intense pineapple tissue respiration within the sealed pack. To this
regard, oxygen resulted completely consumed within 5 days of
storage, both in untreated and UV-C light treated pineapple sticks
trays (Fig. 3). This result suggests that a 200 J/m2 UV-C light
treatment did not modify the physiological respiration of the
packaged fresh-cut fruit. Similar results were obtained by
Chonhenchob et al. (2007), who observed a rapid consumption of
head space oxygen of fresh-cut pineapple packaged in PET trays
stored for 6 days.
Complete depletion of oxygen within the sealed trays (Fig. 3)
would favour lactic acid bacteria development during storage
(Ahvenainen, 1996). As expected, lactic acid bacteria count
increased during storage and, after 15 days, reached 4.3 ± 0.2 Log
CFU/g in untreated pineapple sticks and 2.5 ± 0.4 Log CFU/g in UV-C
light-treated ones. As previously observed for yeasts (Fig. 2), also
lactic acid bacteria counts of UV-C light treated samples resulted
about 2 Log lower than those of untreated ones. These data indicate
a higher microbial stability of the UV-C light treated pineapple
sticks during storage. This result apparently contradicts data
showing no decontamination effect just after exposure of pineapple
sticks to UV-C light (Tables 1 and 2). Due to the peculiar structure of
aggregate fruitlets in pineapple, microbial contamination is not
limited to the stick surface. However, microbial analyses were
performed on the entire fruit tissue and not only on a thin surface
layer. It is thus reasonable that the eventual decontamination effect
of UV-C light on pineapple surface was hidden by the overall microbial
count of the entire tissue (Tables 1 and 2). When the product