Abstract
In this study, we investigated the effects of an ultrasonically activated stream (UAS)
on the removal of microbial contaminants from spinach leaves. The microbial loads
on samples cleaned with and without UAS were enumerated using the cell culture method
and compared against unwashed samples on day 0 and day 6 after cleaning. The effects
of UAS cleaning on leaf quality were also examined through both macroscopic and microscopic
inspection, as well as measurement of the electrolyte leakage rate. Results showed
that the microbial load on samples cleaned with UAS for 2 min was significantly lower
on day 6 after cleaning than on those treated without ultrasound. Comparison between
the cleaning effects of UAS for 40 s versus 2 min indicated that a cleaning duration
of 2 min allowed sufficient time for UAS to disaggregate and detach the microbial
contamination more effectively. In this case, the induction of bacteria into a viable
but non-culturable state does not affect the shelf-life test results as much as it
does with a 40 s clean. UAS cleaning for 2 min did not produce significant surface
damage, which can affect overall leaf quality. These findings highlight the potential
of UAS systems in the salad industry to improve the microbiological quality and shelf
life of salads.
Key Words
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Article info
Publication history
Published online: February 25, 2021
Accepted:
January 24,
2021
Received in revised form:
January 8,
2021
Received:
September 17,
2020
Identification
Copyright
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