January 16, 2022 - 9:36am
Role of eggs in bread
Saw this interesting video, about how eggs (whole, white or yolks) affect bread, some unexpected results for me.
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Saw this interesting video, about how eggs (whole, white or yolks) affect bread, some unexpected results for me.
Thanks Ilya - a good watch. I guess it shows why panettone has lots of egg yolks in it.....
Lance
Interesting thought, indeed the yolks must contribute to the lightness and height there there.
Thanks.
So
whole egg -> softer, fluffier than no egg
egg white on own -> tighter crumb, similar to no egg in size and flavour but firmer to slice?
egg yolk on own-> much fluffier loaf, eggier flavour, darker crunchier crust
I suppose flour with more gluten + yolks might be super fluffy
I suppose flour with less gluten might benefit from the whites
Very interesting video, nice to see what effect adding a whole or only part of an egg has on a loaf of bread and crumb. Thanks for sharing that Ilya.
Benny
That's very useful, thanks. I hadn't known about the effect of egg whites by themselves. It explains why some recipes combine yolks and whole eggs.
Does anyone know the chemistry of what yolks do in the bread?
AFAIK they just add fat, so you should be able to achieve the same effect with oil or butter. Curious to compare side by side whether there is any difference actually.
Egg yolk contains 5 - 8% lecithin. I suspect this also has a role to play as it is an emulsifier.
Lance
Thanks. that would make sense. I was doing to say that my experience is that fat alone mainly changes texture, but I see (below) there is also support for an effect on loaf volume.
B.M. Bell, D.G.H. Daniels, N. Fisher, Physical aspects of the improvement of dough by fat,
Food Chemistry, Volume 2, Issue 1, 1977, Pages 57-70, ISSN 0308-8146, https://doi.org/10.1016/0308-8146(77)90008-5
AbstractShortening containing a fraction which is solid at dough temperatures is an essential ingredient in rapid breadmaking processes, but optional in long fermentation processes. Hypotheses concerning the action of fat are reviewed, and it is concluded that physical mechanisms, rather than those involving lipid oxidation, account for the increased loaf volume on the addition of shortening to the dough. Recent work using ‘model’ fats has shown that increased loaf volume results when sufficient of the solid component remains ‘free’ in the dough, and work with stored flour confirmed the importance of the free lipid fraction. A study of carbon dioxide release from doughs during baking showed that fat increases gas retention in the initial stage of rapid expansion. It is suggested that the solid components of the fat facilitate the production of orientated structures in dough, which can persist even when the temperature exceeds the melting point of the fat, and that these structures favour gas retention in the earliest stages of baking.
This paper does a similar comparison, but for dough mixing properties, and it discusses some of the possible mechanisms.
The video result is interesting, since I've typically found (purely anecdotally) that adding egg white alone will increase loaf volume.
Posting the table in the video. This table might be expanded to include not only water and fat but protein and as mentioned, lecithin. Egg whites contain protein, a lot of it. Protein interacts with the other proteins in the flour. I tend to add fresh egg whites by including them in the water. According to this chart would mean I'm actually reducing the dough hydration slightly (10% per 100g egg white) which I find interesting because I like the dough feel without adding extra water. Especially for low protein flours. For one egg and one kilo loaf of bread, this is about a teaspoon or two of water. Hardly worth the calculation separately but I can imagine that large dough batches would be calculated separately.
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Based on this video I added an egg to my usual loaf reducing water and fat as instructed. The dough felt about the same but wow did it rise! I'll need to scale back in the future to get a more reasonable height for my slicer. The pan is a 4 inch cube. The loaf is almost 6 inches tall.
Wow! Is it normally just the height of the pan?
My goal is 4.5 to 5 inches tall. It is often only 4.25 depending on how far I push the fermentation. And this is already scaled down by 12% from my usual.
That is amazing Gary, wow!
Benny
I scaled it down by 10% (to 200g of flour) and started baking sooner (about 1cm below the top of the pan) and it is still 14cm tall. Only about 1cm shorter than the first one. Wow. I had no idea that the egg would have such a strong effect.
The previous loaf has really nice texture and strength. A slice is strong enough to stand up and makes a great sandwich.
I'm sold on adding egg.
It is about 1 cm shorter and I like the texture better.
Hm.. now I am wondering about using all yolks instead of whole eggs in a kugelhopf to see what happens!
I enjoyed this video overall but at this point I baulked https://youtu.be/haQf0LLDZnc?t=169 he says that eggs can lower the pH and add acidity! This is a fundamental error, sorry to say, eggs actually raise pH, they are slightly basic (pH = ~7+ - 8).
No acidity added by eggs, only taken away, hence why egg yolks are sometimes used to fix a wonky sour LM.