish (fish high in histamine).
Histamine is not hazardous in low concentration. However, when seafood is not properly preserved, the histamine level in the food rises to toxic levels. Moreover, once histamine is produced in seafood, it cannot be eliminated by heating, cooking, or refrigerating the seafood. The seafood poisoning from histamine is technically known as scombroid poisoning. Scombroid poisoning can trigger food allergic reactions. Symptoms of histamine poisoning include:
- tingling or burning in or around the mouth or throat
- rash or hives on the upper body
- drop in blood pressure
- headache
- dizziness
- itching of the skin
- nausea
- vomiting
- diarrhea
- asthmatic-like constriction of the air passage
- heart palpitation
- respiratory distress
These symptoms usually occur within a few minutes to a few hours of rotten food consumption. These symptoms can last from 12 hours to a few days.
Examples of fishes that are prone to developing high histamine levels are:
- mackerel
- Mahi-mahi
- anchovy
- herring
- bluefish
- amberjack
- marlin
Detection of histamine requires heavy lab equipment, and detection takes a lot of time (hours) This makes it difficult to measure histamine levels in-field and on-site such as at import/export point of entry/exit, supermarkets, etc where an immediate histamine check may be required.
Importantly, smelling is not a good way to tell if histamine is present because some histamine-contaminated fish do not smell. This because only fish that spoil in low temperature smell,. Fish that spoil in high temperature do not smell.
The researchers at Iowa State University developed a sensor for checking fish rottenness. They made the sensor by printing graphene on a patch with a method called Aerosol Jet Printing (AJP). Graphene is a carbon-like material which has very interesting engineering properties such as high electrical conductivity and high mechanical strength. Also, graphene does not poison the body or human food when used inside the body or in consumable food.
The researchers made graphene into an ink-like material and then used Aerosol Jet Printing to print the graphene as F-shaped patterns on a patch. This method is a cheaper and easier method to print graphene compared to other methods that require elaborate and heavy lab equipment.
After printing the graphene, the researchers added histamine antibodies to the graphene. These histamine antibodies will give the graphene sensor an affinity for histamine, the signature of rotten fish. Hence, when the sensor is placed in a sample contain histamine, it will strongly attract histamine to itself, and bind the histamine to itself.
These biofunctionalized graphene sensors, as they are called, will only detect histamine. They will not detect other molecules because they have been functionalized with histamine antibodies alone. This makes the sensor a selective sensor. Selectivity is the desired property in biosensor design since detecting other things aside the molecule of interest constitutes noise.
The researchers used the printed graphene sensor to detect histamine by placing the graphene sensor in rotten fish broth, and measuring the electrical properties of the graphene when the broth is rotten versus when the broth is not rotten. The graphene sensor showed remarkably different electrical properties when in rotten fish vs when not in rotten fish.
Based on earlier controlled studies, the researchers showed that this sensor can detect histamine down to 3.41 parts per million (ppm). For perspective, the FDA recommends that histamine levels in fish should be less than or equal to 50 parts per million parts of the fish. The FDA classifies fish with histamine levels of up to 50 ppm as decomposed and of up to 500 ppm as toxic.
This sensor can measure histamine levels from 6.25 ppm to 100 ppm, and it takes only 33 minutes for the sensor to measure histamine levels. The authors propose that this same technique can be used to make other biofunctionalized sensors that measure other poisonous agents in food, like salmonella.
To prevent histamine rise in your raw seafood, make sure you always store your fresh seafood at low temperatures below 70 degrees Fahrenheit until you are ready to cook your seafood.
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