PHYSICAL MEASUREMENTS OF MEAT QUALITY - OPTICAL MEASUREMENTS, PROS AND CONS

This review describes recent progress in understanding the optical properties of meat and considers how optical properties of meat might be used for quality control in the meat industry. The birefringence of myofibrils changes with pH so that, as the pH decreases towards the isoelectric point, the optical path difference increases. Thus, transmittance through muscle fibres is decreased and scattering of light in meat is increased. New ways have been found to monitor pH-related paleness by measuring the light scattered at different wavelengths and angles through the meat. A probe for the optical detection of subcutaneous fat depth in carcasses has been modified so that now it detects the distribution of collagen. UV light is reflected from a dichroic mirror into an optical fibre in the probe, and the fluorescence of connective tissue passing by the optical fibre is detected. Although these and other methods for the optical measurement of various aspects of meat quality are technically very promising, there are formidable problems to be overcome in developing a commercial application. A major industrial commitment to measuring meat quality in individual carcasses is required, together with a willingness to invest in the development of new technology.