In a recent breakthrough in food safety science, researchers designed a new graphene-based biosensor that can accurately detect the freshness of meat.
This biosensor, reported in AIP Advances, identifies chemical byproducts released by animal tissues to identify the age of the meat, presenting a promising approach to ensuring the quality of meat being consumed.
"Despite advancements in preservation techniques, meat remains susceptible to contamination by notorious pathogens like Salmonella and E. coli," Krishna Jangid, a research scientist at Kraken Sense, a biotech company that develops biosensors for pathogen detection in food and liquids, told Tech Times in an interview. "Monitoring meat age allows for timely assessment of microbial growth, aiding in implementing appropriate storage conditions and mitigation strategies to minimize the risk of foodborne illness."
How does meat age?
Living organisms produce a molecule called adenosine triphosphate or ATP, to sustain all the vital functions. These molecules act like tiny batteries that can store chemical energy and release it when necessary to fuel different biological activities performed by our cells.
ATP is produced in the mitochondria, also known as 'the powerhouse of the cell'. The production relies on a key ingredient, oxygen, which is supplied via respiration. After an organism stops breathing, the ATP production comes to a halt for a while, and the existing ATP in the cells begins to break down.
So soon after an animal is slaughtered, the ATP-related chemicals kickstart a process known as muscle-to-meat conversion. At its initial stages, this process is beneficial to enhancing the flavor of the meat, but beyond a certain point, the remnants of ATP degradation can make the meat taste bad and risky to consume.
This new graphene-based biosensor detects hypoxanthine (HXA) -one of the molecules formed during the degradation of ATP - to assess the age of the meat.
HXA starts building up in the animal tissues soon after its death. Measuring the amount of HXA accumulated over time serves as a reliable method for judging the freshness of food and has become an indispensable factor in the food industry, highlighted the researchers in the study.
Studies have found that graphene-a form of carbon and a 21st-century wonder material- and its reduced form show promising results as support materials for electrochemical biosensors due to their exceptional electrical conductivity.
The researchers engineered a flexible electrode-which is the acting electrochemical biosensor- by transforming a polymer-based film into porous reduced graphene using a laser beam. The electrode was then coated with zinc oxide (ZnO) nanoparticles to attract the HXA molecules to the surface of the sensor.
When HXA molecules come in contact with the biosensor surface, it creates a spike in the voltage as HXA transfers its electrons to the sensor. The voltage change has a linear relationship with the presence of HXA molecules which means the amount of voltage increase is a direct indicator of the amount of HXA present in meat.
The sensor tested on some pork tenderloins from the supermarket, and it successfully detected HXA in the meat cuts with 98% accuracy.
While there are many HXA sensing tools available in the market, most of them are either too expensive or have a tedious testing process. This biosensor, however, "offers superior advantages in time, portability, high sensitivity, and selectivity," stated Ngo Thi Hong Le, the lead author of the study in the press release accompanying the study.
Another advantage of this biosensor is that it is enzyme-free, which is apparently a good thing.
"The enzyme-free nature of the sensor's active reagent confers robustness against environmental degradation, bolstering its suitability for real-time meat monitoring applications," Jangid said. "Thus, underscoring a clear trajectory toward the eventual integration of high-performance electrochemical biosensors into the stringent quality control frameworks and food safety protocols employed within the meat industry."
What is the need for freshness detectors?
Cutting-edge refrigeration can significantly slow down the chemical processes allowing us to store meat for lengthy periods and even safely transport it across the globe.
These methods, however, cannot bring the chemical changes to a complete halt. Thus, estimating meat age is essential to track diminishing flavor profiles and to ensure food safety due to its direct correlation with microbial and pathogen proliferation.
According to the World Food Program, approximately 1.3 billion tons of food produced for human consumption go to waste each year. In the meat sector, 23% of the production is either lost or wasted at every step, starting from the farm to the table. A major chunk of that wastage occurs at the stage when the meat is ready for consumption.
In a world burdened with a current cost-of-living crisis, coupled with rising carbon dioxide emissions from food production for a growing population, calls for technologies like meat freshness biosensors can help to curb food wastage.
Easy-to-use and low-cost food freshness monitors can promote a more sustainable approach to food production and consumption. They can help improve industry regulations around quality control and inventory and create avenues for consumer tactics, such as providing attractive discounts for food close to expiry.
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