Dear eschorr,
Which para. of iso22000 are you referring ?
The generic answer depends on what the objective of yr sampling / analysis actually is. This may relate to the above query. It may also relate to the context, eg known variability of yr target parameters, volumes involved.
I daresay yr purchase specification utilizes a nmMc type format for certain micro.parameters.
If so support for lot compliance to specifications minimally involves sampling as per yr specification. As an example can refer to the list of EU microbiological specs for foods. Such a method has well-known limitations but still remains a standard procedure for logistical reasons, inter alia.
Alternatively could use a MIL STD type approach in a variables type format but not so meaningful for zero-tolerant items where the c=0 style is more useful.
Alternatively could be simply ad hoc, sort of like previous suggestion.
In-house facilities tend to do it day-by-day or week-by-week as required. So closer control is theoretically possible. However micro.analysis is slowwwww. Some pathogens can easily take up to a week if using traditional methods.
ISO probably don’t care how you do it (it's a generic standard ) as long as you can VALIDATE what you are doing. Unless the relevant iso22000 para. (??) restricts the options ?
Rgds / Charles.C