Study On The Effect Of Electromagnetic Field Assisted Thawing Of Muscle

With the continuous development and progress of modern technology and the improvement of people’s living standards,consumers’ pursuit of dietary quality and health conditions is increasing,and new requirements are put forward for the freezing and thawing methods and fresh quality of animal and plant foods.However,meat and meat products are rich in protein nutrients and have high water activity,which can cause spoilage and deterioration of food quality during the freezing and thawing process.In particular,the loss of water permeability,protein denaturation and physical damage can cause significant changes in the texture,taste and color of food,which not only leads to economic losses and environmental pollution,but more seriously endangers people’s lives and health.This thesis investigates the basic characteristics and effects of the thawing process of muscle tissue by applying magnetic field biological effects.The details of the study are as follows.Firstly,a magnetic field-assisted thawing experimental system was designed and built.Based on the superposition principle and distribution characteristics of the magnetic field,the inner diameter and number of turns of the coil are determined according to the magnetic field strength and type required for subsequent experiments,and the magnetic field generation system is constructed by a Helmholtz coil and a DC regulated power supply to generate a uniform and stable static magnetic field.And the magnetic field experimental system is simulated,so that the magnetic field direction distribution and the magnetic induction strength value magnitude can be observed more intuitively.Through the magnetic field measurement and monitoring device,the linear relationship between the current intensity and the magnetic field intensity is obtained.At the same time,the homogeneity and stability of the magnetic field generation system during operation are verified by multi-point monitoring over a long period of time.Secondly,the basic characteristics of the magnetic field-assisted muscle thawing process were investigated.It is found that compared with air thawing at room temperature,the thawing time of magnetic field assisted thawing is shortened by21.5-40%.The static magnetic field can enhance the heat transfer of the muscle tissue during the thawing process and increase the thawing speed.The external magnetic field reduces the formation and duration of recrystallization,that is,the time for passing the maximum ice crystal formation zone is shortened.And by microscopic observation of tissue staining,the appropriate magnetic field intensity can reduce the damage to muscle fibers due to recrystallization phenomenon,and the muscle tissue area is significantly increased and the space gap area is significantly reduced.Therefore,magnetic field-assisted thawing can significantly improve the thawing efficiency and quality of frozen muscle tissue.Finally,the effects of thawing assisted by different magnetic field strengths on the physicochemical quality and microstructure of muscle tissue were evaluated.The results show that thawing loss,cooking loss,L* and b* values,TBARS values,and shear force are significantly reduced,while a* values and protein content are significantly increased at appropriate magnetic field strengths（10 Gs,20 Gs,and 30Gs）.The microstructure of muscle tissues is observed by both scanning electron microscopy and transmission electron microscopy,and the results of image analysis show that the tissue samples treated by freezing and thawing inevitably cause certain damage to the microstructure of muscles due to ice crystal formation,in which the fiber bundle gaps in the control group are severely enlarged and the endomysium is also severely torn.However,the thawed beef tissues with appropriate magnetic field strength have more neat and tight arrangement of fiber bundles,and the damage to the muscle microstructure is significantly reduced.The results of the study demonstrate the potential application of homogeneous electromagnetic field in the thawing process of muscle tissues of certain sizes,which will help to effectively maintain the "fresh" quality of muscle tissues and provide people with healthy and high-quality thawed food.The preliminary application of magnetic field-assisted thawing on muscle tissue at the same time provides the theoretical basis and reference significance for the future cryopreservation of human own large-sized tissues and organs.