V.I. Mirgorodsky- Dr. Sc. (Phys.-Math.), Professor, Leading Research Scientist, Fryazino Branch of the Kotel-nikov Institute of Radioengineering and Electronics of Russian Academy of Sciences, Fryazino, Moscow region E-mail: vim288@ms.ire.rssi.ru V.V. Gerasimov - Ph.D. (Phys.-Math.), Senior Research Scientist, Fryazino Branch of the Kotel-nikov Institute of Radioengineering and Electronics of Russian Academy of Sciences, Fryazino, Moscow region E-mail: vvg_288@ms.ire.rssi.ru A.V.Gierus - Ph.D. (Phys.-Math.), Senior Research Scientist, Fryazino Branch of the Kotel-nikov Institute of Radioengineering and Electronics of Russian Academy of Sciences, Fryazino, Moscow region E-mail: agierus@fryazino.net S.V. Peshin - Ph.D. (Phys.-Math.), Senior Research Scientist, Fryazino Branch of the Kotel-nikov Institute of Radioengineering and Electronics of Russian Academy of Sciences, Fryazino, Moscow region E-mail: svp288@ms.ire.rssi.ru

The temperature dependence of the acoustic emission from the samples of yeast was the purpose of this investigation. It is in-teresting for a determination of their potential viability, as it is known that it may be different depending on quality of yeast. For example, in case of warming up of yeast up to the temperature more than 60 ºC they, as is well known, perish and become not suitable for use, in particular, in baking. For execution of the experiment, we used the developed acoustic receivers, which allow registering weak acoustic emission from objects, which acoustic impedances are close to an impedance of water or biological objects. The manufactured receivers of acoustic emission possess, as far as we know, more sensitivity than the known acoustic receivers do. During of experiment execution, it was found that dissolution of the fresh yeast in physiological solution to a consistence, which like sour cream in case of their heating up from temperature 5 ºC up to the temperature about 15 ºC almost does not change, intensity of the acoustic emission. Further temperature increase leads to noticeable increase in acoustic emission in frequency band of 18 - 28 Hz, with a maximum near the frequency of 20 Hz. The emission reaches a maximum at a temperature about 25 ºC. Further tem-perature increase leads to lowering of level of emission with the subsequent stabilizing at a temperature over 30 ºC. Estimation of the value of observed emission, shows that in a maximum it approximately on 4 - 6 orders exceeds the level of thermal oscillations. At the same time, from the samples of yeast, which beforehand warmed to 70 ºC, observable change of emission is not watched. Thus observed noticeable increase in acoustic emission is inherent only for viable yeast while with warmed up to 70 ºC yeast similar increase in emission was not watched. It gives the grounds for use of this phenomenon for quality control of yeast. At the same time, there is open a question about a mechanism of realization of the found acoustic emission: it is caused - by movement of cells of yeast or formation of vials of gas, which are accompanying life activity.

 

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