This is some of the fluffiest bread you can possibly make. It is beautiful, sweet, soft, and
stale resistant. So how do you make something so delightful? Starch. It all comes down to starch.
Inside tiny granules of starch are crystalline and amorphous regions of polysaccharides,
and if you push water deep into those structures and break them apart, you can get this.
Okay, I'm losing it with bread. This is Japanese milk bread. It is soft,
fluffy and made with a very specific chemical process in which you heat or scald a portion of
the flour first. It's also not supposed to go stale easily because of magic. Or
chemistry or whatever, but more on that later. We're going to put that chemistry
to the test by making three different loaves under different conditions. I am so excited
just to eat a ton of delicious bread. I've just been looking at this bread for a day.
But before I cut into it, we will first take a closer look at one of the key bread making
ingredients, flour. What the heck is in flour? I mean, it's a powder that looks incredibly boring,
but there's actually a lot that is happening in this package. It's about 10 to 12% proteins,
a small smattering of assorted polysaccharides and lipids,
and then usually about 70 to 75% starch, and that is what we care about today.
Starch. So starch is a polysaccharide. Poly meaning many and saccharide meaning sugar.
So this is starch and it's made up of lots of glucose molecules all strung together.
Starch molecules usually come in two forms, either amylose, which is a long linear chain,
or amylopectin, which is a branched molecule. Amylopectin is typically
a much bigger molecule than amylose because of all of the linked chains.
Starch is the main way that plants store energy. At the end
of photosynthesis a lot of the produced glucose molecules are stored as starch,
and that starch forms starch granules that vary in size and shape between plants. The largest
amounts are often found in seeds, roots and tubers. Things like potatoes and yams.
I don't really know what I expected to happen there. This is not good. Do not recommend.
But you'd think with the amount of stored sugars in a potato, that it would be sweet.
But it's not because all of those glucose molecules are strung together into starch,
not free as sugar. But enzymes in our body called amylases can break the amylose and
amylopectin molecules down to make them sweet and to free up all that sucrose, glucose.
There are lots of amylases in our saliva, so if I let this sit in my mouth for a while,
it should eventually start to taste sweet. I don't recommend it though. You can also
do this with saltines, but somebody in our household ate all the saltines and left an
empty box. So that demo's going to come later. Anyways, as I mentioned, besides tubers, seeds
often store a lot of starch for developing plants. So when you grind down wheat seeds to make flour,
a lot of that flour is starch. If you zoom in on starch granules, they have really cool
structures. Starch granules grow from the outside, adding layers on top of layers, so they end up
having growth rings like a tree. Fun fact, some experiments have shown that in cereal plants,
which are unfortunately not Froot Loop trees, but rather things like wheat, rye, oats, and barley,
the starch granules grow in day-night cycles. So they grow in the day when there's sunlight
and then they stop at night creating a ring each time. So if you keep a cereal plant like
wheat growing in simulated continual daylight, its starch granules won't have rings. That's so cool.
Within the granules, there are crystalline regions with an ordered structure as well
as amorphous. Within the granules, there are crystalline regions with an ordered
structure as well as amorphous regions without. The crystalline zone is compact.
This is attributed to double helices forming between amylopectin molecules,
binding them closely together. The amorphous regions, on the other hand, are more likely due
to interactions between amylose and amylopectin, hence they're less ordered configuration.
So here's why this matters. Starch granules are typically insoluble in water below 60 degrees
Celsius. Now you can put them in water and they will swell up a bit due to the diffusion
and adsorption of water into the amorphous regions, but if you dry them back out again,
they'll return to their previous form. But something magical happens above 60
degrees Celsius. So this is a roux. It's a combination of heated wheat flour and fat,
and here I've used butter, that's used in lots of different cuisines to thicken things like
soups and sauces, and it's also used to make the very best mac and cheese. Fight me on that.
If you heat starch like this, it'll start to swell and form a gel or paste, and this
is an irreversible process. Even after cooling down, it's going to remain a gel or paste. This
happens because water molecules from the fat get in between the starch molecules, first entering
the amorphous regions that we talked about. This pushes the molecules apart and actually transmits
disruptive forces into the crystalline regions as well, breaking some of the starch molecules
free from the rest of the starch granule. This turns it all sticky and usefully gloopy.
