Interview with Dr. rer. nat. B. Stockebrand, pharmacist


biszet: Once cosmetics have been opened manufacturers often recommend “refrigerated storage” – can you tell me why that is so?

Dr. B. Stockebrand: High quality cosmetics and skin care products are manufactured with extreme care. They contain highly purified ingredients, with virtually no bacteria and no allergens. As soon as the seal on a tube or a jar is broken, even a tiny amount of air suffices to allow bacteria contact with the ingredients and even more bacteria are imported via our fingers. Oxygen in the air, but primarily high temperatures, allow these bacteria to multiply rapidly if insufficient preservatives are present in the products. The trend towards smaller concentrations of preservatives in order to limit the strain on the skin brings with it its own problems.


biszet: How quickly do these bacteria multiply?

Dr. B. Stockebrand: We know of micro-organisms that multiply exponentially with a rise in temperature of 10 °C. When stored at 20 °C under ideal circumstances some bacteria are capable of multiplying 30 times faster than when stored at 10 °C.

biszet: What are the effects of bacteria and germs on the efficacy of cosmetics?

Dr. B. Stockebrand: Bacteria like to feed off the precious ingredients, thus initiating changes in the agents themselves. New metabolic products are excreted such as butyric acid and these completely alter the contents. The anticipated effect fails to take place and can even lead to unintended effects such as the formation of allergies.


biszet: Which ingredients react particularly sensitively to warmth?

Dr. B. Stockebrand: Vitamins A, C and E are the main ones. Many anti-ageing creams contain them in the form of antioxidants. Their role is to prevent destructive oxidation processes in deeper subcutaneous layers where oxidants destroy the tissue. Collagen fibres alter the structure of the deeper skin layers and so wrinkles form. Vitamins can prevent this process but they are very sensitive to heat. The lower the temperature, "the better they feel".


biszet: We often see considerable temperature variations during storage. What effect do these variations have on the creams?

Dr. B. Stockebrand: You’ve surely noticed that after a while creams separate into thicker and thinner components. This is often the result of temperature variations.


biszet: What exactly happens in that case?

Dr. B. Stockebrand: Temperature variations cause particles to move around a lot. Highly complex systems collapse. The ingredients separate out and no longer adhere to each other in the required consistency.


biszet: How can this lead to a cream becoming ineffective?

Dr. B. Stockebrand: Take lecithin, for example. High quality ingredients are coated with lecithin and these penetrate the skin’s deeper layers in the form of microscopically fine particles known as nano particles, where their task is to unfold their anti-ageing effect. Systems such as these are heat-sensitive, which means that the particles break down, and the agents can no longer be transported to their intended destination in the deeper subcutaneous layers.


biszet: Refrigeration is also recommended to preserve the sun protection factor in lotions and creams. Why is this?

Dr. B. Stockebrand: Many substances that provide protection against the sun are absorbed by the bacteria that we have already mentioned. When stored between 20 and 25 °C, products lose around 5–10 % of their efficacy each year. Refrigerated storage cuts down the loss to only a few percent.


biszet: So do you believe it makes sense to use a biszet cosmetics cooler?

Dr. B. Stockebrand: Yes, I believe that storing valuable items in a biszet cosmetics cooler is a good idea for all women who want to protect their creams, because the bathroom is basically totally unsuitable on account of its high humidity and temperature. In addition, I recommend using spatulas rather than fingers to remove cream from jars.


biszet: Thank you for the very informative interview.

Dr. B. Stockebrand: My pleasure.

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