## 1 Introduction  
Cuttlefish belongs to the Mollusca, Cephalopoda and Sepiida, and they live mainly in shallow waters along tropical and temperate coasts. Cuttlefish has typical high protein, low fat characteristics, and is rich in minerals and a variety of essential amino acids. Its meat is crisp, tender, tasty and rich in nutrients. It is very popular among consumers.  
Fresh cuttlefish moisture content is high, the tissue protease activity is strong, the fish is easy to die after capture, easy to rot and deteriorate, not easy to store, the preservation of freshness is difficult [1]. Therefore, proper handling and preservation methods are neededto increase the shelf life of cuttlefish. At present, freezing is still the most important form of fish circulation process, but also to improve the comprehensive utilization of aquatic products and value-added important way.  
Freezing preservation is a preservation method that first uses cooling equipment to lower the temperature of the center of the aquatic products, freeze most of the water inside, and then freeze the aquatic products at \(-18\)\({}^{\circ}\)C and below. The degree of impact on the quality of aquatic products is different. Common freezing methods are mainly air freezing method, flat freezing method, tunnel continuous freezing method, dipping freezing method, liquid nitrogen flash freezing, etc. It was found that the freezing quality of fish products is related to the freezing method and freezing rate. The freezing rate affects the size and uniformity of ice crystals. Quick freezing produces fine and uniform extracellular and intracellular ice crystals, which does little damage to the food structure. However, slow freezing will produce large and irregular extracellular ice crystals, leading to the destruction of muscle structure and reducing the sensory acceptance of food. In addition, the size of ice crystals can increase with the extension of freezing time [2]. Research showed that freezing can inhibit the reproduction of microorganisms, inhibit enzyme activity, slow fat oxidation, protein denaturation, which can make the freshness of fish for several months or even more than a year. Nonetheless, quality deterioration still inevitably occurs during freezing and frozen storage, such as texture softening, fluid losses, color changes, and flavor deterioration. However, different freezing methods, depending on their processes and freezing rates, can have different effects on the degree of protein and fat oxidation, muscle tissue morphology, color and texture, and water loss of aquatic products, etc. [3,4]. [PERSON] et al. [5] evaluated the quality changes of tiger shrimp (Penaueus monodon) frozen using air-blast and cryogenic freezing. The results indicated that freezing the shrimps under the air-blast freezer at the air velocity of 6 m/s had the least freezing loss and same cutting force as the fresh shrimps. [PERSON] et al. [6] concluded that the use of liquid nitrogen freezing improved process yield when compared to the use of spiral freezer. There is hardly any available information about the effects of freezing methods on the integrity, physicochemical, and sensory properties of cuttlefish. Research by [PERSON] et al. showed that compared with static air freezing and air blast freezing, the quality of catfish fillets frozen by liquid nitrogen immersion is better. There have been reports in the literature on the effects of different freezing methods on the quality of other aquatic products, but there is hardly any available information about the effects of freezing methods on the integrity, physicochemical and sensory properties of cuttlefish.  
The aim of this study was to investigate the effects of six different freezing methods on the quality of cuttlefish, and to explore the most suitable freezing method to maintain the quality of cuttlefish by evaluating the changes of physicochemical properties and microscopic results during the freezing process, and to provide theoretical reference and technical support for the preservation of cuttlefish.