Milk preservation using pulsed electric field-an alternate to pasteurisation

Raw milk is not commercially available. Pasteurisation of raw milk not only kills harmful bacteria but also kills the beneficial bacteria. Several of milk's natural components including beneficial bacteria, food enzymes, natural vitamins and immunoglobulin are heat sensitive. These health-promoting components of natural raw milk are destroyed by heating and therefore not present in pasteurised milk. All health-promoting components in milk are retained when it is processed in pulsed electric field where there is no generation of heat. Voltage pulses of 35KV/cm, 400 square pulses of 2.5 microseconds pulse width were applied to the raw milk filled in a parallel plate pulsed electric field processing chamber. Physico chemical parameters (pH, acidity, TSS), microbiological parameters (SPC, coliform), were studied before and after processing. Sensory attributes and shelf life studies were conducted after treatment. It was found that there was no change in physico chemical parameters before and after treatment. It was found that the SPC count was less than 15000 cfu/mL and no coliforms were found. The shelf life of milk at 4°C could be extended to 28 days.