I don't think that storebought baby food adds any vitamins or minerals. The ingredients listed on most of them are: water, green beans. Or water, carrots. They would have to list the chemical name of the vitamin in the ingredients, like ascorbic acid (vitamin C).
It's true, depending on how you cook food, you can lose a lot of vitamins. They usually leech into the water. But since you have to add water back in to puree the food, use the cooking water and you keep the nutrients! Also try to limit the amount of cooking water. I used my rice cooker with a steam basket on top to cook lots of veggies at once. It used a minimal amount of water to boil them in the bottom pan, and the top ones got steamed. Then I used what cooking water I had, plus some when I pureed it with my stick blender.
I bought jars when they were on sale, for traveling or for the foods I didn't like to make myself. Like meats. I tried that, but I don't like it. Then I washed the jars and poured my own baby food into it, then froze them. Or if your baby is a light eater (mine were NOT and ate 5 jars per sitting), you can freeze the puree in ice cube trays and then pop them into labeled zip loc freezer bags.
I also bought unsweetened applesauce. They ate it straight from the can or jar. We go through so much applesauce that we buy a #10 can every time we go to Costco. You'll need it to "dilute" blueberries (frozen) and strawberries (frozen) a little, and anything that could be tart, like cherries (I bought a can) or apricots (home-canned). I bought baby cereal, too, but my kids love Cream of Wheat the best. They didn't like the cereal after a while, except for oatmeal which I mixed with applesauce and or pureed peaches and cinnamon (think apple crisp or peach cobbler) for dessert. Mmmm.
We did peaches, pears, green beans, peas (from frozen), corn, potatoes (when you make mashed potatoes for dinner, set some aside before you add the butter and milk, then add butter and formula or bmilk instead), carrots, and squash. It was really fun to make all that stuff, actually, and it's very satisfying to do something so basic for your baby.
It's also cheaper. I used to have a cost analysis somewhere, but I'm sure it's out of date, now. And I made it when I lived in another state, so that makes a difference in grocery prices.
If you have any questions, feel free to send me a private message!