The pre-treatment method does not significantly influence moisture content decrease from berries
during drying in a vacuum-microwave drier (drying time was 82±2 min); however the drying time for
convective dried halved berries was 36±1 h, for steam-blanched í 38±1 h and for perforated í 74±1 h.
Very similar vitamin C content was detected in fresh cultivated cranberries of the varieties: ‘Stevens’,
‘Bergman’ and ‘Ben Lear’ comparing to vitamin C content in fresh wild cranberries. The lowest vitamin
C content was detected in fresh wild cranberries and cultivated fresh cranberries of the variety ‘Early
Karina Dorofejeva et al. / Procedia Food Science 1 (2011) 433 – 440 439
Black’. Correlation was not found between vitamin C losses, cranberry variety and cranberries’ pretreatment
method during drying in convective and in vacuum microwave driers. With the probability of
95%, detected by means of the analysis of variance, it may be presumed, that pre-treatment method of
cranberries influenced vitamin C decrease during convective and vacuum-microwave drying (P=0.00 <
D=0.05). Vacuum microwave drying method could be recommended for drying of cranberries, it is found
to be less time-consuming and simpler way of processing: drying time of berries in a vacuum-microwave
drier was shorter (82±2 min), pre-treatment is not necessary comparing to drying in a convective cabinet
drier (36í74 h) and vitamin C decrease could be smaller.