For experienced bakers here.. I have a question..
How to store these flour the right way?
-All purpose flour
-baking powder

And how to store cornstarch?

In airtight containers at room temperature, making sure you label them. Some people store their flour in the fridge during summer, since it decreases the risk growth of little bugs/insects in it...

I store all of mine in air tight containers or Ziploc bags. I've done it this way for years and have never had any issues with my flours, baking sodas, baking powders, or cornstarch.

My mom has a tendency to get bugs in her flour when she stores it in the pantry but I've never had that issue. The refrigerator tip might work for her.

I store all of my flour in an airtight container (the OXO pop up containers) in the freezer. I usually keep some AP flour in a smaller container in my pantry because i use it most often.

When I get my flour home, I sift it into a large container. That way I know if there are any bugs in the flour when I get it right home from the store. I put it in an airtight container, and smaller ingredients, I put in mason jars and use my food saver mason jar attachment and vacuum seal it shut. NOTHING gets in that way!

I've heard that, too, but not sure it is true. Think about it - a lot of eggs can stand cold because of a freeze/hibernation style cycle in nature, but they can't stand heat. Once the flour returns to room temperature, who's to say those eggs won't hatch? It's no different than a flower bulb that lays dormant in the winter, then springs to life in the warmth of the summer.

If I were to anything, it would be the heat option. Heating at 180 degrees minimum should kill and sterilize the flour.

Either way, I've never had a problem (or seen bugs) with my flour sifted through a fine mesh strainer, then stored in vacuum sealed jars or airtight containers. Perhaps I've been lucky...God only knows!

I freeze the flour for about a week, and the transfer into air-tight containers and store at room temp. No bugs so far.