Affecting millions of people annually, food poisoning by consumption of contaminated products is a significant health issue. Typically, retailers and manufacturers rely on “sell by” and “good until” dates, as a way to measure the safe shelf life of the things we eat. This is mostly due to the fact that monitoring the bacteria and microorganisms that cause illness are a challenge to detect. While a number of bacteria detection methods do exist, such as gas composition analysis or culturing, they are too cost and time consuming to be used on a practical level.
Researchers at the Institute of Information Optics, Zhejiang Normal University, Jinhua, China are putting their efforts into changing that. Using a method called tunable diode laser absorption spectroscopy, or TDLAS for short, the researchers are using lasers to detect and monitor microorganisms in food.
When bacteria moves across a surface, it leaves behind a slew of microorganisms. Identifying this movement is key to the detection of contamination. “Microorganism growth is almost always associated with the production of carbon dioxide,” researcher Jie Shao said, in a news release. “By assessing the level of CO2 within a closed compartment [..] it is possible to assess the microbial growth.”
The process is performed by using a red, cohesive laser on a biological material, such as a piece of steak. The light disperses through the material. In places where the light is interfered with, the light “speckles”. The speckling of the light is affected by the existence of bacteria on the material. By monitoring the concentration of changes in the laser speckling, the presence of microorganisms can be detected.
TDLAS is used commonly to assess materials that enter a gas phase, since it can be used to measure the concentration of certain gases. In the case of food contamination, monitoring the levels of C02 helps to indicate the level of dangerous bacteria present. Using E. Coli on chicken breast, the researchers were able to find that uncontaminated substances have little to no change in laser speckle, where contaminated surfaces yield differing results.
Using TDLAS to determine the contamination levels of food might not be reserved to just lab testing, either. The lasers needed to perform the process are neither large nor extremely powerful. They are also able to detect bacteria through clear, plastic packaging, like the ones meat products are typically sold in. There’s a significant chance that this technology could find its way into home refrigerators and grocers sooner, rather than later.
That’s not to say that the development will solve all potential food poisoning cases. TDLAS does not distinguish between the types of bacteria, like Salmonella or E. coli, that might be present in food. Identifying viruses or other contaminates would require additional levels of testing. The researchers plan to expand the use of TDLAS beyond food and medical uses, in their experiments. For now, the idea of greatly reducing our chances of contracting food poisoning, through the use of lasers in refrigerators is worth paying attention to.
What are some other ways lasers are used to keep us healthy and safe? We look forward to your responses in the comments!
