I want to start making my own salad dressing because I don't like all of the stuff they put in processed food. However, I still would like my dressings to last more than just a few days in the fridge. What kinds of preservatives (hopefully natural ones) can I use to preserve home-made salad dressings?
What is a "bad preservative"?
The main additive preservatives used today are ascorbic acid, citric acid, ethanol, salt, sodium nitrate (pink salt), sugar, and vinegar - all of which have been used for centuries, and other than with excessive use, are not seen as harmful
Weird chemical preservatives are often only used with weird chemical ingredients, stick to basics and you'll be fine
Pasteurisation, electrical pulse, and other heat treatments are used commercially and give products those amazing shelf live times. Without specific equipment and monitoring systems they are hard to reliable reproduce at home
Your home made dressing will last long enough in the fridge for you to get bored with it and want a new flavour :-)
Your homemade salad dressings will certainly last longer than a few days in the refrigerator. According to Still Tasty, you can keep homemade salad dressing for two weeks in the refrigerator.
However, your salad dressing will separate if you do not include an emulsifier. A separated salad dressing just needs to be mixed up again, which may require warming the dressing if the fat begins to solidify.
Common emulsifiers include mustard powder, honey, and egg yolks (although the last of these introduces its own problems in terms of health risks unless your salad dressing is heated).