Student Theses and Job Vacancies
Dear students,
If you are looking for a topic for your project or thesis, you will find current topic suggestions from our section below - if any are currently available. You are also welcome to contact Prof. Fabian Weber with your own ideas.
We look forward to your interest and exciting suggestions!
Topic: Varietal influence on secondary plant metabolite contents and sensory properties in rosemary and sage - in collaboration with Volmary GmbH
Description:
Sage (Salvia officinalis L.) and rosemary (Rosmarinus officinalis L.) are among the most important aromatic and medicinally relevant medicinal and culinary herbs in Europe. Their valuable properties are primarily attributed to the content and composition of secondary plant compounds—particularly essential oils and polyphenols such as flavonoids, phenolic acids, and terpenes—which are responsible for antioxidant activity, sensory characteristics, and pharmacological relevance. In practice, however, only a limited number of varieties are used, despite substantial genetic and biochemical diversity both within and between species. This diversity presents significant potential for targeted variety selection in the food, pharmaceutical, and cosmetic industries. The choice of suitable varieties should also consider the intended application, as different sectors (e.g., food vs. medicinal products) often entail distinct quality requirements.
The central research question is to what extent different sage and rosemary varieties differ in their chemical composition (essential oils, polyphenols) and sensory properties, and which characteristics are decisive for a differentiated variety profiling. Based on this, it will be evaluated whether certain varieties exhibit a unique profile of bioactive compounds and sensory attributes that justify their use in specific applications (e.g., food, dietary supplements, herbal teas).
Implementation:
A total of eight rosemary varieties and seven sage varieties (clones) will be investigated, all cultivated under controlled conditions. After harvest, the leaves are dried and prepared for analysis. In the laboratory, quantitative and qualitative analysis of essential oils will be performed via steam distillation followed by gas chromatography-mass spectrometry (GC-MS). The polyphenol composition will be determined using high-performance liquid chromatography coupled with mass spectrometry
(HPLC-MS). Additionally, a standardized sensory evaluation will be conducted by trained sensory panels to assess attributes such as aroma, bitterness, aftertaste, and overall impression.
Goal:
Systematic analysis and profiling of various sage and rosemary varieties based on their essential oils, polyphenols, and sensory characteristics.
The study aims to evaluate variety quality not only in terms of yield or biomass, but particularly through chemical and sensory parameters. This will contribute to a more nuanced understanding of variety differences and provide practical relevance for breeding, sustainable cultivation, variety selection, and the valorization of medicinal plants in industrial applications.
Desirable experience:
Working in a chemistry laboratory
Contact person:
Prof. Dr. Fabian Weber: Fabian.weber@uni-kassel.de
Topic: Influence of drought stress and waterlogging on valuable secondary plant compounds in spinach (Spinacia oleracea L.)
Discription:
In addition to its high vitamin and mineral content, spinach is characterised in particular by a range of phytochemicals, including flavonol glycosides and other phenolic compounds, which contribute to its antioxidant capacity as well as its nutritional and sensory quality. At the same time, spinach is sensitive to abiotic stress factors such as drought and waterlogging, which are becoming increasingly significant in practical cultivation. Whilst drought stress has already been extensively studied in many crops, waterlogging in particular represents a critical stressor due to restricted oxygen supply in the root zone, which can trigger profound physiological and biochemical changes.
The focus is on how different water stress conditions affect the concentration and composition of relevant groups of compounds, and what relationships exist between stress intensity, physiological plant response and crop quality. On this basis, the aim is to assess whether waterlogging leads to more pronounced or different changes in bioactive compounds compared to drought stress.
Implementation:
The first step will be to isolate polyphenol-rich extracts from specific foods. These extracts will then be characterised in sensory tests to determine their perception and recognition thresholds. Subsequently, preference tests will be conducted to establish whether certain compounds are preferred. The same solutions will be examined in the laboratory for their bioactive properties in order to identify any correlations.
Goal:
Investigation of the influence of drought stress and, in particular, waterlogging on the formation and changes in value-adding secondary plant compounds in spinach.
The aim of this study is to assess the stress-dependent quality of spinach not only in terms of yield and biomass, but above all in terms of value-adding compounds. This is intended to make a nuanced contribution to our understanding of the interactions between water stress, plant metabolism and food quality.
Desirable experience:
Working in a chemistry laboratory
Contact person:
Prof. Dr. Fabian Weber: Fabian.weber@uni-kassel.de
Topic: Comparison of analytical and sensory determination of the astringency of red wine
Description:
Astringency is a characteristic feature of red wine and other foods such as tea, chocolate or berries. It is described as a drying, astringent or rough mouthfeel and is considered a key quality characteristic. The physiological cause lies in the complexation of the proteins contained in saliva by polyphenolic compounds, especially tannins (also known as tannins). This interaction leads to a reduction in mucosal moisture and thus to the typical "dry" impression in the mouth.
Tannins are high-molecular polyphenols whose composition in wine depends heavily on the grape variety, climate, ageing conditions and, above all, the winemaking process. During cellar work, the cellar master can specifically influence the amount of tannins and their physico-chemical properties through maceration time, temperature, pressing pressure and mechanical processing. Precise control of these factors is crucial in order to achieve a balanced, pleasant astringency - neither too dominant nor too weak.
Despite their central importance, the quantitative determination of tannins in wine has so far been challenging. Therefore, there are only limited correlations between the tannin levels measured in the laboratory and the actual perceived astringency.
Implementation:
To combine existing analytical methods for tannin determination with a standardized, sensory assessment of astringency by a trained panel. This will be based on established protocols that include both chemical analysis and sensory evaluation.
Aim:
The work should enable a systematic comparison of the different analytical parameters with sensory data and potentially provide new, practical correlations or predictive models for astringency development in viticulture. The results could be of great benefit to wine production: they would provide winemakers and cellar masters with a tool to specifically control the tannin structure and thus the sensory quality of the wine during production. The work thus combines analytical chemistry, sensory science and practical application - an exciting and relevant topic for modern wine science.
Desirable experience:
Working in a chemical laboratory
Contact person:
Prof. Dr. Fabian Weber: Fabian.weber@uni-kassel.de