October 2, 2022 - 11:10am
Residual sugar content in a baked loaf
I'm starting to track macro nutrients a little more and a question popped up as I was compiling macro nutrient data for some of my breads...
If I add something like 5% sugar to a dough at mixing, how much of that sugar is consumed during fermentation? If there's residual sugar that helps with sweetness and crust/toast color, is that from the sugar or is it from starches that didn't get consumed because simple sugars were available? I'd have to think that yeast and/or LAB would consume the simple sugars first. Is more consumed in a sourdough loaf than a commercial yeast loaf with the presence of both yeast and LAB's?
Just curious if anyone has seen/read anything on the topic...
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On a label ignore the "of which sugars" column. Carbs... of which sugars, is there is mislead you. Your body will convert all the carbs into sugar. Unless there's another column which says... of which polyols. Polyols, e.g. Erythritol or Xylitol etc, are sugars which your body cannot make use of. So if a label reads:
Then from a dietary perspective read it as 110g carbs/sugars.
When you sprout grains, do extended autolyse or the length of time bread is made these carbs are broken down into simple sugars for the yeast to eat. Just how much sugar the yeast/bacteria have eaten is not something one can guess. If your toast is browning well there's more sugar left than toast which doesn't brown well. If you're adding in sugar enough for the toast to brown then you've defeated your purpose in keeping the sugars low.
Yes and no. Agree that everything ends up as sugar, but the blood sugar spike and how the body handles that from a fueling standpoint are different if it's a carb consumed as a simple sugar or as a complex carbohydrate. For me, I'm more interested in the Added Sugar column.
I guess I'll keep it simple and err on the conservative side. If I add 5% sugar to a loaf, then I'll assume none of it was consumed and it's still there in the Added Sugar column. Saves the time it will take doing the research that probably won't have a definitive answer. :-)
Even when calculating how many carbs the bread has, the process itself breaks down the carbs into simple sugars... "When you sprout grains, do extended autolyse or the length of time bread is made these carbs are broken down into simple sugars for the yeast to eat".
So you can't even take the carbs, added in as flour, and take that number as it is.
The only way to know all the sugar has been used up is when the dough can't rise anymore after being de-gassed. Anything in-between, from the beginning stage till the over fermented stage, is a total guess unless you literally have a way of breaking some of the loaf down into it's 'elements'. But if you're interested in added sugar, which is cause for concern, then don't add any in.
For my whole grain loaves, I usually don’t. It comes into play when I’m helping my wife finish off a loaf before it goes bad. She’s not a big bread eater and prefers more of a plain sandwich loaf that’s on the sweet side. Agree though…. Easiest answer is to just leave it out.
As Abe stated, if your crust is brown and your crumb turns brown when you toast it, then your bread still has plenty of sugar. Adding sugar to white flour is like sugar coating a chocolate bar; not really needed. As for your question about how much of that sugar is consumed by the yeast? I'd venture a guess at not much of any in a total sugars type of calculation since most bread fermentations don't get close to consuming all the carbohydrates in the flour, much less in added sugars.
Longer fermentations would, in theory, consume more carbohydrates, just not enough to make a dent in the sugar you are talking about. I've only once or twice made bread that approached the point where there weren't enough sugars left in the dough to give me a nice brown crust.
Good question, Troy!
In commercial breads, like Wonderbread, 5%of sugar added to flour will be completely gone after fermentation, proofing and baking. They are added strictly for the needs of fermentation, not for taste. For sweetening effects, i.e. for the taste, more sugar is needed.
I used Wonderbread as an example, because
1) these breads contain 2-3% commercial yeast and usually about 5% added sugar
2) they are well fermented, with preferments, total fermentation time (preferment, bulk fermentation, bench rest, proof) is at least 5-6hours, with good keeping qualities.
The numbers are as following
Each 1 g of compressed yeast or 0.35g of instant consume 0.35g of sugar per hour at 30C/85F. Therefore in a batch of bread dough with 2%of compressed yeast they will consume 0.7baker's % of added sugar per each hour of fermentation.
