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22. Effects of pH on the Fluorescence Fingerprint of ATP

Author

Rahman Md. Mizanur, Shibata, Mario, Nakazawa, Naho, Hagiwara, Tomoaki, and Osako, Kazufumi

Subjects
ATP, 蛍光指紋によるマグロの鮮度および熟成度の非破壊モニタリング, pH, Fluorescence fingerprint, Nondestructive measurement of freshness and maturity of tuna by fluorescence fingerprint, Nondestructive, Frozen food, 科学研究費研究成果, Instrumentation
Abstract

Nowadays, fluorescence spectroscopy has been used as a potential method for nondestructive quality measurement of food materials. Fluorescence fingerprint (FF) of adenosine 5’-triphosphate (ATP) has been observed during the quality assessment of different raw food materials. Although the fluorescence spectra of ATP can be affected by various factors including pH, the details are not clarified yet. Thus, the study attempts to demonstrate the effects of pH (5.0-8.0) on the FF data of ATP standard solutions (10, 5 and 1 µmol/mL for both frozen and non-frozen states). The results of the present study revealed that the strength of the fluorescence signal was influenced by not only the concentration of ATP but also by the pH of samples. The highest fluorescence intensities were observed from the non-frozen ATP solutions at pH 5.0 for each concentration which declined drastically with increasing pH. The majority of frozen ATP samples showed the similar trends of wavelength conditions to get highest fluorescence intensity. Small pH changes affected the intensity and spectral characteristics of FF and it even shifted the peak wavelength conditions. The implementation of this method would be a help to ensure the validity of FF and optimize it as a technique that can be used to verify the effects of pH on many constituents of food.

Published
2016

23. Recrystallization of Ice Crystals in Sucrose Solution Containing Sodium Alginate and Its Relationship to Dynamic State of Freeze-concentrated Matrix Evaluated by Dielectric Relaxation Measurement.

Author

Chuandong FANG, SHIBATA, Mario, and Tomoaki HAGIWARA

Subjects
DIELECTRIC relaxation, ICE crystals, RECRYSTALLIZATION (Metallurgy), SODIUM alginate, DIELECTRIC measurements, ALGINATES, SUGARCANE
Abstract

The effect of sodium alginate addition on the recrystallization of ice crystals in 40% sucrose solution at -10 oC was experimentally determined. The dynamic state of the freeze-concentrated matrix was investigated by the dielectric relaxation measurements to discuss the mechanism of sodium alginate addition effect on the ice recrystallization. The recrystallization of ice crystals was significantly inhibited by the addition of 3%, 5%, and 10% alginate. And the recrystallization rate constant tended to decrease with increasing alginate concentration. The dielectric relaxation behavior of all samples was well fitted by the combined equation of the two Cole-Cole relaxations indicating the existence of two relaxation process with different relaxation time: fast and slow processes. Based on the preceding research, the fast one and slow one was interpreted as relaxation of free water and that of solute-coupled water, respectively. Increasing sodium alginate concentration, both the fast and slow relaxation time tended to become larger, indicating that slower water mobility in freeze-concentrated phase. This result suggested that the slower water mobility by addition of sodium alginate contributed to the ice recrystallization suppression. [ABSTRACT FROM AUTHOR]

Published
2021

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