Deaths and crippling sickness due to food poisoning are rampant. While these are caused by deadly bacteria in the food, in most cases tests are either not carried out, or there are delays in getting the results. Most common victims are those at social gatherings like weddings and ceremonies involving feasts, where tests are inevitably not conducted prior to consumption.
But now, a group of scientists from Osaka Metropolitan University (OMU) in Japan have developed a food testing technique that can deliver results in under an hour as against two days otherwise required to detect harmful bacteria in food – practically delivering the potential of on-the-spot test-and-results to avoid possible food poisoning.
The new technique developed by the research group led by Professor Hiroshi Shiigi at the Graduate School of Engineering, OMU, involves accurately – and almost in a jiffy – determining the presence of harmful bacteria in food through an electrochemical method using a water-soluble salt called tetrazolium salt (abbreviated as ‘MTT’). This is found to successfully detect presence of bacteria in food within an hour with neither complicated operations nor expensive equipment for the testing. The study has been published in Analytical Chemistry.
The study focussed on using the potential of the electrochemical properties of tetrazolium salts to develop a simple method of assessing the bacterial count in food products. MTT is known to have excellent bacterial cell membrane permeability and changes to the insoluble reduced form of formazan inside the cell, and the number of viable cells was estimated by focusing on the reduction current of MTT remaining in the suspension. Formazan is related to formic acid and is obtained through the action of tetrazolium salts. It produces colour when the MTT comes in contact with live tissue – in this case, the bacteria – to reveal the presence of bacteria. In the process, the number of viable bacterial cells was estimated by focusing on the reduction current of MTT remaining in the suspension.
However, Prof Shiigi’s team faced a challenge: dissolved oxygen is an important substance for bacterial activity, but it interferes with MTT’s electrochemical response. They worked out a process that eliminated that interference, and the real-time observation revealed the MTT’s detection ability of the bacteria was completed in just 10 minutes.
The method provided a quick estimation of the number of viable bacteria in the food sample, opening avenues to rapid testing of food products even at the sites of consumption.
Prof Shiigi, while confirming that this technique does not involve complicated operations or expensive equipment, now plans to develop a portable sensor to carry out the tests as part of practical applications that are likely to enhance food safety manifold.
The development of this technique would revolutionise food safety and testing practices worldwide. While conventional food testing methods are time-consuming, in the face of delivery deadline pressures, this quick and accurate method of detecting bacteria in food products would be a promising way to cut production and delivery schedules.
The OMU website quotes Prof Shiigi: “With this method, we can quickly measure the number of viable bacteria, allowing us to confirm the safety of food products before they leave the factory and prevent food poisoning,”