The most common form of series punctuation (at least in the US) is to place a comma after each item in the series. Some style guides say that, when using and, the comma before the and is optional. Using that approach, your phrasing would read
Prepared, packaged and priced beef, pork, chicken and seafood.
Some guides say the comma should be used before the and.
Your concern that some might find this difficult to understand is warranted. This is a sentence fragment rather than a full sentence, and that may contribute to the issue. An alternative that might help is
Prepared, packaged and priced: beef, pork, chicken and seafood.
After prompting from tchrist, I have found two online style guides that suggest a comma can be used before the and in a series (National Geographic says do it and Garbl's says it's optional). The above text has been modified accordingly. I don't have access to the fee-based guides but would welcome input from those who do.