My name is Davide and I am writing you from Italy. I was wondering if you would be so kind to give an answer to the following:
Last week I was preparing dinner in my kitchen, I reached for a new flour box, one of those carton boxes which contain a sealed plastic bag inside, and when I have opened the plastic bag I have immediately noticed that there were some tiny insects inside. The bag was perfectly sealed so how can it be? Is it possible for insects to form in such an environment?
They probably were in there as eggs, which hatched. I frequently find tiny insects in similar foods, such as grits and oatmeal. There probably was some oxygen in there when they sealed it. Those critters don’t need much oxygen, I guess.
I’ve heard recommendations to freeze a bag of flour for a few days after bringing it home (seal it in a zipper-close-style plastic bag first, to help keep moisture out), to kill any insects/eggs already present, then take it out and store in an airtight container. This should minimize chances of insect infestation.
freezing only kills adults and larvae. the eggs while not hatching will still remain viable. you can allow eggs to hatch and refreeze before the adults lay eggs, eventually the egg population will be diminished.
I do not know what regulations Italy has, but in the U.S., there would have generally been a date on the box that indicated “Use by” or “Expiration” or “Best before” or something similar. The point of those dates is, in part, to prevent your experience. Since boiling or baking will destroy the eggs, the assumption, (or hope), is that the product will be used prior to the eggs hatching. Using the product after that date increases the possibility that the eggs will hatch and the larvae begin to contaminate the product. Depending on the product, exposure to heat will reduce the amount of time that the product is free of hatched eggs or other organic activity.
It is simply not possible with current technology to guarantee 100% elimination of small contaminants, such as eggs and even rodent feces. The U.S., (and, I presume, most developed countries), does set a maximum allowable contamination. For Grade 1 wheat in the U.S., there may be no more than .004 of a kilogram of contaminants in one kilo of wheat and, specifically, there may be no more than 1 particle of “animal filth,” 1 castor bean, 2 crotalaria seeds, 0 pieces of glass, 3 stones, or four unidentified objects in one kilo, and the total of the above “permitted” contaminants must not exceed 4. (So one crotalaria seed and one castor bean reduce the permitted stones to 2.)
I opened a previously-unopened bag of Reese’s cups recently that I had had since last Xmas. I had gone thru several of them before I noticed that I was sharing these morsels with larvae, most likely pantry moth larvae, as I had seem them snooping in the cabinet on occasion.
I don’t know how they got in there, but they did. They’re tricky. But I doubt that the eggs had been in there for almost a year.
