The specific ingredients and processes for making dressings and sauces can vary. However, the major ingredients used generally consist of emulsified vegetable oils that are high in unsaturated and poly-unsaturated fats. Such fats are particularly susceptible to oxidation. Consequently, preservatives are often added to improve taste stability and shelf life.
Historically, these preservatives have been synthetic ingredients such as Ethylenediaminetetraacetic acid (EDTA) and tertiary butylhydroquinone (TBHQ).
These ingredients will diminish the “naturalness” of the mayonnaise in the eyes of the consumer. Furthermore, the use of EDTA is not allowed in many countries.