부산대학교 도서관

The effect of fat globules contained in milk on sterilization using intense pulsed electric field (PEF) is described. PEF with a pulse width of 2 µs and an electric field of 25 kV/cm were applied to four types of bacterial liquids (Listeria innocua, 108 CFU/mL) including carboxymethyl cellulose (CMC) solution, skim milk, homogenized and non-homogenized milk. Temperature history of bacterial solution was precisely controlled so as to be the same under all treatment conditions. The bactericidal effect of PEF was weakest in the non-homogenized milk, whereas it was strongest in the CMC solution. Numerical analysis of the electric field suggests that a fat globule distorts the surrounding electric field and produces the region with the reduced electric field, where bacteria receive less stress. Volume of the region with reduced electric field greatly depends on the diameter of the fat globule. This analysis coincides the experimental results.