Now, if the water content is above 60%, this process is called gelatinization.
If it's below this, it's called melting or also referred to as a dual transition regime. Regime?
Regime. But we have lost
the bread thread. What does this have to do with my fluffy bread? Well, breads like this
have histories in both China and Japan, and they use heated flour starters to get their textures.
Tangzhong, the Chinese iteration of this, is made by simmering water, milk, and flour together.
Yudane, which originated in Japan, is made instead by pouring boiling water over the flour and then
mixing them together and letting it sit before you make the rest of the bread. Now, in both cases,
it is not all of the flour, but just a small portion that is added to the later dough mixture.
By adding these small portions of preheated starch, the resulting bread should be fluffier
and softer due to the starch gelatinization. Sure, I could just tell you this, but I could also
explain with bread. So here comes the delicious experiment. I'm going to make the same recipe
at least three ways. One with no Tangzhong, one with 6%, and one with 12%. Why these ratios? Well,
because I had a recipe and that made the math easiest. We're going to do six, which is what the
recipe recommended, and then zero and then double it, make it 12. Math. Then if I'm really crazy,
I only have three loaf pans, but we might make some other loaves too just to see how it goes.
Doing the roux, or scalding or Yudane, or Tangzhong process like this before
baking gives that starch time to gelatinize before you start actually making the bread,
rather than just waiting for it to happen during the baking process
itself. The gelatinization process is gradual and happens as the temperature slowly rises.
For example, in wheat flour, the gelatinization typically starts around 60 degrees Celsius and
continues until about 85 degrees Celsius. Doing this process in a controlled fashion
before baking ensures that a greater proportion of the starch is going to undergo gelatinization
than might just during baking itself, ensuring a nice softer bread texture.
Now, this technique is used in multiple different kinds of bread, including milk bread,
but also pane grano arso, or burnt wheat bread in Italy. This gelatinization is the same reason
why you boil bagels before cooking them. That hot water gelatinizes the starch on the outside
of the bagel, giving it a different texture to the non-gelatinized starch on the inside.
Just blew your mind didn't I? Okay, so we're around 160 Fahrenheit.
Elaine, you can put what that is in Celsius on the screen. But yeah, we're really thickening up here.
Okay, so this is my 12%. I'm at a step where I got to punch it down and roll it out and all that,
but it's the most appealing to look at and it rose the most. So I'm kind
of liking it, but it is a little sticky. Elaine, I think this is just for you because
there's no way that ACS is going to be cool with this. This is not a cooking channel. Oh, shoot.
Now there's a research paper that looks at how the structure of bread changes as you change the
percentage of Yudane. As the percentage increased, so too did the saccharide and water content of the
bread. However, at the same time, volume and gas retention went down. This is likely because the
gelatinization impacts the gluten structure in the bread, and so it's probably a little
less structurally sound and can't quite hold up as big of a structure. However,
a less sturdy bread also means a softer bread. So let's see. Now I get to show you the bread
that I made and then I get to try it. I'm very, very, very excited about this. Okay,
so this is the bread just made using non gelatinized flour. It looks fine from the
outside. It does not have a lot of give, but I also don't want to crush it. So like bread, bread.
This is the bread made using the recommended amount of pregelatinized starch. It's a little
bit softer. I can feel that, but actually it looks pretty similar from the outside.
This one, my final one, is the bread that I made using double the amount of pregelatinized
starch. Couple things you might notice. It's got a valley in it. I think two things happened. One,
it might be too soft to support a structure. Fair, interesting. Two, I forgot... Well, I noticed I
had to play with the liquid ratios a little bit to get this to be something even close to a dough
because just putting in the recommended amount of milk plus the recommended amount of the
pregelatinized starch, it was too much liquid. So then I had to add a little bit more flour,
but I think there just might have been too much liquid. This was a wet dough.
It's a little dense. It's got a crumb, but we got some nice air bubbles in there. I'd
eat this bread. I will eat this bread. Let's be real. I'm going to eat all these breads.
