(of a seal or closure) complete and airtight. • insulated or protected from outside influences: a hermetic society.
(OED, 2nd Ed, accessed through U of MN Libraries)
"Those flasks which were not hermetically sealed were soon swarming with maggots, but the others remained free of them" (A History of Food, page 663).
Sentence: My mother's delicious beef stew was hermetically sealed so that I may enjoy again this winter.