#13 The science behind the Lusse-bun

So Lucia is here and sure, the candles lighting up the December darkness accompanied by the tunes of some or our most beloved, traditional Christmas carols is lovely. But let’s be honest, is not what really warms our souls the following feasting on “glögg”, “Lussebullar” and “pepparkakor”? The golden saffron buns most commonly known as “Lussebullar” (Lucia buns), “Lussekatter” (Lucia cats – yes, really) or “saffransbullar” (saffron buns), comes in many shapes and forms. All delicious and typically the real reason people show up at the Lucia celebrations. Nothing can however beat your own home baked Lusse-buns and so it is time to switch out your laboratory coat for an apron and start experimenting in the kitchen!

Cooking and baking is in many ways similar to laboratory work. Chemical reactions are the basis behind the recipes and what is a recipe if not really a laboratory protocol? Or is it the other way around? Just as in the lab, it certainly helps if you understand why you are adding the different ingredients at the suggested ratios. Knowing what is essential to the recipe and where you can play around and adjust helps you improvise when needed and improve the recipe according to your taste. The advantages of baking Lusse-buns over doing yet another experiment at the lab tonight are clear – and many. How many you ask? Well that depends on the size of your Lusse-bun batch.

Let´s start from the basics. All you really need to bake bread is flour, water and yeast. Optionally, you can also add salt, sugar and fat. The flour contains gluten precursors and starch, gives flavor and builds the bulk of the bread. Water is needed to make gluten from the precursors and to allow the yeast to multiply and produce carbon dioxide. Important, since the CO2 gas bubbles produced by the yeast is what transforms the dough into an airy foam (= a collection of closed bubbles) instead of a dense block. Salt is in addition to seasoning also slowing down the yeast. If the yeast works too fast before gluten forms, the gas escapes. Sugar adds a sweet flavor and also feeds the yeast so it can multiply, although generally enough food for the yeast is already available in the flour. Fat from oil or butter will prevent gluten from forming large sheets, as it gets in the way of the small sheets joining up (hence the name shortening), resulting in a softer bread. For our sweet and soft Lusse-buns, we obviously need to add both sugar and fat!

During baking, the heat in the oven will then expand the CO2 bubbles produced by the yeast, until the bubble walls break and the gas escapes. A sponge; a network where air and water can flow through, is formed. At the same time, the heat will denature proteins and starches so that they can link up into solid webs that will hold the structure and shape of the bubble, also after the gas is gone. If the bread is removed from the oven before the proteins have become firm, the bubbles will shrink down and the bread collapse. If the gas has not yet escaped the bubbles, it would cool down and contract after the bread be removed from the oven and the bubbles would be crushed by the resulting vacuum. Instead, after a proper baking time, as the bread slowly cools, the hot air and steam filling the bubbles will be replaced by air from the room.

So what about the characteristic and inviting yellow color of the Lusse-buns? That comes from crocin, a molecule in saffron closely related to carotenoids, including β-caroten which gives carrots their orange color. Although I did not have the time to fact check the following information, Wikipedia states that crocin is an antioxidant with anti-proliferative action against cancer cells that may also be antidepressant. So maybe just to be safe, we should all eat a few extra Lusse-buns this year. What are you waiting for? Go home and start baking!




For those who want to know more, read:

“Culinary reactions: The everyday chemistry of cooking” by Simon Quellen Field

(Photo from Pixabay.com)

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