The development trend of cosmetic preservatives

Cosmetics have the functions of whitening, moisturizing, moisturizing, etc. These functions are attributed to the effects of various active ingredients. They are mostly oils or nutrients, which are highly susceptible to microbial infection and deteriorate, resulting in a decline in product quality. Preservatives are substances that prevent the growth of microorganisms in a product. In cosmetics, the role of preservatives is to prevent products from microbial contamination, extend product shelf life, and ensure product safety.

1. The general mechanism of action of preservatives

The preservative is essentially a protective agent that inhibits and kills microorganisms in cosmetics and maintains the quality of cosmetics for a long time. Preservatives are not fungicides. They do not have a strong immediate bactericidal effect and can only work if they are in sufficient concentration and in direct contact with microorganisms. Preservatives act to impede cell growth by inhibiting the synthesis of enzymes that are basal metabolism in cells or the synthesis of important nucleic acids and proteins of living organisms.

2. Factors affecting the role of preservatives

The effect of preservatives is related to many factors

2.1 The effect of pH

The change of pH affects the dissociation of organic acid preservative and thus affects the activity of preservatives. For example, 2-bromo-2-nitro-1,3-propanediol is very stable at pH=4, and its activity can be maintained at pH=6. One year, pH=7 is only a few months active.

2.2 Effects of solid particles and gels

Some cosmetics contain powder particles such as kaolin and aluminum silicate, which can adsorb preservatives and cause loss of preservative activity. However, some adsorbents adsorb the preservatives and adsorb the bacteria in them, so that they are placed in high concentration antiseptic. The agent enhances its antibacterial effect. The combination of a preservative and a water-soluble polymer gel reduces the concentration of free preservatives in the formulation and reduces its effectiveness.

2.3 Effect of nonionic surfactant solubilization

Various surfactants in cosmetics, especially nonionic surfactants and preservatives, form a dissolution-complexing effect that affects the activity of the preservative. The oil-soluble nonionic surfactant (HLB = 3-6) has a greater inactivation effect on the preservative than the water-soluble nonionic surfactant having a higher HLB value.

2.4 Effect of deterioration of preservatives

Some factors can affect the deterioration of the preservative itself, thus reducing the antiseptic effect. Such as light, heating, etc. caused by decomposition of preservatives, failure caused by biochemical reactions or losses caused by radiation sterilization.

2.5 Other effects

In addition, the distribution of preservatives in the oil-water phase, the presence of flavors and chelating agents, will affect the activity of the preservative to varying degrees.