Smart Choice
The traditional label and more
The collaborating companies started by looking at the traditional label – one sticker on individual fruit. But they found that the gases released from a fruit as it ripens – the volatiles – could be localised. A difference in gas production occured between the stem and the base of the fruit. The issue of safe food-contact materials also caused significant barriers to individual label production.
"We were testing them initially directly on fruit, there were quite a few hurdles to pass because direct food-contact regulations are much more demanding than those that relate to the packaging, and so we opted for the simpler route to market – put them on the package."
By placing the sensor inside a package containing four pieces of fruit, the aroma volatiles are trapped and the accumulative gases react with the sensor, causing the colour to change.
Consumers already use fruit aromas to select fruit, but using a more conventional method – sniffing.
"Melons are a good example. People try to determine the ripeness by smell – we're exploiting that, using the chemistry of the colour change involved in the sensors," says Dr Sharrock. Without giving away all the "secret herbs and spices", Mr McInness describes the sensor as a multi-laminate construction with a reagent that has natural compounds encapsulated in the middle. The reagent, when exposed to the volatiles from the fruit on an accumulative basis, causes a chemical reaction that creates the colour change in the label.
Although pears may not seem like the obvious choice to work with, the explanation is quite simple. Unlike other fruits, many varieties of pear do not change colour as they ripen. This makes choosing fruit a difficult task for customers without squeezing each fruit to test its firmness. ripeSense not only makes the decision-making process easier for consumers, it eliminates waste in supermarkets by limiting the damage caused to fruit by customers testing it out.
