APPLICATION OF HIGH ELECTRIC FIELD PULSE TECHNIQUE FOR MICROBIAL INACTIVATION IN MILK

Milk contains a high level of nutrients such as protein, calcium, vitamin A and vitamin B12 which are beneficial for human consumption. However, the conventional thermal process for reduction of microbial contamination in milk results in destruction of some important nutritional values of the milk. The aim of this research was to study alternative nonthermal processes for reduction of contaminating microbes using high electrical field pulse (HEFP) treatment of ultra filteredmilk. A preliminary investigation of biological and physiochemical characteristics in raw milk was carried out. The milk was first subjected to ultrafiltration treatment and then to HPEF treatment for one minute in a TEFLON treatment chamber at 25 degrees C. The ultrafiltration treatment succeeded in reducing the amount of protein to appropriate amount for HPEF applicationand lipid in the milk. The results from ultra membrane filtration of the raw milk showed a reduction of total solids by approximately 13.05% when the milk was passed through 0.7 and 0.4 tm membranes. The effect of HPEF on bacterial reduction in the ultrafilration treated milk was then studied over the following ranges of applied pulse intensities and number of pulses: applied intensity: 0, 40, 60, 80, and 100 kV/cm, number of pulses: 1, 30, 50, and 150 in the one minute treatment period. The results showed that application of 100 kV/cm and 30 pulses resulted in 9.93% death of E.coli but only 7.94% death of S. Typhimurium. A statistical analysis showed that increasing the electric Field intensity significantly increased the death percentages of both bacteria with p = 0.039 and p = 0.043, respectively.