What is the secret science of the perfect croissant? From the air between layers, to the ratio of the audible crunch to buttery centre, Lune Croissanterie spills the beans on some of their croissant chemistry.
“I’m actually a qualified aerospace engineer,” says baker and director of Melbourne’s Lune Croissanterie, Kate Reid.
While the leap between mathematics, fluid mechanics, aeroelasticity, and pastry might seem unlikely at first – Lune has married up science and baking to create croissant heaven.
Since opening in 2012, Kate’s purpose-built croissant laboratory has made headlines around Australia and the world and conjured lengthy queues and waitlists. But what is this secret science and croissant chemistry that Lune has perfected?
“So I guess I am not a typical pastry chef, nor am I classically trained,” Kate continues. When long hours in front of the computer didn’t seem like the perfect career match for Kate, she turned to her passion for pastry, encouraged by regular trips to France and a stint in the raw pastry kitchen at Du Pain et des Idées in Paris.
Lune's croissant lab in Fitzroy, Melbourne
“There was something so beautiful about croissants, yet it became clear to me – and my engineering brain – that they weren’t so easy to make. I’ve always loved a challenge, and making croissants seems to be the perfect combination of craft and science.”
According to Kate, the perfect croissant is a precise combination of elements, with an exacting, almost academic pathway to creating it.
“An excellent croissant is super light, with an open inner honeycomb structure. The butter taste must be prominent, but not leave a greasy taste in your mouth. Finally, the outside shell of the pastry must be delicate, with an audible crunch when you bite into it, and you should end up covered in shards of pastry.”
Kate is mostly self taught. She estimates she understood only about 15-20% of the croissant process from her time in the kitchen in Paris, the rest – she decided to decipher herself, reverse engineering the flavours and bite she wanted to achieve in her own croissant creations.
“I used trial and error to develop techniques that resulted in the properties that I look for in a good croissant,” she explains. “My background in engineering played a big part in the development of these techniques. I would change one variable at a time and analyse the differences it made to the final baked product. If it was an improvement it would become the new baseline technique.”
While Kate won’t reveal Lune’s exact recipe, she’s happy to divulge a little of her science. It’s a three-day process that begins with making the dough, and a slow overnight fermentation. On the second day, the pastry is ‘laminated’ – the process of creating many layers of buttery dough. Then the croissants are shaped into a crescent moon figure.
They’re then left overnight to ‘prove’ – where they rest at a specific temperature and humidity in order to activate the yeast. Finally, the pastries are egg washed and baked on the third day.
“There are many, many tiny little steps within this process that I’m not going to divulge; as the saying goes ‘the devil is in the detail’ and that is truly where the magic lies in a Lune croissant!”
She does reveal that Lune uses a rather unorthodox turning process (le tournage) with their croissant dough, which really separates them from the century-old classic French technique. For Kate, the perfect amount of layers in a croissant depends almost entirely on the type of ‘turns’ you use – single, double, or letter – and the number and combinations of turns you complete for each pastry.
“This is a tightly kept secret at Lune,” she says. “I devised the type and number of turns for the pastry based on the outer crunch, level of gluten development and honeycomb structure I wanted to achieve.”
But research has not ceased at Lune – and the laboratory continues to experiment with variables to the recipe.
“With time and experience, we are constantly learning more about how all the different variables affect the final product - ingredient, environment, time, technique,” Kate adds. “So our process is constantly evolving and improving based on our built up knowledge.”