State University Extension
Preserving Food Safely - 01600605
In general, it is not a good practice to add oil or
margarine to fruits or vegetables that will be processed.
Oil or margarine will not go into solution but will form an
unstable emulsion with tiny oil droplets scattered
throughout the product. Heat does not penetrate the oil
droplets very well, therefore microorganisms or spores in
the oil droplet may survive processing. Even in an acid
product (such as tomato sauce), the micro-environment
immediately surrounding an oil droplet may not be the same
pH as the rest of the product, thus permitting the growth of
microorganisms that could not otherwise grow in an acid
medium. It is best to process the product without added
oil; if desired, oil can be added just before serving.
Another alternative is to freeze the product.