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Views: 0 Author: Site Editor Publish Time: 2026-08-04 Origin: Site
Sodium propionate (CAS: 137-40-6, E number: E281) is the sodium salt of propionic acid, widely used as an antimicrobial preservative across food, animal feed, and industrial sectors. It appears as a white crystalline powder or granular solid with a faint characteristic odor, freely soluble in water, and is recognized as one of the most effective mold inhibitors for yeast-leavened baked products.
Property | Specification |
Chemical Formula | C₃H₅NaO₂ |
Molecular Weight | 96.06 g/mol |
CAS Number | 137-40-6 |
E Number | E281 |
Appearance | White crystalline powder or granules |
Odor | Odorless or faint characteristic odor |
Solubility in Water | ~100 g/100 mL at 15°C (freely soluble) |
Solubility in Ethanol | Slightly soluble |
pH (10% solution) | 8.0–9.5 |
Melting Point | 285–286°C |
Effective pH Range (antimicrobial) | 2.5–5.5 |
Sodium propionate (E281) is primarily used as a food preservative to inhibit mold and bacterial growth, extending shelf life without altering taste or texture significantly.
Application | Typical Usage Rate | Function |
Bread & baked goods | 0.1%–0.3% of flour weight | Prevents mold (rope) and extends shelf life |
Cakes & pastries | 0.1%–0.3% | Mold prevention in high-moisture baked goods |
Tortillas & flatbreads | 0.2%–0.3% | Extends ambient shelf life |
Cheese & dairy products | 0.1%–0.3% | Surface mold inhibition |
Processed meat preparations* | Per local regulation | Antimicrobial agent |
Soy products | Per local regulation | Mold control |
Beer & malt beverages | Trace levels | Prevents microbial spoilage |
Sodium propionate serves as a critical feed additive in livestock nutrition, particularly for ruminants.
Function | Target Species | Benefit |
Mold inhibitor | All animal species | Preserves feed quality during storage; prevents mycotoxin formation |
Silage additive | Cattle, sheep | Improves silage fermentation and aerobic stability |
Energy supplement | Dairy cattle | Provides gluconeogenic precursor; helps alleviate negative energy balance post-calving |
Ketosis prevention | Transition dairy cows | Reduces incidence of subclinical and clinical ketosis |
Growth promoter | Swine, poultry | Improves feed efficiency and weight gain |
Gut health | Poultry, swine | Modulates intestinal microbiota; reduces pathogenic bacteria |
Beyond food and feed, sodium propionate is used in various industrial processes:
Industry | Application |
Leather tanning | Used as a mold inhibitor in leather processing and storage |
Textile manufacturing | Anti-mildew agent for textiles and fabrics |
Paper & packaging | Preservative for paper products exposed to high humidity |
Adhesives & glues | Prevents microbial degradation in water-based adhesives |
Paints & coatings | In-can preservative for water-based paints |
Chemical synthesis | Intermediate for producing propionic acid derivatives and esters |
De-icing formulations | Component in some runway and road de-icing products (less corrosive than chloride salts) |
Application | Description |
Grain preservation | Applied post-harvest to prevent mold growth on stored grains and cereals |
Silage treatment | Improves aerobic stability of silage at the farm level |
Soil treatment | Limited use as a soil fungistat in specialized agricultural contexts |
Post-harvest treatment | Extends storage life of certain crops vulnerable to fungal spoilage |
The antimicrobial mechanism of sodium propionate is based on the action of undissociated propionic acid:
1. In its dissociated form (at neutral pH), sodium propionate is largely inactive
2. In acidic environments (pH < 5.5), propionate ions convert to propionic acid (the undissociated form)
3. Undissociated propionic acid penetrates the microbial cell membrane
4. Inside the cell (higher internal pH), the acid dissociates, releasing H⁺ ions and propionate anions
5. This disrupts the cell's pH gradient, inhibits enzyme systems, and interferes with energy metabolism — effectively stopping mold and bacterial growth
Feature | Sodium Propionate (E281) | Calcium Propionate (E282) | Potassium Sorbate (E202) | Sodium Benzoate (E211) |
