There is something about the under developed green in a tomato as it adds a zip to the tomato /but not too much/. Whenever I select tomato fruits, I try to find a slight unready green at the skin’s surface, as I find they have a nice acidic bite – a balanced to the fruit.
A tomato can stay green depending on several factors, and the outside temperature is one factor to turn it red. Tomatoes will only produce lycopene and carotene, two substances that help a tomato turn red, between the temperatures 10-29 C. If it is any cooler than 10 C tomatoes will stay a stubborn green. Any warmer than 29 C., and the process that produces lycopene and carotene comes to a screeching halt.
Tomatoes are also triggered to turn red by a chemical called ethylene. Ethylene is odorless, tasteless and invisible to the naked eye. When the tomato reaches the proper green mature stage, it starts to produce ethylene. The ethylene then interacts with the tomato fruit to start the ripening process. But from our experience consistent winds can carry the ethylene gas away from the fruit and slow the ripening process.