Sodium benzoate and potassium sorbate, two food preservatives, have one common feature - large output and wide application.

As usual, let's first look at the basic properties:

"Sodium benzoate" white powder, slightly fragrant, easily soluble in water and ethanol, molecular weight 144.12

"Potassium sorbate" white powder, odorless or slightly smelly, easily soluble in water and ethanol, molecular weight 150.22

The second is the application scope of the national standard gb2760-2014 for food additives:

"Sodium benzoate" can be used in preserves, sweets, condiments, beverages (especially carbonated drinks) and other fields, with less application scenarios

"Potassium sorbate" can be used in cheese, preserves, candy, bread, pastries, cooked meat products, beverages, seasonings, bean products, wine and other fields, with rich application scenarios

Start with sodium benzoate, which has a longer history:

Sodium benzoate is an acidic preservative. The best pH range for preservative is 2.5-4.0. When the pH of food is > 4, the preservative effect is very weak.

The reason is that sodium benzoate plays an antibacterial role, mainly relying on the undissociated sodium benzoate under acidic conditions. It is easier to penetrate the cell membrane, interfere with the cell membrane, inhibit the respiratory enzymes in the cell, and then inhibit microbial reproduction.

Sodium benzoate has a wide antibacterial range and can inhibit the reproduction of yeasts, molds and some bacteria.

So, what food has a pH between 2.5 and 4.0?

The answer is: high acid foods, such as carbonated drinks, vinegar and soy sauce;

Limitations of use

In addition to the food field, sodium benzoate is also the preferred preservative for many liquid drugs. However, sodium benzoate is not suitable for use in meat products. On the one hand, it is in the pH range, on the other hand, it reacts with some substances in meat products.

The safety of sodium benzoate has been controversial in recent years. For example, in the toxicological basis, the oral LD50 index of rats is 2700mg / kg for sodium benzoate and 4920mg / kg for potassium sorbate (FAO / who, 1994).

At present, sodium benzoate is a food preservative allowed in GB2760, which shows that the health commission recognizes the safety of sodium benzoate in food at this stage.

Potassium sorbate is an acidic preservative. When pH is lower than 5, the anti-corrosion effect is the best. At pH 5-6, it still has a good anti-corrosion effect.

Under acidic conditions, undivided potassium sorbate can penetrate the cell membrane, inhibit intracellular dehydrogenase, and then affect the reproduction of microorganisms.

Anaerobic bacillus (common in vacuum packaged food), the "fish out of the net" of potassium sorbate, can achieve the antiseptic effect by compounding nisin.

Limitations of use

The dosage of potassium sorbate was large. With the increase of the concentration of potassium sorbate, the antibacterial rate increased significantly. Taking meat enema as an example, the maximum allowable addition of potassium sorbate is 1.5g/kg.

Potassium sorbate can be said to be a brother of food preservatives, which is widely used. Studies have shown that the residue of potassium sorbate in the hind legs of slaughtered pigs is 0.069g/kg (MA Yushan. 2006), while the maximum residue of potassium sorbate in cooked meat products (except meat enema) is 0.075g/kg.