Err, no? I live in Montreal, I've carried produce and other kinds of food by bike or by walk in -30C to +40C weather. It doesn't take so long that your food becomes damaged.

If you're carrying frozen food, we have bags with insulation and reflective foil on the inside. Put your frozen food there and even in +40C weather it will take much more than 15 minutes to thaw. Besides, buses and obviously the metros are acclimatized to a temperature of more or less 25C.

It really is just a non-issue. I assure you your produce are left outside for more than 20 minutes. There is no impact at all on freshness, and walkable cities promote smaller grocery stores that tend to have fresher food.

It's remarkable to see people so detached from their natural origins to believe produce will freze or spoil when extracted from the supermarket and exposed to the outside world for a few minutes. Unless you are living at the North-Pole and need to walk more than half an hour in arctic blizzards, there is physically no way your food can freeze on the way back from the supermarket.

Food grows outside, in direct sunlight, exposed to scorching heat or near-freezing temperatures. Most of the plant based food is still living in the shelf when you purchase it, and has imune systems to fight-off bacteria and the like that would otherwise colonize it. The only concern are products of animal origin in the heat, but even the most sensitive like refrigerated fresh fish, still needs at least a few hours in hot weather before they can become problematic.