Super sterilizing effect LED will enter the fresh keeping market.

The best condition for using this method is the weak acid environment of pH 4.5 at 4-15 C, scientists say. Acidic foods such as fresh cut fruits and instant meat can be kept fresh without further chemical treatment under low temperature and blue LED.

Although LED is usually used as an energy saving light source, they also have bacteriostatic effect. Bacterial cells contain photosensitive compounds that absorb the visible part of the electromagnetic spectrum (400-430 nm), which is mainly blue LED light. Exposure to blue light LED triggers a series of reactions within the cell, leading to death.

In the past, the study on the Bacteriostasis of LED light was mainly based on the addition of photosensitizers in food samples, or the verification of the effect of light sources near the light source (less than 2 cm). These conditions can not really be applied to food preservation. Scientists from National University of Singapore first demonstrated the effects of food and other factors such as temperature and pH on the bacteriostatic effect of LED light.

The research team placed three main pathogens, Listeria monocytogenes, Escherichia coli O157:H7 and Salmonella typhimurium (Salmonella Typhimurium) under blue light LED, and adjusted them to different acid base values, respectively. The results showed that Lester and Escherichia coli O157:H7 were the same.

The results showed that under acidic or alkaline conditions, the bacteriostatic effect was better than neutral. Acidic conditions have stronger inhibitory effects on Lester bacteria, but for Escherichia coli O157:H7 and Salmonella typhimurium, the alkaline environment is the best, but the acidic environment can also be effectively inhibited. In 2013, a team of researchers found that blue light LED had the strongest inhibitory effect on bacteria at low temperatures.

"Combining these results, we found a possible way to preserve acidic foods without chemical treatment at low temperatures," said Yuk Hyun-Gyun, associate professor of research. This may satisfy people's growing demand for natural food without relying on chemicals such as acidifying agents and artificial preservatives to preserve food.

These findings have potential value for fresh food cabinets and food supplies, for preserving fresh fruits and instant seafood such as sushi and smoked salmon and cold meat products. This technology can also be used for retailers, such as food street and supermarkets.

Yuk said: "next, we hope to apply this LED technology to real food samples, including fruits, seafood and meat, and see if they can kill pathogens without destroying food." The team is also studying the use of LED technology to keep fresh or increase the nutrients in stored vegetables.

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