Madeleine Plötz

Prof. Dr. Madeleine Plötz


Research Focus & Metrics

Academic Career Length

7Years (2020-Present)

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

Representative Publications

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16 April 2020 in Foods
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Journal Article
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NGNils Th. Grabowski
Nils Th. Grabowski
STSéverin Tchibozo
Séverin Tchibozo
AAAmir Abdulmawjood
Amir Abdulmawjood
FAFatma Acheuk
Fatma Acheuk
MGMeriem Msaad Guerfali
Meriem Msaad Guerfali
MPMadeleine Plötz
Madeleine Plötz
Entomophagy is an ancient and actually African tradition that has been receiving renewed attention since edible insects have been identified as one of the solutions to improve global nutrition. As any other foodstuff, insects should be regulated by the government to ensure product quality and consumer safety. The goal of the present paper was to assess the current legal status of edible insects in Africa. For that, corresponding authorities were contacted along with an extensive online search, relying mostly on the FAOLEX database. Except for Botswana, insects are not mentioned in national regulations, although the definitions for “foodstuff” allow their inclusion, i.e., general food law can also apply to insects. Contacted authorities tolerated entomophagy, even though no legal base existed. However, insects typically appear in laws pertaining the use of natural resources, making a permit necessary (in most cases). Pest management regulation can also refer to edible species, e.g., locusts or weevils. Farming is an option that should be assessed carefully. All this creates a complex, nation-specific situation regarding which insect may be used legally to what purpose. Recommendations for elements in future insect-related regulations from the food hygiene point of view are provided.

10 February 2022 in Antibiotics
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SSSeverin Michael Steffan
Severin Michael Steffan
GSGolshan Shakeri
Golshan Shakeri
CKCorinna Kehrenberg
Corinna Kehrenberg
EPElisa Peh
Elisa Peh
MRManfred Rohde
Manfred Rohde
SKSophie Kittler
Sophie Kittler
Campylobacteriosis is a worldwide-occurring disease and has been the most commonly reported zoonotic gastrointestinal infection in the European Union in recent years. The development of successful phage-based intervention strategies will require a better understanding of phage–bacteria interactions to facilitate advances in phage cocktail design. Therefore, this study aimed to investigate the effects of newly isolated group II and group III phages and their combinations on current Campylobacter field strains. A continuous workflow for host range and efficiency of plating (EOP) value determination was combined with a qPCR-based phage group identification and a liquid-based planktonic killing assay (PKA). An advanced analysis scheme allowed us to evaluate phage cocktails by their efficacy in inhibiting bacterial population growth and the resulting phage concentrations. The results of this study indicate that data obtained from PKAs are more accurate than host range data based on plaque formation (EOP). Planktonic killing assays with Campylobacter appear to be a useful tool for a straightforward cocktail design. Results show that a group II phage vB_CcM-LmqsCP218-2c2 and group III phage vB_CjM-LmqsCP1-1 mixture would be most promising for practical applications against Campylobacter coli and Campylobacter jejuni.

16 April 2020 in Pathogens
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SKSophie Kittler
Sophie Kittler
RMRuth Mengden
Ruth Mengden
IKImke Korf
Imke Korf
ABAnna Bierbrodt
Anna Bierbrodt
JWJohannes Wittmann
Johannes Wittmann
CKCorinna Kehrenberg
Corinna Kehrenberg
Among intestinal coliform microbes in the broiler gut, there are potentially pathogenic Escherichia (E.) coli that can cause avian colibacillosis. The treatment with antibiotics favors the selection of multidrug-resistant bacteria and an alternative to this treatment is urgently required. A chicken model of intestinal colonization with an apathogenic model strain of E. coli was used to test if oral phage application can prevent or reduce the gut colonization of extraintestinal pathogenic E. coli variants in two individual experiments. The E. coli strain E28 was used as a model strain, which could be differentiated from other E. coli strains colonizing the broiler gut, and was susceptible to all cocktail phages applied. In the first trial, a mixture of six phages was continuously applied via drinking water. No reduction of the model E. coli strain E28 occurred, but phage replication could be demonstrated. In the second trial, the applied mixture was limited to the four phages, which showed highest efficacy in vitro. E. coli colonization was reduced in this trial, but again, no reduction of the E. coli strain E28 was observed. The results of the trials presented here can improve the understanding of the effect of phages on single strains in the multi-strain microbiota of the chicken gut.