Best for | Yeast-leavened baked goods | Non-yeast baked goods, tortillas | Cheese, wine, syrups, dressings | Acidic foods, beverages, sauces |
Yeast impact | Minimal at use levels | Slight inhibition possible | Inhibits yeast | Inhibits yeast |
Water solubility | Excellent (~100 g/100 mL) | Good (~49 g/100 mL) | Good (~58 g/100 mL) | Good (~63 g/100 mL) |
Effective pH range | 2.5–5.5 | 2.5–5.5 | Up to 6.5 | 2.5–4.0 |
Calcium content | None | Contains calcium (~21%) | None | None |
Sodium content | Contains sodium | None | None | Contains sodium |
Target microbes | Molds primarily; some bacteria | Molds primarily; some bacteria | Molds, yeasts; limited bacteria | Yeasts, molds; limited bacteria |
Regulatory status | GRAS (FDA), E281 (EU) | GRAS (FDA), E282 (EU) | GRAS (FDA), E202 (EU) | GRAS (FDA), E211 (EU) |
Sodium propionate (E281) is primarily used as a food preservative in baked goods such as bread, cakes, and tortillas to prevent mold growth. It is also widely used as a feed additive for livestock — particularly dairy cattle — as a silage preservative and energy supplement. Additional industrial uses include leather tanning, textile anti-mildew treatment, and mold inhibition in paints, adhesives, and paper products.
Yes. Sodium propionate has been evaluated by multiple international food safety authorities and is classified as GRAS (Generally Recognized As Safe) by the U.S. FDA and approved as food additive E281 by the European Food Safety Authority (EFSA). The Joint FAO/WHO Expert Committee on Food Additives (JECFA) has assigned it an ADI of "not limited," indicating very low toxicological concern at typical use levels.
Common foods preserved with sodium propionate include: bread, rolls, buns, cakes, muffins, pastries, tortillas, pita bread, certain cheese products, processed meat preparations, and soy products. It is also used in beer production at trace levels.
In baked goods, the typical usage rate is 0.1%–0.3% of flour weight (i.e., 10–30 g per 10 kg of flour). The exact amount depends on product moisture content, pH, expected shelf life, and local regulatory limits. Always consult regional food additive regulations for permitted maximum levels in specific food categories.
Yes. Sodium propionate is authorized as a feed additive for all animal species. It serves as a mold inhibitor in compound feed, a silage additive for improved fermentation, and an energy supplement for ruminants. In dairy cattle, it is particularly valued for helping prevent ketosis and alleviating negative energy balance in transition cows.
No. Propionic acid (CAS 79-09-4) is the parent acid. Sodium propionate is the sodium salt of propionic acid. In application, sodium propionate converts to the active propionic acid form in acidic environments (pH < 5.5), which provides the antimicrobial effect. The salt form is preferred in food and feed because it is easier to handle (solid powder vs. corrosive liquid), less volatile, and less odorous than free propionic acid.
Sodium propionate has a typical shelf life of 24 months when stored in original, sealed containers under cool, dry conditions. It is slightly hygroscopic, so exposure to moisture should be minimized to prevent caking and degradation.
Store in a cool, dry, well-ventilated area at temperatures below 30°C (86°F). Keep containers tightly sealed when not in use to prevent moisture absorption. Avoid proximity to strong oxidizers and strong acids. Standard packaging is 25 kg multi-wall paper bags or fiber drums with inner PE liner.
Sodium propionate (E281, CAS 137-40-6) is a versatile and well-established antimicrobial agent with a strong safety profile recognized by food and feed regulatory authorities worldwide. It excels as a mold inhibitor in yeast-leavened baked goods due to its high solubility and yeast compatibility, serves as a valuable gluconeogenic energy precursor in dairy cattle nutrition, and finds broad utility across industrial preservation applications. When selecting between sodium propionate and calcium propionate, the decision typically hinges on solubility requirements, yeast fermentation compatibility, and desired mineral contribution (sodium vs. calcium).
