Manufacturing & Supply Chain

From the outside you can’t tell whether pre-packed fish is still fresh. Once you remove the plastic it’s immediately obvious but, by then, it has already in your kitchen! So PhD student Jenneke Heising from Wageningen University in the Netherlands is working on packaging with a built-in nose that tells your smartphone how fresh the fish is- before you buy it.

Heising’s research, into three ways of measuring the freshness of packaged fish, has been published in the Journal of Food Engineering. The three methods have one thing in common: they all involve measurements using a sensor in the packaging.

As the fish decays, various substances are released into the air inside the pack and they subsequently dissolve in water in the sensor. The research investigated the practicality of using sensors that measure acidity, conductivity or ammonia. The ammonia sensor does not appear to be very useful because the substance is only released once the fish is almost ‘off’. Acidity is unreliable because temperature appears to have too much influence on the readings. However, conductivity looks promising, Heising says.

Various substances released from the fish cause water to conduct electricity more easily. At differing temperatures, Heising investigated whether the sensor readings represented how fresh the fish was. ‘We can see an effect very rapidly and that is just what we need. It seems we’ve found a good method. To confirm that, we’d also like to know in more detail which substances cause that effect. That’s what we’re investigating at the moment.’

Ultimately this research should lead to a tiny chip being packed in with fish, probably a small piece of gel containing a chip that can be read with RFID. This will enable supermarkets and other retailers to judge the freshness of the fish without opening the packaging. And consumers should also be able to read the chip information with their smartphones.

So no more smelly surprises when you get home!