13 March 2021 in Current Clinical Microbiology Reports
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LSLisa Siekmann
Lisa Siekmann
MPMadeleine Plötz
Madeleine Plötz
CKCarsten Krischek
Carsten Krischek
Purpose of Review: Curing—the treatment of meat products with nitrite and nitrate—is controversially discussed by consumers, as increased consumption of cured foods might negatively influence human health. Recent Findings: However, omitting of curing chemicals might reduce microbiological safety, thereby increasing the risk to consumer health. Also, besides the addition of nitrate/nitrite, meat products are additionally preserved within the hurdle principle by other methods such as chilling, ripening, or heating. Summary: The present article focuses on the addition of plants/plant extracts or plasma-treated water as nitrate sources and the direct treatment of meat products with plasma for nitrate generation. With regard to color and microbial safety of cured meat products, which are relevant to the consumers, promising results were also obtained with the alternative curing methods. Nonetheless, it is doubtful to what extent these methods are viable alternatives, as the curing chemicals themselves and not their origin are problematic for consumer health.

22 May 2023 in Insects
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BLBarbara Lemke
Barbara Lemke
LSLisa Siekmann
Lisa Siekmann
NGNils Th. Grabowski
Nils Th. Grabowski
MPMadeleine Plötz
Madeleine Plötz
CKCarsten Krischek
Carsten Krischek
The use of proteins from insects, plants, microalgae, fungi or bacteria as an alternative to proteins of animal origin such as meat, fish, eggs or milk can meet the worldwide protein demand in the future. As the consumption of whole insects might be problematic or unacceptable for many consumers, especially in European countries, the use of homogenized insects or protein extracts from insects for the production of products might be a possibility to overcome general acceptability problems. However, the quality criteria of these products have to be comparable with consumers’ expectations with regard to known products. Therefore, in the present study, we produced a meat product, replaced 10% and 20% of the pork with homogenized larvae of Tenebrio molitor and Hermetia illucens, and determined different physicochemical and sensory parameters at production and during modified atmosphere storage for 21 days. Additionally, the alteration of different bacteria species during this storage was analyzed in challenge tests. After production, the addition of insects resulted in higher cooking losses and pH values in the products with 20% insects, higher pH and yellowness, lower lightness, protein and hardness results in the Hermetia products, as well as higher yellowness and lower protein and hardness values in the cooked meat products with Tenebrio molitor. During modified atmosphere storage, the color differences principally remained, whereas the concentrations of inoculated Bacillus cereus, Listeria monocytogenes and Escherichia coli were not influenced by the addition of insects to the cooked meat products. The sensory results of the insect products, especially at higher concentrations and with Hermetia illucens, worsened during modified atmosphere storage. The addition of homogenized insect larvae, especially at higher concentrations and particularly of Hermetia illucens, influences different physicochemical and sensory parameters of the cooked meat products.

6 March 2023 in Foods
Verified
Journal Article
Open access
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VGVanessa Große-Peclum
Vanessa Große-Peclum
LSLisa Siekmann
Lisa Siekmann
CKCarsten Krischek
Carsten Krischek
GAGeorg Avramidis
Georg Avramidis
COChristian Ochs
Christian Ochs
MPMadeleine Plötz
Madeleine Plötz
Foodborne diseases are mainly caused by the contamination of meat or meat products with pathogenic microorganisms. In this study, we first investigated the in vitro application of TRIS-buffered plasma-activated water (Tb-PAW) on Campylobacter (C.) jejuni and Escherichia (E.) coli, with a reduction of approx. 4.20 ± 0.68 and 5.12 ± 0.46 log10 CFU/mL. Furthermore, chicken and duck thighs (inoculated with C. jejuni or E. coli) and breasts (with natural microflora) with skin were sprayed with Tb-PAW. Samples were packed under a modified atmosphere and stored at 4 °C for 0, 7, and 14 days. The Tb-PAW could reduce C. jejuni on days 7 and 14 (chicken) and E. coli on day 14 (duck) significantly. In chicken, there were no significant differences in sensory, pH-value, color, and antioxidant activity, but %OxyMb levels decreased, whereas %MetMb and %DeoMb increased. In duck, we observed slight differences in pH-value, color, and myoglobin redox forms for the Tb-PAW, which were not perceived by the sensory test persons. With only slight differences in product quality, its application as a spray treatment may be a useful method to reduce C. jejuni and E. coli on chicken and duck carcasses.