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September 06-08, 2018 | Edinburgh, Scotland
Food safety and Hygiene
International Conference on
Journal of Food Technology and Preservation | ISSN: 2591-796X | Volume 2
Process optimization with a single screw extrusion of low moisture food
Andy Moreno
USA
Since extrusion is the major thermal process used in 95
percent of all pet food production, the primary issues are
the retention time in extrusion thermal processing and the
monitoring of the temperature along the extruder barrel as
measured at the highest level in the extrusion process (Rokey,
& Baldwin (2013); Pet food Industry, 2013). Salmonella is
known to be extremely resistant to lethal treatments in low-
moisture foods (Carrasco, et al., 2012).
The heat resistance of Salmonella is affected by many
factors, mostly by strain and serotypes tested, previous
growth and storage conditions, the physical and chemical
food composition, test media, and the media used to recover
heat-damaged cells. Salmonella heat resistance generally
increases with reducing moisture (Podolak, et al., 2010).
Salmonella survivor cells can enter a viable but nonculturable
(VBNC) state, which is a dormant state of the vegetative cells
and a survival strategy for many nonsporulating bacterial
species (Podolak, p. 1927)
• Issues to consider in optimizing the lethality step against
these “survivor” Salmonella cells:
• Is any unprocessed material bypassing the lethality
(cooking) step (Podolak, p. 1921)?
• Since the lethal damage occurs during the dehydration
process, more rapid cell destruction may occur at
temperatures lower than 700C (Podolak, p. 1924).
• Are sublethally injured cells revived post-processing
treatment because of moisture (Podolak, p. 1927)?
• Could agitation of the suspension before heat treatment
enhance the lethal effect of the heat process, kill step
(Podolak, p. 1928)?
• Could the thermal death time be experimented with to
determine optimal kill effects (Podolak, p. 1928)?
• Has the heat resistance of the Salmonella pathogen
in the specific low-moisture product(s) been studied
specifically, rather than applying published D- and z
values from the literature (Podolak, p. 1932)?
• Was the oxygen and moisture content examined as
elements of Salmonella survival of sub lethally heat-
damaged cells (Podolak, p. 1927)?
• Are any aerosols created which could cross-contaminate
the produce post-lethality step(s) (Carrasco, et al., 2012,
p. 547)?
• Has the water and soil involved the lethality step(s)
been tested for the presence of Salmonella (Carrasco,
et al., p. 549)?
• Has the particle density and fat content been optimized
to increase lethality (Carrasco, et al., p. 549)?
• Is there evidence of biofilm formation in the post-
lethality step(s)/areas (Carrasco, et al., p. 551)?
e:
Food Safety 2018, Volume 2
DOI: 10.4066/2591-796X-C1-003