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: Sensory perception of secondary plant substances (polyphenols) in comparison to their bioactive properties
Description:
Polyphenols are plant secondary metabolites that are widely found in food and are thought to contribute to the health benefits of a plant-based diet. Numerous bioactive properties have been demonstrated in vitro, and a few in vivo. At the same time, it is known that polyphenols contribute to the sensory properties of plant-based foods by imparting a bitter taste and influencing mouthfeel (e.g. astringency). They therefore play an important role in sensory quality and, consequently, in consumer acceptance of foods.
However, the molecular structures responsible for these properties and the question of whether they are interrelated have not yet been investigated.
Implementation:
The first step will be to isolate polyphenol-rich extracts from specific foods. These extracts will then be characterized 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:
The aim is to investigate whether there are structural links between sensory and bioactive properties. This is based on the hypothesis that certain molecular structural elements of polyphenols influence consumers’ acceptance and selection of nutritionally beneficial foods. As sweet and sour tastes are largely responsible for the flavor characteristics of plant-based foods, it is assumed that polyphenols have a subconscious influence on consumer opinion that lies below the threshold of perception.
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