Much more sugar (per hour) is consumed during proof, since proofing is done at higher temp. 5% of added sugar will be gone by the time the loaf is proofed and baked.
Baking further reduces sugar content of baking goods: 20% of all added inverted sugar is lost in baking and 5-8% of all added sucrose (table sugar).
Baking literally burns off sugar calories
Toast color is mostly due to the availability of amino acids in bread crumb, not to sugars. That is why even tiny amounts of milk added to the bread dough improve toast color. Milk is rich in lysine, wheat is not.
I thought milk causes bread to toast better because yeast cannot eat the lactose which will be available sugar to caramelise when toasted.
And because it is an available sugar it reacts with the protein. It's not the protein alone.
Caramelization (burning of sugars) is one reaction, Abe, and Mallard - browning reaction of aminoacids with sugars - another.
Lysine is the limiting factor, not sugar, mostly because during fermentation microbes (yeasts and bacteria) consume available aminoacids. They need "protein" nutrition, not just straight sugar and water. And that is why overfermented dough produces pale loaves. All available aminoacids are gone.
And that is why steak or even fried eggs brown so well even though there is practically no sugar in meat or egg. Obviously, milk browns on its own (as in baked milk) just fine as well, because it contalns both free aminoacids and a modicum of sugars. It is not due caramelization, since lactose caramelizes at very high temp (400+F), it's due to Mallard rxn which runs perfectly well at lower temps.
Learn something new everyday. Another good tidbit to apply to my baking.
https://www.kingarthurbaking.com/blog/2022/02/15/understanding-the-maillard-reaction-in-baking
Without sugar, there is no maillard reaction, which requires protein and sugar (plenty of sugars in a slab of beef) plenty of protein left after fermentation.
https://bakerpedia.com/processes/maillard-reaction/
Not likely a home baker will replicate wonderbread conditions at home.
As for being relatively sugar free....
https://joybauer.com/photo-gallery/worst-foods-for-diabetes/white-bread/
Dont eat white bread if you have trouble with sugar in your diet.
What are the sugars in beef?
There are little free sugars in meat, but there are plenty of carbonyls in other molecules that may react with amino acids:
https://www.washingtonpost.com/archive/lifestyle/food/2006/09/13/its-brown-not-browned/e05514c2-0e9e-429b-8038-3f505a7a9b24/?itid=lk_inline_manual_14
Might be behind a paywall.
Also, the sheer abundance of amino acids in meat will help drive the reaction with any suitable carbonyl compound.
No paywall. Excellent explanation, alcophile. Thank you for your clarification and contribution.
Prof. Wolke answers the toasting question that Troy touched upon as well. Browning of a toast involves (amino parts of) proteins and (sugar parts of) starch.
In case the referenced link will rot:
Dont plan on making any meat bread this week but ....
Sugars, or their cousins are needed to provide fuel to muscle. Mostly in the form of glycogen. which help create the lactic acid that turns muscle into meat or hurts like hell when out of shape after hard excercise.
This is the source for my comment on sugar in meat.
https://www.medicalnewstoday.com/articles/287494
Seems there is dispute over naming conventions.
In some ways, both answers are correct. But that's the problem with what is known in chemistry as "trivial names". That's why the IUPAC implemented a standardized nomenclature system to reduce confusion for chemicals. It may increase confusion for non-scientists:
Neu5Gc (Neu is the IUPAC symbol for neuraminic acid); so,
N-Glycolylneuraminic acid (or 5-Glycolylneuraminic acid) = Neu5Gc, or
5-(glycoylamino)-3,5-dideoxy-D-glycero-α-D-galacto-non-2-ulopyranosonic acid = Neu5Gc
The Neu5Gc molecule is a neuraminic acid derivative, which are part of a larger class called sialic acids (also a trivial name of a class of compounds). These molecules are technically sugars but they aren't the familiar reducing sugars usually discussed in the context of Maillard reaction.That's probably waaaaay more chemistry than anyone wanted.
Also, Neu5Gc is still a minor component of beef: 70 µg/g. That 8 oz steak only has ≈16 mg of Neu5Gc total. Other carbonyl containing compounds must also be involved in the Maillard reaction of the meat.
