Preservative means prevents microbial growth or prevent the product in response to microbial growth substances. In cosmetics, preservatives’s role is to protect the product, made from microbial contamination, prolong the shelf life of the product; to ensure the safety of products, preventing consumers from the use by the microbial contamination of the product caused by the possibility of infection. Cosmetics are subject to microbial contamination caused deterioration, in general, can be reflected in the appearance. Such as mold and yeast used in product packaging edge place Meidian; microbial contamination of products appear cloudy, precipitation, color change, pH change, foaming, stale, if emulsion may be breaking into pieces. If preservatives added quantity is not enough, it is possible for microbial adaptation to the surrounding environment, resistance, leading to corrosion failure.
1 antiseptic mechanism
Cosmetics microbial survival and reproduction is dependent on a number of environmental factors: the physical aspects of the environment temperature, pH, osmolarity, radiation, static pressure; chemical aspects of water, nutrients (C, N, P, S source), oxygen, organic growth factor.
In some ointment such as containing low water products, microorganisms in general is not growing, for the majority of bacteria, the most suitable for the growth of PH range is close to neutral (6.5~ 7.5), strong acid and strong alkali is not suitable for the growth of microorganisms, such as common acid products, anti-corrosion effect usually parallel than neutral product.
The role of preservatives on the microbial can produce an effect only in the case of direct contact with a sufficient concentration and microbial.
In addition the effect of interfacial tension on the microbial growth is one of the reasons why, in some surfactants used in very high in the formula is not easy, microbial growth, in this respect, cationic surface active agent performance more prominent, and anionic and non-ionic on microbial physiological toxicity is very small. In general, the bacteria most suitable for production of temperature of 30to 37 DEG C, and the mold and yeast is 20to 25 DEG C, so can use high temperature disinfection methods, but individual bacillus in adaptation to the environment, generate a protective film, even though 80to 90 DEG C high temperature short time cann’t be its killing.
The role of microbial preservatives that there is sufficient concentration of micro-organisms which are in direct contact with, you can make a difference. Preservative is first and cell outer membrane contact, adsorption, passes through the cell membrane to the cytoplasm, then in various parts of the body work, the block of cell reproduction or kill them. In fact, mainly of preservatives on the cell wall and cell membrane effect, in addition to the new supersedes the old. The other is the activity of enzymes that affect cell metabolism or genetic particle structure of the cytoplasmic part.
2. The classification of preservative
Most preservatives are through contact with the cell membrane, and cell wall fractions, mainly react with proteins, disruption of microbial cell protection structure or interfere with cell the new supersedes the old., affect the normal cell growth in order to achieve the purpose, anti-corrosion, cation is mainly through affecting the osmotic pressure, so that the cell membrane rupture, shrinkage and loss of water, thereby sterilizing.