11 terms

Chemical Preservatives

Kinds of organic acid chemical preservatives
Typically used in foods below pH 5.5
Mode of action: chemical preservatives
Are in both the charged and uncharged form
The charged form can not cross the cell membrane
SO: need to be low pH food. This will assure that the uncharged form is the predominant form
Travels across cell membrane into the cytoplasm of the organism.
Cytoplasm closer to neutral pH
Causes uncharged form to dissociate and become charged form plus a proton
Protons acidify the cytoplasm
Cell spends energy to transport protons out of cell
Loss of ATP for doing cell reactions
Acetic Acid
May be as sodium acetate
Targets bacteria and yeast
Used at concentrations of <0.1 - 0.8%
Used in baked goods, cheese, olives, gravies, causes, meat and poultry
NOTE: due to antimicrobial activity may be sprayed on carcasses to decrease E. coli population.
Lactic Acid
Found in fermented foods
Effects bacteria
Used in concentrations from <0.4 to 2%
Used on meats and as a sanitizer
Propionic Acid
Found in Swiss Cheese
Effects yeast, mold, rope-forming bacteria
Used at concentrations from 0.3% and up
Good for baked products and cheeses
Benzoic Acid
Found naturally in cranberries
Effective against molds
Used at concentrations <0.1%
Foods include jams, jellies, beverages
Sorbic Acid
Found naturally in Rowanberries
Effective against molds and some bacteria
Used at concentrations of 0.1-0.3%
Foods it is used in include baked goods, wine, cheese
Used in the cure for bacon, hams, hotdogs
Contribute to meat flavor and color
Are antimicrobial (esp. Clostridium)
Also serves as antioxidant
Works better in anaerobic setting than aerobic setting
Often utilizes ascorbate (reducing agent which scavenges oxygen)
Government regulations limit it to 156 ppm for most products and 100-120 for bacon
NOTE: Sodium erythorbate works to accelerate cure and it inhibits nitrosamine formation
Parabenzoic Acids
As side chain increases efficacy does too
As side chain increases solubility decreases
Often used in more than one form (i.e. methyl and propyl)
Effective against molds and yeast less so for bacteria
Foods: baked goods, beverages, fruit products, jams, jellies, syrups, salad dressings, wine
Sodium acid pyrophosphate
Tridosium phosphate
Tetrasodium pyrophosphate
More effective against Gram Positive organisms
At 0.5% inhibit some Bacillus and Clostridium species

Activity: Related to ability to chelate metal ions
Includes binding of cations that are essential to proper cell wall formation
Includes sulfur dioxide
Potassium sulfate
Potassium and sodium metabisulfite

Used primarily in fruits and vegetables to control spoilage yeast and molds, acetic acid bacteria and malolactic acid

Used in wine to control natural yeast, spoliage microorganisms as well as preventing post fermentative spoilage (formation of vinegar)

Acts on cytoplasmic membrane, DNA replication, protein synthesis and enzyme activity.