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 Microjet generator for highly viscous fluids
13.02.2018 | Tokyo University of Agriculture and Technology

nachricht Sweet route to greater yields
08.02.2018 | Rothamsted Research

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: Developing reliable quantum computers

International research team makes important step on the path to solving certification problems

Quantum computers may one day solve algorithmic problems which even the biggest supercomputers today can’t manage. But how do you test a quantum computer to...

Im Focus: In best circles: First integrated circuit from self-assembled polymer

For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.

In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...

Im Focus: Demonstration of a single molecule piezoelectric effect

Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale

Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...

Im Focus: Hybrid optics bring color imaging using ultrathin metalenses into focus

For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.

But today's glass-based lenses are bulky and resist miniaturization. Next-generation technologies, such as ultrathin cameras or tiny microscopes, require...

Im Focus: Stem cell divisions in the adult brain seen for the first time

Scientists from the University of Zurich have succeeded for the first time in tracking individual stem cells and their neuronal progeny over months within the intact adult brain. This study sheds light on how new neurons are produced throughout life.

The generation of new nerve cells was once thought to taper off at the end of embryonic development. However, recent research has shown that the adult brain...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on High Temperature Shape Memory Alloys (HTSMAs)

15.02.2018 | Event News

Aachen DC Grid Summit 2018

13.02.2018 | Event News

How Global Climate Policy Can Learn from the Energy Transition

12.02.2018 | Event News

 
Latest News

Stiffness matters

22.02.2018 | Life Sciences

Magnetic field traces gas and dust swirling around supermassive black hole

22.02.2018 | Physics and Astronomy

First evidence of surprising ocean warming around Galápagos corals

22.02.2018 | Earth Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>