Heat resistance of Lactobacillus spp. isolated from Cheddar cheese

Mesophilic Lactobacillus spp. are the dominant organisms in mature Cheddar cheese. The heat resistance of broth grown cultures of Lactobacillus planta rum DPC1919 at temperatures between 50 and 57.5 degrees C, Lact. plantarum DPC2102 at temperatures between 48 and 56 degrees C and Lact, paracasei DPC 2103 at temperatures between 50 and 67.5 degrees C was determined. The z-va lues for Lairs. plantarum DPC1919, Lact. plantarum DPC2102 and Lacs. paraca sei DPC2103 were 6.7 degrees C, 6.2 degrees C and 5.3 degrees C, respective ly. Lactobacillus paracasei DPC2103 showed evidence of injury and recovery, especially at higher temperatures, Milk grown cultures of strains DPC2102 and DPC2103 showed greater beat resistance than broth grown cultures, raili ng of the death curves and a nonlinear z-curve. Of the three strains, Lact. paracasei DPC2103 had the potential to survive pasteurization temperatures , whether grown in milk or broth.