Standard advice is rolling boil for 1 minute (this is overkill)

Log reduction rates
1log reduction = 90%
2log reduction = 99%
3log reduction = 99.9%

The log reduction rate for pasteurisation is 5log

The reason why a rolling boil is recommended it's because there is no need to monitor temperature or calculate log rates

WAPI units simplify this, it's a small tube with soybean wax designed in such a way that it requires heating at 150f for 5 minutes before it will melt, so if it's melted 5log has been achieved, In a continuous heat scenario in the field it's likely results would be greater than 5log.

Fuel efficiency doesn't always correlate to flame size
160f
Very low flame - 5m15s - 5g spent
Low flame - 3m38s - 5g spent
Medium - 2m36s - 6g spent
High flame - 2m11s - 7g spent

Boil 3 add 1 method
Boil 750ml then add 250ml should lead to pasturisation
for sea level boil 5 add 2