Problemes lies a l'utilisation de semi-conducteurs sensibles aux gaz pour la determination en fermentation de l'ethanol.

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Ebulliometre automatique pour determiner la concentration en ethanol des vins et des milieux de fermentation

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Mesures physiques permettant le suivi biologique de la fermentation alcoolique en oenologie

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Evaluation of chemical parameters in soft mold-ripened cheese during ripening by mid-infrared spectroscopy

The suitability of mid-infrared spectroscopy (MIR) to follow the evolution throughout ripening of specific physicochemical parameters in Camembert-type cheeses was evaluated. The infrared spectra were obtained directly from raw cheese samples deposited on an attenuated total reflectance crystal. Significant correlations were observed between physicochemical data, pH, acid-soluble nitrogen, nonprotein nitrogen, ammonia (NH4+), lactose, and lactic acid. Dry matter showed significant correlation only with lactose and nonprotein nitrogen. Principal components analysis factorial maps of physicochemical data showed a ripening evolution in 2 steps, from d 1 to d 7 and from d 8 to d 27, similar to that observed previously from infrared spectral data. Partial least squares regressions made it possible to obtain good prediction models for dry matter, acid-soluble nitrogen, nonprotein nitrogen, lactose, lactic acid, and NH4+ values from spectral data of raw cheese. The values of 3 statistical parameters (coefficient of determination, root mean square error of cross validation, and ratio prediction deviation) are satisfactory. Less precise models were obtained for pH. � American Dairy Science Association, 2007

PHOTOIONIZATION CROSS SECTION MEASUREMENT IN 5p AND 5s SUBSHELLS OF EXCITED BARIUM ATOMS BETWEEN 40 eV AND 140 eV PHOTON ENERGY

Nous présentons ici la première mesure de sections efficaces de photoionisation en couches internes d'un atome préparé dans un état excité. Des atomes de baryum ont été portés dans les états excités 6s5d1,3D à l'aide d'un laser continu, et ionisés en couche interne à l'aide du rayonnement synchrotron émis par ACO. Nous montrons que, dans ce cas particulier, le plus grand écrantage induit par l'électron 5d produit une diminution de l'énergie de liaison des électrons internes dans l'atome excité. Nous observons également une augmentation de l'interaction entre les voies 4d → εl et 5p → εl, 5s → εl au-dessus des seuils 4d.We present the first measurement of an inner-shell photoionization cross section in an excited atom. Barium atoms were laser-excited to the 6s5d11,3D states and photoionized by synchrotron radiation from ACO. It is shown that the larger screening of the nuclear charge induced by the 5d electron leads to a decreasing of the binding energy of the inner electrons in the excited atom. We observe also an increasing of the interchannel interaction between the 4d → εl and 5p → εl, 5s → εl channels

Middle infrared spectroscopy characterization of ripening stages of Camembert-type cheeses

Mould-ripened soft cheeses like Camembert produced at pilot scale were analyzed in order to evaluate the potential of mid-infrared spectroscopy to follow the ripening phenomena. Two cheese zones (core and under-rind) were analyzed directly and were then fractionated by selective precipitation to obtain more specific parts. Cheese slices and their fractions were analyzed by attenuated total reflectance. Analysis of variance showed the significant absorbance changes on spectra sets, mainly in the regions assigned to the vibrations of alcohol and amide groups. By principal component analysis of spectral data, two different steps of ripening can be described. The spectral studies of other fractions than whole cheese provided no additional information. Using partial least-square regressions-based spectral sets, made it possible to determine ripening day with an error of 1 day. © 2006 Elsevier Ltd. All rights reserved