Aspergillus is a mould and forms spores. They can survive a long time and under extremely harsh conditions and are extremely resistant to heat, cold, and dryness. Freezing doesn’t achieve anything, making it even worse. Heating to boiling point for at least 30 minutes can kill all living form but not the spores which would germinate after cooling. To kill them you have to sterilize them, meaning at 125°C at high pressure. So its easier to avoid the concerned food like nuts, seeds, and dried fruit.
