304 Chapter 16
and (3) heating by steps ( Δ T) that consist of
an increase in the internal temperature of the
ham through steps, not exceeding 25 – 30 ° C
each time. This process avoids excessive
heating of the surface of the ham. An example
of the heating profi le for this type of treat-
ment is shown in Figure 16.2 B. The cooking
effi ciency, weight loss, and yields may be
different for the last two cooking methods
(cooking at a fi xed internal temperature and
cooking by steps) as shown in Table 16.1. It
has been reported that slow heating rate
forms a protein network with better water
binding and less jelly losses. This means low
cooking damage, a more tender product, and
better slice cohesion (Desmond and Kenny
2005 ). Several enzymatic reactions, oxida-
tions, Maillard reactions, etc., take place in
the hams during cooking, and all of them
contribute to the fi nal development of sensory
characteristics typical of cooked hams
(Toldr á 2006b ). So, the conversion of cre-
atine into creatinine was reported to be pro-
portional to the heating intensity, and the
creatinine - to - creatine ratio in the surface of
the ham could be used for control purposes
as an effective indicator of the internal tem-
perature reached within the ham (Mora et al.
2008a, b ).Cooling
Cooling is also a delicate stage to ensure the
wholesomeness of the hams. Cooling must
achieve temperatures of the ham below
4 – 5 ° C, and this may be achieved by air blast,
immersion in cold water, or with cold water
showers. Examples of cooling profi les of
hams are shown in Figures 16.2 A and 16.2 B.
The fi nal cooling from 40 to 15 ° C is consid-
ered the most critical period and should
be restricted to less than 4 hours when pos-
sible (Desmond et al. 2000 ). Slow cooling
conditions may be dangerous, due to the
long periods at relatively high temperatures
when microorganisms might grow. Vacuum
cooling was reported to offer reduced coolingunder vacuum to avoid further undesired oxi-
dations and improve salt diffusion. The treat-
ment may be continuous, or it may alternate
tumbling and resting. The tumblers may have
inner baffl es to optimize the homogenization
of the brine inside the hams.
Cooking
This is a delicate stage that requires a rigor-
ous control of time and temperature to
achieve the fi nal desired effect and ensure the
wholesomeness of the product (Ponce -
Alquicira 2005 ). The aim of heat treatment is
microbial destruction and enzyme inactiva-
tion. The heat treatment is calculated in order
to combine the maximal inactivation of
pathogen and spoilage microorganisms for
an extended shelf life of the product with
minimal effect on the sensory characteristics
(Guerrero - Legarreta 2001 ).
Boned hams are canned in special molds
that will give the fi nal shape. Hams can
optionally be packaged in special plastic that
allows a better water retention (zero water
loss) and hygienic storage and distribution.
Cooking can be considered as pasteurization,
since internal temperature of the ham reaches
up to 72 ° C for 30 to 60 minutes. Cooking is
usually performed in hot - water baths. There
are two heat transfer mechanisms: convec-
tion (heat transfer from the heating medium
to the ham surface) and conduction (heat
transfer mechanism from the ham surface to
the inner areas) (Guerrero - Legarreta 2006 ).
The speed of temperature increase and its
control during cooking is important. So,
cooking can be operated in three ways
(Toldr á 2007 ): (1) heating at a fi xed tempera-
ture where the ham may not reach the wished
internal temperature; (2) heating until reach-
ing a determined temperature inside the ham
(usually 68 ° C), but this process may give
some excessive heating of the surface of the
ham by over - exposure to the heating medium
(an example of the heating profi le for this
type of cooking is shown in Figure 16.2 A);