Yeah, I think that's a little softer. Might be
placebo effect. No, it's a softer bread. Sad bread number three, oh, it is raw at
the bottom. Great British Bake Off would yell at me for this. It's very soft though. I wonder
if this guy baked longer would've been okay. All right. This is bread number one.
You toast that, you put some butter and honey on it. Oh my god, it's a nice bread.
This is my appropriately pre gelatinized bread. I do think it's softer. I don't know that it's that
much sweeter. No side by side there is maybe a little sweetness difference there. Okay,
I'm bought in. I like it. Let's try my sad bread.
That one is so fluffy, so soft. Can't believe I'm saying this.
I got to do this again, and I got to do this one and I got to bake
it longer. The portion of the bread that is baked is so soft and so nice.
All of them are delicious. The one I want to keep eating though is the mutant one.
But there's another special thing about this bread. It's not supposed to go stale. When
bread cools down, the starch molecules inside of them start to set with water molecules gradually
pushed away from the starch. The bread becomes soft and chewy rather than gel-like and this is
a good thing and it's called retrogradation. But after it sits for a long time, the retrogradation
continues and the starch fractions reassociate in different forms and rates creating crystalline
and amorphous zones. This can affect the texture of the bread causing it to harden and go stale.
Except that's not quite the case in this bread. When that starch pregelatinized in the
Yudane before baking, it becomes more prone to breakdown during the baking process by amylases
found in the flour. This means that there are more sugars present, giving it a sweeter taste, but it
also means that the average length of the starch molecules becomes shorter. Since retrogradation
requires starches of a minimum length to happen, Yudane bread tends to have shorter
chains on average than other bread. This means it experiences less retrogradation and staling.
Additionally, in many breads, fat molecules in the dough interact with the gelatinized molecules,
creating a kind of support structure that also delays this staling or retrogradation.
More gelatinized molecules in the Tangzhong or Yudane bread means more opportunities for this
interaction and fresher bread longer. So through the power of video magic,
we're going to fast-forward a few days and then see how I feel about
how stale these loaves are then. Time travel. Before I get into testing the staleness of bread.
Learning the science of how starch behaves in the kitchen to make this video has absolutely
changed the way that I think about using starch in cooking, and I think is going to change the way
that I cook forever. It has changed the way that I think about adding starch to sauces,
to thicken them. It has changed the way that I think about why if you put mashed potatoes in
the blender, they're going to get all gluey. Why when I was boiling beans for dinner last night,
the water was all bubbly and stiff bubbles that were sticking together.
It has changed how I cook in the last week. Okay, let's judge bread staleness. This is
my very scientific poke test. It's stiff now. It's very, there's not a lot of give,
especially around the edges. We got a stiff bread. This is the one with the pregelatinized
starch and there is a noticeable difference. It is a little stiffer around the edges,
but the center is just much softer. Oh, our poor said weirdo loaf. This doesn't seem fair.
It was raw on the bottom. I'm sorry loaf of bread. Oh, major difference. This one, stiff
bread on both sides. This one is still softer. Much more give in the pre gelatinized bread.
Taste test. Yeah, I think that's stale. I'll eat anything. I'm the worst person to do this
test. So yeah, it's a little stale, but it's fine. This one is our pre gelatinized bread.
Yeah, it's definitely still softer. I'd say it's probably still past its prime as well,
but it's been a week since I baked them. Had I only baked one and had I not been specifically
saving them, I probably would've eaten all this bread by now. I think it would have remained
not stale within the period of time in which I would've happily eaten a whole loaf of bread.
Now if you have any kind of bread that goes stale, you actually can reheat it in the microwave and
that will temporarily cause gelatinization to occur. Again, rebonding starch molecules
with water and temporarily creating a softer texture. But once it cools back down again,
it's going to be stale. You can also try and prevent staling in any bread in how
you store it. Retrogradation happens faster at cooler temperatures, so putting your bread in
the fridge is actually going to make it go stale faster. But it will not retrograde when frozen. So
your best bet is to actually put your bread in the freezer and you just toast it up when you want it.
But no matter how you slice it, and I will not apologize for this pun,
you got to try some bread with gelatinized starches. It is delicious.
Can we also put a disclaimer at some point in this video that this is a chemistry channel
and not a cooking channel? You should not take my advice on how to make this bread.