How to tell if a rutabaga is fresh

This, I confess, is just a guess—I'd suggest adding some pectin.

Pectin is a thickener that occurs naturally in fruit, but its likely absent entirely in the fruit juice you've been using. However, it's probably present in the fruit purée used in the commercial products.

Pectin is, for example, the primary (if not only) jelling agent in jam, jelly, and preserves. In the store, Sure-Jell and Certo are common brands.

I'd try to get HM pectin (the one that isn't sold as "low sugar") to set first. It'll probably provide a firmer fruit snack. LM pectin may work, too, if you don't have enough sugar (I doubt insufficient acidity will be an issue).

I suggest, as an alternative to ice cube trays, use cornstarch molding. Basically, you press an indentation into cornstarch, and then pour the stuff in. Let it cool & dry in the cornstarch. Then remove the cornstarch. You can re-use the dry part of the cornstarch. This will deal with the stickyness, but the finish will be more matte.

The yellow color could be just a sign of what it was fed. According to the USDA:

THE COLOR OF POULTRY

1. What is the usual color of raw poultry? Raw poultry can vary from a bluish-white to yellow. All of these colors are normal and are a direct result of breed, exercise, age, and/or diet. Younger poultry has less fat under the skin, which can cause the bluish cast, and the yellow skin could be a result of marigolds in the feed.

You could have an older chicken that had marigolds in what it was fed.

On the flip side, I was always taught that if any meat smells bad, it isn't good to eat. If it was my chicken in the kitchen, I would take it back to the store or just throw it out.

If you are still debating on if it is good to eat, you could always take it back to the store where you purchased it, or contact the USDA Poultry Hotline.