Their description (in the article I linked to) was rich.
“ The team first conducted a systematic survey of common foods and found that red meats – beef, pork and lamb – are rich in a sugar called Neu5Gc and provide the primary sources of this sugar in the human diet.”
Rich in one context, minor in another?
Not meat bread, but George Carlin has MeatCake:
https://youtu.be/aVgUzvxw7dk
funny.
Thanks Mariana! I haven’t tracked fermentation or proofing temps overly close, but I’m usually around 0.7% ADY and fermentation times are 4-5 hours from initial mix to bake. Sugar addition (or honey) is usually 3-5%.
I’ll have to review your numbers and make an educated guess the next time I make a loaf.
Use her numbers if you or anyone you are baking for has or might have diabetes.
Not for diabetes but thank you for the heads up! Just entering the final prep for a big mountain bike race and watching the nutrition a little closer.
As a former middle distance runner i understand your not all that concerned about loading up on high glycemic carbs before race day. Best of luck!
For sure…. Right now I’m focusing more on the timing of the intake and managing carb intake to match fueling requirements for big workout days and maintaining a balanced intake during an off day. “Unfortunately”, I have all this bread around and don’t always have the best discipline. 🤣
Honey is a bit different, Troy. It's not just sugar by weight but water+sugar, and it's sugars in their invert form. So 20% of all sugar added with honey will be gone during baking simply due to baking! The rest of it - diring fermentation.
So if you are watching sugar content, honey not just adds aroma and sugars, it is safer.
That said, watching blood sugar spikes is not the same as watching sugar contents of foods. People have unique blood sugar reactions to the same foods. Some people's blood sugar will spike sharply if they eat bread, others - moderately, while the rest show no rxn at all. One needs to wear a continuous blood sugar monitor for a couple of weeks to determine their personal blood sugar reaction to all of their commonly eaten foods.
This is true for those who are diabetic and want to avoid blood sugar spikes and crashes and for those who are watching their weight, since blood sugar spikes lead to fat deposition ( calories from food are converted to fat and stored by the body if blood sugar spikes after meals).
More about it here
Not sure I’d be taking nutritional advice from a computer scientist, even if his speciality was in systems biology.
Following the advice of the American diabetes association
https://diabetes.org/
‘Might be a better choice.
I did learn something interesting about all these so called diets. Grain gets a very bad rap nowadays and is blamed for all ills. It's all... eat only protein, or loads of fat, or every 12 hours etc. But apparently carbs are our bodies preferred energy source and if you make it wholegrains it's better for your stomach microflora. People on these high fat and high protein, low carb diets have poorer gut health.
Whole grains are absolutely an essential part of any healthy diet. Plenty of evidence against the so called paleo diets. Unfortunately, these type of things take on an almost religious type of advocacy based more on faith and confirmation bias than actual facts.
And our understanding of nutrition is always changing. Partly because it's so complex. However one thing has never changed and that is a balanced diet. Something which is rarely done nowadays. It's always cutting out something completely or eating too much of something. I agree... wholegrains play an important role in our diets and I intend on enjoying them.
Ötzi
A mummified human found in the Austrian Alps, had a "high carbohydrate" diet consisting of grains (Einkorn) and fruit. And meat.
Any food that was consumed 5,000 years ago is OK with me today.
The last meal of a 5000 year old human... Einkorn, Fruit and Meat. Sounds pretty decent for someone way back then.
I'd be ok with that too.
What, no wonderbread or ring dings in that pouch?
Wonderbread won't help you climb an Alp :)
Come to think of it I haven't baked with Einkorn in a while. After the Community Bake I think i'll try my hand at 5000 year old Alp bread.
I’ll grind up a pound and join you!
A flat bread. Eaten with meat and he snacked on fruit. Probably flour + water + salt, kneaded into a dough, rolled out flat and baked on a hot plate. Just a guess. Would make a nice wrap for some freshly caught and cooked wild game. Fruit would be dried and treated like an energy bar.
That would be my thought as well.