As tomatoes ripen, they change in color from green to orange to red. Assessing when they're at peak ripeness is done with the naked eye, and is therefore somewhat subjective. Thanks to research being conducted at Spain's University of the Basque Country, however, producers may soon be using a laser device to take the guesswork out of the equation.

Led by Josu Trebolazabala, the scientists experimented with utilizing a portable Raman spectrometer to gauge the ripeness of tomatoes. Putting it in fairly basic terms, a Raman spectrometer non-destructively determines the composition of an object by shining a laser on it, then analyzing the manner in which that object's molecules scatter the light.

Although a larger lab-based Raman spectrometer provided more precise readings, the portable model was nonetheless found to be accurate enough for use in gauging ripeness in the field.

"When the tomato is green, the main pigments are chlorophyll (hence its green colour) and the waxy cuticles, which are on the outside," says Trebolazabala. "Once the colour changes to orange-coloured, compounds of a different type are observed; the carotenoid compounds are activated. The tomato gradually acquires nutrients until it reaches its optimum point, in other words, when the lycopene (the red carotenoid) is at its maximum level. After that, the tomato begins to lose its carotenoid content, as shown by the analyses conducted on overripe tomatoes."

The technology could reportedly also be used to assess other food plants that change color as they ripen, and has already been successfully tested on pumpkins.

A paper on the research was recently published in the journal Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy.

Source: University of the Basque Country