Thats actually pretty accurate. The vitamins/minerals start to degrade very quickly after harvest, and most fresh produce isn't "ripe" like we think it is, when they harvest. Most food is picked 1-2 weeks early while still green, this allows for long distance shipping with less damage to the valuable cargo. If it needs to be ripened quickly for harvest, the will gas it with ethelene gas (might be spelling that wrong, its the same gas released by ripening bananas). This causes the colors to change and "look ripe" without taking the extra time. Frozen veggies are picked, flash cooked, and frozen generally within a few hours of harvest.