Direct observation of the surface structure of French fries by UV–VIS confocal laser scanning microscopy

Achir, Nawel; Vitrac, Olivier; Trystram, Gilles

doi:10.1016/j.foodres.2009.10.004

Cited by 34 publications

(32 citation statements)

References 26 publications

(25 reference statements)

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“…The assumption of no oil pickup during immersion stage can be assessed from the geometry of defects enabling oil penetration in potato products: cut cells, damaged cell junctions, or cell walls . By considering that oil passages are idealized as converging circular tubes, with a diverging angle

ϕ

(

ϕ = 0

for open cells and

ϕ > 0

for defects between cells), the capillary pressure, denoted p C , is given by (see Eq.…”

Section: Theorymentioning

confidence: 99%

“…Comparatively to previous models, it would enable to simulate numerically the oil barrier effects created by the arrangements of cells, cell walls, and starch. These developments are particularly essential to elucidate why oil is mainly located within the first two cell layers when French fries are prepared from fresh potatoes whereas it can reach core regions in parfried frozen French fries …”

Section: Introductionmentioning

confidence: 99%

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Microscopic imaging of biphasic oil‐air flow in French fries using synchrotron radiation

Patsioura

Vauvre

Kesteloot³

et al. 2015

AIChE Journal

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Spontaneous oil percolation in French fries was studied dynamically at cellular scale using deep‐UV synchrotron radiation enabling to image simultaneously the fluorescence of cell walls and of dyed oil. Experimental results report 75 oil filling kinetics of potato parenchyma cells previously emptied and equilibrated with superheated steam in conditions mimicking immersion frying. Counter‐current oil‐air flow was found the dominant factor controlling the kinetic of oil penetration, whereas, trapped bubbles delay the passage of oil from the first to the second cell layer for additional several minutes. The frequency of occurrence of passages between layers was assessed much lower than the percolation threshold suggested by the hierarchical honeycomb arrangement of cells. A description relating microscopic oil‐air flow and oil uptake is detailed in a companion paper. © 2015 American Institute of Chemical Engineers AIChE J, 61: 1427–1446, 2015

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ϕ

(

ϕ = 0

for open cells and

ϕ > 0

for defects between cells), the capillary pressure, denoted p C , is given by (see Eq.…”

Section: Theorymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Microscopic imaging of biphasic oil‐air flow in French fries using synchrotron radiation

Patsioura

Vauvre

Kesteloot³

et al. 2015

AIChE Journal

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“…Observation of starch melting [61,[63][64][65] (microscope) 0D approaches in nuggets: densitometry [50,51], porosimetry [52,53] versus frying time Details of cell walls (SEM: [59], AFM: [66]) 0D/1D approaches in French-fries: surface washing and densitometry/porosimetry [54] 3D direct observation of oil location (CLSM) and surface reconstruction [30,57] 1D/2D approaches in French-fries: infrared microspectroscopy [55], oil dyeing [56,57], radiolabeling [58], dynamic wicking [59] (4) Freezing, long-term storage 0.285 a) (0.085 b) ) [14] Lack of studies Observation of tissue damages (SEM: [67])…”

Section: Raw Materials and Frying Conditionsmentioning

confidence: 99%

“…Non-invasive observations of fried potato strips were carried out using either micro-computed X-ray tomography (model V|tome|X combined with DatosX_Rec reconstruction software, General Electric, USA) at a resolution of 1200 Â 1200 Â 1000 voxels or by UV laser (351 nm) scanning confocal microscopy at a resolution of 4096 Â 4096 Â 50 voxels as described in [30]. Dynamic observation of oil uptake was achieved by illuminating the sample with a deep-UV synchrotron source at 295 nm (Synchrotron Soleil, Gif-sur-Yvette, France) and collecting images at 1 frame/s in epifluorescence mode with the help of a UV-VIS electron-multiplied charge-coupled device camera (model PIXIS 1024, Princeton, USA).…”

Section: Structure Surface and Oil Imagingmentioning

confidence: 99%

“…During immersion frying, drying transforms a material with almost homogeneous properties into a composite one comprising a rubber core or crumb sandwiched between two glassy layers/crusts. Strong mechanical stresses are very likely to accumulate at their interface [18,27,30,31], causing local deformations and ruptures of the capillary network. A broad range of mechanical behaviors is expected according to normal stressesdue to steam pressure gradients -or volume shrinkagecaused by moisture loss (i.e., change in length or volume of cell constituents)dominate [32].…”

Section: Introductionmentioning

confidence: 99%

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Microscopic oil uptake mechanisms in fried products*

Vauvre

Kesteloot²,

Patsioura

et al. 2014

Euro J Lipid Sci & Tech

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The increasingly poor perception of fried products encourages the development of rupture technologies to reduce oil uptake. The current available descriptions of oil uptake mechanisms remain incomplete, neglecting: (i) the critical role of the total pressure gradient inside hygroscopic materials during cooling, (ii) the coupling between mechanical ruptures and oil uptake routes, (iii) the different configurations of biphasic oil-air flow inside the material: co-and counter-currents. This paper demonstrates how additional understanding could be gained by using high-resolution, dynamic and non-invasive techniques, including X-ray micro-computed tomography, UV-VIS laser or synchrotron source microscopy, and new generations 3D percolation models fitted on digitized structures. The critical role of air in hindering/preventing oil absorption is particularly highlighted. The effects of cell injuries and starch on the creation of cavities and oil absorption are discussed on parfried French fries subjected to different surface pretreatments.

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Fluorescence Spectroscopy in Food Analysis

Albani

2012

Encyclopedia of Analytical Chemistry

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Food is vital for life, thus it is very important to know how to maintain its quality and thus to detect and analyse all components interfering with food quality. This article describes application of spectrofluorometry combined with high‐performance liquid chromatography (HPLC) in food analysis. Spectrofluorometry allows measuring structural changes in food proteins, whereas HPLC combined with fluorescence helps to study toxins, pathogenic microbes, heating effects, fat oxidation, vitamins, additives, amino acids, and enzyme activity in food.

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Direct observation of the surface structure of French fries by UV–VIS confocal laser scanning microscopy

Cited by 34 publications

References 26 publications

Microscopic imaging of biphasic oil‐air flow in French fries using synchrotron radiation

Microscopic imaging of biphasic oil‐air flow in French fries using synchrotron radiation

Microscopic oil uptake mechanisms in fried products*

Fluorescence Spectroscopy in Food Analysis

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