Also known as the salt of bisulfite
What is Sodium Bisulfite
Sodium bisulfite is used for its antioxidant capacity in food preservation for baked goods, wine, dried fruit and jams. It is also used as a reducing agent in cookie and cracker production.1
Sodium bisulfite can be prepared by reacting sulfur dioxide gas, SO2, in a solution containing alkaline hydroxide, e.g. sodium hydroxide (NaOH) or sodium carbonate (Na2CO3). Also, under certain conditions, this reaction can produce sodium sulfite, Na2SO3. Reacting a solution of sodium sulfite with additional sulfur dioxide gas can produce it ass well.2
When suspended in water, bisulfite anions generate a sulfurous acid. The sulfurous acid subsequently reacts with the cysteine amino acids, creating S-sulfocystein residues within the protein structure. These residues inhibit the restoration of disulfide bonds. Essentially, sodium disulfite acts as a cap, covering the reactive thiol group on cysteine so it is unavailable to reform a disulfide bond.1 These actions result in a very relaxed and pliable dough, eliminating chances of it tearing as it passes through the reduction rollers.
In baking applications, sodium bisulfite is commonly used as a reducing agent to break down the gluten matrix in breads or snack crackers, consequently relaxing the dough. In fruit-filled pastries or donuts, its oxidation inhibiting capabilities prevents browning.
The reaction of sodium bisulfite with disulfide bonds in wheat is extensive, cleaving nearly all the disulfide bonds. Incidentally, there is far greater danger of over-dosing a formulation with it compared to other reducing agents.1
Precaution should be taken when using sodium bisulfite. Some individuals may present a sensitivity. Sulfites present an unpleasant aftertaste in finished products and it must be declared on the label if more than 10 ppm is present in the final product.1
It is a significant source of vitamin B1 when utilized as an additive in food.
FDA Legal Requirement
Sodium bisulfite is GRAS regulated by FDA in the article 21CFR182.3739 in the Code of Federal Regulations.3
- Fort, Emily L. “Effect of Reducing Agents on Batter Consistency and Physical Characteristics of Bread from Sorghum Flour.” Kansas State University Master Thesis (2016): 17-18.
- Kisielewski, James, and Don Robertson. “Patent US7985396 – Process for Production of Sodium Bisulfite.” Google Patents. Google, 26 July 2011. www.google.com/patents/US7985396. Accessed 16 June 2017.
- “CFR – Code of Federal Regulations Title 21CFR182.3739.” Accessdata.fda.gov. 1 Apr. 2016. www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?fr=182.3739. Accessed 16 June 2017.