ANSC 3700: Week 6 Postmortem Muscle

Lactic Acid

What is the byproduct of anaerobic respiration that causes a pH drop in meat?

7.4

What is the pH of living muscle?

5.6 within 6-8 hours

What is a normal post-mortem pH?

Isoelectric point

pH at which a molecule carries no net electrical charge or is electrically neutral

5.1

What is the isoelectric point in meat?

PSE

What would meat with a pH of 5.3 be considered?

DFD

What would meat with a pH of 6.0-6.5 be considered?

Pork

What species is problematic when it comes to having too low of a pH in meat?

Protein Denaturation

High temperatures during processing can lead to ______ ________.

1.Delay

-ATP available, replenished with CP

-Muscle extensible and elastic

2.Onset

-ATP becomes limited

-Begins to lose extensibility

3.Completion

-ATP exhausted, permanent cross-bridges

-Muscle completely inextensible

4.Resolution

-Muscle fibers tear at Z-lines

-Some extensibility returns

What are the 4 stages of Rigor Mortis?

The animal loses all of its methods for protecting itself, such as its hide, lymphatic system, etc.

What is a food safety issues that arise during the conversion of muscle to meat?

Breakdown of Z-Lines

How is tenderness and extensibility regained after rigor mortis has completed?

Calpains

What is the calcium activated enzyme that is responsible for the breakdown of Z-Line proteins?

Calpastatins

What are calpain inhibitors?

Cathepsin

What is the lysosomal protease that can break down troponin, nebulin, titin, and tropomyosin?

Papaya

What fruit produces papain?

Pineapple

What fruit produces bromelain?

Figs

What fruit produces ficin?