The Fresh Loaf

News & Information for Amateur Bakers and Artisan Bread Enthusiasts

HELP - Oxidizer vs Antioxidant RE: Ascorbic Acid

DanAyo's picture

HELP - Oxidizer vs Antioxidant RE: Ascorbic Acid

I would like to better understand the affects of Ascorbic Acid in bread dough. But what I read is confusing.

In the article it states, “In baking, it is used as an oxidizing agent for dough mixing.“

But further research states this. “Vitamin C (ascorbic acid (AA)) is very popular for its antioxidant properties.” Here is the article.

Confusion - Oxidation and Antioxidant seem to be opposites.


Definition of oxidize


transitive verb

1: to combine with oxygen Other chemicals then oxidize the sulfur dioxide to form sulfuric acid, which along with the nitric acid increases the acidity of the dewdrop    
  •  Definition of antioxidant


    : a substance (such as beta-carotene or vitamin C) that inhibits oxidation or reactions promoted by oxygen, peroxides, or free radicals

I imagine the answer will be technical. I hope it can be explained in such a way that a simple minded person can understand. I am curious to learn...DannySorry, the copy and paste didn’t work (format) properly.


wheatbeat's picture

This is a tough one and I am no expert. I have to think back to my organic chemistry days too! I do have a few master bakers I can ask if you want the definitive answer, but let's see if I can take a crack at it myself.

For bread, an oxidizer and a reducer are opposite terms that describe a desired effect. For example, if you take a bunch of actively replicating yeast, kill them in the microwave and then add some of that to your dough, you will have a strong 'reducer' introduced to your bread in the form of glutathione. Glutathione weakens the gluten network and makes dough softer. 

Vit C doesn't directly act on dough as was once commonly thought. It is broken down by the dough's enzymes into a compound called glutathione oxidase (which eliminates the softening effect of glutathione from your dough).

So Vit C = less glutathione (reducer).  Something that decreases a reducer in your dough is technically an oxidizer.

The pathway Vit C takes to eliminate free radicals is different. For that, it gives one of its electrons to a free radical which stabilizes the radical (with the help of Vit E). When it gives up its electron, it makes itself into a radical, but one that is much more stable and non-damaging to the body.

Bottom line: Vit C is an anti-oxidant when you are talking about free radicals, but this has no application to bread. With bread, it is an oxidizer because it acts to eliminate a reducing agent.

Is your head spinning? :) 

DanAyo's picture

I wished my intelligence matched my inquisitiveness <LOL>

My curiosity causes me to ask questions, that my brain is not equipped to comprehend. But so far, that hasn’t stopped me from questioning.

I appreciate your answer, and will continue to ponder...


mwilson's picture

Short answer:
Ascorbic acid (AA) / Vit C is a reducing agent. However, when added to dough it kick starts an enzymatic chain of events which leads to the oxidation of glutathione and ultimately the formation of strong (disulphide) gluten bonds.

Technical answer:
The use of AA in bread dough takes advantage of naturally occurring enzymes in the flour. In combination with molecular oxygen AA is transformed in dehydroascorbic acid (DHAA) by flour enzyme ascorbate oxidase. DHAA is the oxidised form of ascorbic acid. Another flour enzyme glutathione dehydrogenase processes DHAA and glutathione (GSH) to form oxidised glutathione (GS) and ascorbate, after which a disulphide (S-S) bridge can form (GS-SG).

Thoughts: The good thing about using AA is you don't need much and it doesn't bleach / whiten dough.

PS. Sorry Danny but the pizza update is very delayed. I've just stepped out to answer this one. Now, back to the minefield that is statistics!

cfraenkel's picture

Interesting question, and one to which (as someone with a serious food allergy - (corn)) I beg you not to take action on.  It is so hard for those of us with allergies to find food to eat, and adding anything can put me from the yes to the no category.  ie: iodized salt, fortified flour, sugar, citric acid. I understand your curiosity, but I feel like it is important to get the word out there for the allergic community.

EastOceanAir's picture

Hi Danny,

For your curious mind, check this paper (STUDIA UBB CHEMIA, LXI, 2, 2016 (p. 103-118)), especially at p.105.

Read for your leisure time.



DanAyo's picture

I was doing well to comprehend the paper UNTIL it came to the charts. Really wished I had the brain power to comprehend the latter section.

In the past I have used AA on a limited basis and only for a single formula that required an extremely exhaustive warm and extended ferment. But I have no problems using it. It just isn’t necessary for my other breads,

What I am about to tell is strange. Teresa Greenway asked me to do a write up pertaining to AA. In the past my results were super. In preparation for the article, test were conducted. I think 3 individual test were conducted in total. Would you believe, none of the 3 test manifested the results that were consistently manifested in the past. Results from numerous past bakes utilizing AA were consistent and unfailing. I have no real explanation. The only variable thinkable is the AA. In the past a 1000mg Vitamin C tablet was crushed and used as percentage. I ran out of the darn tablets. The first of the last 3 test used a generic Vitamin C tablet. No dramatic change in volume or dough strength between the control bread and the AA loaf. For the next 2 experiments I bought AA in powdered form.  Once again, no drastic difference in volume or perceived dough strength.  I scratched my head, informed Teresa that at this time no justification came to mind that accounted for the discrepancy. <No Clue>

If you or anyone else has thoughts, I like to hear them.

The image below is an attempt to prove that I am not a complete loon LOL.

This is what it shows. I have baked Teresa’s SFSD way in excess of 100 loaves. I know from experience that 1 kilo of Morbread flour mixed according to her formula and fermented in strict adherence to her method should slightly rise above the top of a 6qt Cambro. Keep in mind, the image below is of a 9qt Cambro. The faint black line on the Cambro indicates the 6qt level. These results were not unusual.

If interested , this post deals with some of my venture into AA.