THE well-used "squeeze test" to find a ripe avocado could be a thing of the past if a university in the United Kingdom has its way.
Cranfield University has developed and tested technology using a laser and small vibration to test the individual fruits' resonant frequency, giving a reliable assessment of ripeness without damaging the avocado.
The university says the technique could reduce waste by up to 10 per cent and help fulfil consumer demand for ready-to-eat fruit.
According to Cranfield, up to 30 per cent of avocado fruit is currently wasted due to damage caused by testing during grading, with a further 5pc loss at retail.
The current way to test ripeness is through a pneumatic device which pushes into the fruit, or manual testing.
The university adapted a technology more often used in automotive factories to test the uniformity of large engineered parts.
Laser Doppler vibrometry (LDV) beams a laser at the fruit to measure refracted light and uses small vibrations to test the resonant frequency.
The vibrations are caused by a simple automated impact device which taps the fruit. The LDV test was proven to accurately predict the ready-to-eat stage of avocado fruit.
Cranfield University director of environment and agrifood, Professor Leon Terry, said hard fruits create a higher frequency than soft fruits, so the team calculated the perfect frequency for a ripe avocado and accurately measured this with the LDV test.
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"Leaving the fruit undamaged is of great benefit and vastly reduces waste. The test we have developed could be extended to other fruits," Professor Terry said.
The UK reported imports nearly 100,000 tonnes of avocados per year.
The avocados travel on conveyor belts in single file, which means the LDV can test them individually.
Research fellow Dr Sandra Landahl said the team tested the accuracy of LDV on a real factory line, under lab conditions.
"The method has real potential, giving accurate measures of ripeness without damaging fruit. If developed, a simple 'traffic light' system could sort the fruit into those that are ripe, for discard or for storage, helping industry tackle food waste at this point in the supply chain," Dr Landahl said.
Cranfield University is co-leading the new BBSRC Quality and Food Loss Network, a new initiative to link researchers with industry to find solutions for the huge food waste challenges facing the supply chain.
The paper 'Non-destructive discrimination of avocado fruit ripeness using laser Doppler vibrometry' is published in Biosystems Engineering.