Thermal Processing 177the product during cooking helps improve
juiciness (Ritchey and Hostetler 1965 ) but
also helps with the profi tability of producing
cooked, further processed products. Cooking
temperature (Loucks et al. 1984 ; Shin et al.
1992 ), cooking rate (Hearne et al. 1978 ;
Boles and Swan 2002a ), and fi nal internal
temperature (Ritchey and Hostetler 1965 ;
Laakkonen et al. 1970 ; Beilken et al. 1986 ;
Fjelkner - Modig 1986 ) all affect cook yields.
Increased cooking temperatures result in
higher temperature gradients from the outside
to the inside of the processed products.
Increased surface temperature during frying
resulted in increased evaporative losses but
had little effect on the water drip loss from
the product (Oroszv á ri et al. 2005b ). Hearne
et al. (1978) however found greater evapora-
tive and total cooking losses when meat cores
were heated at a slow rate compared with a
faster rate of cooking.
Laakkonen et al. (1970) reported weight
loss of meat pieces increased almost linearly
to the seventh hour of cooking and remained
relatively constant after that as the samples
were held at 60 ° C. Ritchey and Hostetler
(1965) observed that as internal temperature
of steaks increased, the cooking losses also
increased. Fjelkner - Modig (1986) reported
increased cooking losses from 15% to 25% –
30% as internal temperature of pork increased
from 68 ° C to 80 ° C. Internal product tem-
perature can affect the type of losses seen
from meat. Hearne et al. (1978) reported
evaporative losses were greater when cores
were cooked to higher internal temperatures.
Bengtsson et al. (1976) reported increased
cooking loss as the time of cooking and inter-
nal temperature increased. These researchers
found evaporative losses created an almost
straight line, indicating that evaporation
occurred from the wet surface of the meat for
the entire cooking time and that surface
temperature was therefore below the oven
temperature. Additionally, these researchers
reported that most of the losses occurring
between 65 ° C and 70 ° C were evaporativeproducts like hamburger patties or fresh
pork sausage patties. Cooking has a lesser
effect on whole - muscle products, but it still
happens. The change in dimension is caused
by moisture loss and changes at the myofi -
brillar level. Boles and Shand (2008) reported
dimensional changes of stir - fry slices were
affected by both meat cut used and slice
thickness. The greatest dimensional changes
(esp. shrinkage of length and width) were
observed in slices made from the inside and
outside round. Samples that had intact con-
nective tissue around the slices had less
dimensional changes, suggesting that intact
connective tissue may have some impact on
the dimensional changes observed. Bouton et
al. (1976) reported that connective tissue had
a major impact on the dimensional changes
in meat. Collagen shrinkage with increased
cooking temperature will contribute to
dimensional changes seen in a meat product.
As slice thickness increased (2, 4, or 8 mm),
the changes in length and width were reduced.
As the slices became thinner, there would
be less water available to migrate to the
surface, causing fi bers to become drier and
shrink more on heating, increasing cook
loss and dimensional change (Boles and
Shand 2008 ). Bouton et al. (1976) reported
increased myofi brillar contraction as end -
point temperature increased. This change in
contraction was associated with increased
cooking loss. Bouton et al. (1976) suggested
that changes in meat fi bers ’ length happened
in three zones. Temperatures between 40 ° C
and 45 ° C resulted from changes in the myo-
fi brillar structure, while changes between
55 ° C and 60 ° C were primarily caused by
changes in collagen, and above 70 ° C were
both from myofi brillar and connective tissue
changes.
Cooking Losses
Cooking losses or cook yields are very
important in processed products as well as
fresh products. Maintenance of moisture in