337Chapter 19
Canned Products and P â t é
Isabel Guerrero Legarreta
Introduction
Canning is probably the most effi cient meat
preservation method. It ensures the destruc-
tion of pathogens and spoilage microorgan-
isms and allows foods to be easily handled
and transported. In addition, canning pro-
vides food for various distribution types:
retail in small can sizes (250 to 500 ml) for
domestic purposes; wholesale (750 ml to 1 L)
for industrial restaurants and central facili-
ties; and for hospitals, schools, and other
institutions (946 ml, 1.89 L, and 3.89 L).
Canned products ’ processing is calculated
according to the expected shelf life: from
semi - preserves requiring further preservation
methods, to full and tropical preserves, with
a shelf life of 4 years at 25 ° C and up to 1 year
at 40 ° C, respectively. Heat treatments are
also applied to develop specifi c sensory char-
acteristics or physical properties, such as gels
in luncheon meats or spreadability in p â t é.
This chapter discusses the theoretical prin-
ciples of thermal treatment and the meat -
canning process. Finally, p â t é fabrication and
quality characteristics are also described.
Effect of Intrinsic and Extrinsic
Meat Characteristics on Meat
Microbial Populations
Microbial communities in foods are not
stable; heterotrophic populations change
with time and the presence of specifi c chemi-
cals. Meat is a very rich substrate, containing
almost all nutrients necessary to support a
wide variety of microbial populations. Raw
materials for canned meats can be previously
processed or refrigerated. The specifi c micro-
bial associations in refrigerated raw meats
are nonfermenting Gram psychrotrophs such
as Pseudomonas, Alcaligens, Flavobacterium,
Shewella, and Moraxella. When the meat is
cured, such as with sausages or other previ-
ously processed meats treated with nitrates,
nitrites, salt, and phosphates, the dominant
bacterial populations change to Gram -
positives, such as Micrococcus, Lactobacillus,
Carnob acterium, and Brochothrix. However,
meat sanitation depends on the destruction
of specifi c microorganisms, particularly
pathogens; shelf - life extension depends on
intrinsic food characteristics, such as chemi-
cal composition and external conditions,
especially temperature, time, and nutrient
availability.
Among spoilage microorganisms in
canned meats, C. thermosacarolyticum is
of the fi rst importance; its spores can survive
and develop at very high temperatures.
Other spoilage microorganisms in meats
are the psychrophiles Pseudomonas sp. and
Achromobacter ; the mesophiles E. coli and
Bacillus subtilis ; the facultative thermophiles
Streptococcus thermophilus and the already
mentioned Clostridium perfringens ; and the
strict thermophiles Cl.thermosaccharolyti-
cum and Bacillus stearothermophilus
(Zamudio 2006 ).
Not all preservation methods are com-
pletely effi cient; generally, more than one
is applied, according to the well - known