Try using a ripening supplement like 'General Hydroponics KOOL BLOOM'.

I've never heard of or experienced anything like that before. My only thoughts are maybe your greenhouse somehow had a buildup of gas that forced them to change colors before they were ripe. (Akin to placing them in a paper bag to force their color, but on a larger scale)

I pick my tomatoes green and let the ripen off of the vine.

They normally taste better if they ripen on the vine, though they do tend to be softer that way.