How do I get rid of sour milk smell in a backpack?

1. Empty the backpack and remove all loose items. This will help you identify the source of the smell and make it easier to clean.

2. Take the backpack outside and air it out for several hours. This will help dissipate the smell.

3. If the smell persists, clean the backpack with a mixture of equal parts white vinegar and water. Scrub the backpack inside and out with a sponge or old toothbrush, then rinse it with clean water.

4. Allow the backpack to dry completely before using it again.

Additional tips:

* Place one or more of the following inside the bag while it is closed for extended periods of time: baking soda; cat litter; or charcoal or carbon filter used for filtering drinking water/aquarium cleaning

* Use an enzymatic cleaner designed to remove odors from fabrics. These cleaners break down the proteins and bacteria that cause smells.

* If the backpack is made of a delicate material, test the cleaning solution on a small, inconspicuous area before using it on the entire backpack.