Research highlight

Physical sciences: Ripe for the picking? An a-peel-ing spectrometer

Scientific Reports

September 9, 2016

A hand-held device that can evaluate the ripeness of different varieties of apples is presented in Scientific Reports this week. The spectrometer, which weighs 48g, works with an application on a smartphone via a wireless connection, to collect, store and analyse data from the device.

Optical spectroscopy - a technique in which the properties of objects can be studied based on their interactions with light - has a number of applications including assessing food quality, environmental sensing and pharmaceutical testing. However, most spectrometers used in industrial- or laboratory-based applications are expensive, bulky and require an accompanying computing device to capture data. Previous research has produced portable smartphone spectrometers; however, the data they provide has been inconsistent.

Anshuman Das and colleagues created a prototype spectrometer 88mm x 37mm x 22mm in size, with a dedicated application interface on a smartphone. The authors then used the spectrometer to evaluate the ripeness of three different varieties of apples - Golden Delicious, Empire and McIntosh. This was done by measuring the UV fluorescence from chlorophyll present in the skin of the apples during the ripening process over a period of 11 days, and their results correlated with destructive firmness tests on the fruit.

The authors argue that optical tests that are non-destructive, such as the one their device performs, could assist farmers in determining optimum harvest times. They also suggest the device could be adapted for consumer applications for testing fruit ripeness.

doi: 10.1038/srep32504

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