Biochemical processes are controlled by detecting a plurality of selected controllable variables and dependent variables and actuating controllers for maintaining said controllable variables within predetermined tolerance values in response to said detected controllable variable values and a time profile of each of said tolerance limits. On-line, real-time computer calculations are performed to determine the status of said process from said detected dependent and controllable variable values. Said controllers may be manually or automatically actuated in response to said calculated status, or the timeprofiles of the tolerance values may be automatically or manually adjusted in response to said calculated status.