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Can certain light spectra give herbs more taste?

Researchers from Aarhus University are investigating if different types of new, advanced LED lamps in greenhouses can improve the taste of herbs. 

[Translate to English:] Forskere undersøger, om forskellige farver af lys kan påvirke smagen af krydderurter. Foto: Carl-Otto Ottosen

The greenhouses of the future may start to look like colourful light shows if the results from a research project at Aarhus University pan out and show that different light colours both can affect the taste and size of herbs. 

The aim of the project is to investigate the possibilities for using specific light spectra from LED lamps to give herbs more taste. This could be particularly relevant during the winter when there is not so much sunlight and the taste needs to be improved.

Light consists of a whole spectrum of colours. The colour of light can affect plant growth in many different ways. For example, red light results in elongation growth, which means the plants grow taller, while blue light results in more compact growth.  

- Just think of a forest where the plants stretch towards the sunlight, says Professor Carl-Otto Ottosen from the Department of Food Science at Aarhus University. He is the leader of a new research project that has received funding from Energi Fyns Udviklingsfond (Funen Energy Development Fund), and that is why light will be shed on herbs from the island of Funen in particular – and literally speaking. 

Light’s colour affects plant growth

Blue and red light both affect the stomata in plant leaves, which in turn help regulate photosynthesis – the process by which plants produce sugar.

- We know from earlier studies in potted plants and lettuce that an increasing proportion of blue light compared to red light increases the content of secondary compounds, e.g. anthocyanins, phenolic acids and etheric oils. They can act as a defence against pests or as antioxidants. The more blue light that hits the plant – that is, the more the light moves towards the ultraviolet range – the more energy hits the plant. That is why herbs grown outdoors often have a stronger taste, Carl-Otto Ottosen explains.

Development of new, advanced and energy-saving LED lamps for use in greenhouses also brings new possibilities in that it is possible to manipulate the colour and intensity of the lighting. The aim is to create plants with a more compact growth and more intense colours in the leaves and flowers, and herbs with more intense taste. However, systematic comparisons of plant growth, taste and colour at various light wavelengths and levels under controlled and documented climate and light conditions are lacking. The new project will contribute to making up for that. 

Which light colours give the best taste?

The project researchers will select certain species of herbs and focus on the plants’ reactions at different combinations of light in closed systems in three phases of the plants’ production: germination, growth and senescence. 

- It might not be necessary to replace all the lamps if you can suffice with providing the right light combination for a shorter period of the production and thus reduce costs, says Carl-Otto Ottosen. 

With the aid of advanced equipment, the researchers will measure the plant’s photosynthesis and stomatal regulation. This will be combined with measurements of plant growth, developmental speed, taste and content of relevant substances. Perhaps most interesting will be measuring to which extent light can be used to change the composition of a plant’s content of various compounds, including taste compounds.  

- The results may pave the way for multi-layer production, which in turn can make it easier to grow herbs or other crops in cities, also known as urban farming, says Carl-Otto Ottosen.


The project is connected to iFOOD Aarhus University Centre for Innovative Food Research and is being carried out in collaboration with the GUDP-supported project Intelligent Light and EU’s Interreg project SmartGreen.


For more inforrmation please contact: Professor Carl-Otto Ottosen, Department of Food Science, email: coo@food.au.dk, telephone: +45 8715 8373, mobile: +45 2290 3105