In compliance with the FDA requirement
of a 5 Log reduction of microorganisms
in fruit juices and beverages
The conditions adopted in the present research for the recovery of
L. monocytogenes injured cells confirmed their effectiveness,
allowing the sub-lethal injury evolution in the surviving population
to be followed as the severity of the treatment increases. Additionally,
fluorescent cell staining methods provide additive information
on the injured cell physiology.
To the best of our knowledge, while some authors obtained
promising results applying pressures as high as 600 MPa at room
temperature, little is known about the effects of sub-zero temperature
HHP treatments on the maintenance of the organoleptic and
functional traits of smoothies, and such an intriguing aspect remains
to be investigated.
Concerning the problem of sub-lethal injured cells, their
behaviour during the storage of the smoothies should not be
overlooked. Such an intermediate physiological state prevailing in
the survivor population of the most effective treatments could be
recovered by the residual metabolic activity in permissive environmental
conditions, which differs from the conditions of
smoothies. These aspects have been investigated in our laboratory
(Zacconi & Scolari, submitted for publication) as an important
factor in determining the applicability and safety of pressure
treatments in the smoothies industry