Which agents or method I applying to neutralizing penicillin antibiotics to highest recovery from products for enumeration test?
Aseptically dilute your sample with diluent containing beta-lactamase or penicillinase prior to performing your test
The neutralizer add before pouring the medium?
If your goal is enumeration I would suggest membrane filtration technique instead of pour plate. If no other possibility then add neutralizer to sample or add it to the medium, before pouring