(Nanowerk Spotlight) In today’s interconnected world, food supply chains have grown increasingly complex, spanning multiple countries and involving numerous intermediaries. This complexity has led to a heightened risk of foodborne illnesses due to contamination.
Traditional methods for detecting pathogens in food are often labor-intensive and time-consuming, requiring samples to be sent to centralized labs for testing. These methods are not only inefficient but also incapable of real-time monitoring, leaving a significant gap in our food safety infrastructure.
Researchers from McMaster University in Canada have developed an innovative food packaging system that can detect Salmonella contamination in packaged foods without having to open or manipulate the products. This new “Lab-in-a-Package” platform integrates a redesigned packaging tray, a buffer-saturated membrane, and a highly sensitive Salmonella sensor to enable continuous, real-time monitoring of food safety.
The existing paradigm for food safety is far from ideal. It involves taking samples from food batches and sending them to centralized labs for testing. This approach is fraught with inefficiencies. For starters, it’s time-consuming, often taking days or even weeks to get results. During this time, the food items in question are usually held back from the market, leading to significant food waste and economic losses.
Moreover, these tests often require the food to be treated with various reagents, which can alter their natural properties and make them unsuitable for consumption. The limitations of this system have long been recognized, but solutions have been elusive—until now.
The “Lab-in-a-Package” system is an innovation that addresses many of these challenges head-on. At its core, the system consists of a specially designed food packaging tray and a reagent-infused membrane. The tray is designed with a 45° incline to maximize the localization of fluids onto a sensing interface, which is crucial for accurate pathogen detection.
Schematic illustration of the Lab-in-a-Package platform. a) Complete Lab-in-a-Package in situ detection platform with inclined packaging tray, reagent-saturated membrane, and sensor incorporation shown for RTE chicken products. Imaging procedure involving fluorescence scanning is also shown. b) Inclined food packaging trays with angles ranging from 45° to 90° to optimize test sample localization. c) Depiction of membrane saturation with reagent components, diffusion of buffer components and target analyte to sensor surface, and fouling prevention. d) FNAP sensor development with corresponding material surface and biochemical modifications. (Reprinted with permission by Wiley-VCH Verlag)
The membrane serves a dual purpose: it acts as a reagent-immobilizing matrix and an antifouling barrier for the sensor. This dual functionality ensures that the sensor remains accurate and reliable over time. What sets this system apart is its adaptability; it can be universally paired with various pathogen sensors, making it a versatile tool in the fight against foodborne illnesses.
To further enhance the system’s capabilities, the researchers developed a new synthetic fluorescent nucleic acid probe (FNAP) that is highly specific to Salmonella Typhimurium, one of the most common causes of food poisoning. This probe functions as a substrate for cleavage by the RNase H2 protein of the pathogen. A Salmonella-responsive fluorescent sensor was then optimized, involving this synthetic DNA probe that signals when cleaved by the Salmonella enzyme RNase H2.
By tracking an attached fluorophore and integrating a fluorophore-quencher pairing into the FNAP construct, probe cleavage due to Salmonella presence translates into a real-time fluorescent signal. This nanoscale probe provides high specificity, detects within 8 hours, and functions at food storage temperatures of 4 °C to 45 °C.
Rigorous testing demonstrated high specificity to Salmonella with a detection limit of 1000 cells per gram of food within 8 hours.
One of the most compelling features of the “Lab-in-a-Package” system is its ability to perform in situ pathogen detection. This is a game-changer in the field of food safety. It means that the system can detect pathogens within the closed food packaging, eliminating the need for the package to be opened or the food to be manipulated in any way. This not only reduces food waste but also increases the efficiency of the entire food supply chain.
The system has undergone rigorous testing, including trials with artificially contaminated bulk, ready-to-eat chicken products. It has consistently shown high detection performance. Moreover, it has been successfully tested in real-world scenarios using a handheld fluorescence scanner with smartphone connectivity, making it a practical solution for widespread adoption. The system remained effective when Salmonella was introduced via cross-contaminated gloves, surfaces, and knives, realistically mimicking potential exposure routes.
The materials used in the “Lab-in-a-Package” system have been carefully selected to meet regulatory standards. The packaging tray and membrane interface are developed with specific objectives such as sensor visualization, sample solution localization, and analyte diffusion. All materials are selected from the Indirect Food Substances provisions, ensuring they meet the stringent regulatory requirements for food safety.
As the authors point out, the “Lab-in-a-Package” system represents a significant advancement in the field of food safety. Its ability to perform real-time, in situ pathogen detection without requiring any manual intervention is nothing short of revolutionary. While the system has been demonstrated for the detection of Salmonella in chicken, its universal design means it could potentially be adapted for other types of pathogens and food products. As we move into an era where food safety is more critical than ever, innovations like the “Lab-in-a-Package” system are paving the way for a safer, more efficient food supply chain.
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