We bought two bags of pears from the supermarket over a week ago (bought one, got one free). They were very hard and under-ripe. We also bought some bananas at the same time so I thought I'd try a bit of an experiment.

I had heard about bananas helping to ripen fruit, due to them giving off small amounts of ethylene gas. I tore a small hole in one of the bags of pears and poked a couple of bananas in, leaving them there for just over a week. I ate one of the pears today and it had ripened 'just right' - soft enough to eat but not too soft or juicy. When I got home I tried a pear from the 'control' group. It was of a very similar ripeness. The bananas seemed to have had a negligible effect