On-line ultrasonic velocity monitoring of alcoholic fermentation kinetics

Abstract

In this work, fundamental aspects on the ultrasonic velocity monitoring of alcoholic fermentations in synthetic broths (glucose, fructose and sucrose) and natural media (must and wort) are reported. Results are explained in terms of monosaccharide catabolism, polysaccharide hydrolysis, gas production and microorganism growth. The effect of each one of these subprocesses upon ultrasonic velocity has been independently studied. It is shown that, regarding the sound propagation, the simplest systems behave as ternary dissolutions of sugar and ethanol in water, where, in the course of time, substrates are transformed into metabolites according to the fermentation reaction. A semi-empirical approach, based on the excess volume concept and the density and velocity measurements of binary mixtures, has been used to calculate these magnitudes in the ternary mixtures and to obtain the concentrations of the main solutes throughout the fermentations, reaching a good correlation (especially for the media of simplest composition). In all the processes analyzed, the data obtained from the ultrasonic measurements followed the changes caused by the yeast metabolism, asserting the potential of mechanical waves to monitor fermentations and, in general, biotechnological processes.

Monitoring CO2 storage using ghost reflections retrieved from seismic interferometry

“…Comparing the values in the left-most column in Table 2 with those in the right-most column of the estimated velocities, we see that when ethanol of about the total amount of the calculated pore volume is injected in the sandstone reservoir the estimated velocity is higher than that for the sandstone saturated with brine. Resa et al (2005Resa et al ( , 2009 Table 3 and Fig. 3, respectively) and Vatandas et al (2007, Fig. 3) performed ultrasonic measurements of the binary mixture water-ethanol, and reported that when the ethanol concentration in the water is low, the measured P-wave velocity is higher than that for pure water.…”

Bioprocess monitoring and control via adaptive sensor calibration

“…Typically used sensor equipment for analyzing fluid properties are in direct contact with the fluid of interest [3,4] (http:// www.iul-instruments.de/pdf/vitalsensors_2.pdf; http://www. Furthermore, investigations in ultrasonic monitoring of certain fermentation processes including ternary mixtures containing sugar and ethanol were also reported [13][14][15]. Over the last decades, the importance of non-invasive, indirect measurement using ultrasonic sensors for such uses became more and more practical, since they provide rapid response, good long-term stability and high resolution as well as accuracy [5,6].…”

Optoelectronic sensor for measuring ethanol content during grape must fermentation using NIR spectroscopy

“…Previous works use refractometric techniques for measuring ethanol in mixtures with water (Yeh et al 2009;Jiménez Riobóo et al 2009) but the refractive index of fermenting grape must samples is a result of their composition and, consequently, it does not depend exclusively on the ethanol concentration (Jiménez-Márquez et al 2013. Works which use ultrasounds to measure ethanol in mixtures with water (Gomes et al 2001) have the same problem in carbohydrate aqueous solutions and fermenting media (Resa et al 2004(Resa et al , 2009Lamberti et al 2009). The ethanol concentration was also predicted by means of CO 2 and either density or pressure measurements (El Haloui et al 1988;Picque et al 1991).…”