CANADA – A team of Concordia researchers has developed a novel, low-cost, accurate, and user-friendly system that detects the presence of the toxin putrescine in beef to increase food safety.

Putrescine, as its name implies, produces the foul smells associated with putrefying meats and, when ingested in high quantities, can result in headaches, vomiting, diarrhea, and heart palpitations. Additionally, it has been related to an increased risk of colorectal cancer.

The supply chain that brings meat to market worldwide is highly complex and usually very efficient. But when disruptions in one part of the world can result in transportation delays an ocean and a continent away, meat spoilage becomes a very real risk to food producers, vendors, and consumers. This is especially true if food inspection protocols are lax.

“Making a rapid, easy-to-use biosensor for people to check the quality of the food they are eating is empowering. We wanted to make a device that anyone could use, that is disposable and contained no toxic materials,” says lead author Alaa Selim, MSc 22, now pursuing her Ph.D. at the University of Saskatchewan’s Vaccine and Infectious Disease Organization.

Her co-authors include her former Ph.D. student colleagues at the Shih Microfluidics Lab, James Perry, Mohamed Nasr, and Jay Pimprikar, as well as Steve Shih, associate professor of electrical and computer engineering.

“We believe our work is a first step toward using sensors in the meat preparation industry. In addition, we believe this type of sensing can be used for other fields like environmental sampling of heavy metal contamination and cancer and disease diagnostics,” said Steve Shih, the Concordia University Research Chair in Microfluidics for Biological and Chemical Analysis.

For Selim, the most important thing to a consumer is their health and the health of their family. 

“I want anyone, regardless of their background in technology, to be able to use this, whether it’s a college student, a busy mom, or people working in the restaurant industry,” she said.

The technique behind the sensor relies on cell-free protein synthesis, which produces a protein using the biological machinery of a cell without actually using the living cell. 

The researchers, whose work is published in the journal Applied Bio Materials, found that the putrescine repressor protein PuuR, found in the E.coli bacteria, could be used to indicate the presence of putrescine.

To check if the researchers could visually detect the presence of putrescine under UV light, putrescine was added to the cell-free system that was producing the repressor in a solution and placed on a paper device.

“Making a rapid, easy-to-use biosensor for people to check the quality of the food they are eating is empowering. We wanted to make a device that anyone could use, that is disposable and contained no toxic materials.”

The biosensor was able to detect the presence of putrescine after an hour, and after four hours, the researchers were convinced that their results were quite accurate.

Then they started testing real flesh samples.

To determine how much putrescine accumulated over a period of many days, little beef slivers were compared to those maintained in the freezer, the refrigerator, and at ambient temperature.

The putrescine levels in the samples from the freezer and refrigerator were surprisingly low while those stored at room temperature revealed rather high amounts, which would be enough to make anyone who ate them ill.

They discovered some correlation between their biosensor’s results and those of sophisticated chromatography used for food inspection.

The biosensor won’t be readily available in a fully working, commercial form anytime soon, but the researchers are hopeful about its possibilities.

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