Comma use dividing two lists in one sentence

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.

SUPPLEMENT

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.

Your sentence is perfectly fine; you need not worry about any further comma or semi-colon. Just remove that extra comma after packaged. We usually don't use a comma before and.

The question of using the comma before the word "and" is a common one with writers. It's called the Oxford comma or the serial comma. Both are correct, depending on the style guide you're using. The NY Times doesn't use it, many other publications do. It's a choice made by the writer/editor and needs to stay consistent after the decision is made. However, there was a recent ruling by a judge in Maine (I think) that said that omission of the Oxford comma was confusing when describing the requirements for the employees at a Dairy. He ruled that the serial/Oxford comma was legally needed to resolve the issue of clarity. So while it's not always the style to use the Oxford comma, it's always clearer in communication and has been ruled as such in a US court. Yay for the Oxford comma!

Recast the sentence. You are not beholden to it that way: nothing was etched in stone. If it seems confusing, then it is.

You can't write any sentence and expect someone to put in proper punctuation. Sometimes the sentence itself borders on ambiguity, and therefore should be recast.

To quote William Watt:

To best thing about writing something on paper is that you can always change it. It is easier to twist a bad sentence on paper into a good one, than it is to write one out of the clear blue air.