Tutors: Jonathan Piard, Tom Gérard-Hirne, Thomas Bidaud, Marianne Kjellberg, Fayna Mammeri/ chemists
Project manager: Stéphane Coulaud
Objectives:
Firstly, the classes learn how chemistry works to isolate as many colours in nature as possible. Obviously, we think of green, red and orange, but where are all the other colours hiding and how can we obtain them? Then, the students and their contributor tackle the task, using the Pantone colour chart for inspiration, of offering a series of sweet and savoury foods for tasting.
Workshop:
Natural dyes
The workshop is organised in two phases. During the first half of the workshop, the students discover the colouring properties of various foods: beetroot, carrot, red cabbage, parsley, spinach, cherry, bell pepper, etc. They learn to recognise the molecules (anthocyanins, carotene, chlorophyll, lycopene, etc.) that give food their colour and to test the ways that can be used to extract their active substances.
From extraction to stabilisation
Protocols are set up for each type of food and desired colour. Decoction and infusion in aqueous, acid or alkaline environments, centrifugation tests, etc. give different results depending on the desired intensity of the dye. An experiment is conducted on the various colours obtained from the same food – red cabbage. Later, the challenge consists of reinvesting this solution for use in food and learning how to obtain a colour chart that is as rich as possible using plants.
Edible colours
The workshop then focuses on using colours, particularly in food preparations. The students take it in turns to prepare hot and cold foods, drinks (soft drinks, cocktails and milkshakes), sweets and treats. After experimenting, a menu is compiled to prepare for the final rendition.
Outcome:
On the occasion of the school “Open Day”, the students organised a demonstration. The programme included making sweet, coloured jellies (spinach, red pepper, lemon and cherry), soft drinks, carrot-coloured milk, lemonade dyed with red cabbage and a colour chart made from beetroot juice. Other demonstrations involved creating colours to match the Pantone colour chart. The final result matched the reference Pantone 1795 with an infusion of berries; an infusion of green tea (Pantone 613) gave a solution matching Pantone 132; and an infusion of red cabbage (Pantone 2612) gave a solution matching Pantone 2768.
Acknowledgements: Sophie Griveau, École nationale supérieure de chimie de Paris
Outings (selection):
- Chemistry workshop, Palais de la découverte
Participating schools:
- Class 4 Segpa, Collège Le Clos-Saint-Vincent, Noisy-le-Grand
- Class 4 Segpa, Collège Jean-Zay, Bondy
- Class 3, Collège Picasso, Montfermeil
- Class 3, Collège Claudel, Villepinte
- Class 3, Collège Saint-Exupéry, Noisy-le-Grand
Avec la période de confinement, les démarches initiées en collège ont connu quelques changements, également quelques aménagements et surprises. Le moment est venu de présenter ce qui a été finalisé par les élèves, les enseignants et les intervenants. Cet espace de diffusion rapporte nombre de témoignages visuels, sous des formats à la fois fixes et animés, et invite les visiteurs à une découverte différenciée : en cela par projet identifié ou d’une manière plus aléatoire.