Consumer smartphone and packaging with “built-in nose” tests freshness of supermarket fish
New packaging that helps supermarkets and consumers tell how fresh fish is being developed by PhD candidate Jenneke Heising from Wageningen University in The Netherlands.
The research behind the packaging, which uses a “built-in” nose to send information to a smartphone, was published in November 2013 in the Journal of Food Engineering.
Fish can be a complicated product for supermarkets because few foodstuffs are as variable as fish. Even a the catch from a single fishing boat can contain fish with very different shelf lives. Water temperature, the sex of the fish and the type of food a fish has recently eaten can all influence the speed at which the meat decays.
Three ways of measuring freshness
The research examined three ways of measuring the freshness of packaged fish, all involving the use of a sensor in the packaging.
As the fish decays, various substances are released into the air inside the packaging and they subsequently dissolve in water in the sensor. Ms Heising has investigated the practicality of using sensors that measure acidity, conductivity or ammonia.
According to the research, ammonia 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, the research showed that measuring conductivity “looks promising”.
Conductivity says something about freshness
Various substances released from the fish cause water to conduct electricity more easily, according to Ms Heising. At differing temperatures, Ms 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,” Ms Heising said. “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,” she said.
Chip inside packaging with fish
Ultimately, this research could lead to a tiny chip being packaged in with fish. The chip will indicate how long the product can be kept.
“I’m thinking of a small piece of gel containing a chip that can be read with radio frequency identification (RFID),” Ms Heising said.
This would enable supermarkets and other retailers to judge the freshness of fish without opening the packaging.
“And consumers should also be able to read the chip information with their smartphones,” Ms Heising said.