Bottling cream-based salad dressing. Preservative advice? I would like to bottle my home made salad dressing that is mayo- and cream-based. I was wondering what kind of preservatives I could use to lengthen shelf life. Also, I am using garlic powder as an ingredient. Are there any problems using garlic powder with mayo?
Switch out the cream. 
Mayo is stable, cream is not. Yogurt as a replacement may give you a slight extension (higher pH).

There's no issue using garlic powder.