Analysing the impact of the egg-to-milk ratio in brioche formulas

In the first part of my forever-unfinished feature How to be a pastry chef? – the checklist, I asked you some questions about brioche with the aim to develop your curiosity and drive you to research important techniques. It went along the following lines:

Do you know brioche dough is an emulsion? Do you treat it as such? Can you knead it by hand or in a mixer without over-heating it? And which temperature should the butter be?

But although these points are fundamental in a technical approach, I’ve since had been absorbed by some other questions that belong to the food science realm.

How do the milk and eggs respectively affect the texture of a brioche? Which kind of flour yield to the softest crumb? And how much butter is too much?

As with any mixture experiment, we have to study each of these variables – liquids ratio, flour properties, butter quantity – separately in order to develop an understanding on how they each have an impact on the finished product.
And for no other reason than it has obsessed me for years, I’ve chosen to start by examining the effect of the egg-to-milk ratio in rich doughs.

Eggs or milk?

If you ask Eric Chavot, a true brioche – or as he would say, une vraie brioche – is made using eggs as the only source of hydration.
And while I’m certain many would agree, the subject of brioche – from its etymology to its formula – has always been a controversial one.

In my kitchen, I tend to use a combination of both eggs and milk; with more or less of each depending on the texture I want to achieve. A knowledge that’s really more empirical than anything; and perhaps, relies a bit too much on wishful thinking.
So today, we will stop counting shooting stars and start analysing percentages. It will take five different loaves. Over two kilograms of flour and perhaps a litre or two of milk. A box of eggs. Most likely two. And hopefully, a few worthy notes that will improve my understanding of rich doughs.

The approach

1. Develop a control formula that will act as a reference point during the experiment.
2. Define the range into which the variables will fluctuate.
3. Establish the method: ingredients (on both quantitative and qualitative – brand, temperature – points of view), process (order of incorporation, kneading time/speed, proofing time/temperature, shaping, baking time/temperature)
4. Make successive batches of brioches, each with a different ratio of egg to milk. All other variables (see method above) remain unchanged.
5. Record the organoleptic properties of each batch:
– texture (our main focus point): thickness/hardness of the crust, crumb appearance and mouthfeel.
– colour: darkness of the crust, tint of the crumb.
– flavour and smell.
I haven’t decided yet on whether or not to include objective qualities – such as: crust thickness in mm, loaf size, or even weight of the baked brioche – to measure the response. Yes, even though this is a matter of mixture design, I mostly want to document the results in a comprehensive yet accessible and home-practicable way.
6. Analyse the results.

Developing the control formula

I could have used my favourite stand-alone brioche recipe, the one pictured above and which I told you about in Paris Pastry Club and the one I made tropéziennes with.
But out of all my rich dough recipes, it stands out by its high hydration and high fat quantity.

I thus wanted to create a generic rich dough recipe. To do this, I analysed my favourite recipes, ranging from brioche to burger buns, from challah to kanelbullar.
On the table below, you can see the ones that I consider the more relevant, with BRIOCHE 2 being my usual, the one I just mentioned.

Brioches: bakers percentage

	bullar	brioche 1	brioche 2	brioche 3	burger buns	brioche 4
flour	100%	100%	100%	100%	100%	100%
hydration	64%	58%	65%	60%	64%	60%
eggs	38%	19%	55%	60%	13%	20%
milk	26%	38%	11%	0%	51%	40%
fat	28%	15%	58%	40%	19%	16%
sugar	13%	19%	11%	12%	6%	20%

Note: the hydration values, although inaccurate since milk and eggs don’t hydrate the dough fully (respectively at 88% and 76.15%), could have also been labelled “liquids”. I did however choose to go with “hydration” for ease of understanding and recipe development.

I then went ahead and calculated an average formula as seen on the table below. And by multiplying the bakers percentages, I got the recipe for two brioche loaves.
As you can notice, some of the measurements would be quite difficult to put into practice, so I used this “average recipe” as a guideline.

Brioches: average

	BAKERS %	for two 500g loaves
flour	100%	500	g
hydration	62%
fat	29%	147	g
sugar	14%	68	g
eggs	34%	171	g
milk	28%	138	g

Brioche #1: Control formula

quantity		ingredient	BAKERS %
500	g	flour	100%
70	g	caster sugar	14%
15	g	yeast	3%
8	g	salt	2%
180	g	milk	36%
180	g	egg	36%
150	g	butter	30%
1103	g	total weight

The percentages I chose to keep are as such:
– flour 100%
– caster sugar 14%
– milk 36%
– egg 36%
– butter 30%

As you can see, I’ve increased the total liquids (milk+eggs) as when I first baked the control brioche, I realised that with only 62% liquids the dough was way too dry so I had to add 60g of liquids (30g egg and 30g milk), bringing the total hydration to 72% instead.
This can be due to 2 factors:
– I calculated the average formula using recipes from my French/English recipe notebooks, and thus missed to take into account the Swedish flour’s high absorption capacity
– when making such a small batch of dough (I halved the recipe) the kneading can take twice as long as when making a larger batch, and the dough has more surface to loose moisture from

I then added 3% of yeast and 2% of salt, and our control formula was done.

This control formula is a perfect starting point as its egg-to-milk ratio is 50%-50%, which will allow us to really analyse its impact on the dough and on the finished brioche.

The mixture design

I have in mind to make 5 different “brioche” recipes. Yes, “brioche” in quotes, as our experiment will range from actual brioche to pain au lait [literally, milk bread].

	1: control	brioche 2	brioche 3	brioche 4	brioche 5
milk	50%	0%	100%	33%	67%
egg	50%	100%	0%	67%	33%

Here are the different formulas, each associated with a number, which is used as both a name and a rank. We will start with the control brioche 1, move onto brioche 2, and so on.
As you can see above, we’re starting with the most extreme formulas as we might be able to stop our experiment after brioche 3, in the eventuality that the results will have given us enough information about the impact of the egg-to-milk ratio in the dough.
I will, however, most likely still decide to conduct brioche 4 and 5, with my personal recipe collection in mind.

Ressources

– A clear explanation of mixture design.
– A few notes on brioche.
– A five-minute brioche?

TO COME

I hope you’ll like this experiment as much as I do, even the most boring parts. Follow #briochestudy on Instagram for real-time science 🙂

And, of course, I wish you all the happiest new year! To 2016 and brioches. X