The application of P improved tenderness of the ST muscle. The reason
why only the ST muscle was affected by the stunning could be explained
by the differences in metabolic and contractile properties between
both muscles. It is well accepted that the ST muscle is mainly involved
in locomotion and exercise during pre-slaughter handling. Thus, the
response given—by both muscles as a result of different pre-slaughter
and slaughter condition—could also be influenced by their activities.
Most of the colour values (L*, a*, b*, hue and chroma) of both muscles
remained unaffected by the various stunning methods; however, they
appeared redder (greater a* value) when the animals were subjected
to thoracic sticking following the application of LPPS and PS stunning.
Furthermore, penetrative stunning followed by thoracic sticking (PS)
also reduced cooking loss and lipid oxidation while improving waterholding
capacity and tenderness. The lowered TBARS level highlights
the benefits of PS in reducing lipid oxidation in beef. This could be
explained by the higher percentage of blood loss following LPPS
and PS, compared to unstunned slaughter followed by penetrative
stunning (US) (Figure 5). The findings further support earlier reports
that residual blood in the carcase and meat determine their stability
and shelf life.