If you do not trust that the foods you can buy in the store are natural enough for your baby, you do not have to give them those foods. You can make your own homemade baby food. The ones in stores are better than they ever were, but you may still find some contain things (like preservatives) that you do not want to put into your baby's body. Making your own food is a bit time consuming, and storage may be tricky as well, but your baby can benefit from the time and attention you put into making great and simple foods for baby on your own.
You may not want to buy the baby foods you see in the stores, but you can use these for reference. The usual foods they make for baby are the ones that most doctor would recommend for a starting point. That means when you make homemade baby food you want to work on things like peas, green beans, squash, sweet potatoes, and carrots for first vegetables, and things like bananas, applesauce, and pears for fruits. These are all easily found in most grocery stores so finding the right ones can be easy enough.
When you buy fruits and vegetables to make homemade baby food, you want to make sure these foods are as pure as they can be. You can look for organic foods in your local grocery, or find these foods at your local farmer's market. The problem with farmers markets is that they will not have all foods at all times of the year. Otherwise, they are a great place to get pesticide free foods (ask to make sure) to make homemade baby food. You may find other sources for natural or organic foods if you search online.
Even when you have chosen something that is organic, you must take the time to thoroughly wash all items before you use them. You can get fruit and vegetable cleaners, or you can soak and scrub on your own. Make sure all peels are removed so you know all dirt is gone. Food should be as ripe as possible so that they are easier to puree, which is what you will do when baby first starts to eat them. Inspect final products for lumps, as these can be choking hazards to baby.
It can be time consuming to make homemade baby food, but there are some great processors on the market to help you do this much more quickly and efficiently. They come with instructions that can help you make the best foods for your baby. You also need a good system for storage. These foods will not be good for long. You can learn more about making and storing them for later use if you want to make a bunch at once. Remember, as with jarred foods from the store, never dip the spoon and feed straight from the storage container, as this contaminates the entire serving. Dish out what baby will eat and save the rest for later.