The E-Nose Knows
People have some questionable ways to tell if meat is fresh, but this machine learning-based approach gives objective measures.
If you have ever come home from the grocery store and thought something did not smell quite right as you were unpacking the bags, only to find a package of meat that should have been eaten last week as the culprit, then you know all too well the importance of monitoring the food supply chain. But aside from a quick sniff that may only catch the worst cases, how sure can you really be about the freshness of the meat you choose?
An international, cross-disciplinary team has developed a solution to this problem that can provide us with objective information about meat freshness. Taking a cue from the mammalian olfactory system, in which scent molecules simultaneously bind multiple receptors, and with varying affinities, to create a sort of scent signature, the team has created an electronic nose that can be packaged with meat.
The first component of the new method is a colorimetric barcode that can detect the type and concentration of twenty different gases. Packaging these barcodes along with meat causes them to create a colorful scent fingerprint that gives information about freshness. The fingerprint is complex, however, and the meaning of a particular set of gases and their concentrations is not obvious. To understand what the barcode is telling us, the researchers turned to machine learning.
Over four thousand images were collected to retrain a ResNet 101 deep convolutional neural network. The trained network was assessed with 686 images of barcodes monitoring three types of meat. The overall accuracy in determining the level of freshness was found to be 98.5%.
The inference model is able to run on a smartphone, which makes it possible for food chain suppliers, retailers, and end customers to get an up-to-the-minute freshness assessment. The team noted that the barcode can be easily mass-produced and the components are biodegradable and non-toxic. There is no mention of production cost, but assuming it to be very low at scale, it would be great to see these barcodes included in every package of meat at the grocery store. I suspect it would give consumers a much greater peace of mind than a quick sniff.