Heat-induced Toughening in the Semitendinosus Muscle of Beef Carcasses Held at Pre-rigor Room Temperature in Ethiopia

Abstract

Carcasses from some Ethiopian public abattoirs are stored at room temperature for six
to twelve hours before being sent to butcher shops where they are sold. The purpose of
this study was to examine the effects of age, breed, and pre-rigor room temperature on
the instrumental properties of the semitendinosus muscle. The blood samples, pH, and
meat samples (48) were collected from 24 carcasses obtained from four cattle breeds
under two age categories. The samples were held at pre-rigor room (24) and chill (24)
temperatures for 24 hours and aged for 7 days to evaluate tenderness using Warner
Bratzler-Shear Force, water holding capacity, cooking loss, thawing loss, and color
(L*, a*, b*). The results of the study revealed that the post-slaughter 6-hour mean
temperature and pH of samples held in the pre-rigor room and chill temperatures were
29.5 0.79 °C, 6.09 ± 0.05, and 25.35 0.97°C, 6.02 ± 0.04, respectively. The
proportion of heat-induced toughening for semitendinosus muscle held at pre-rigor
room and chill temperature were 12.5% and 4.2%, respectively. Heat induced
toughening differed between breeds and age categories. Tenderness of muscle samples
held at pre-rigor chill temperature was tender (36.05±1.22 N) while samples held at
pre-rigor room temperature were intermediate (40.38±1.42 N). The water holding
capacity of the muscle samples held at pre-rigor room temperature ranged from 62.83
to 73.2% while for samples held at pre-rigor chill temperature water holding capacity
increased from 69.2 to 73.33%. Higher thawing and cooking losses were observed for
samples held at pre-rigor room temperature compared to chilled one. In conclusion,
keeping carcasses at pre-rigor room temperature has contributed to lowering the
quality of beef produced at public abattoirs. It was recommended that a good practice
of keeping carcasses at pre-rigor chill temperature until rigor mortis resolute need to
be introduced in public abattoirs before being dispatched to butcher shops