3.5.2.2. Antimicrobial activity in salads. In our study, the antimicrobial
activity of the active film was also assessed in the packaged
salad. Changes in the microbial population of the salad during
storage time are presented in Fig. 2. In general, the microbial counts
had significant differences (p < 0.05) during storage time and by
packaging treatment. The antimicrobial properties of the films incorporated with Proallium® were significantly higher than the
controls. The storage Enterobacteriaceae counts increased gradually
in the packaged salad at 4 C and reached maximum levels of
8.08 log units (Fig. 2A). All developed films decreased enterobacterial
growth in comparison with the control, and this reduction
was related to the concentration of Proallium® in PLA. The cell
densities at the end of storage were 7.74, 7.48 and 7.30 log units for
PLA containing 2%, 5% and 6.5% of Proallium®, respectively. While
the bacterial counts are fairly high, it is important to note that high
levels of enterobacteria are common in raw vegetables, and it has
been reported that they should not be used to indicate the microbiological
quality of fresh vegetables (Little, Roberts, Youngs, &
Louvois, 1999). Regarding aerobic bacteria, although PLA 5%
(p < 0.05) and 6.5% (p < 0.01) Proallium® were able to decrease the
bacterial counts after 3 days of storage, only the film with the
highest concentration of active agent (6.5%) was found to be
effective up to 5 days of storage (Fig. 2B). The results showed that
yeasts were able to grow in the control salad at 4 C and reached
maximum levels of 5.70 log units (Fig. 2C). All samples packaged
with active film had antifungal activity throughout the storage
time, and this activity reached a maximum by the fifth day
(p < 0.01). With respect to moulds, salad packaged with active films
(5% and 6.5%) had lower counts on the third day compared with the
control group and at 6.5% throughout the 7 day period (Fig. 2D).