How fruits are quality-tested for ripeness: sweetness, firmness, and color

How Fruits Are Tested For Ripeness

In the past, the only way to test the sweetness or firmness of fruits, such as apples, peaches, and apricots, was to select samples of the newly-harvested fruit and eat them! Farmers assumed that if they used this type of destructive testing on a few fruits, they would know about the condition of all the others in the batch.

Now, every individual fruit can be tested using non-destructive technologies to grade and sort them. Imaging spectroscopy or multi-spectral imaging can measure the sweetness and firmness of fruit.

Testing Fruit Quality

An optical detector fuses four laser beams, each at a different waveband of light, into one. An imaging spectrograph, a digital camera, and a computer analyze the amount of laser light that is absorbed by the fruit. This indicates the sweetness of the fruit, while the firmness is measured by the amount of light bounced back.

This technology has many other applications in industry and in space exploration, but in the fruit industry it is used to sort fruit just after it has been picked.

Orange growers have always had the desire to make their oranges as orange as possible! Oranges grown in some parts of the world are dull and lack color because there are no cold nights, while those grown in areas with cool nights are usually brighter in color.

Now, orange growers take their freshly-picked oranges to large buildings where ethylene gas is used to stimulate the chlorophyll in the oranges to bring out more natural color.

After that, each fruit is photographed from every possible angle using a digital camera. Computers use these pictures to record any undesirable marks on the skin at the same time as analyzing the size, color, and shape of each orange.

Depending on the demands of the market, the grower can set the required grade specifications in the computer. Any oranges which do not meet the required standards are removed from the production line and later used to produce juice.

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Comments 4 comments

Ardie profile image

Ardie 5 years ago from Neverland

I never knew farmers used such in-depth analysis to test fruit for ripeness. I just thought they "knew" if it was picking time = ripe fruit :) Thanks for teaching me something new!

Haunty profile image

Haunty 5 years ago from Hungary Author

I have cherry trees and I pick them in the summer. Then I analyze the cherries and eat them all!!!

Ardie profile image

Ardie 5 years ago from Neverland

OOh, I have apple trees. Together we could make some might fine pies :) My way to know if the apples are ripe is if they taste ok!

Haunty profile image

Haunty 5 years ago from Hungary Author

You bring the apples, I bring the cherries, and we make the pies together. :)

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