Feb. 16, 2022
Benzoic acid is an organic acid that was first used in food almost 100 years ago. It is found naturally in plums, cinnamon, and cloves. The free acid form is insoluble in water and the sodium salt (sodium benzoate) is often used because of its greater solubility. The antibacterial activity of benzoic acid is mainly directed against yeasts and molds. As mentioned for other organic acids, the anti-microbial activity is greatest at low pH values. The effect is caused by the greater permeability of the union form into microorganisms. The most common uses of benzoic acid are in carbonated beverages, pickles, sauces, and jellies. Non-food applications of the antimicrobial function of benzoic acid are found in cosmetics.
Benzoic acid CAS: 65-85-0 occurs naturally in plants (fruits, nuts, spices, and vegetables), fungi, and animal tissues, but can also be produced by microorganisms during food processing and/or added as a food additive. Rich natural sources of benzoic acid are strawberries (up to 29 mg/kg), pepper and mustard seeds (up to 10 mg/kg), cloves, tansy, thyme, and nutmeg (up to 50 mg/kg), and cinnamon (up to 335 mg/kg). Levels of benzoic acid in milk also increased dramatically during fermentation, possibly due to the activity of lactic acid bacteria, pseudomonas, and/or E. coli. Levels of up to 24 mg/L have been reported in fermented milk. levels of benzoic acid in raw cow's milk cheese matured for 6 months can be as high as 250 mg/kg.
In addition to its natural occurrence in foods, benzoic acid and its derivatives are often added as antibacterial and fungal preservatives or flavoring agents. Benzoic acid has a low taste threshold, low volatility, and a broad antibacterial spectrum. Although the undissociated form of benzoic acid has been shown to be more effective as an antimicrobial agent, salt is more commonly used in food applications due to its better water solubility. The maximum antimicrobial activity of benzoic acid has been described to be between pH 2.5 and 4.5. Obviously, benzoic acid and its derivatives are therefore most often used as preservatives in acidic foods.
Benzoic acid is used as a preservative in a variety of foods. Benzoic acid retards the growth of yeasts and molds, and the effective agent is the undissociated acid. The main food groups that contribute to dietary intake of benzoic acid are various foods that are allowed at the following levels; various foods 200-1000 mg/kg (prepared salads, sweets, etc. 1500 mg/kg; dietary supplements, pickled vegetables 2000 mg/kg; liquid eggs 5000 mg/kg; cooked seafood 2000 -6000 mg/kg) and soft drinks 150 mg/kg, non-alcoholic beer 200 mg/kg (sacramental grape juice 2000 mg/kg, liquid tea concentrate 600 mg/kg). The Acceptable Daily Intake (ADI) for benzoic acid is 5 mg/kg body weight.
Benzoic acid or its sodium salt benzoate was the first chemical preservative permitted for use in food in the United States. It is still widely used in a large number of foods today. Benzoic acid has a fairly low pK (pK 4.20), so its primary antimicrobial effect, due to the undissociated acid, would be in high acid foods such as cider, soft drinks, and condiments. It is best suited for foods with a pH below 4.5, but can also be used in margarine, fruit salads, sauerkraut, jams, and jellies. Benzoate is primarily used as a mold and yeast inhibitor in high acid foods and is less active at pH levels above 4.0, limiting its use against bacteria. Benzoic acid is naturally found in cranberries, plums, strawberries, apples, and yogurt.