Author: Site Editor Publish Time: 2022-09-19 Origin: Site
1. Sorbic acid and its potassium salts
Sorbic acid is colorless needle crystal or white crystal powder, odorless or slightly irritating odor, with good light resistance and heat resistance. However, if exposed to the air for a long time, it is easy to be oxidized and discolored, and it is difficult to dissolve in water. Therefore, potassium salts that are easily soluble in water are generally used. Sorbic acid and its potassium salt have a broad antibacterial spectrum and can be used in almost all foods with a pH value below 6.0. They are the most widely used acidic food preservatives. Sorbic acid and its potassium salts can effectively inhibit mold, yeast and aerobic bacteria, but are almost ineffective against anaerobic bacteria. Its toxicity is much lower than other preservatives, and the rational use of preservatives is stronger than propionate.
Sorbic acid combines with the sulfhydryl group in the microbial enzyme system to destroy many important enzymes of microorganisms, thereby inhibiting the function of microbial growth. In addition, it can interfere with transmission functions, such as the transmission of oxygen by cytochrome C, and the energy transmission on the surface of cell membranes, thereby inhibiting the proliferation of microorganisms and achieving the purpose of product preservation.
2. Propionic acid and its sodium and calcium salts
Propionic acid is a colorless oily clear liquid with a specific odor, a slightly pungent oily rancidity. Sodium and calcium propionate are white powders with good water solubility, stability to light and heat, and smell similar to propionic acid. Both propionic acid and propionate are easily absorbed by the human body and participate in the normal metabolic process of the human body without harmful effects, but the antibacterial effect is not as strong as that of sorbic acid. Propionic acid and salts have good antifungal effects, such as effective against mucor, less bacterial inhibition, and no yeast inhibition, so they are often used in cakes, bread and cheese. Calcium salts cannot be used together with the leavening agent sodium bicarbonate, which will generate insoluble salts and reduce the production of CO2. The alkalinity of sodium salts will delay the fermentation of the dough. Therefore, sodium propionate is commonly used in western pastries, and calcium propionate is commonly used in bread.
Propionic acid and its sodium and calcium salts are acid-type preservatives, and the main preservatives are undissociated propionic acid. Propionic acid is a monocarboxylic acid, which can inhibit the synthesis of β-alanine by microorganisms and play an antibacterial effect.
3. Dehydroacetic acid and its sodium salt
Dehydroacetic acid is colorless to white needle-like or flake-like crystals, or white crystal powder, weakly sour, insoluble in water, and turns yellow under direct light. Sodium dehydrogenate has the odor of acetic acid and is easily soluble in water, so sodium salt is commonly used. Sodium dehydrogenate has a wide antibacterial range, and has inhibitory effects on bacteria, yeasts, and molds (except Mucor and Mycobacterium sp.) that cause spoilage. The inhibitory effect is relatively stable. When the pH value is less than 9, the best effect is achieved. Easily decomposed by heat during processing.
It mainly inhibits the growth of microorganisms by destroying the substructure of microbial cells and related enzymes.
4. Sodium diacetate (sodium diacetate)
Sodium diacetate is white crystalline powder or crystalline solid with an acetic acid odor, easily soluble in water and ethanol. Sodium diacetate is a new type of high-efficiency, broad-spectrum antibacterial and antifungal agent recognized as safe and reliable. The final metabolites in the human body are water and carbon dioxide. Sodium diacetate is effective against Aspergillus niger, Rhizopus niger, Aspergillus flavus, Trichoderma viride, etc. significant inhibitory effect. In addition, sodium diacetate also acts as an integrator to shield metal ions that cause oxidation in food.
The bacteriostatic effect of sodium diacetate comes from acetic acid. Acetic acid can penetrate into the cell wall of microorganisms, which can interfere with the growth of various enzymes in the cells, or denature the proteins in the cells of microorganisms, so that it can effectively prevent mildew and corrosion, and its antibacterial effect is excellent. in calcium propionate and potassium sorbate.
Nisin is a white or slightly yellow crystalline powder or granule with a slightly salty taste. It needs to be dissolved in water or liquid when used. The optimum pH is 3.0. It is a polypeptide compound composed of a variety of amino acids. It is an efficient and non-toxic natural preservative. It has a significant inhibitory effect on most Gram-positive bacteria and their spores, including Bacillus, heat-resistant spoilage bacteria and Clostridium sporogenes. etc., but not effective against Gram-negative bacteria, yeast and mold. At present, it is mainly used for food preservation with high protein content. Such as meat, dairy processing, etc., cannot be used in foods with low protein content, otherwise they will be used by microorganisms as a nitrogen source.
It can inhibit the synthesis of peptidoglycan in the cell wall, block the synthesis of cell wall and phospholipid compounds, and cause the leakage of intracellular substances, decrease the membrane potential, and cause cell lysis.