Student Theses and Job Vacancies

Polyphenols are phytochemicals that are widely found in foods and are believed to contribute to the health benefits of a plant-based diet. Numerous bioactive properties have been demonstrated in vitro, and a few have also been demonstrated 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). Therefore, they 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.

This project investigates whether there are structural correlations between sensory and bioactive properties. It is based on the hypothesis that there are molecular structural elements of polyphenols that influence consumer acceptance and selection of nutritionally beneficial foods. Since 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.

First, polyphenol-rich extracts will be obtained from specific foods. These extracts will then be characterized in sensory tests with regard to their perception and recognition thresholds. Subsequently, popularity tests will determine whether certain compounds are preferred. The same solutions will be examined in the laboratory for their bioactive properties to identify correlations.

If you have any questions, please contact: Fabian.Weber[at]uni-kassel[dot]de

Spinach (Spinacia oleracea L.) is one of the most important leafy vegetables in terms of cultivation and human nutrition. In addition to its high content of vitamins and minerals, spinach is particularly characterized 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. While drought stress has already been extensively studied in many crops, waterlogging in particular poses a critical stress due to limited oxygen supply in the root zone, which can trigger profound physiological and biochemical changes.

The aim of the planned thesis is to investigate the influence of drought stress and, above all, waterlogging on the formation and alteration of value-adding phytochemicals in spinach. 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. Based on this, the study aims to assess whether waterlogging leads to stronger or different changes in bioactive compounds compared to drought stress.

The study will be conducted experimentally under controlled conditions. To this end, spinach plants will be subjected to defined water supply regimes, such as an unstressed control, drought stress, and waterlogging. Subsequently, morphological and physiological parameters such as biomass, leaf area, and visible stress symptoms will be recorded. In the laboratory, selected phytochemicals will be analyzed, particularly flavonols and, where applicable, other compounds.

The study aims to evaluate the stress-dependent quality of spinach not only based on yield and biomass, but primarily through value-adding compounds. This is intended to provide a nuanced contribution to understanding the interactions between water stress, plant metabolism, and food quality.

If you have any questions, please contact: Fabian.Weber[at]uni-kassel[dot]de