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Hinrich Hermann F Holthusen

PhD Student

Hinrich Hermann F Holthusen


PhD project: Characterisation of the heat-shock response in apples triggered by short hot-water treatments (short-HWT) by using fungal pathogens as indicators

University: Aarhus University, Faculty of Science & Technology

DepartmentDepartment of Food Science

Supervisor: Merete Edelenbos, PhD, Associate professor

Project supervisor: Roland, W. S. Weber, PhD, Affiliated professor

Co-supervisors: Roland, W. S. Weber, PhD, Affiliated professor;

Project term: 01.02.2015 – 15.05.2021

Education: MSc in Horticulture, Humboldt-Universität zu Berlin, Berlin, Germany


Due to favourable climatic conditions, rots of apples caused by fungal infections are one of the most important threats in Northern European production areas like the Lower Elbe region, Denmark, or the Netherlands. Although most infections are initiated before harvest, the appearance of symptoms is often delayed until storage. Because there are no practicable alternatives, fungicide treatments are common practice.

Despite early reports on the effectiveness of hot-water treatments (HWT) against storage rots), efforts to develop this technology have not been conducted until recent years. The lack of effective fungicides in the increasing organic fruit farm sector has provided fresh interest in alternative methods like HWT during the late 1990s. The discovery of the heat-shock response as the mode of action of HWT and its wide range of effectiveness against different fungi as well as further improvements to the technology may provide a boost to the general acceptance of the method. Giving a similar level of efficacy as conventional HWT, short-HWT allows the treatment of apples with higher temperatures for a shorter time period. While experimental data on a laboratory scale are available, scale-up as well as information on energy consumption, process integration and ideal time of treatment are still lacking.

Most storage rot fungi infect before harvest and exist as latent infections in the fruit skin. Infections do no become visible until the storage period is under way. Early detection of latent infections would help to assess the decay risk of a particular batch of apples because HWT could be applied in a more targeted manner to vulnerable batches. For the detection of Penicillium expansum on apple fruit volatile organic compounds (VOC) were known as biomarkers in cultivar ‘Golden Delicious’. Such profiles may be used for an early detection of presence of fungi in fruits.


The aim of the project is to evaluate the effectiveness of short-HWT compared to conventional HWT in respect of minor storage rots. In the project, the duration of the protective effect as well as the systemic effect of the heat-shock response will be investigated. Determination of the influence of fruit core temperature at the time of HWT on the efficacy of the treatment is another key factor which will be optimized within the project.

It is an additional aim to develop a method for the early estimation of the decay risk of fruit, which allows restricting of HWT to endangered batches only.


A method will be developed to artificially inoculated fruits with rots under natural. Inoculated fruits will later be used to evaluate the efficacy of short-HWT in terms of minor storage rots. Artificially inoculated and natural infected fruits will be compared with their respond to HWT. Production of VOCs of artificially inoculated apples with Penicillium expansum will be measured by GS-MS to estimate the decay risk within the latent stage of the fungi.

HWT will be performed on natural infected as well as artificially inoculated fruits (P. expansum). Time series will be conducted to reveal the systemic response to HWT as well as the duration of the protective effect of the heat-shock response. Development of the fungi is measured over time. Artificially inoculated fruits will be used to determine whether the temperature difference between pre-incubation and HWT has any effect on the efficacy of the treatment. The outcome of all experiments is the basis to further improve the HWT technology and especially the optimized process integration.


ESTEBURG Fruit Research and Advisory Centre, Jork, Germany. Key parts of the project will take place at ESTEBURG Centre.



Journal article (commissioned)

Bahlo, J., Hilbers, J., Görgens, M., Holthusen, H. H. F. & Clever, Michael (2013). Vorernteführungen 2013. Mitteilungen des Obstbauversuchsringes des Alten Landes 68(10): 317–320.

Holthusen, H. H. F. (2013). INTERPOMA 2012. Bodenmüdigkeit und Nachbauprobleme. Mitteilungen des Obstbauversuchsringes des Alten Landes 68(1): 10–13.

Holthusen, H. H. F. (2014a). Strategien zur Minimierung von Pflanzenschutzmittel-Rückständen im Kernobst. Mitteilungen des Obstbauversuchsringes des Alten Landes 69(5): 121–130.

Holthusen, H. H. F. (2014b). Pflanzenschutzmittel-Rückstandssituation an der Niederelbe und Minimierungsstrategien. Obstbau 39(7): 392–398.

Holthusen, H. H. F., Harms, F. & Palm, G. (2015). Bekämpfung der Blutlaus im Frühjahr. Mitteilungen des Obstbauversuchsringes des Alten Landes 70(4): 124–131.

Holthusen, H. H. F., Vladimirova, P. & Tenbrink, P. (2013a). Dithiocarbamate in Handschuhen als Quelle für Fruchtkontaminationen. Mitteilungen des Obstbauversuchsringes des Alten Landes 68(9): 294–296.

Holthusen, H. H. F., Vladimirova, P. & Tenbrink, P. (2013b). Dithiocarbamate auf Äpfeln – ohne Pflanzenschutzmittelanwendung. Arbeitshandschuhe als mögliche Kontaminationsquelle. Obstbau 38(10): 558–560.

Klein, W., Steffens, M., Stehr, R., Ralfs, J.-P., Köpcke, D., Palm, G. & Holthusen, H. H. F. (2011). Vorernteführungen 2011. Mitteilungen des Obstbauversuchsringes des Alten Landes 66(10): 325–331.

Lindstaedt, J., Wichura, A., Holthusen, H. H. F., Weber, R. W. S. & von Kröcher, C. (2013). Modellvorhaben „Demonstrationsbetriebe integrierter Pflanzenschutz“. Mitteilungen des Obstbauversuchsringes des Alten Landes 68(5): 156–158.

Weber, R. W. S. & Holthusen, H. H. F. (2013). Sporen von Penicillium expansum im Wasser der Schwemmentleerung von Äpfeln. Mitteilungen des Obstbauversuchsringes des Alten Landes 68(7): 222–223.

Holthusen H. H. F., Weber R. W. S. (2021) Apple blossom-end rot due to Neonectria ditissima is initiated by infections at full flowering and incipient petal fall. New Zealand Plant Protetction 74(2S):S2–S8. https://doi.org/10.30843/nzpp.2021.74.11727

Conference article

Holthusen, H. H. F. & Chmielewski, F.-M. (2011). Klimawandel und Apfelertrag - Einfluss von Witterung und Klima auf die Ertragsbildung an der Niederelbe. DGG-Proceedings, Vol.1 No.3, p.1–5. 47. Gartenbauwissenschaftliche Tagung, Hannover, Germany. DOI: 10.5288/dgg-pr-01-03-hh-2011


Albrecht-Daniel-Thaer-Award 2011 for an execllent MSc graduation in 2010

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