Browsing by Subject "Ultraschall"

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Process analytical technology in food biotechnology
(2017) Stanke, Marc; Hitzmann, Bernd
Biotechnology is an area where precision and reproducibility are vital. This is due to the fact that products are often in form of food, pharmaceutical or cosmetic products and therefore very close to the human being. To avoid human error during the production or the evaluation of the quality of a product and to increase the optimal utilization of raw materials, a very high amount of automation is desired. Tools in the food and chemical industry that aim to reach this degree of higher automation are summarized in an initiative called Process Analytical Technology (PAT). Within the scope of the PAT, is to provide new measurement technologies for the purpose of closed loop control in biotechnological processes. These processes are the most demanding processes in regards of control issues due to their very often biological rate-determining component. Most important for an automation attempt is deep process knowledge, which can only be achieved via appropriate measurements. These measurements can either be carried out directly, measuring a crucial physical value, or if not accessible either due to the lack of technology or a complicated sample state, via a soft-sensor.Even after several years the ideal aim of the PAT initiative is not fully implemented in the industry and in many production processes. On the one hand a lot effort still needs to be put into the development of more general algorithms which are more easy to implement and especially more reliable. On the other hand, not all the available advances in this field are employed yet. The potential users seem to stick to approved methods and show certain reservations towards new technologies.
Ultraschallbasierte simultane Konzentrationsbestimmung der Komponenten Zucker und Ethanol in wässrigen Fermentationsfluiden
(2014) Schöck, Thomas; Hitzmann, Bernd
At alcoholic fermentation processes in aqueous solutions there are converted various sugars (mono-, di- and polysaccharides) into ethanol and carbon dioxide by diverse intermediate steps. In the industrial production, ultrasound based methods for the analysis of the composition of the fermentation fluid are advantageous due to their robustness, price cheapness and the possibility for the accomplishment of on line measurements. Within the scope of the present work there are presented several methods for the simultaneous determination of the sugar and ethanol content in the fermentation fluid based on the analysis of ultrasound parameters, also at the presence of dissolved carbon dioxide gas, and compared with respect to the accuracy of their predictive values. Initially there is investigated the behavior of the parameters sound velocity and adiabatic compressibility in standardized aqueous fluids in dependency of the concentration of the components sugar (2 -16 mass percent) and ethanol (1- 6 mass percent), the CO2 partial pressure (0 – 3,013E+05 Pa) and the temperature (2 – 30° C). Thereby the disaccharide saccharose acts as a model substance for the sugar fraction. From the data field of the sound velocity two polynomial calibration models for the sugar / ethanol concentration are extracted with the methods of the multiple linear regression (MLR) and the partial least squares (PLS-) analysis. The minimal accessible standard deviation of the concentration values determined by the particular model from the reference values lies for the MLR method at 0,6 mass percent for the sugar and 0,2 mass percent for the ethanol fraction. The PLS-analysis yields a standard deviation for the sugar and ethanol values of 0,36 and 0,13 mass percent respectively (fluids without a CO2 fraction), as well as 0,5 / 0,17 mass percent (fluids including a CO2 fraction). A further analytic method uses a linearized model of the adiabatic compressibility and the density for the sugar / ethanol determination. The analysis of two physical parameters at this method yields a significant increase of the model quality. For fluids without a CO2 fraction there is reached a minimal standard deviation of 0,06 mass percent for the sugar and 0,07 mass percent for the ethanol concentration. For CO2 containing fluids the corresponding values results to 0,06 / 0,13 mass percent.