Study On The Structure And Texture Properties Of Jellyfish(rhopilema Esculentum Kishinouye)during Heating And Desalting Process

Jellyfish(Rhopilema esculentum Kishinouye) is a seafood traditional eaten in China with high economic value. Raw jellyfish consists of more than 95% water, and the rest is mostly collagen. Since autolysis easily happens in jellyfish post-harvest, appropriate processing is important for its storage. Salting is the most popular processing method for jellyfish. However,traditional desalting takes a long time and the residual aluminum is harmful to human health.This means that it is worthwhile to develop new technology for jellyfish processing.This paper consists of two parts. The first part investigates the effect of heating on the structural and textural properties of jellyfish, and provides a new processing model to control the quality of jellyfish product. The second part looks at the change in the structure and textural properties of jellyfish during the desalting process, which provides references for the optimal desalting method and quality control.Structure and texture properties of the umbrella, scapulet, gastric column and oral arms from fresh jellyfish were investigated first. The results showed that the amount of collagen fibers in the oral arms was more than in the umbrella, scapulet and gastric column, and the fiber array was more dense. There was the smallest amount of collagen fibers in the gastric column, and the fiber array was loose with larger gaps between fibers. The hardness,chewiness, and springiness of the oral arms were higher than those of the other parts. During the initial stage of heating, the amount of water and nutrients in the jellyfish decreased;therefore the weight of the jellyfish decreased, the gaps between the fibers became smaller,and the fiber array became denser. With an increase in the heating time, holes appeared in the structure and the collagen fibers, which were dyed red, gradually got lighter, which means they were dissolving. Finally, the fibers were completely disintegrated; therefore the organizational structure was damaged. During heating, the hardness index of the jellyfish increased and then decreased; springiness and cohesiveness only increased. Hardness had a significant decrease during the 60°C test at 30 min、the 80°C test at 5 min, and the 100°C test at 3 min. Brittleness was affected significantly by temperature; however, once heated at 60°Cfor 3 min, 80°C for 1 min, and 100°C for 30 sec, the brittleness indexes cannot be determined.The jellyfish could be processed and have a good texture when heated at 60°C for up to 3 min,80°C for up to 1 min, or 100°C for up to 30 sec.The desalting process was affected by temperature. The results showed that the quality and salt was decreased when desalting occurred at 4°C and 25°C, while there was no significant changes on hardness and elasticity. The gaps between collagen fibers were increased, which lead to the loss of soluble protein and polysaccharides. The quality and salt content of the jellyfish decreased faster when processed at 50°C. This meant a rapid decline in hardness, and the structure of the jellyfish was damaged due to the degeneration of collagen.