e85 blends can vary. I bought myself an e85 octane tester off fleabay to test each batch I buy. I use United Petroleum blended e85. Its made from grain stock at a Bio refinery in Dalby QLD and distributed via United Petroleum. The last batch I bought tested at 108 octane. At $1.20/L, it hard to beat.
Found a bit more info on United's web site regarding the production of ethanol based fuels...
Untied Petroleum