Reduction of bacterial counts and inactivation of enzymes in bovine whole milk using pulsed electric fields
2014
Sharma, Pankaj | Oey, Indrawati | Bremer, Phil | Everett, David W.
Bacterial count reduction and enzyme inactivation in bovine whole milk by pulsed electric field (PEF) processing combined with pre-heating and intermediate cooling was compared with that induced by thermal treatments (maximum of 63 °C for 30 min and 73 °C for 15 s). Milk was pre-heated to 55 °C for 24 s and PEF-treated in continuous mode at electric field intensities of 15.9–26.2 kV cm−1 for 17–101 μs. PEF treatments reduced the number of inoculated (8.3 log cfu mL−1) Escherichia coli and Listeria innocua to less than 2 log cfu mL−1. PEF treatments at 20.7–26.2 kV cm−1 reduced the total plate count and indigenous alkaline phosphatase activity to a level similar to that measured following thermal treatments. Treatment at 26.1 kV cm−1 for 34 μs, combined with pre-heating, reduced the activity of plasmin, xanthine oxidase and lipolysable fat by 12%, 32% and 82%, respectively, compared with raw milk.
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