I've used vinegar with good results, but I didn't have a cornucopia of fruit outside my door OR in my kitchen. Don's answer was quite thorough and I have no doubt it would work. However, many of us are not motivated to go to such great lengths unless we are driven to madness by the continuing problem. You may have to stay with your parents for a couple of days to get it all done!
I was concerned about the recommendation of Draincare. Is it safe for the environment? So I googled it: http://biokleenhome.com/products/household/general Sounds good to me and it appears to be sold at big-box stores, although I'm sure there are other "safe" products available.
I would start out with the quickest solution (keep the fruit in the fridge; empty and clean the garbage can; clean all surfaces, then wipe them again with diluted vinegar; "treat" the drain in the kitchen sink), see if it solves the problem, and take it from there.
Please let us know what happens!