Fundamental study on perspectives for post-harvest bioprotection of cereal crops

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dc.contributor.advisor Arendt, Elke K. en Schmidt, Marcus 2019-01-25T10:16:54Z 2019-01-25T10:16:54Z 2018 2018
dc.identifier.citation Schmidt, M. 2018. Fundamental study on perspectives for post-harvest bioprotection of cereal crops. PhD Thesis, University College Cork. en
dc.identifier.endpage 290 en
dc.description.abstract As a result of the rapidly growing human population, reducing post-harvest crop losses of cereals due to microbial pests has major importance. Therefore, recent advances and emerging technologies for chemical, physical and microbial grain decontamination were reviewed as part of this thesis. It became evident that no single treatment can sufficiently decontaminate cereals without quality deterioration. This thesis investigates the spread of a fungal contamination during storage if the crop is treated inappropriately. During 6 weeks of storage, the ergosterol content (measure of fungal bio-mass) increased from <0.75 ppm to 44 ppm. Substantial levels of mycotoxins, such as deoxynivalenol and zearalenone were found in concentrations up to 953 ppb and 78 ppb, respectively. Also the grain quality was reduced due to the degradation of carbohydrates and proteins by fungal hydrolytic enzymes. Consequently, the gluten quantity and network strength was substantially lowered, inducing dough and bread quality deterioration. This was particularly expressed by the increased dough stickiness, bake loss and open crumb structure. The optimisation of the antifungal performance of Lactobacillus reuteri R29 due to increased accumulation of phenyllactic acid (PLA) or reuterin was investigated also. While both compounds efficiently inhibited spore germination of Fusarium culmorum (106 spores/mL) in vitro, only PLA could successfully extend the microbial shelf-life of bread (4 days, 100%). Furthermore, emerging microbial, physical and chemical methods of decontamination, were investigated during cereal storage. While microwave (2 min, 800 W), microwave+NaOCl (5%), sorbate and propionate (both 5%, 10 min), high pressure (10 min, 300 MPa, 30°C) treatment and vacuum packing fully inhibited fungal growth and mycotoxin accumulation, ultrasound, quaternary ammonium compounds, cold plasma and LAB were not successful. However, the dry microwave treatment induced protein denaturation, resulting in poor quality of the resulting dough and breads. Finally, plant derived antimicrobial peptides were studied at the example of the cowpea-thionin II. After extraction and partial purification, the peptide was identified by N-terminal sequencing. The antifungal activity against 3 major food spoilage fungi (104 spores/mL) was shown. The extract was found to be resistant against heat treatment but lost its antifungal activity in presence of cations. Finally, it was successfully used to protect stored wheat grains from fungal spoilage. Overall, this thesis provides a valuable contribution to the knowledge regarding fungal spoilage and the possibilities and actual shortcomings of diverse emerging approaches and technologies for food preservation. en
dc.format.mimetype application/pdf en
dc.language.iso en en
dc.publisher University College Cork en
dc.rights © 2018, Marcus Schmidt. en
dc.rights.uri en
dc.subject Cereal research en
dc.subject Antifungal agents en
dc.subject Bioprotection en
dc.subject Cereal storage en
dc.title Fundamental study on perspectives for post-harvest bioprotection of cereal crops en
dc.type Doctoral thesis en
dc.type.qualificationlevel Doctoral en
dc.type.qualificationname PhD en
dc.internal.availability Full text available en Not applicable en
dc.description.version Accepted Version
dc.contributor.funder Department of Agriculture, Food and the Marine en
dc.description.status Not peer reviewed en Food and Nutritional Sciences en
dc.check.type No Embargo Required
dc.check.reason Not applicable en
dc.check.opt-out No en
dc.thesis.opt-out false
dc.check.embargoformat Embargo not applicable (If you have not submitted an e-thesis or do not want to request an embargo) en
dc.internal.conferring Spring 2019 en

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© 2018, Marcus Schmidt. Except where otherwise noted, this item's license is described as © 2018, Marcus Schmidt.
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