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Foods 2017, 6(5), 37;

In Situ Raman Analysis of CO2—Assisted Drying of Fruit-Slices

Lehrstuhl für Technische Thermodynamik (LTT), Friedrich-Alexander-Universitaet Erlangen-Nuernberg (FAU), Am Weichselgarten 8, 91058 Erlangen, Germany
Erlangen Graduate School in Advanced Optical Technologies (SAOT), Friedrich-Alexander-Universitaet Erlangen-Nuernberg (FAU), Paul-Gordan-Straße 6, 91052 Erlangen, Germany
Department of Industrial Engineering, University of Padova, via Marzolo 9, 35131 Padova, Italy
Author to whom correspondence should be addressed.
Academic Editor: Carl J. Schaschke
Received: 27 March 2017 / Revised: 12 May 2017 / Accepted: 12 May 2017 / Published: 15 May 2017
(This article belongs to the Special Issue High Pressure Technologies in Food Processing)
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This work explores the feasibility of applying in situ Raman spectroscopy for the online monitoring of the supercritical carbon dioxide (SC-CO2) drying of fruits. Specifically, we investigate two types of fruits: mango and persimmon. The drying experiments were carried out inside an optical accessible vessel at 10 MPa and 313 K. The Raman spectra reveal: (i) the reduction of the water from the fruit slice and (ii) the change of the fruit matrix structure during the drying process. Two different Raman excitation wavelengths were compared: 532 nm and 785 nm. With respect to the quality of the obtained spectra, the 532 nm excitation wavelength was superior due to a higher signal-to-noise ratio and due to a resonant excitation scheme of the carotenoid molecules. It was found that the absorption of CO2 into the fruit matrix enhances the extraction of water, which was expressed by the obtained drying kinetic curve. View Full-Text
Keywords: drying; fruit; carbon dioxide; high pressure; Raman spectroscopy; water; water content; in situ; pasteurization drying; fruit; carbon dioxide; high pressure; Raman spectroscopy; water; water content; in situ; pasteurization

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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

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Braeuer, A.S.; Schuster, J.J.; Gebrekidan, M.T.; Bahr, L.; Michelino, F.; Zambon, A.; Spilimbergo, S. In Situ Raman Analysis of CO2—Assisted Drying of Fruit-Slices. Foods 2017, 6, 37.

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