Teruo Nakayama

RELATIONSHIPS BETWEEN BINDING QUALITY OF MEAT AND MYOFIBRILLAR PROTEINS: III: Contribution of Myosin A and Actin to Rheological Properties of Heated Minced‐Meat Gel

Myosin A and myosin B gels formed by heating exhibited similar binding abilities as measured by the breaking energy, but different physical properties. At equivalent concentrations, myosin A gels exhibited smaller values for the Youngs modulus of elasticity and larger values for strain at the breaking point. It was inferred from the results of a simple model experiment that in sausage manufacture the physical properties of the heat set minced meat gel are of the myosin B type when no pyrophosphate is present, and similar to the myosin A type when pyrophosphate is added. In the latter case, the contribution of actin may be significant. The binding quality of the heat set myosin B gel increased with myosin concentration. Hence, the binding quality of sausage should be influenced by the myosin B content of meat.

RELATIONSHIPS BETWEEN BINDING QUALITY OF MEAT AND MYOFIBRILLAR PROTEINS

The binding quality of the heat set gel increased when F-actin was present in an appropriate ratio to myosin A. It increased further when tropomyosin was added to the myosin A/F-actin model system. The water holding capacity was increased by tropomyosin only. Thus, the contribution of not only myosin A but also of native tropomyosin and actin should be controlled in sausage manufacture. The presence of 0.6 M NaCl or KCl in the sol was necessary to produce high binding quality and high water holding capacity of heated myosin B gels. NaCl is preferred because of the taste effect on the meat product. Heating temperature (65, 80, or 90°CC) affected the physical properties of heated myosin B gels. The water holding capacity and the maximum relaxation time decreased with increasing temperature. In the manufacture of meat products, the heating temperature should be selected in accordance with the desired properties in the finished product.

DISCUSSION OF THE BINDING QUALITY OF MINCED MEATS BASED ON THEIR RHEOLOGICAL PROPERTIES BEFORE AND AFTER HEATING

Raw fish meat and three muscle groupings of cockerel meat were analyzed for total nitrogen, myofibrillar and sarcoplasmic proteins, non-protein and residual nitrogen, fat, pH, moisture and hydration capacity. Stress relaxation measurements were made on both raw and heat coagulated samples. Tensile strength measurements were made on heat coagulated samples. Using breaking energy as an index of binding, myofibrillar protein content and hydration were tentatively related to binding quality. Equilibrium modulus values offered an indication of the presence of crosslinking after heating. The rheological behavior of fish meat could be explained by a seven element model and that of cockerel meat by a five element model before heating. An analysis is presented of the mathematical treatment of rheological measurements and their relationship to binding quality and chemical composition of the tested samples.

SPINAL PATHWAY MEDIATING RETICULOPETAL VOLLEYS

Reticular evoked potentials in response to stimulation of the dorsal rootlet (L5) in the cat were recorded under FlaxCdil. Successive sections were made on the spinal cord at the level of Th 13. The amplitude of the reticular response was reduced and the latency was prolonged after section of the dorsal funiculi. Subsequent hemisection of the cord resulted in further delay of the reticular response when the stimulus was. given to the side sectioned, but the latency remained unchanged on stimulation of the opposite side. Stimulation of the dorsal funiculus gave rise to a reticular response.