What Are Cosmetic Preservatives?

Preservatives are needed to stop the growth of fungi, moulds and bacteria. if you don't use a preservative, you must 
treat your products as fresh food;keep them sealed, in the fridge and throw them away after 3 days. 

Old and out of date books, often site wheatgerm oil as a preservative, which it certainly is not.It will not stop fungi, 
mould or bacterial growth and is usually rancid before you even open the bottle. 

I never use wheatgerm oil in any product.

Reference Creating Organic Skincare/Mike Harmon