EFFECTS OF MICROFLUIDIZER(R) TECHNOLOGY ON BACILLUS-LICHENIFORMIS SPORES IN ICE-CREAM MIX

We studied the effect of Microfluidizer(R) technology (sometimes refer red to as ''microfluidization''), a new ultra-high pressure homogeniza tion process, on spores of Bacillus licheniformis in ice cream mix. Fo ur batches of pasteurized ice cream mix were preheated to 33, 36, 44, or 50 degrees C, and spores of B. licheniformis were added to yield an inoculum of 2.0 x 10(4) spores/ml of mix. Samples were treated at 50, 000, 100,000, 150,000, and 200,000 kPa. Respective percentages of spor e destruction ranged from 6 to 68%. As process pressure in the Microfl uidizer(R) system increased, the temperature of the product also incre ased. At the Microfluidizer(R) system outlet, temperatures ranged from 46 to 88 degrees C. Therefore, a combination of forces, including hig h pressure and temperature, likely had a multiplier effect on spore de struction during Microfluidizer(R) processing of ice cream mix. Data s uggest that it might be possible to design a pasteurizer-Microfluidize r(R) system that would inactivate most bacterial spores in dairy foods without the extreme heat treatment currently required in commercial p rocessing operations.