Phytochemicals
Current trends in food and agriculture, such as the protein transition, are creating a growing interest in natural plant-based ingredients. As a result, phytochemicals (phyto meaning ‘plant’ in Ancient Greek) are becoming increasingly prevalent and important in food. The term ‘phytochemicals’ describes a bewildering number of small molecules from plants, which can be divided into many distinct classes based on their biosynthetic origin and structure. Phytochemicals include, but are not limited to, the following classes: (iso)flavonoids (e.g. flavan-3-ols and isoflavones), stilbenoids (e.g. resveratrol), (hydroxy)cinnamic acids (e.g. coumaric acid, ferulic acid), phenolamides (e.g. avenanthramides), (neo)lignanamides (e.g. hordatines), triterpenoid glycosides (e.g. saponins), and carotenoids. Phenolic compounds, which make up several of these classes, are the most widespread and broadly studied. Phenolics and other phytochemicals can be reactive and are prone to structural changes during plant growth, and during processing and storage of plant-based food products or ingredients. These structural changes modulate phytochemicals’ molecular and functional properties.
Description of theme
Despite the fact that phytochemicals are present in much smaller quantities in foods than carbohydrates, proteins, and lipids, they can strongly affect food properties. These effects, ranging from enhanced bio- or techno-functionality to (undesirable) colour formation, can be due to the inherent properties of phytochemicals or due to the reactivity of these compounds. Understanding the effects of phytochemicals on the properties of food products and ingredients is essential due to the aforementioned trends in plant-based food. Our phytochemical research is focussed on three main areas.
1) Advanced phytochemical analysis: Analysis and structure elucidation of phytochemicals is at the core of our work on these compounds, as it is essential in studying phytochemical reactivity. Due to the high structural diversity of phytochemicals, their analysis can be quite challenging. We develop analytical approaches to obtain structural information on individual phytochemical molecules, as well as overall compositional data of phytochemicals present in plant-derived materials (including industrial waste streams or by-products). To this end, we employ a diverse array of advanced analytical techniques, including ultra-high performance liquid chromatography (UHPLC), high resolution mass spectrometry (HRMS), ion mobility spectrometry (IMS), and nuclear magnetic resonance (NMR) spectroscopy.
2) Oxidation of phenolic compounds: One of the most well-known examples of the oxidation of phenolic compounds is the enzymatic browning reaction that leads to formation of brown colour upon cutting or bruising of fruits. Besides undergoing enzymatic oxidation, phenolic compounds can auto-oxidise to form brown and insoluble reaction products. Phenolic oxidation reactions are often considered to be undesirable, as they can negatively affect the attractiveness of foods or ingredients. On the other hand, controlled (enzymatic) oxidative coupling may also be used as a tool to modulate the structure and properties of phenolic compounds, which can lead to improved bio- or techno-functionality. We study these reactions to tackle challenges associated with undesired oxidation as well as exploring the potential of controlled oxidation as a valuable universal tool to modify phenolic compounds.
3) Interactions of phytochemicals with other food molecules: Phytochemicals are known to interact covalently and non-covalently with various other food molecules, including proteins and metals. Protein-phenolic interactions can affect sensory, techno-functional, and bio-functional properties in plant protein products. Similar to our work on phenolic oxidation, we investigate how these interactions can be prevented or how they may be exploited to enhance the functionality of both plant proteins and phenolic compounds. With regards to metal-phenolic interactions, we study the resulting formation of dark discolouration (e.g. in iron-fortified food products) and explore opportunities related to the complexation of metals by phenolic compounds.
The aims of the FCH theme Phytochemicals are to (i) characterize phytochemicals from various plant materials using advanced analytical techniques; (ii) monitor changes in phytochemical composition during plant growth, and during processing and storage of plant-derived food products or ingredients; (iii) modify phytochemicals with chemical, enzymatic, or microbial approaches, in order to improve their properties; and (iv) study interactions of phytochemicals with proteins and micronutrients.
Research Projects
- Oxidation of green tea phenolics. Junfeng Tan.
- Fungal prenyltransferases as tools to produce antimicrobial prenylated phenolics. Pimvisuth Chunkrua.
- Bio-purification of plant proteins: elimination of off-flavours, anti-nutritional compounds and phytoestrogens. Pauline Damhof.
- In-depth characterization of food lipids and phytochemicals with ion mobility mass spectrometry. Carlo de Bruin.
- ProTip – Understanding protein-phenolic interactions: Tipping the scales in our favour! Solange Ha.
- Unlocking the antioxidant potential of co-passengers of plant protein ingredients in emulsions. Quirine Hafkamp.
Recently completed PhD projects:
- Tapping into oxidative coupling of barley phenolamides. Annemiek van Zadelhoff, defence date: 28-10-2024.
- Discolouration by iron-phenolic interactions – Colourful insights into the mechanisms and proposed solutions for food fortification. Judith Bijlsma, defence date: 14-09-2023.
- Prebiotic potential of green and black tea phenolics – Metabolite and microbiota profiling, and green biorefinery for sustainable production. Zhibin Liu, defence date: 07-04-2021.