Examples of the application of optical process and quality sensing (OPQS) to beer brewing and polyurethane foaming processes

Engelhard, Sonja; Kumke, Michael U.; Löhmannsröben, Hans‐Gerd

doi:10.1007/s00216-005-3364-4

Cited by 16 publications

(7 citation statements)

References 17 publications

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“…The fact that NIR measurements could be made with minimum or no sample preparation, coupled with the availability of robust, easy to operate instruments with high signal-to-noise characteristics, has made this technique a promising tool for at-line and on-line monitoring of microbial growth. 1,2 Several research groups have investigated the utility of NIR spectroscopy as an analysis technique for various fermentation processes such as wine 3 and beer 4 fermentation and batch, fed-batch, and continuous cultivations [5][6][7][8] in combination with chemometric techniques. Multiple scattering of light by the cells poses a significant challenge in the development of NIR-based methodologies to extract reliable chemical and physical information contained in the spectra of growing suspension of microbial cells.…”

Section: Introductionmentioning

confidence: 99%

Changes in the Absorption and Scattering Properties in the Near-Infrared Region during the Growth of Bacillus Subtilis in Liquid Culture

2009

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Multiple scattering of light by cells poses a significant challenge in the development of near-infrared-based methodologies to reliably extract chemical and physical information contained in the spectra collected during the bacterial growth cycle. The extent of information that can be obtained from NIR spectra could, in principle, be vastly improved if the scattering and absorption effects can be effectively separated. This study focuses on the methodology for extracting the bulk optical properties over the course of the bacterial growth cycle and investigates the nature and extent of changes in the optical properties with time. By inverting the radiative transfer equation (RTE) using three measurements, total diffuse reflectance, total diffuse transmittance, and collimated transmittance, the bulk absorption coefficient (microa), the bulk scattering coefficient (micros), and the anisotropy factor (g) are extracted and their changes during the course of the growth cycle are investigated. In this study, a simple bacterial growth system consisting of Bacillus subtilis growing in an aqueous solution (minimum medium) was investigated. The changes in the optical properties of this system during bacterial growth, stationary, and decline phases were investigated by inverting the measurements using the adding-doubling method to solve the RTE in the wavelength region of 950-1850 nm. This study shows that during growth in liquid culture, the absorption and scattering property changes can be consistently extracted from measurements under multiple light scattering conditions. The estimation of the anisotropy factor was not reliable beyond 1200 nm at low bacterial cell counts, but reliability increased with increasing biomass concentration. At all stages in the growth cycle, the anisotropy factor could not be reliably extracted in the first overtone region. However, this does not appear to adversely affect the estimation of the absorption and scattering coefficients.

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Section: Introductionmentioning

confidence: 99%

Changes in the Absorption and Scattering Properties in the Near-Infrared Region during the Growth of Bacillus Subtilis in Liquid Culture

2009

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“…This approach has proven its utility for quality and safety assessment of packaged products, including modified atmosphere packaged meats, fish, cheese, 154 green produce, readyto-eat foods. 153,155 Solid-state O 2 sensors were also used with beverages to control beer brewing, 156 quality and sensory characteristics of pre-and post-pasteurized lager. 157 These sensor systems enable the identification of faulty packs, problems with packaging materials and processes, manufacturing, storage and transportation issues, batch testing and shelf life studies with a large number of packs.…”

Section: Food and Microbial Safetymentioning

confidence: 99%

Biological detection by optical oxygen sensing

2013

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Recent developments in the area of biological detection by optical sensing of molecular oxygen (O2) are reviewed, with particular emphasis on the quenched-phosphorescence O2 sensing technique. Following a brief introduction to the main principles, materials and formats of sensor technology, the main groups of applications targeted to biological detection using an O2 transducer are described. These groups include: enzymatic assays; analysis of respiration of mammalian and microbial cells, small organisms and plants; food and microbial safety; monitoring of oxygenation in cell cultures, 3D models of live tissue, bioreactors and fluidic chips; ex vivo and in vivo O2 measurements; trace O2 analysis. For these systems, which enable a range of new bioanalytical tasks with different samples and models in a minimally invasive, contact-less manner, with high sensitivity, flexibility and imaging capabilities in 2D and 3D, relevant practical examples are presented and their merits and limitations discussed. An outlook of future scientific and technological developments in the field is also provided.

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“…To overcome the superposition of inphase background fluorescence that alters the phase of the detected signal, we used a novel 53.5 and 31.3 kHz two-frequency phase modulation that allowed us to screen out the interference. 4,5,[38][39][40] Measurements were carried out by averaging five consecutive 4 s exposures. Measurements were taken every 15 min.…”

Section: Real-time Oxygen Measurementmentioning

confidence: 99%

Microphysiological flux balance platform unravels the dynamics of drug induced steatosis

Ehrlich¹,

Tsytkin-Kirschenzweig²,

Ioannidis³

et al. 2018

Lab Chip

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Drug development is currently hampered by the inability of animal experiments to accurately predict human response. While emerging organ on chip technology offers to reduce risk using microfluidic models of human tissues, the technology still mostly relies on end-point assays and biomarker measurements to assess tissue damage resulting in limited mechanistic information and difficulties to detect adverse effects occurring below the threshold of cellular damage. Here we present a sensor-integrated liver on chip array in which oxygen is monitored using two-frequency phase modulation of tissue-embedded microprobes, while glucose, lactate and temperature are measured in real time using microfluidic electrochemical sensors. Our microphysiological platform permits the calculation of dynamic changes in metabolic fluxes around central carbon metabolism, producing a unique metabolic fingerprint of the liver's response to stimuli. Using our platform, we studied the dynamics of human liver response to the epilepsy drug Valproate (Depakine™) and the antiretroviral medication Stavudine (Zerit™). Using E6/E7LOW hepatocytes, we show TC50 of 2.5 and 0.8 mM, respectively, coupled with a significant induction of steatosis in 2D and 3D cultures. Time to onset analysis showed slow progressive damage starting only 15-20 hours post-exposure. However, flux analysis showed a rapid disruption of metabolic homeostasis occurring below the threshold of cellular damage. While Valproate exposure led to a sustained 15% increase in lipogenesis followed by mitochondrial stress, Stavudine exposure showed only a transient increase in lipogenesis suggesting disruption of β-oxidation. Our data demonstrates the importance of tracking metabolic stress as a predictor of clinical outcome.

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Examples of the application of optical process and quality sensing (OPQS) to beer brewing and polyurethane foaming processes

Cited by 16 publications

References 17 publications

Changes in the Absorption and Scattering Properties in the Near-Infrared Region during the Growth of Bacillus Subtilis in Liquid Culture

Changes in the Absorption and Scattering Properties in the Near-Infrared Region during the Growth of Bacillus Subtilis in Liquid Culture

Biological detection by optical oxygen sensing

Microphysiological flux balance platform unravels the dynamics of drug induced steatosis

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