the bugs eggs are in the flour, etc when you buy it.
It's there when they grind it. Flour everywhere has them. Yes, in the US too. The tropical weather
just makes the eggs grow faster than higher latitudes. Irradiation would cure all that but it's not something people are ready to accept.
We have stopped using Tupperware. They make new stuff under the brand name Snap ware or the cheaper yet good Steralite available at WalMart and other discount stores. They have flaps on the lids that snap down and the lid has a removable soft ring that compresses for a nice fit. The containers and lids nest. They are water
tight and come in assorted sizes large and small.
I also like US Plastics web site (google to find). They do great mail order and have every type of industrial plastic known to man. Nalgene in all flavors and all sizes too. Good prices. Lots of lab ware stuff and containers for very nasty liquids.
None of this will stop bugs in flour from growing. Microwaves may slow them down but they don't sterilize the flour. Storage
of kitchen commodities is a serious operation. The sea and warm climates are not suitable for these to be left in anything other than industrial strength containers. It's why tropical cultures don't grind or process these until they are to be used.
Knowing how to cook is an art form. Aboard ship simple pleasures like eating take on extra special status. Knowing how to store food
is a science and you need to expand you abilities and weapons if you choose to eat well aboard. It's a goal we all should strive for (the eating better part). The old salts would have eaten better if they knew how.