Rather than use the microwave,I simply fill the sink with quite warm/hot water,then place a glass full of water in the sink,into which goes the bottled juice.Once warmed up,I aerate(Dremel clone wearing a little cup-shaped brush)until the juice is loaded with tiny bubbles,then leave overnight in dark cupboard minus tops.Result is like steeping for 7 days (minimum approx) in 7 hours.I can't say it definitely results in the exact same taste as natural steeping as taste is subjective,but I'm happy to use my own brews after this treatment next day(which is handy if you're a juice whore like me & go through 10-15+ ml's per day as I can't seem to get ahead of my juice usage to let them steep longer)