Not A Preservative! What Is It That Has Such A Magical Preservation Effect?
Jan 21, 2021
Lactic acid bacteria, I believe everyone is familiar with it, is a collective term for a group of Gram-positive bacteria with different morphology, metabolic properties and physiological characteristics. At present, many lactic acid bacteria are recognized as safe food-grade microorganisms. They are one of the normal flora in the digestive tract of humans and animals. They play an important role in maintaining the normal physiological functions of the body's gastrointestinal tract and are an important beneficial microbial flora in the intestinal tract.
Due to its multiple probiotic effects, the application of lactic acid bacteria in the fields of dairy product fermentation, food processing, medicine and health, and the prevention and treatment of livestock and poultry diseases has been continuously explored. It is mainly reflected in two aspects: on the one hand, it is developed into a health function or high Nutritional value of lactic acid bacteria fermented food; on the other hand, it is also the subject of our company's research for many years. Through lactic acid bacteria and its metabolites as a natural non-toxic and side-effect antibacterial substance, it is applied to food to exert the effect of comprehensive preservation and extend product preserve period.
Lactic acid bacteria are not preservatives, so why does it have antibacterial and fresh-keeping effects?
In fact, it is not the lactic acid bacteria themselves that play an antibacterial effect, but they can produce a large number of bacteriocin antibacterial substances in addition to lactic acid, acetic acid, hydrogen peroxide and diacetyl during the fermentation process. What mechanism do these substances keep fresh?
1. Various organic acids
Lactic acid bacteria produce various organic acids, including lactic acid, acetic acid, and a very small amount of formic acid, propionic acid, butyric acid, etc., which can improve the micro-ecological environment in the product and create an environment that is not conducive to the growth of harmful bacteria. Promote the fermentation ability of its enzyme system. Studies have shown that organic acids have a stronger antibacterial effect than inorganic acids, and the antibacterial activity of weak organic acids increases with the decrease of environmental pH. The antibacterial activity of weak organic acids is related to the non-dissociation state of the molecules, especially under low pH conditions, the non-dissociated molecules of organic acids occupy a larger proportion, thereby improving the antibacterial ability of organic acids. Lactic acid is the main antibacterial factor of organic acids in lactic acid bacteria, followed by citric acid, while malic acid, oxalic acid and tartaric acid have relatively little influence on the antibacterial effect.
2. Diacetyl
Diacetyl is a flavor substance produced by certain lactic acid bacteria strains in the process of fermenting food (generally dairy products such as cream, butter and cheese) and has a certain antibacterial effect. Compared with gram-positive bacteria, diacetyl is more sensitive to gram-negative bacteria and yeast, and diacetyl is one of the few antibacterial compounds that can effectively inhibit gram-negative bacteria, yeast and mold. Diacetyl has the greatest antibacterial effect under acidic conditions. For example, low-quality diacetyl (a few mg/L) under acidic conditions will have an inhibitory effect on E. coli, and as the pH value decreases, its antibacterial activity increases.
3. Hydrogen peroxide
Dahiya and Speeh studied the antibacterial activity of Lactobacillus lactis and Lactobacillus bulgaricus, and confirmed that the hydrogen peroxide contained in the fermentation filtrate has an inhibitory effect on Staphylococcus aureus. According to the research on the antibacterial properties of hydrogen peroxide, its antibacterial activity will increase with increasing temperature.
4. Bacteriocin
Lactic acid bacteria can metabolize to produce a large class of peptides, precursor peptides or protein substances with antibacterial activity, namely bacteriocins, which have good thermal stability, acid and low temperature resistance. Bacteriocins are produced by certain bacteria (including Lactobacillus plantarum, Streptococcus thermophilus, Lactobacillus bulgaricus, etc.) through ribosome synthesis. In addition to their inhibitory effects on related strains, some bacteriocins (such as acidophilus) Lactobacillus bacteria) also have a broad-spectrum antibacterial ability, which can inhibit a variety of bacteria, such as Staphylococcus, Clostridium, Salmonella, Shigella, etc., which play a role in controlling pathogens and microbial rancidity. Important role.
5. New antibacterial substances
In addition to the above substances, some new antibacterial substances such as pyroglutamic acid, reuterin, benzoic acid, methyl hydantoin and other substances have been discovered in the metabolites of lactic acid bacteria in recent years. But the antibacterial spectrum is very wide, and it has certain antibacterial effect on Gram-negative bacteria, Gram-positive bacteria and fungi.
As a class of highly safe food-grade microorganisms, lactic acid bacteria can not only endow fermented food with a unique natural flavor, texture and structure, but also metabolize to produce a variety of antibacterial and antioxidant substances, which have inhibitory effects to varying degrees. The growth of microorganisms in food keeps the fresh taste and flavor of food. We, Guangzhou Baiqing Biological Co., Ltd., have been committed to the research and development of antibacterial and fresh-keeping applications of lactic acid bacteria fermentation products for many years, so that they can be applied to bread, cakes, spicy snack foods, and play a significant role in preservation of product preservation, anti-oxidation, anti-aging The effect greatly increases the added value of the product.
