I was making spaghetti and was chopping up a tomato to add to my spaghetti sauce. When I sliced it open I noticed that the middle was kinda mushy and a little liquidy... and was a light shade of brown. I'm pretty new to cooking and I've never sliced open a tomato so I'm not really sure if that tomato was fresh or bad. Is the tomato OK to eat or should I toss it out? Also, how long do tomatos last after you buy them? I bought the tomatos on Monday.