Optimization and validation of spiral staged drying process for Euphausia superba meal

Antarctic krill (Euphausia superba) meal is one of the most important processed products of E. superba, and its quality iscritical to the quality of the subsequent shrimp oil and other deep processing products. However, in the yield and quality of E. superba meal processing, there is still a big gap between China and leading countries in the E. superba industry such as Norway. Spiral drying has the advantages of autonomously pushing material and reducing the accumulation of materials, suitable for E. superba drying; compared to constant temperature drying, staged drying process can consider the drying efficiency and energy consumption, and can effectively ensure the stability of product quality. In order to optimize the spiral drying process parameters of E. superba powder and obtain a high quality and efficient drying process of E. superba meal, the staged drying process of E. superba was studied by using spiral drying equipment, and the optimum experiment was designed on the basis of Box-Behnken experimental design principle based on single factor experiment. The effects of the first stage drying temperature, the switch node and the second stage drying temperature on the drying time, the content of fat and astaxanthin were studied. The results showed that the order of influence of different factors on drying time and astaxanthin content was first stage drying temperature (A) > second stage drying temperature (C) > stage switching moisture (B), and the order of influence on fat content was stage switching moisture (B) > first stage drying temperature (A) > second stage drying temperature (C). Response surface obtained the optimal process parameters for the first stage drying temperature at 105 °C, stage switching moisture of 50%, the second stage drying temperature of 88 °C. Under this condition, drying time, fat and astaxanthin content were 160 min, 16.83%, and 159.32 μg/g, respectively; the quality of the E. superba meal under the spiral staged drying were better than that of spiral constant temperature drying. The study shows that the use of an optimized spiral drying process can effectively improve the quality of shrimp meal while ensuring drying efficiency. This study can provide technical references for the high-quality production of E. superba and E. superba meal shipboard processing technology and the development of localization of key equipment.