Research
Here you will find information about the main research focuses and current research topics of the Department of Molecular Food Technology.
Research focus
At the Chair of Molecular Food Technology, secondary plant metabolites are the central area of research. The focus of the work is on phenolic compounds and carotenoids and their role in food. The interdisciplinary, strongly science-oriented research includes elements of food chemistry, food technology and microbiology.
Valorization of side streams from food production
Sustainability in food production is often associated with the avoidance of waste and the utilization of side streams. For this reason, the Chair of Molecular Food Technology attaches great importance to the development of suitable processes for exploiting the potential of residues of plant origin and the analytical characterization of these valuable materials. Extensive relevant work over the past 20 years (see publications) has shown that by-products of fruit and vegetable processing are a rich source of bioactive compounds, especially secondary plant substances and high molecular weight components of the plant cell wall.
There are numerous potential applications of the valuable compounds obtained from food production residues. For example, they can be used as ingredients in functional foods in order to achieve additional health benefits over and above their pure nutritional value. They can also be used as natural food additives (antioxidants, colorants, preservatives) in response to the increasingly critical attitude of consumers towards synthetic additives. However, as natural substances are in many cases less stable than synthetic compounds, appropriate measures must be taken to preserve the ingredients and characterize their reactions and interactions with other components of the food matrix.
Reactions of phenolic compounds
Phenolic compounds, especially those with an o-dihydroxy structure, can be oxidized either chemically or enzymatically to form quinoid systems. These are electron-deficient compounds that act as Michael acceptors and can undergo reactions with nucleophiles, such as thiol or amino groups. With NH2 groups, the formation of Schiff bases and subsequent reactions are also possible, including decarboxylation analogous to the Strecker degradation of amino acids. The oxidation of chlorogenic acid in the presence of amino acids leads to the formation of green benzacridines, which have potential as food colorants. A reaction with tryptophan produces red dyes with a complex structure.
Microorganisms can also convert phenolic compounds in a variety of ways. Work with lactic acid bacteria on the antibacterial activity of plant phenols has shown that hydroxycinnamic acids can be converted to the corresponding metabolites by decarboxylases or reductases. As these metabolites have a lower antibacterial activity than the hydroxycinnamic acids, it can be assumed that these reactions are detoxifying conversions by the lactic acid bacteria. Such reactions are also of interest from a food technology perspective in that they can be employed for the biotechnological production of phenolic metabolites, which can be used with other compounds to synthesize technofunctional or biofunctional food ingredients.
Influence of technological measures on secondary plant metabolites
During the processing of plant-derived raw materials, secondary plant metabolites may be subject to extensive reactions that depend on the processes used, the food matrix and external factors. Thermal processes often lead to degradation, particularly in the presence of oxygen, although in many cases the resulting compounds have not yet been sufficiently investigated. There is also still a need for research into the changes at molecular level when using non-conventional food preservation methods, e.g., ultrasound, cold plasma and pulsed electric fields. Current work is therefore concerned with systematic studies on selected secondary metabolites in order to describe the influence of food processing on their stability.
Sensory properties of food and food ingredients
In food sensory analysis, product properties are assessed using the five senses of sight, hearing, touch, smell and taste. A distinction is made between hedonic and descriptive sensory analysis. In hedonic tests, consumers evaluate the products subjectively and acceptance or preference is often tested. Descriptive sensory analysis requires trained testers who have trained their senses in previous training sessions and have familiarized themselves intensively with the product to be tested. This allows for objective assessment of food so that, for example, profiling or testing for differences can be carried out.
Current work at the Professorship of Molecular Food Technology is focusing on the hedonic and descriptive sensory analysis of aquafaba. Thereby, the description of the aroma profile and its use as an egg substitute in various foods is investigated. Orange juice and wine are also key areas of research and are assessed by an intensively trained panel.
Quality and authenticity control of food
Food fraud may occur in many forms and affect practically all product groups, including functional foods and food supplements. The detection of fraudulent manipulation of foodstuffs requires sufficiently specific analytical methods, especially since complex ingredient profiles are usually involved. Furthermore, the availability of reference substances facilitates analysis immensely and helps to reliably check the quality and authenticity of products. However, plant secondary metabolites in particular are often not commercially available as standards or are extremely expensive. The Chair of Molecular Food Technology is therefore working on the development of suitable methods for specific products, using UPLC-DAD-MS/MS and UPLC-IMS-ToF-MS as sensitive and specific analytical instruments. ASE, CCC, flash chromatography and preparative HPLC can be used to isolate reference substances from complex matrices.
Current research topics
You can find our current research topics with further information here:
Aquafaba
By-product of chickpea production
Analysis of sensory and functional properties and optimisation through fermentation and use as an egg substitute
Wine
Strategies against Botrytis damage
Viticultural and enological strategies to prevent quality losses due to Botrytis cinerea
Orange juice
Bioavailability of carotenoids from orange juice
Improving the bioavailability of carotenoids from orange juice through innovative homogenisation strategies