ITALY –Consumers could soon tell whether a frozen foodstuff has been thawed and then refrozen thanks to a technology created by scientists at the Istituto Italiano di Tecnologia in Italy.
Ivan Ilic, Mario Caironi, and their colleagues published the discovery in ACS Sensors under the title “Self-Powered Edible Defrosting Sensor”.
Food, especially meat, can be frozen to extend its shelf life, which greatly minimizes waste while maintaining food quality and safety.
However, freezing and thawing have an impact on the quality of food, and this is particularly hazardous when repeatedly freezing and thawing meat because it can greatly increase the number of pathogenic bacteria.
Therefore, it is crucial to deliver frozen meat to the end consumer without thawing.
In the food supply chain, temperature sensors are frequently used to gauge the temperature of food containers (e.g., refrigerators).
These sensors cannot be used by end consumers directly because they are made to monitor food conditions along the supply chain.
The researchers coupled a temperature-activated galvanic cell and an ionochromic cell to enable the device to detect defrosting events.
Previously, galvanic cells were exploited as detectors in ingestible electronics: a galvanic cell, assembled without an electrolyte, would start generating electricity only after being immersed in gastric acid─an electrolyte.
The sensor is entirely composed of edible elements, such as table salt, red cabbage, and beeswax.
The galvanic cell uses an aqueous electrolyte solution to function, and it can only generate current at temperatures over the solution’s freezing point.
Tin ions are released from the ionochromic cell using the current created during the defrosting process. Combining with natural dyes changes the hue and reveals information regarding defrosting occurrences.
The sensor’s response temperature can be adjusted between 0 and 50 degrees Celsius (32- and -58 degrees Fahrenheit).
“This device is a proof of concept that such a sensor can be created using only edible materials. The miniaturization of such self-powered devices through smaller wax chambers and printed thin films of metals and an optimized design will produce a fully edible sensor.
“When designing such a sensor, it is of crucial importance to isolate the chambers filled with electrolytes from the food,” said the researchers.
The device can be utilized in the supply chain in several ways thanks to the temperature range. As a sensor, it can measure the amount of time that an object was exposed to above-the-threshold temperatures, and as a detector, it can send out a signal indicating that such exposure occurred.
The technology might guarantee that frozen food is handled properly and is safe for consumption, according to the study.
Additionally, the sensor could be used by both supply chain employees and customers, guaranteeing that the food remained correctly frozen along the whole supply chain.