pH changes in the conversion of muscle to meat
True or False? pH fall post exsanguination is caused by the formation of lactic acid from glycogen through anaerobic glycolysis
The rate of pH drop and the ultimate level (or pHu ) is affected by a variety of factors, let's take a few minutes to recap.
During early post-mortem changes in the muscles of slaughtered animals, the pH falls from around 7.00 - 7.20 in the muscle of a living animal to 5.30 - 6.80 as its final value. This final value is called ultimate pH (pHu).
Ultimate pH values are reached at different post mortem times depending on:
- muscle type
- stress immediately preslaughter
- stress over the preslaughter period
The reason for the pH fall is the formation of lactic acid from glycogen through anaerobic glycolysis.
A normal pH decline in pork longissimus muscle is represented in Figure 2.
Normal decline is characterised by a gradual decrease from approximately pH 7.0 in living muscle to a pH of about 5.6 to 5.7 within 6 to 8 hours post-mortem, and then to an ultimate pH of about 5.50.
- In beeflongissimus muscles the ultimate pH of 5.5 - 5.6 occurs at 18 - 24 hours post mortem.
- In chickenlongissimus ultimate pH values are usually higher, ending at pH 6.00 or more at 2 - 4 h post mortem under commercial chilling conditions.
Did that section make sense? Why not take this opportunity to test your understanding with the following?
Please read the statement then choose whether it is true or false.
The normal final pH value in pork or beef is between 5.50 and 5.90.