You won't need to freeze them. My family has been eating off of 50lbs of flour and 25lbs of sugar that we've had in food storage buckets for the last 8 months. The only problem we've run into is lumpy sugar. But, our containers are not
O-ring sealed either. My recommendation would be to actually eat off your supplies and replenish as needed. Idea is, say you keep 100lbs of flour in a few of these containers. When the first 50 is gone, switch to eating the other and buy another 50lbs. That way you rotate stock. Same with your rice and sugar. That way when SHTF you've still got at least 50lbs of flour, 25lbs of sugar, etc. Assuming you've got a good stock of all your dry goods you could concievably not leave home for a good 2 months. My family buys almost everything grocery related from BJs (a wholesale club). Once prior to moving we stopped going shopping except for milk, eggs and such for about 2 months so we wouldn't have to move food. We didn't exactly starve, and though our cabinets were a little more bare than I like to see, we still
moved some food.
Just don't overlook stocking spices, baking powders/soda, yeasts by the brick, some canned milk, powdered milk, tomatoe sauce, beans, veggies, etc...even coffee. If you're not a member of a discount club like BJs or SAMs, become one if this is the plan. Stocking up like that will take a few months and feel horid in the grocery bills, but once you're there maintaining that stock is actually cheaper in the long run than buying from a regular grocer. Also if you ever suddenly become unemployed and are then underemployed for a longer period--happens to average American more often than SHTF situation--you won't have to worry about family going hungry for a while.
Now I'm assuming you're already well stocked on the ammo