can recover quickly after HPP treatment at 500 MPa. When the
samples were treated at 900 MPa pressure a significant (p< 0.05) reduction of TVC of log 2–3 was observed when compared to the nonpressure treated samples on day five. The reduction was 2.2 log after 10 s, 2.7 log after 20 s, 1.6 log after 30 s and 1.9 log after 60 s (Table 3) indicating a better effect when the treatment time was shorter. It should be pointed out that the number increased more rapidly after treatment at 500 MPa time indicating that the cells are more damage after treatment at 900 MPa. The effects on LAB count
were very clear. After treatment at 900 MPa 2.9–4.1 log decrease was observed and after storage for 26 days the count was 0.7–2 log lower after treatment for 30 and 60 s compared to 10 and 20 s indicating better effect after longer treating time. The HPP treatment had significant (p< 0.05) effect on the growth of LAB, both at 500 and 900 MPa and it was obvious that the recovery after 900 MPa treatments
was difficult. A reduction of 4 log was observed after treatment
time for 20–60 s at 900 MPa. After storage for 26 days the LAB
count was 3.4–6.1 log cfu/g in 500 MPa treated samples compared to 8.1 log cfu/g in untreated samples indicating that LAB are sensitive to HPP treatment. The number of LAB on NAP was up to 1.2–4 log higher than total count on LH after treatment at 500 MPa.The difference was not as high after 900 MPa. The increase of LAB was considerably faster after HPP treatment at 500 MPa (Table 2) indicating that they