The preservative is a substance to prevent the growth of microbial. It has sustained inhibition for microbial growth. In different circumstances, it can inhibit the most prone corruption. Particularly it still has a persistent effect in the inadequate general sterilization. Preservation for fiber and wood, we can use mineral oil, coal tar and tannin. The formaldehyde, mercuric chloride, toluene can be uses as preservatives in biological specimens. For light-based small discretion, the benzoic acid, nitro-the chaff knee derivatives or lipids resin is effective.

The commonly used preservatives are acetic acid, lactic acid, benzoic acid and sorbic acid. The cosmetics material can inhibit bacteria and fungi. In solution, weak acid with pH in the dissociation of the undissociated state between dynamic equilibrium. Class of preservatives in the case of low pH has the greatest antibacterial activity, because the molecules mostly in non-ionizing state, the non-ionized organic weak acid molecules are lipophilic, it can be free through the plasma membrane.

Many small organic molecules have a good antiseptic effect, such as cinnamic acid, benzoic acid cool. Actual Bu, many antibacterial ingredients is naturally occurring in plants, oregano, cloves, litchi, etc. can be extracted to the antibacterial action of substances, including the vanilla phenol, ferulic acid, the allyl ether, the more guaiacol. These astaxanthin ingredients are generally hydrophobic substances make the cell membrane dysfunction or membrane rupture, eventually leading to microbial death. Quantitative structure-activity studies of benzoic acid, cinnamic acid and benzaldehyde, measured by reversed-phase HPLC lipophilicity parameters and their anti-monocytogenes listeria monocytogenes performance were significantly related.

Most natural antimicrobial peptides, the inhibitory effect caused by the disruption of membrane function, such as ceropin and nisin formed in the bacterial cell membrane potential dependent channels, leading to small molecules within the cell overflow leaving the cell death, ion channel-forming ability of these peptides inhibit microbial important reason.

In cosmetics, preservatives role is to protect the products against microbial contamination, extend product shelf life; to ensure the safety of products, to prevent consumers from possible infection caused by the use of the products of microbial contamination. Cosmetics subject to microbial contamination caused by deterioration, under normal circumstances, can be reflected in appearance such as molds and yeasts are often in the packaging of the product edge and places such as moldy: microbial contamination of the product appears cloudy, precipitation, color change, PH value change, foam, sour, if the emulsion is possible demulsification, into blocks. If the preservative is added is not enough, may arise when the micro-organisms to adapt to the surrounding environment for the growth, resistance, resulting in tretinoin anti-corrosion failure.

Most preservatives have reactions with cell wall components after contacting with the cell membrane, especially for the proteins. It will destroy the protecting structure of microbial cells or interfere with cell metabolism, affect cell normal growth to achieve the anti-corrosion The cation is mainly affect its osmotic pressure and makes membrane rupture, shrinkage and water loss, thus it achieves the purpose of bactericidal.Source: