I am not sure what IFS requires as to an alert system but I do know how testing food defense as we have done breach consulting with "Get out of Jail Letters." those were the fun assignments!
To do a food defense challenge -- get someone (a friend or contactor that no one at the company knows) and tell them their job is to attempt to breach your property, building, bypass your systems you have set up, etc - in general to gain access to areas your company is suppositly defending
Have that person document the entire exercise (body cam would be great for this) in forensic format.
Be sure to give the person a letter with your info on it in case your personnel call the police - we forgot this step on our first breach exercise of a bonded food warehouse in California! 
Edited by SQFconsultant, 03 July 2020 - 12:26 PM.