According to the micro-header news, the scientists said that the best condition for using this method is a weak acid environment at pH 4.5 at 4-15 °C. Acidic foods such as freshly cut fruits and ready-to-eat meat can be kept fresh without further chemical treatment in low temperature and blue LED environments.
Although LEDs are often used as energy-saving light sources, they also have bacteriostatic effects. Bacterial cells contain light-sensitive compounds that absorb visible parts of the electromagnetic spectrum (400-430 nm) and this part is mainly blue LED light. Exposure to a blue LED triggers a series of reactions inside the cell that eventually lead to its death.
In the past, the study of the antibacterial effect of LED light was mainly carried out by adding a photosensitizer to a food sample or verifying the effect when the light source is very close (less than 2 cm). These conditions cannot be truly applied to food preservation. Scientists from the National University of Singapore have for the first time demonstrated food-related factors such as temperature and pH, and how they affect the bacteriostatic effect of LED light.
The team placed three major food-borne pathogens, Listeria monocytogenes, E. coli O157:H7 (Escherichia coli O157:H7), and Salmonella Typhimurium, under blue LEDs and adjusted them separately. To different pH values.
It was found that the bacteriostatic effect was better than neutral under acidic or alkaline conditions. Acidic conditions are more inhibitory against Listeria, while for E. coli O157:H7 and Salmonella typhimurium, alkaline environment works best, but acidic environment can also achieve effective inhibition. A 2013 study by the research team found that blue LEDs have the strongest inhibitory effect on bacteria at low temperatures.
Associate Professor Yuk Hyun-Gyun, research director, said: "Combining these results, we have found a possible way to preserve acidic foods without chemical treatment at low temperatures. This may satisfy the growing demand for natural foods without It is necessary to rely on chemicals such as sour agents and artificial preservatives to preserve food."
These findings have potential value for food preservation cabinets and food supplies, serving fresh cut fruits, ready-to-eat seafood such as sushi and smoked salmon, and cold meat products. This technology can also be used by retailers such as food courts and supermarkets.
Yuk said: "Next, we hope to apply this LED technology to real food samples, including fruits, seafood and meat, to see if it can effectively kill pathogens without destroying the food." Research to use LED technology to preserve freshness or increase nutrients in stored vegetables.