THE COMBINED EFFECT OF PULSED ELECTRIC FIELDS AND CONVENTIONAL HEATING ON THE MICROBIAL QUALITY AND SHELF LIFE OF SKIM MILK

摘要

The effect of pulsed electric fields (PEF), conventional heating (H) at 60 or 65C for 21 s and PEF + heat (PEFH) treatments on the total growth of aerobic bacteria and the shelf life of skim milk was investigated. The PEF-processed skim milk was equivalent to conventionally heat-treated skim milk. After 14 days of storage, PEF-processed skim milk exhibited a total bacteria count of 5.4 log cfu/mL when treated at 28, 32 and 36 kV/cm for 84 μs, whereas heat-treated skim milk exhibited 5.9 and 5.3 log cfu/mL. PEFH treatment of skim milk produced a superior product in bacterial and shelf-life quality compared to either PEF or conventional heating alone and prolonged the shelf life of skim milk to 30 days when stored at 4C. Thus, the shelf life of skim milk stored at 4C was extended beyond 14 days.