answer caret-left caret-right close-large facebook hamburger linkedin mail password question repeat-password thumb triangle twitter username youtube circle-right trending search checkmark pin alert
Asked on 12.09.2023.

Sodium metabisulphite

I understand some studies show that in biscuits residues of sodium metabisulfite after baking are extremely small and difficult to analyse. Are there any scientific references that confirm this?

Answered on 13.09.2023.

Dear Alison,

I assume there is scientific research available as well, although it will probably be old. I think it is accepted as common knowledge that Sodium Metabisulphite evaporates during the baking process.

EDIT: In Manley's technology of biscuits, crackers and cookies, there are some references to research into to sulphite (residues) in biscuits:
- Thewlis B.H. and Wade, P. (1970): 'Investigation of the fate of sodium metabisulphite added to hard sweet biscuit doughs.' FMBRA Report 46
- Thewlis B.H. and Wade, P. (1974): 'An investigation into the fate of of sulphites added to hard sweet biscuit doughs.' J Sci Fd Agric, 25, 99-105.

That sulphite evaporates is also my own experience. Since it is an allergen, I would always have products analysed at a per recipe basis to verify that any remaining Sodium Metabisulphite is under the legal (EU) limit of 10 mg/kg for the allergen, expressed in SO2. In that case it doesn't have to be declared on pack as an allergen (in the EU). I would do regular checks to verify that the sulphite content remains at or below the desired level. Higher dosage does leave higher residues.

Kind regards,
Remco Vos

Answered on 13.09.2023.

Hi, Alison. Check the following book:

Peter Wade; Biscuits, cookies, and crackers, Volume 1; 1998; Chapter 5.6 ( He says "0,14% remained in the product as sulphite".

He cites Basil H. Thewlis & Peter Wade; An investigation into the fate of sulphites added to hard sweet biscuit doughs; 1974.

Kind regards,


Answered on 13.09.2023.

Dear Mr Baldwin,

SMBS usage is GMP.  If it is used abnormally excess of more than required or without altering maida quality for the particular product and you want to make the product by adding more smbs for the process flexibility you will end up with Sulphur residues in the biscuit.  It may not happen in GMP usage and will carry to Sulphur residues in the end product.  it reacts with the cysteine amino acids present in glutenins and gliadins, creating S-sulfocysteine residues within the protein structure, which inhibit the formation and/or restoration of disulfide bonds during mixing and rest period. This is what I know.  To my knowledge no one validated this with analytical results but if any one gives I also will learn.

Answered on 13.09.2023.

Hello Alison,

It will depend on the recipe and process, but our analytical results show that 65-85% of sulfite is decomposed during baking. But I'd recommend making analyses in your product to confirm.



Answered on 13.09.2023.

Hi again, Alison,

   here's a method for sulphite analysis:

Answered on 14.09.2023.

To determine the amount of sodium metabisulfite in cookies, a chemical analysis can be performed. One of the most common methods is iodine titration, in which an iodine solution is added to the sample extract and titrated with a sodium thiosulfate solution until the end point is reached. There are also other methods, such as high-performance liquid chromatography (HPLC) and UV-Vis spectroscopy. It is important to follow local rules and regulations to ensure that the final product meets safety and quality standards.

Normally, all MBS evaporated, but depending on the the quantity that you use. So, It is important to check how much residual do you have into the product.

If you have less than 10 ppm, you don´t need to inform it. If you have more than 10 ppm, you must inform it.

Do you know the answer?
Help Alison Baldwin by registering and answering.
Register now
Join the platform
Register for free and access all features.
Join biscuit people
Looks like you don’t have a subscription to do that. Want to upgrade?
Upgrade subscription