(57) A method for determining and controlling the proper modified or unmodified atmosphere packaging for cut or uncut respiring perishables such as cauliflower, lettuce and broccoli includes the steps of determining the respiration rate of the respiring perishable, preparing a plurality of packages containing the respiring perishable with each package having a different permeant factor, determining a value called atmosphere quotient for each of the packages according to this formula: atmosphere quotient equals permeant factor divided by respiration rate; subjecting each of the packages to known conditions of temperature and pressure over a known period of time and correlating the subjective and objective indicia of quality, appearance and marketability of the respiring perishable from each package to the atmosphere quotient values determined according to the foregoing formula, and then varying one or more of the values of the components that affect permeant factor to achieve and maintain the optimum value or range of values for atmosphere quotient.