|MadSci Network: Microbiology|
There are two general approaches that can be taken to reduce mold growth on bread:
In the U.S. calcium propionate is typically used as a chemical preservative in bread and bakery products. It is an effective anti- mycotic in the ranges of pH typically found in bread. You would need to check with the Australian regulatory agency to determine if its legal and available for use. Likewise you would need to identify Australian manufacturers or distributors to get samples.
An alternative is the use of reduced water activity (a measure of the amount of free water available in a food, similar to measuring the relative humidity of the food). Mold can't grow below an Aw of 0.85. This is why dry products such as jerky, dried eggs, etc. won't mold (as long as they are protected from picking up moisture from the air). Bread of low Aw is typically dry and somewhat unappetizing, typical of some crackery type products (in the U.S. Melba Toast).
Try the links in the MadSci Library for more information on Microbiology.