Why does the house smell of vinegar?

I came home from work yesterday to find the house smelling of vinegar. O had reduced eight large bargain mangoes (50p each, reduced from £2) to a large pot of spicy mango and lime chutney. Tonight, fortified (or weakened, maybe) by a large martini of Blackwood Shetland gin, home-made elderfliwer cordial, Cinzano, lime juice and frozen wild raspberries from the park, we set about bottling the chutney. In the end, we managed 11 jars, some large, some small. With all ingredients included, the cost per jar was about 60-75p each. Not bad. And, in a month's time, it will taste fabulous! The hand is O's, putting waxed paper discs on the top of each jar before the lid goes on.