Progress in understanding the paleness of meat with a low pH: keynote address

Abstract

Meat with a low pH is generally paler than at a high pH. Paleness related to pH is caused by light scattering. Myofibrils are a primary cause of pH-related light scattering in meat, but light scattering is also related inversely to sarcomere length. We do not yet know the relative importance of surface reflectance from myofibrils vs. refraction through the depth of myofibrils. Precipitation of sarcoplasmic proteins is added to myofibrillar scattering when pH is extremely low, or when pH reaches low levels while meat is still hot. Scattering tends to decrease the length of the light path through meat. This reduces selective absorbance by myoglobin. Thus, the colour of meat is more conspicuous when pH is high. Recent experiments show a direct contribution from mitochondria to the optical properties of meat. Progress in this subject helps explain meat colour and may help us improve optical methods for predicting meat quality on-line.


South African Journal of Animal Science Supp 2 2004:1-7