Rule 32.9.503 - OPERATIONS AND OPERATING PROCEDURES- PASTEURIZATION(1) The milk or cream must be pasteurized at the plant where the milk or cream is processed into the finished product.(2) The cream for buttermaking must be pasteurized at a temperature of not less than 165° F. and held continuously in a vat at such temperature for not less than 30 minutes; or pasteurized by HTST method at a minimum temperature of not less than 185° F. for not less than 15 seconds; or it must be pasteurized by any other equivalent temperature and holding time which will assure adequate pasteurization. Additional heat treatment above the minimum pasteurization requirement is advisable to insure improved keeping-quality characteristics. Adequate pasteurization control must be used and the diversion valve must be set to divert at no less than 185° F. with a 15-second holding time or its equivalent in time and temperature to assure pasteurization. If the vat or holding method of pasteurization is used, vat covers must be closed prior to holding period to assure temperature of air space reaching the minimum temperature before holding time starts. Covers must also be kept closed during the holding and cooling period.(3) The pasteurization of cream for plastic or frozen cream must be accomplished in the same manner as in (2) above, except, that the temperature for the vat method may be not less than 170° F. for not less than 30 minutes, or not less than 190° F for not less than 15 seconds or by any other temperature and holding time which will assure adequate pasteurization and comparable keeping-quality characteristics.Secs. 81-2-102, 81-22-102 MCA; IMP, Secs. 81-2-102, 81-22-102 MCA;