Papers by Charles Ghommidh
Capacitance measurements can give valuable information on the physiological state of a culture. S... more Capacitance measurements can give valuable information on the physiological state of a culture. Sequential nutrient limitations for batch and fed-batch CHO fermentations were monitored online.
Biotechnology and Bioengineering, 1992
The sucrose hydrolysis activity of dense spherical yeast flocs, cultivated on a sucrose medium in... more The sucrose hydrolysis activity of dense spherical yeast flocs, cultivated on a sucrose medium in a continuous reactor with internal settler, is nearly proportional to the particle surface. From computer simulation, in good agreement with experimental determinations, the calculated sucrose penetration depth is in the range 0.2–0.3 mm, a dimension smaller than the usual diameter of strongly flocculating yeast particles. From specific gravity determinations, the flocs can be considered as homogeneous and cannot exhibit a fractal structure, reported in the literature for a number of microbial aggregates. However, the analysis of the sucrose hydrolysis rates reveals that the cell density may be lower in the outer layer of the flocs. © 1992 John Wiley & Sons, Inc.
Electronic Journal of Biotechnology, 2010
An electronic nose (E-nose) coupled to gas chromatography was tested to monitor alcoholic ferment... more An electronic nose (E-nose) coupled to gas chromatography was tested to monitor alcoholic fermentation by Saccharomyces cerevisiae ICV-K1 and Saccharomyces cerevisiae T306, two strains well-known for their use in oenology. The biomass and ethanol concentrations and conductance changes were measured during cultivations and allowed to observe the standard growth phases for both yeast strains. The two strains were characterized by a very similar tendency in biomass or ethanol production during the fermentation. E-nose was able to establish a kinetic of the production of aroma compounds production and which was then easy to associate with the fermentation phases. Principal Component Analysis (PCA) showed that the data collected by E-nose during the fermentation mainly contained cultivation course information. Discriminant factorial analysis (DFA) was *Corresponding author able to clearly identify differences between the two strains using the four main principal components of PCA as input data. Nevertheless, the electronic nose responses being mainly influenced by cultivation course, a specific data treatment limiting the time influence on data was carried out and permitted to achieve an overall performance of 83.5%.
Sensors and Actuators B-chemical, 2006
Ethanol is the major constituent of the head-space of alcoholised beverages and generate a strong... more Ethanol is the major constituent of the head-space of alcoholised beverages and generate a strong signal on the sensor arrays used in electronic noses, impairing aroma discrimination. Head-space de-alcoholisation strongly improved the aroma sensing ability of a MOS-based Enose. However, discrimination was still affected by the original alcohol content, because ethanol decreased the aroma compound volatility. This effect was quantified by gas chromatographic analysis in the 0-12% (v/v) ethanol concentration range, further demonstrated on reference samples using a electronic nose coupled with a de-alcoholisation system and illustrated during a discrimination study between spirits, beers and wines. The amplitude of ethanol effect could not be quantitatively predicted from usual physico-chemical characteristic of aroma compounds.
Food Control, 2006
Application of an impedance sensor to determine the salt content, moisture and water phase salt (... more Application of an impedance sensor to determine the salt content, moisture and water phase salt (WPS) of fresh salted Atlantic salmon (Salmo salar) fillets was estimated. Three probes with different electrodes geometries were concurrently tested. Whatever the probe used, the salt content of samples was successfully evaluated (R 2 > 0.822) by linear prediction models based on conductance and increment capacitance data. WPS was correctly predicted (0.732 < R 2 < 0.890) using these same data to determine the prediction model. Nevertheless, the prediction of moisture based only on impedance measurements was not efficient. In this case, adding the sample lipid content in models yielded to better result (0.668 < R 2 < 0.757).
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Papers by Charles Ghommidh