TY  - JOUR
A1  - Bertz, Morten
A1  - Schöning, Michael Josef
A1  - Molinnus, Denise
A1  - Homma, Takayuki
T1  - Influence of temperature, light, and H₂O₂ concentration on microbial spore inactivation: in-situ Raman spectroscopy combined with optical trapping
JF  - Physica status solidi (a) applications and materials science
N2  - To gain insight on chemical sterilization processes, the influence of temperature (up to 70 °C), intense green light, and hydrogen peroxide (H₂O₂) concentration (up to 30% in aqueous solution) on microbial spore inactivation is evaluated by in-situ Raman spectroscopy with an optical trap. Bacillus atrophaeus is utilized as a model organism. Individual spores are isolated and their chemical makeup is monitored under dynamically changing conditions (temperature, light, and H₂O₂ concentration) to mimic industrially relevant process parameters for sterilization in the field of aseptic food processing. While isolated spores in water are highly stable, even at elevated temperatures of 70 °C, exposure to H₂O₂ leads to a loss of spore integrity characterized by the release of the key spore biomarker dipicolinic acid (DPA) in a concentration-dependent manner, which indicates damage to the inner membrane of the spore. Intensive light or heat, both of which accelerate the decomposition of H₂O₂ into reactive oxygen species (ROS), drastically shorten the spore lifetime, suggesting the formation of ROS as a rate-limiting step during sterilization. It is concluded that Raman spectroscopy can deliver mechanistic insight into the mode of action of H₂O₂-based sterilization and reveal the individual contributions of different sterilization methods acting in tandem.
KW  - hydrogen peroxide
KW  - optical spore trapping
KW  - Raman spectroscopy
KW  - sterilization conditions
KW  - temperature
Y1  - 2024
U6  - http://dx.doi.org/10.1002/pssa.202300866
SN  - 1862-6319 (Online)
SN  - 1862-6300 (Print)
IS  - Early View
PB  - Wiley-VCH
CY  - Berlin
ER  - 
TY  - JOUR
A1  - Huck, Christina
A1  - Poghossian, Arshak
A1  - Bäcker, Matthias
A1  - Reisert, Steffen
A1  - Schubert, J.
A1  - Zander, W.
A1  - Begoyan, V. K.
A1  - Buniatyan, V. V.
A1  - Schöning, Michael Josef
T1  - Chemical sensors based on a high-k perovskite oxide of barium strontium titanate
JF  - Procedia Engineering
N2  - High-k perovskite oxide of barium strontium titanate (BST) represents a very attractive multi-functional transducer material for the development of (bio-)chemical sensors for liquids. In this work, BST films have been applied as a sensitive transducer material for a label-free detection of adsorbed charged macromolecules (positively charged polyelectrolytes) and concentration of hydrogen peroxide vapor as well as protection insulator layer for a contactless electrolyte-conductivity sensor. The experimental results of characterization of individual sensors are presented. Special emphasis is devoted towards the development of a capacitively-coupled contactless electrolyte-conductivity sensor.
KW  - barium strontium titanate
KW  - high-k material
KW  - contactless conductivity sensor
KW  - multi-functional material
KW  - hydrogen peroxide
Y1  - 2014
U6  - http://dx.doi.org/10.1016/j.proeng.2014.11.258
SN  - 1877-7058
N1  - EUROSENSORS 2014 ; European Conference on Solid-State Transducers <28, 2014>
VL  - 87
SP  - 28
EP  - 31
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Kirchner, Patrick
A1  - Oberländer, Jan
A1  - Suco, Henri-Pierre
A1  - Rysstad, Gunnar
A1  - Schöning, Michael Josef
T1  - Monitoring the microbicidal effectiveness of gaseous hydrogen peroxide in sterilisation processes by means of a calorimetric gas sensor
JF  - Food control
N2  - In the present work, a novel method for monitoring sterilisation processes with gaseous H2O2 in combination with heat activation by means of a specially designed calorimetric gas sensor was evaluated. Therefore, the sterilisation process was extensively studied by using test specimens inoculated with Bacillus atrophaeus spores in order to identify the most influencing process factors on its microbicidal effectiveness. Besides the contact time of the test specimens with gaseous H2O2 varied between 0.2 and 0.5 s, the present H2O2 concentration in a range from 0 to 8% v/v (volume percent) had a strong influence on the microbicidal effectiveness, whereas the change of the vaporiser temperature, gas flow and humidity were almost negligible. Furthermore, a calorimetric H2O2 gas sensor was characterised in the sterilisation process with gaseous H2O2 in a wide range of parameter settings, wherein the measurement signal has shown a linear response against the H2O2 concentration with a sensitivity of 4.75 °C/(% v/v). In a final step, a correlation model by matching the measurement signal of the gas sensor with the microbial inactivation kinetics was established that demonstrates its suitability as an efficient method for validating the microbicidal effectiveness of sterilisation processes with gaseous H2O2.
KW  - hydrogen peroxide
KW  - sterilisation
KW  - Bacillus atrophaeus
KW  - calorimetric gas sensor
Y1  - 2012
U6  - http://dx.doi.org/10.1016/j.foodcont.2012.11.048
SN  - 0956-7135
VL  - 31
IS  - 2
SP  - 530
EP  - 538
PB  - Elsevier
CY  - Amsterdam
ER  -