Phytochemicals

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 of molecules: (iso)flavonoids (e.g. flavan-3-ols and isoflavones), stilbenoids (e.g. resveratrol), lignans, (hydroxy)cinnamic acids (e.g. coumaric acid, ferulic acid), phenol-amides (e.g. avenanthramides), isothiocyanates, triterpenoid glycosides (e.g. saponins), carotenoids, and porphyrins (e.g. chlorophylls). Phenolics, which make up several of these classes, are the most widespread and broadly studied group of phytochemicals. Phenolics and other phytochemicals are prone to structural changes during plant growth, processing, storage, and passage through the gastrointestinal tract. These changes in structure also lead to changes in their properties, which can range from enhanced bioactivity to undesirable colour formation.

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. In this respect, three main characteristics of phytochemicals are relevant in food science & technology.

1) Bioactivities: Phytochemicals can possess a wide variety of beneficial bioactivities and health-promoting properties, including: antioxidant activity (e.g. hydroxycinnamic acids and flavan-3-ols), positive effects on cardiovascular health (e.g. proanthocyanidins and phytosterols), anticancer and (anti-)estrogenic activity (e.g. isoflavones), prebiotic effects (e.g. flavan-3-ols), and antimicrobial activity (e.g. isothiocyanates, stilbenoids, (iso)flavonoids). FCH theme Phytochemicals closely collaborates with FCH theme Plant Bioactives to study bioactivities of phytochemicals.

2) Sensory properties: Phytochemicals are important in determining the attractiveness of foods, especially with respect to colour and taste. For instance, anthocyanins are responsible for the desirable colour of red wine and many different types of berries, whereas enzymatic browning reactions in fruit (e.g. apple, banana) are often regarded as undesirable. The main taste sensations associated with phytochemicals are bitterness and astringency.

3) Reactivity & undesirable interactions: Enzymatic coupling of phenolics by polyphenol oxidase (PPO) or by autooxidation, as well as metal-phenolic interactions, and interactions of phytochemicals with proteins are all challenges in designing foods and ingredients from plant-derived materials. This is becoming increasingly relevant considering the growing demand for natural food ingredients and the transition from animal- to plant-derived raw materials.

The aim of the FCH theme Phytochemicals is to (i) characterize phytochemicals from various plant materials using advanced analytical techniques; (ii) monitor changes in phytochemical composition during plant growth, processing, storage, and passage through the gastrointestinal tract; (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.

To this end, we employ a diverse array of advanced analytical techniques, including ultra-high performance liquid chromatography (UHPLC), high resolution mass spectrometry (HRMS), and nuclear magnetic resonance (NMR) spectroscopy.

Research Projects