Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Ever tried a 'laser delicious' apple?

04.12.2014

Researchers in Lebanon and France develop laser biospeckle method to help farmers harvest climacteric fruits -- like apples, bananas, pears and tomatoes -- at their precise peak in ripeness

The ability to detect when to harvest "climacteric" fruits -- such as apples, bananas, pears and tomatoes -- at the precise moment to ensure "peak edibleness" in terms of both taste and texture may soon be within reach for farmers, thanks to the work of a team of researchers from Saint Joseph University in Lebanon and the Université de Bretagne Occidentale de Brest in France.


The team's setup to measure speckle patterns involves coherent light, a laser beam, polarizers and quarter-wave plates to generate different incident polarizations, and a CMOS or CCD camera to record the fruits' speckle pattern.

Credit: R.Nassif


This is the speckle pattern recorded when illuminating an apple.

Credit: R.Nassif

As the team reports in a paper published in The Optical Society's (OSA) journal Applied Optics, they recently demonstrated a laser biospeckle technique capable of detecting fruits' climacteric peak.

What's the significance of this climacteric peak? "Fruits are divided into two categories: climacteric or nonclimacteric fruits," explained Rana Nassif, a postdoctoral researcher affiliated with both Saint Joseph University and the Université de Bretagne Occidentale de Brest. "Climacteric fruits continue their maturation off the tree or vine, so these fruits emit ethylene and are characterized by a climacteric peak--indicating a maximum ethylene release.

"This peak signals that the fruit has reached its maturity." After this point, the fruit is more susceptible to fungal invasion or begins to degrade from cell death.

By tapping biospeckle activity, generated by illuminating a biological medium with coherent light, the researchers studied the evolution of two batches of Golden apples' speckle patterns as they underwent the ripening process in both low- and room-temperature environments.

To do this, the team uses a rather simple setup that involves coherent light, a laser beam, polarizers and quarter-wave plates to generate different incident polarizations, and a digital camera to record the speckle pattern. "Simplicity and low cost are the key advantages of our technique," noted Nassif.

How does it work? Laser light interacts with any medium through different processes such as scattering, absorption and reflection. Photons scattered by the medium interfere with the incident light field to create a speckle pattern. "A group of sparkling and dark grains called 'speckle grains' make up this pattern. If the medium is biological -- meaning that it presents some sort of cell activity -- its speckle pattern will show changes with time," she said. "And this pattern depends on the medium's scattering properties, as well as its own nature."

Once obtained, speckle patterns can be correlated with a reference standard, which is based on emitted ethylene concentrations obtained by a principal component analysis. "This approach allows us to validate biospeckle as a noninvasive alternative method to respiration rate and ethylene production, which are used today for climacteric peak detection and as a ripening index," said Nassif.

The team explored the diffusion properties and inner activity aspects of the apples via speckle grain size, recording the temporal correlation between a set of images, consecutively, in different light polarizations. "On one hand, the changes the speckle grain size underwent marked an inflection point corresponding to the climacteric peak for apples stored at room temperature. While on the other hand, the time correlation coefficient behavior demonstrated a rise in the apples' activity until the day of climacteric peak was reached, followed by a decrease that marked the beginning of the deterioration stage."

Beyond apples, Nassif and colleagues are also monitoring the ripening of "Conference" pears -- performing backscattered speckle images on the fruits during the ripening phase. They supplemented these images with fluorescence and biochemical measurements.

"By doing this, we were able to show that as the glucose content increases, the circular degree of polarization decreases," Nassif said. In technical terms, she added, "This signature is expected for a medium that constituted a significant portion of small 'scatterers,' in which the Rayleigh diffusion regime outweighs the Mie regime. We also noticed a decreasing speckle grain size, which can be attributed either to increasing glucose or the decreasing of absorption."

What's next for the team? "In the near term, we're working on speckle theoretical studies based on Monte Carlo simulations -- taking into account light polarization and media characteristics," said Nassif. "These simulations can be used to differentiate and quantify the diffusion coefficient variations and its effect from those of absorption on the fruits' speckle image."

Then, they'll focus on comparing these simulations with experiments done on latex spheres -- a mix of spheres of varying diameters -- to vary the diffusion and absorption coefficient.

And, of course, one of the team's ultimate goals is to develop a portable tool to enable farmers to noninvasively assess their fruits' maturity in orchards or fields to detect the optimal time to harvest their crops. "This is of great interest to fruit farmers--especially since most tests used today are either destructive or based on visual criteria that are often wrong," noted Nassif.

Paper: "Detection of Golden apples climacteric peak by laser biospeckle measurements," by R. Nassif et al., Applied Optics, Vol. 53, Issue 35, pp. 8276-8282(2014).

http://www.opticsinfobase.org/ao/viewmedia.cfm?uri=ao-53-35-8276&html=true

About Applied Optics

Applied Optics publishes articles emphasizing applications-centered research in optics, moving the potential of science and technology to the practical. Published three times each month, Applied Optics reports significant optics applications from optical testing and instrumentation to medical optics...from holography to optical neural networks...from lidar and remote sensing to laser materials processing. Each issue contains content from three divisions of editorial scope: Optical Technology; Information Processing; and Lasers, Photonics, and Environmental Optics. It is edited by Joseph Mait of the U.S. Army Research Laboratory. For more information, visit http://www.OpticsInfoBase.org/AO

About OSA

Founded in 1916, The Optical Society (OSA) is the leading professional organization for scientists, engineers, students and entrepreneurs who fuel discoveries, shape real-life applications and accelerate achievements in the science of light. Through world-renowned publications, meetings and membership initiatives, OSA provides quality research, inspired interactions and dedicated resources for its extensive global network of optics and photonics experts. OSA is a founding partner of the National Photonics Initiative and the 2015 International Year of Light. For more information, visit http://www.osa.org 

Jason Socrates Bardi | EurekAlert!

Further reports about: OSA Optical coefficient ethylene fruits optics polarization ripening

More articles from Agricultural and Forestry Science:

nachricht Researchers discover a new link to fight billion-dollar threat to soybean production
14.02.2017 | University of Missouri-Columbia

nachricht Important to maintain a diversity of habitats in the sea
14.02.2017 | University of Gothenburg

All articles from Agricultural and Forestry Science >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Impacts of mass coral die-off on Indian Ocean reefs revealed

21.02.2017 | Earth Sciences

Novel breast tomosynthesis technique reduces screening recall rate

21.02.2017 | Medical Engineering

Use your Voice – and Smart Homes will “LISTEN”

21.02.2017 | Trade Fair News

VideoLinks
B2B-VideoLinks
More VideoLinks >>>