Dynamic Light Scattering Techniques and Their Applications in Food Science

Alexander, Marcela; Dalgleish, Douglas G.

doi:10.1007/s11483-005-9000-1

Cited by 87 publications

(52 citation statements)

References 69 publications

(76 reference statements)

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“…As an inexpensive scattering fluid with comparable properties, homogenized household milk (diluted with two parts water) was then used instead. Milk contains microscopic fat globules, which undergo analogous Brownian motion, also studied with photon correlation spectroscopy (Alexander & Dalgleish, 2006;Holt et al, 1973;Robin & Paquin, 1991). Given that the cost per volume is orders of magnitude lower than that of microsphere suspensions, several of the initial experiments were carried out with laser light scattering in milk.…”

Section: Dynamic Light Scatteringmentioning

confidence: 99%

Long-baseline optical intensity interferometry

Dravins

Lagadec

Nuñez

2015

A&A

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Context. A long-held vision has been to realize diffraction-limited optical aperture synthesis over kilometer baselines. This will enable imaging of stellar surfaces and their environments, and reveal interacting gas flows in binary systems. An opportunity is now opening up with the large telescope arrays primarily erected for measuring Cherenkov light in air induced by gamma rays. With suitable software, such telescopes could be electronically connected and also used for intensity interferometry. Second-order spatial coherence of light is obtained by cross correlating intensity fluctuations measured in different pairs of telescopes. With no optical links between them, the error budget is set by the electronic time resolution of a few nanoseconds. Corresponding light-travel distances are approximately one meter, making the method practically immune to atmospheric turbulence or optical imperfections, permitting both very long baselines and observing at short optical wavelengths. Aims. Previous theoretical modeling has shown that full images should be possible to retrieve from observations with such telescope arrays. This project aims at verifying diffraction-limited imaging experimentally with groups of detached and independent optical telescopes. Methods. In a large optics laboratory, artificial stars (single and double, round and elliptic) were observed by an array of small telescopes. Using high-speed photon-counting solid-state detectors and real-time electronics, intensity fluctuations were cross-correlated over up to 180 baselines between pairs of telescopes, producing coherence maps across the interferometric Fourier-transform plane. Results. These interferometric measurements were used to extract parameters about the simulated stars, and to reconstruct their twodimensional images. As far as we are aware, these are the first diffraction-limited images obtained from an optical array only linked by electronic software, with no optical connections between the telescopes. Conclusions. These experiments serve to verify the concepts for long-baseline aperture synthesis in the optical (somewhat analogous to radio interferometry) and to optimize the instrumentation and observing procedures for future observations with large arrays of Cherenkov telescopes, aiming at order-of-magnitude improvements of the angular resolution in optical astronomy.

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Section: Dynamic Light Scatteringmentioning

confidence: 99%

Long-baseline optical intensity interferometry

Dravins

Lagadec

Nuñez

2015

A&A

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“…In contrast with DLS, DWS requires turbid or concentrated systems as the photon path through the sample is treated as a random walk phenomenon [20]. DWS is an ideal technique to study the dynamics of change in dairy systems, such as renneting or acidification of milk or destabilization of dairy emulsions [2].…”

Section: Diffusing Wave Spectroscopymentioning

confidence: 99%

“…In the case where there is no correlation between particles, values of diffusion coefficient can be treated as in traditional DLS and used to calculate the average diameter of the particles present in the sample. However, the value of l* has to be determined; l* is defined as the photon transport mean free path [2,20] and it is related to the randomization (or decorrelation) of the photon path over many scattering events. This randomization is related to the physical properties of the sample as well as their spatial arrangement.…”

Section: Diffusing Wave Spectroscopymentioning

confidence: 99%

“…The measurement of l* not only allows for the calculation of the diffusion coefficient in DWS measurements, but more importantly relates to changes in the interactions between the particles. For this reason, interest in the DWS technique for dairy systems lies in its potential to be used as a tool to measure the dynamics of interactions in situ with minimal sample disturbance [2,15,20].…”

Section: Diffusing Wave Spectroscopymentioning

confidence: 99%

“…By combining DWS and rheological measurements on acid-induced aggregation of skim milk (using glucono-δ-lactone, GDL) it is possible to observe changes occurring in the preceding stages of aggregation by following the development of l* [1,2,10]. In both heated and unheated milk, values of 1/l* increase much before the change (because of aggregation) in the size of the casein micelles.…”

Section: Diffusing Wave Spectroscopymentioning

confidence: 99%

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Spectroscopic methods to determine in situ changes in dairy systems – ultrasonic and light scattering

Alexander¹,

Corredig²

2007

Lait

Self Cite

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-Many of the techniques currently employed to study the aggregation of dairy systems are either invasive or not able to identify changes at the early stages of aggregation. Recently, diffusing wave spectroscopy (DWS) and ultrasonic spectroscopy (US) have shown promise as samples can be observed in situ without any preparation or disruption. With DWS measurements we can obtain information on size, spatial correlation between the colloidal particles and their movement. With high resolution ultrasonic spectrometers the velocity or attenuation of a sound wave propagating through the sample can be observed while physical chemical changes occur to the sample (for example, gelation, phase separation). DWS and US have been recently employed in the study of the interactions between proteins and other ingredients in milk-based systems. Although the changes observed during the measurements of complex systems such as milk are still to be fully understood, it is clear that these spectroscopic techniques present great potential to derive further information on the dynamics of change in aggregating systems. ultrasonic spectroscopy / diffusing wave spectroscopy / colloidal aggregationRésumé -Méthodes spectroscopiques pour déterminer in situ les changements dans les systèmes laitiers : ultrasons et diffraction de la lumière. Beaucoup de techniques actuellement employées pour étudier l'agrégation des systèmes laitiers sont soit invasives, soit incapables d'identifier les changements au tout début de l'agrégation. Récemment, la spectroscopie de diffusion d'ondes (DWS) et la spectroscopie ultrasonique (US) se sont avé-rées prometteuses puisque les échantillons peuvent être observés in situ sans préparation ni destruction. Avec les mesures DWS, on peut obtenir des informations sur la taille, la corrélation spatiale entre les particules et leurs mouvements. Avec les spectromètres ultrasoniques à haute résolution, on peut observer la vitesse ou l'atténuation d'une onde sonore se propageant au travers de l'échantillon pendant que les changements physico-chimiques ont lieu dans l'échantillon (par exemple gélification, séparation de phase). La DWS et l'US ont été récemment employées dans l'étude des interactions entre protéines et autres ingrédients dans les systèmes à base de lait. Bien que les changements observés au cours de la mesure de systèmes complexes comme le lait ne soient pas encore complètement compris, il est clair que ces techniques spectroscopiques présentent un potentiel important pour obtenir des informations sur la dynamique des changements dans les systèmes s'agrégeant. spectroscopie ultrasonique / spectroscopie DWS / agrégation

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The use of advanced spectroscopic techniques to understand texture in dairy foods

Alexander

Corredig

2014

Food Texture Design and Optimization

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Dynamic Light Scattering Techniques and Their Applications in Food Science

Cited by 87 publications

References 69 publications

Long-baseline optical intensity interferometry

Long-baseline optical intensity interferometry

Spectroscopic methods to determine in situ changes in dairy systems – ultrasonic and light scattering

The use of advanced spectroscopic techniques to understand texture in dairy foods

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