## 1 Introduction  
Food texture is the sensory expression of food structure and its response to external forces, which refers to the comprehensive sensing of the rheological properties of food via mechanical, tactile, visual, and auditory methods. Food texture is a physical property related to the internal structure and state of food [1, 2]. As one of the various classification methods on food texture from different perspectives, [PERSON] divides the texture of food into three categories, namely mechanical properties, geometric properties, and other properties, where mechanical properties include the hardness, elasticity, cohesion, adhesion, and thewability of food [3]. The geometric characteristics mainly represent the shape, size, and direction of food particles. At the same time, the texture of food also includes other properties, such as juiciness, gresiness, and wetness.  
Scallops, which are rich in protein and trace elements with low levels of fat, have been popular with the population's increasing demand for healthy food. Subsequently, how to protect the quality of scallops in the circulation process in a way that can be objectively and accurately evaluated has become a concern of many researchers. scallops are a typical mollusk composed of sarcoplasmic protein and myofibrillar protein macro-molecules, and the changes in the characteristics of myofibrillar fibers are closely related to the qualitative characteristics of the adductor muscle of scallops [4]. The application of ultra-high pressure will destroy the non-covalent bonds in the protein, and the activity of protease changes with the increase in pressure, which hydrolyzes the protein in the adductor muscle of scallops and loosens the fibrous tissue. The effect of ultra-high pressure also destroys the mesh structure of proteins [5; 6; 7], thus affecting the cohesion, hardness, elasticity, and other structural indicators of scallop adductor muscles [8]. Therefore, there might be a correlation between protein structure and textural changes in closed-shell scallop muscles.  
Ultra high-pressure packaging technology could maintain the composition of macromolecules, such as proteins, while water molecules enter the macro-molecular groups and would adhere to the amino acids of proteins through filling and infiltration, thus breaking the non-covalent bonds in the tertiary structure of proteins [9]. The molecular chain of the denatured protein molecules would be stretched out so that its original three-dimensional structure is changed during pressure relief. The muscle fibers and adhesive tissues would be relaxed. In particular, treatment with ultra-high pressure would only change the non-covalent bond structure of the molecules, as it maintains the covalent bond structure of small molecules to a great extent and also protects the natural quality and nutritional value of food [10; 11].  
Ultra high-pressure packaging could improve textural characteristics and protein stability and extend the shelf life of Chinese tubular whip shrimp and black tiger shrimp [12; 13]. Furthermore, the influence of ultra-high-pressure technology on the quality of scallops was studied [14]. The treatment of scallops through pressure at 250 MPa for 5 min could improve the texture of the shell muscle of scallops. Ultra-high pressure was also used to package different kinds of scallops and significantly improved water-holding capacity, reduced the total number of colonies, and extended the shelf-life of the scallops [15; 16]. This article links the changes in protein structure and texture of scallop adductor muscle under ultra-high pressure, which could lay a foundation for the further exploration of the mechanism of ultra-high pressure action.