Researchers from Cranfield University created a new technique to measure the ripeness of an avocado without damaging the fruit. This could reduce food waste by up to ten percent and fulfill the consumer demand for ready-to-eat avocados. The new technique uses a laser and small vibrations to test fruit resonant frequencies and conduct ripeness assessment without damage.

Avocado at Cranfield University's Plant Science Laboratory. Source: Cranfield UniversityAvocado at Cranfield University's Plant Science Laboratory. Source: Cranfield University

Up to 30 percent of avocado fruit is currently wasted because of damage caused by testing during grading and five percent more is lost at retail. The current ripeness test uses a pneumatic device that pushes into the fruit manually.

The new technique took technology used to test the uniformity of large engineered parts in auto factories and adapted it for ripeness testing. The technology is called Laser Doppler Vibrometry (LDV). LDV beams a laser at the fruit to measure overacted light and uses vibration to test resonant frequency. Vibrations are caused by an automated impact device that taps into the fruit.

The LDV test accurately predicts the ready to eat stage of avocado fruit. Hard fruits create a higher frequency than soft fruits. The team calculated the perfect frequency for ripe avocado and measured it with LDV.

The test can be conducted with no damage to the fruit. The LDV test could be implemented on the conveyor belt and scan individual fruits as they travel down the belt to be sorted by the existing automatic sorting mechanism. LDV was tested in a real avocado factory line under lab conditions.

A paper on this new system was published in Biosystems Engineering.