Buyer guide
Sodium benzoate, potassium sorbate or calcium propionate? Choosing a food preservative
How the three most common food preservatives differ — the pH range each works in, which foods they suit, and what to specify when buying.
By Sheetal Aromatics · Updated · 5 min read
Why pH decides most of the choice
Sodium benzoate, potassium sorbate and calcium propionate are all salts of weak organic acids. In each case it is mainly the undissociated acid that inhibits microbes, and the proportion of undissociated acid rises as pH falls. So each preservative has a pH range in which it works well, and outside that range a much higher dose achieves much less.
Sodium benzoate (E211)
Benzoic acid has a pKa of about 4.2, so sodium benzoate is most effective in clearly acidic products — roughly pH 4.5 and below. That makes it a standard choice for carbonated soft drinks, fruit juices, sauces, pickles, chutneys and syrups, as well as liquid pharmaceutical and personal-care products.
In beverages that also contain ascorbic acid (vitamin C), formulators should be aware that benzoate and ascorbate can form trace benzene under heat and light; formulation and storage are managed to prevent this.
Potassium sorbate (E202)
Sorbic acid has a pKa of about 4.8, so sorbates stay useful up to around pH 6.5 — a wider range than benzoate. Potassium sorbate is effective against moulds and yeasts and is common in cheese, dairy desserts, chemically leavened bakery products, dried fruit, wine and cosmetics. Because it also inhibits yeast, it is generally not added to yeast-raised dough.
Benzoate and sorbate are frequently used together in beverages to cover a broader spectrum of spoilage organisms.
Calcium propionate (E282)
Calcium propionate inhibits moulds and the bacteria responsible for "rope" in bread, while having little effect on baker's yeast. That is why it is the standard preservative for bread and other yeast-raised bakery products. It is also used in some processed foods and in animal feed.
Where sorbitol fits
Sorbitol (E420) is not a preservative but is often bought alongside them. As a humectant it binds water and keeps products soft and moist; sorbitol 70% solution is widely used in toothpaste, confectionery and pharmaceutical syrups.
Regulation and what to specify
Which preservatives are permitted, in which foods and at what level, is set by the regulations of the market where the product is sold — for example FSSAI in India, Codex for many export markets, or the EU additives regulation. Always check the current rules for your product category. When buying, state:
- Food, pharma or technical grade, and the standard you work to
- Physical form — powder, granules or, for sorbitol, crystallising or non-crystallising solution
- Documents required with each lot (COA, SDS)
- Regular volume and preferred pack size
This guide gives general information about common trade and chemistry practice. It is not regulatory or technical advice for a specific product or market — confirm requirements for your application and destination before ordering.
Related industries: Food & Beverage · Cosmetics & Personal Care · Pharmaceutical
