24 months of storage, the values remained fairly constant. The
?Brix at month 0 was 36.06 and at month 24 was 36.63, an increase
of 1.6%. The % Acid increased 9.8% during storage, while the pH did
not change.
The change in color that occurred during storage of the straw-
berry beverage (data not shown) was calculated using Eq. (1):
D E ¼ ½ð D LÞ 2 þ ð D aÞ 2 þ ð D bÞ 2 ?
1=2
ð1Þ
The calculated color difference, D E, was 1.4. A color difference of
around 2.3 corresponds to a ‘‘just noticeable difference’’ (Sharma,
2003). Therefore, the color of the strawberry beverage produced
from the PEF processed strawberry purée remained fairly constant
during the 24 month shelf life.
4. Conclusions
Strawberry purée was pasteurized using a pilot plant PEF sys-
tem. The population of E. coli ATCC 35218 in strawberry purée
was reduced by more than 7 log at 52.5 ?C and 24.0 kV/cm.