Post mortem proteolysis and tenderization of beef muscle through infusion of calcium chloride
Post mortem proteolysis and tenderization of beef muscle through infusion of calcium chloride
olo POLIDORI 0
ssimo TRABALZA-MARINUCCI 0
o FANTUZ 0
o POLIDORI 0
0 Dipartimento di Scienze Veterinarie, Università degli Studi di Camerino , via Circonvallazione 93, 62024 Matelica (MC) , Italy
- A study involving 48 beef carcasses was conducted in order to evaluate the effects of 0.3 M calcium chloride (CaCl2) injection on final tenderness in muscle Longissimus thoracis et lumborum. Injection of beef carcasses with CaCl2 accelerated post mortem tenderization process. Ca2+-dependent proteases (m -calpain and m-calpain) and their inhibitor (calpastatin) activities were all significantly (P < 0.01) decreased in CaCl2 injected animals (n = 24) compared with control animals (n = 24). Tenderness, assessed by measuring shear force, was significantly improved (P < 0.05) by CaCl2 injection both at two and eight days post mortem.
Factors affecting muscle tenderness have
been extensively researched over the past
50 years [11, 15, 19]. Meat tenderness is
primarily determined by two muscle
components such as connective tissue and the
contractile apparatus . Over the last two
decades, most investigations have been
focused on the nature of the changes that
occur at the level of the endogenous
proteolytic systems [1, 4, 5, 10]. The infusion of
CaCl2 or NaCl into carcasses has been used
for acceleration of post mortem proteolysis
and tenderization process [6, 7, 12]. The
present study was conducted to determine
whether the activation of the
calciumdependent proteases I (m -calpain) and II
(m-calpain) is the mechanism through which
infusion of beef carcasses with CaCl2
immediately after death accelerates the
2. MATERIALS AND METHODS
Forty-eight crossbred beef cattle reared
on the same farm were used in this trial. All
animal were slaughtered at a mean body
weight of about 550 kg, and carcasses were
divided into two groups. Twenty-four
carcasses were used as control group
(slaughtered according to normal procedures), and
the remaining twenty-four carcasses were
infused (500 ml) with 0.3 M CaCl2. The
above solutions were infused using a
pumping device (five injection sites, the distance
between each injection site was 7.5 cm) in a
section of the Longissimus Thoracis et
Lumborum (LTL) muscle, 40 cm in length, from
first to the sixth lumbar vertebra .
After completion of the infusion process
(within 45 min after slaughter), infused and
control carcasses were put in a cold room
at a controlled temperature of 2 °C.
Twentyfour h after slaughter, the entire LTL was
removed from each carcass. Samples
designated for shear force determination,
weighing approximately 100 g, were removed
from LTL between the 12th and 13th rib
interface. Chops were taken from the
midregion of each sample and roasted on a metal
tray, according to the procedures of Riley
et al. [
Samples for sarcomere length
determinations were prepared at 48 h after
slaughter, following the procedures of Koolmes
et al. . The Ca2+ dependent proteases-I
(m -calpain), -II (m-calpain) and their
inhibitor were prepared from 100 g of LTL
at 24 h post mortem, according to
Koohmaraie et al. . The total calcium
contents of the LTL was measured using
standard techniques, with an atomic
absorption spectrophotometer .
Data were analysed by the method of
least squares using the general linear model
procedure of the SAS  and results were
expressed as least square means. The
statistical model used in this study was a
simple one way analysis of variance.
3. RESULTS AND DISCUSSION
The calcium content (m g.g–1 wet tissue)
of the carcasses infused with CaCl2 was
significantly (P < 0.01) increased
(approximately · 100) compared to the control
groups (Tab. I), in similarity with the results
obtained by Koohmaraie et al. . In another
study by Koohmaraie et al.  calcium
content in beef loins injected with 0.3 M CaCl2
was increased about 120-fold compared to
the control group.
Infusion of carcasses with CaCl2
significantly (P < 0.05) lowered LTL shear
force values both at two and at eight days
post mortem compared with the control
groups (Tab. I), according to a previous
study  in which shear force values of
lamb carcasses infused with 0.3 M CaCl2
were found to be significantly decreased
both at one and seven days post mortem
compared to the control carcasses. In another
study conducted on beef carcasses , CaCl2
injection of LTL muscle resulted in a
Post mortem tenderization in beef muscle
significant acceleration of post mortem
tenderization as determined by shear force
value at 1 day after slaughter. As previously
reported by Koohmaraie et al. [6, 7], of
several concentrations of calcium chloride
solution examined, a 0.3 M solution was most
effective in reducing shear force value in
The m-calpain activity and inhibitor
activity at 24 h post mortem were lowered
(P < 0.01) in carcasses infused with 0.3 M
CaCl2, while in the treated carcasses there
was no m -calpain activity remaining (Tab. I).
Based on the results of the present
experiment, CaCl2 injection results in activation of
m -calpain and m-calpain, which eventually
results in loss of their activities because of
autolysis [16, 20].
Calcium infusion did not have a
significant effect on sarcomere lengths (Tab. I).
Therefore, differences in shear force values
between treatment groups cannot be
attributed to differences in sarcomere length,
according to the results obtained also in
previous experiments [3, 17] .
The results of this study indicated that
infusion of beef carcasses with calcium
chloride accelerated post mortem tenderization.
The loss of m -calpain activity and the
significant decrease in m-calpain activity
are due to autolysis of these proteases in the
presence of calcium [7, 8]. Based on the
results obtained in the present study, we
suggest that activation of Ca2+-dependent
proteases results in tenderization in meat
tenderness. More research is required to
investigate properties controlling the
Ca2+dependent proteases system to consistently
produce tender meat.
Present study was partially supported by the
University of Camerino, funds 2000, principle
investigator Prof. Paolo Polidori.
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