Roland Kerpes

Mr. Roland Kerpes

orcid

Research Focus & Metrics

Academic Career Length

11Years (2016-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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2 January 2021 in Foods
Verified
Journal Article
Open access
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TAThekla Alpers
Thekla Alpers
RKRoland Kerpes
Roland Kerpes
MFMariana Frioli
Mariana Frioli
ANArndt Nobis
Arndt Nobis
KHKa Ian Hoi
Ka Ian Hoi
TBThomas Matthias Becker
Thomas Matthias Becker
The high loss rate of bread is generally known to contribute to the alarmingly high numbers in worldwide food waste. Correct storage techniques are believed to enable the reduction of preventable food waste. Therefore, the influence of storage parameters on staling and spoilage behavior of German bread within the limits of common household methods was investigated in this study. The aim was to generate reliable data for staling and spoilage using different storage methods (PE-layered microperforated paper bag, plastic bag, and fridge and bread box) to bridge the gap between consumer’s needs and scientific research questions. Everyday routines of life, such as visual inspection, were compared with microbiological techniques and were found to represent an adequate tool for microbial safety control. Visually undetectable fungal growth has not been found to result in the production of mycotoxins (fumonisins B1 and B2 and ochratoxin A) in quantifiable or harmful concentrations. Thus, disgust should prevent any foodborne health risks as the visual appearance should lead to avoiding the consumption of spoiled food before mycotoxins are produced in amounts causing adverse health effects within the limits of this experimental setup. Additionally, the storage temperature especially was found to influence the kinetics of staling processes, as a reduction accelerated the staling process. Further, crumb moisture loss was found to contradict a long shelf life but, on the other hand, an elevated humidity was shown to provoke excessive microbial growth and should therefore be observed when designing suitable storage methods. Further, the correct choice of the bread type stored and a good sanitary practice represent simply accessible ways to prolong the storage period of bread loaves.

1 September 2017 in Trends in Food Science & Technology
Verified
Journal Article
Closed access
RKRoland Kerpes
Roland Kerpes
SFSusann Fischer
Susann Fischer
TBThomas Matthias Becker
Thomas Matthias Becker

2 June 2021 in Frontiers in Fungal Biology
Verified
Journal Article
Open access
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Marco EigenfeldMarco Eigenfeld
Marco Eigenfeld
RKRoland Kerpes
Roland Kerpes
TBThomas Matthias Becker
Thomas Matthias Becker
In yeast, aging is widely understood as the decline of physiological function and the decreasing ability to adapt to environmental changes. Saccharomyces cerevisiae has become an important model organism for the investigation of these processes. Yeast is used in industrial processes (beer and wine production), and several stress conditions can influence its intracellular aging processes. The aim of this review is to summarize the current knowledge on applied stress conditions, such as osmotic pressure, primary metabolites (e.g., ethanol), low pH, oxidative stress, heat on aging indicators, age-related physiological changes, and yeast longevity. There is clear evidence that yeast cells are exposed to many stressors influencing viability and vitality, leading to an age-related shift in age distribution. Currently, there is a lack of rapid, non-invasive methods allowing the investigation of aspects of yeast aging in real time on a single-cell basis using the high-throughput approach. Methods such as micromanipulation, centrifugal elutriator, or biotinylation do not provide real-time information on age distributions in industrial processes. In contrast, innovative approaches, such as non-invasive fluorescence coupled flow cytometry intended for high-throughput measurements, could be promising for determining the replicative age of yeast cells in fermentation and its impact on industrial stress conditions.

6 September 2022 in Foods
Verified
Journal Article
Open access
PDF file
KBKai Rupert Büchner
Kai Rupert Büchner
JHJana Haagen
Jana Haagen
ASAshtri Sastrosubroto
Ashtri Sastrosubroto
RKRoland Kerpes
Roland Kerpes
JFJessica Freiherr
Jessica Freiherr
TBThomas Matthias Becker
Thomas Matthias Becker
Consumer health concerns and regulatory policies lead to a growing demand for sugar-sweetened beverage alternatives. A reduced energy content can be achieved using artificial sweeteners, which often also convey a metallic or bitter off-flavor. Therefore, the alteration of sweetness perception and masking of potential off-flavors are paramount for improving sweet beverages. Trigeminal stimuli, such as capsaicin (spicy) or menthol (cooling), have been used to influence taste perception in food items, although their use in beverages has not yet been systematically investigated. Here, the influence of menthol on sweetness perception in an aqueous solution is examined both on the sensory and psychophysiological level. The addition of menthol had no sensory effect on sweetness perception; however, psychophysiological measurements suggest a boost in the physiological response to cold perception through the addition of sugar. Moreover, menthol addition shifted the recognition threshold of unpleasant bitterness of the sweetener acesulfame-K from 21.35 to 36.93 mg/L, masking the off-flavor. These findings illuminate the complexity of trigeminal perception influences on taste. Further investigation of these effects can render trigeminal stimuli an effective tool to enhance beverage aroma and flavor.

1 March 2016 in Journal of Cereal Science
Verified
Journal Article
Closed access
RKRoland Kerpes
Roland Kerpes
VKVerena Knorr
Verena Knorr
SPSusanne Procopio
Susanne Procopio
PKPeter Koehler
Peter Koehler
TBThomas Matthias Becker
Thomas Matthias Becker

21 April 2023 in Analytical and Bioanalytical Chemistry
Verified
Journal Article
Open access
PDF file
Marco EigenfeldMarco Eigenfeld
Marco Eigenfeld
LWLeonie Wittmann
Leonie Wittmann
RKRoland Kerpes
Roland Kerpes
SSSebastian Schwaminger
Sebastian Schwaminger
TBThomas Matthias Becker
Thomas Matthias Becker
For industrial processes, a fast, precise, and reliable method of determining the physiological state of yeast cells, especially viability, is essential. However, an increasing number of processes use magnetic nanoparticles (MNPs) for yeast cell manipulation, but their impact on yeast cell viability and the assay itself is unclear. This study tested the viability of Saccharomyces pastorianus ssp. carlsbergensis and Pichia pastoris by comparing traditional colourimetric, high-throughput, and growth assays with membrane fluidity. Results showed that methylene blue staining is only reliable for S. pastorianus cells with good viability, being erroneous in low viability (R2 = 0.945; $$\widehat{\sigma }$$ σ ^ = 5.78%). In comparison, the fluorescence microscopy–based assay of S. pastorianus demonstrated a coefficient of determination of R2 = 0.991 at $$\alpha =0$$ α = 0 ( $$\widehat{\sigma }$$ σ ^ = 2.50%) and flow cytometric viability determination using carboxyfluorescein diacetate (CFDA), enabling high-throughput analysis of representative cell numbers; R2 = 0.972 ( $$\alpha =0$$ α = 0 ; $$\widehat{\sigma }$$ σ ^ = 3.89%). Membrane fluidity resulted in a non-linear relationship with the viability of the yeast cells ( $$\alpha \ne 0$$ α ≠ 0 ). We also determined similar results using P. pastoris yeast. In addition, we demonstrated that MNPs affected methylene blue staining by overestimating viability. The random forest model has been shown to be a precise method for classifying nanoparticles and yeast cells and viability differentiation in flow cytometry by using CFDA. Moreover, CFDA and membrane fluidity revealed precise results for both yeasts, also in the presence of nanoparticles, enabling fast and reliable determination of viability in many experiments using MNPs for yeast cell manipulation or separation.