ha, that's a confusing answer! If the vegetable/fruit is in season and from a store that has very fresh produce, then fresh. If not, then frozen. If you grow your own food, then always fresh, or if you shop at a local produce market etc. then fresh. I mixed it up with both of my children and used both depending.
Are you asking Volume, or Nutrients? For volume, sweet potatoes make a TON! They are also high in nutrients and recommended for a first food for babies. You can also start with avocado as a first food. With avocado, you don't cook it, so what you see is what you get. Highly nutritious and has a lot of healthy fats that babies need. Foods that do not make much volume are apples & pears. I found that the cheapest items to make were sweet potatoes, carrots and various squashes. They made a good amount and my kids liked them. I always advise to not make much to start with for each food because your baby may hate it. Olivia wouldn't eat green beans no matter what I did! She still wont' touch them!
Total guess, here, and I hope I don't offend, but with twins, if they were premature, be careful about food introduction because their bellies might not be as developed. Wait the full 4 days or more before introducing a new food, beware of any rashes, trouble with poop etc.
Ethan - June 21, 2009
Olivia - December 5, 2010
5w3d - October/November 2012
My Ovulation Chart