A Norwegian idea

The idea of Keep-it® arouse from a scientist that noticed that the writing on car park tickets disappeared in sunlight. That gave him the idea for a shelf life indicator for food, based on a combination of chemical processes, time and temperature. This eventually resulted in the “Keep-it® shelf life indicator”, which was launched in Norwegian supermarkets in 2012. By the end of 2016 Keep-it Technologies® has sold 22 million indicators.

One hot summer day in 1992 Professor Per-Olav Skjærvold parked his car as usual at the Tullinløkka open air car park in central Oslo before taking the train to the Norwegian University of Life Sciences at Ås. But on that particular day he started to puzzle over something that would eventually lead to the Keep-it indicator.

His car’s front window was filled with 40 or so car park tickets. Several of them so bleached by the sun that it was difficult to read what was printed on them. Skjærvold was wondering how the poor car park attendant was going to spot today’s ticket. Then he thought: “What if there was a ticket that gradually changed from green to red when the paid-for time expired?”

On the journey to the agricultural college, Professor Skjærvold thought about possible solutions. Could photo technology be used? Would it be possible to control and delay the film developing process for a polaroid picture, for example? Inspired by these ideas he contacted his colleague Professor Petter Heyerdahl, a long standing “confederate” in the field of mechanics and physics. They took photos with an instamatic camera, cut the polaroid pictures immediately into narrow strips and put them in the deep freeze. Then they examined how the images developed at various temperatures and over different time periods to map the delay in the development process. These experiments were also performed under different light conditions. They quickly realised that they could manipulate and delay the development process by means of the temperature. This led them to believe that the technology could somehow also be used to check on the progress of other temperature sensitive products. In other words, the idea of a shelf life indicator for food was born.

At the same time, Skjærvold and Heyerdahl realised that the photo development process was too fast at higher temperatures, and that they would have to come up with a solution where the process went much slower and with better accuracy and controllability. Could a chemical process work better?

The following year, as a result of this realisation, the pair contacted another colleague, Brit Salbu, a professor of chemistry and basic research. During the first few meetings, Professor Salbu immediately became interested in the “device”, and was absolutely clear in her assessment of what was needed to develop it into a commercial product. “We must have a colour, we must have a diffusion process and we must have a stabiliser,” she said. Salbu drew inspiration from the chemicals examined in various doctoral theses, and together with her department engineer Helge Lien, she carried out countless experiments in the period between 1993 and 2001. Among the substances investigated were alginates (extracts from seaweed) and the pigment Prussian blue. The breakthrough came in 2001, when the principles for a shelf life indicator was verified in the laboratory.