Flow direction of main nutrient substances in Antarctic krill (Euphausia superba) during heat treatment

Shrimp meal is one of the most important processed products of Antarctic krill (Euphausia superba). During processing, heat treatment will cause the loss of nutrients and the destruction of active substances, which is the most important factor that determines the quality of shrimp meal. In order to grasp the changes and flow paths of the main substances during the processing of shrimp meal, by measuring the changes in the content of main nutrients such as moisture, ash, protein, lipid and the loss of functional components such as fatty acids and astaxanthin in the two key processes involving heat treatment, cooking and drying, the flow path and reasons for changes of each main substance were analyzed. The results showed that 8.49% of water was lost during the cooking process, and 63.5% of the water was lost during the drying process, mostly in the form of evaporation; the protein lost 1.12% during the cooking process, of which 0.87% flowed to the cooking liquid, and the loss was mainly water-soluble protein. The loss of 6.05% during the drying process; the lipids were reduced by 1.11% and 1.61% during the cooking and drying processes. Further analysis of the fatty acid composition revealed that the content of polyunsaturated fatty acids decreased from 45.57% to 43.65%. The relative content of EPA is reduced by 0.41% and 1.16% respectively during the drying process. The relative content of DHA does not change much during the cooking process, but is reduced by 0.68% during the drying process. Astaxanthin is a heat sensitive substance, which was affected by heat treatment and reduced by 29.4 and 58.6 mg/kg during the cooking and drying processes. The ash content was reduced by 2.85% and 0.85% during the cooking and drying process respectively; the results showed that the main substances lost during the cooking process were the soluble substances in the cooking liquor and a small part of the heat-sensitive substances, and the drying process mainly caused moisture evaporation and destruction of heat-sensitive substances such as astaxanthin. The study initially grasped the content changes and flow paths of the main substances during the processing of E. superba shrimp meal, analyzed the reasons for the changes and the main influencing factors, and discussed and proposed a plan to reduce the material loss, which can be used for the subsequent processing of Antarctic krill meal. The optimization of parameters provide a theoretical basis, which is of great significance for improving the quality of shrimp meal and promoting the high-quality utilization of E. superba resources.