Effects Of Microscopic Changes Of Muscle Fibers On Rheological Properties Of Tan Mutton During Storage Period

In this paper,Tan mutton in different parts during storage at 4 C was studied.The rheological parameters such as modulus of stress relaxation and consistency coefficient,flow index,apparent viscosity of flow under static state,storage modulus,loss modulus,loss angle and complex viscosity under dynamic state were measured by rheometer.The ultrastructure of muscle fibers of Tan mutton during storage was observed by atomic force microscopy(AFM).The micromechanical parameters were determined and the muscle fiber diagrams of the two parts after 24 hour chilling were observed by field emission scanning electron microscope(FISEM).The results are as follows:(1)The stress relaxation experiment under the static condition of Tan mutton emulsion and the ramp experiment under Flow stateThe stress relaxation experiment showed that the stress relaxation modulus of Tan mutton during storage period decreased with the increase of storage days,it indicated that the ability of Tan mutton to resist elastic deformation under external force increased with the increase of storage days.The Flow experiment showed that the Tan mutton was a non-Newtonian fluid and exhibits pseudoplastic behavior.The apparent viscosity decreased with the increase of shear rate.The longissimus dorsi muscle was stored in 2,4,6,and 8 days.The Ostwald-de Waele model had a coefficient of fit of 0.9245,0.986,0.992,0.986,and the Ostwald-de Waele model of the hind leg muscles at 2,4,6,and 8 days had a coefficient of fit of 0.744,0.911,0.346,and 0.604.The model fitting effect of the long muscle was better than that of the hind leg muscle,which indicated that the flow effect of the longissimus dorsi muscle was better than that of the hind leg muscle during processing.Overall,the Ostwald-de Waele model was superior to the Herschel-Bulkley model,and the Ostwald-de Waele model was a better description of the meat flow characteristics.(2)Frequency-oscillation experiment under the dynamics of Tan muttonThe storage modulus and loss modulus increased with the increase of the angular frequency,it indicated that the rigidity and plasticity of Tan mutton increased with the increase of the angular frequency.The values of storage modulus,loss modulus and complex viscosity decreased with the storage time,it showed that the elasticity and viscosity of the Tan mutton decreased with the storage time;the results were the same as the trend of change the static apparent viscosity.The results of static and dynamic rheological experiments were consistent with the Cox-Merz equation.(3)Determination of micromechanical properties and ultrastructural measurement of muscle fibers of Tan mutton during storageThe results showed that under the atomic force microscope,the elastic modulus and elastic modulus of the Tan muscle fibers decreased with the storage time,and the viscosity coefficient decreased with the storage time.The muscle fiber profile of the Tan mutton measured by AFM gradually became blurred with the increase of storage days,and it was difficult to see the microstructure such as sarcomere.Scanning electron microscopy was used to measure the image of the longissimus dorsi and hind leg muscles after cooling for 24 h.The results showed that the two parts were in the same time period and under the same treatment,the overall morphology of myofibrils and the fascia.The degree of shedding was different,it showed that the degree of hydrolysis and maturity of the two parts was different.