·
Linear Formula OHCCHO · 2NaHSO3
·
Molecular Weight 266.16 (anhydrous
basis)
·
Beilstein Registry Number 3898061
Sodium bisulfite (sodium hydrogen sulfite) is a chemical compound with the chemical formula NaHSO3. Sodium bisulfite is a food additive with E number E222.
Detailed
description
This salt of bisulfite can be prepared by bubbling sulfur dioxide in a solution of sodium carbonate in water. Sodium bisulfite in contact with chlorine
bleach (aqueous solution of sodium hypochlorite) will generate heat and form sodium bisulfate and sodium chloride.
Uses in food and FDA ban
While the related compound, sodium metabisulfite, is used in almost all commercial wines to prevent oxidation
and preserve flavor, sodium bisulfite is sold by some home winemaking suppliers
for the same purpose. In fruit canning,
sodium bisulfite is used to prevent browning (caused by oxidation) and to kill
microbes.
In the case of wine making, sodium bisulfite
releases sulfur dioxide gas when added to water or products containing water.
The sulfur dioxide kills yeasts, fungi, and bacteria in the grape juice before
fermentation. When the sulfur dioxide levels have subsided (about 24 hours),
fresh yeast is added for fermentation.
It is later added to bottled wine to prevent the
formation of vinegar if bacteria are present, and to protect the color, aroma
and flavor of the wine from oxidation, which causes browning and other chemical
changes. The sulfur dioxide quickly reacts with oxidation by-products and
prevents them from causing further deterioration.
Sodium bisulfite is also added to leafy green
vegetables in salad bars and elsewhere, to preserve apparent freshness, under
names like LeafGreen. The concentration is sometimes high enough to cause
severe allergic reactions.
On July 8, 1986, sodium bisulfite was banned from
use by the FDA on fresh fruits and
vegetables in the United States following the deaths of 13 people and many
illnesses, mainly among asthmatics.
Bisulfite DNA sequencing
In this technique, sodium bisulfite deaminates cytosine into uracil, but does not affect 5-methylcytosine, a methylated form
of cytosine with a methyl group attached to carbon 5.
When the bisulfite-treated DNA is amplified via polymerase chain
reaction, the uracil is amplified as thymine and the
methylated cytosines are amplified as cytosine. DNA sequencing techniques are then
used to read the sequence of the bisulfite-treated DNA. Those cytosines that
are read as cytosines after sequencing represent methylated cytosines, while
those that are read as thymines represent unmethylated cytosines in the genomic
DNA.
Industrial uses
Sodium bisulfite is a common reducing agent in the
chemical industry, as it readily reacts with dissolved oxygen:
2 NaHSO3 + O2 → 2 NaHSO4
It is usually added to large piping systems to
prevent oxidative corrosion. In biochemical engineering applications, it is
helpful to maintain anaerobic conditions within a reactor. Sodium bisulfite
should not be confused with sodium bisulfate which is used as a pH lowering chemical
for swimming pools.
In drinking water treatment, sodium bisulfite is
often added after super chlorination, to reduce the residual chlorine before
discharging to the service reservoir.
In wastewater treatment, sodium bisulfite is often
added following disinfection with chlorine prior to discharging the effluent to
the receiving water. Residual chlorine can have a negative impact on aquatic
life.
In Steam Boilers, sodium bisulfite has been a
reliable oxygen scavenger in boiler feedwater for approximately 60 years. This
compound is characterized as having fast reaction times, low use-cost, years of
proven performance, availability. Sodium bisulfite when used in steam boilers
has FDA and USDA approvals.
PRICE
$217.12/KG OR $98.69/IB
For more information:
mobile: +2348039721941
contact person: emeaba uche
e-mail: emeabau@yahoo.com
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