1 day after people; The 100,000 grocery stores in the world are now silent without people. Automatic sprinklers still keep the produce fresh and the food still appears appetizing. But microscopic organisms and insects are already here waiting to make their move. The FDA already allowed small amounts of insect parts in food and now without humans to consume the food insect eggs will hatch and bacteria will multiply.
1 week after people; The power has gone out and that means there is no longer refrigeration in grocery stores. Meat and dairy products require temperatures less than 4 degrees and as the temperature rise these products began to spoil within hours. Bacteria accumulate on the meat and add chemicals that hasten decomposition. As fruit ripens they release ethylene which causes the fruit around them to ripen and spoil quicker. Airborne spores land on the produce and develop into mold. Blow flies and maggots begin to eat up the meat products while fruit flies start to eat up the fermenting fruits. The smell of rotting meat and fruit soon also attracts rats.
10 days after people; Escaped pets and zoo animals begin to feast on the food in the stores, which in some cases the best place to eat when nuclear power plants collapse.
3 weeks after people; Lactic acid bacteria has caused the milk in the grocery store to curdle and sour. The lack of refrigeration has also caused butter to go bad.
3 months after people; Fruits have shriveled up and rotted away. Meat has been completely rotted away and only bones are left. Rats and insects such as merchant grain beetles, red ants and cockroaches are now eating up the dry goods. Canned beans are rotten and begin to explode.
2 years after people; All produce on grocery store shelves has by now been eaten away or decomposed; pests that evolved to live off of human food now either go extinct or begin to eat something else.
30 years after people; The structure of grocery stores has deteriorated after three decades of snow and rainfall and their roofs cave in and collapse. Plant life begins to colonize the interior.
4,000 years after people; Groccery stores are now gone, but sealed jars of honey continue to endure.