Processing technology, quality characteristics and 

application status of Antarctic krill powder

YANG Liu1,2 , WANG Lumin2, ZHOU Guoyan1, GUO Quanyou2, ZHENG Hanfeng2, 

ZHENG Yao2, YANG Xu2, WANG Wanyong3, QIN Ganjing3  

(1．School of Health Science and Technology, University of Shanghai for Science and Technology,

 Shanghai200093, China; 2．East China Sea Fisheries Ｒresearch Institute，Chinese Academy of Fishery Sciences，

Shanghai200090，China; 3．Jiangsu Sunline Deepsea Fishery Co. Ltd., Lianyungang Jiangsu, China)

Abstract: Antarctic krill is a kind of small crustacean widely distributed in the waters of the Southern Ocean. Its biological resources are rich, about 0.651.00 billion tons. The main fishing countries are Norway, China, Chile, Japan, etc. It is rich in protein, astaxanthin, phospholipids and other nutrients, and is known as the “future animal protein warehouse of mankind”. Antarctic krill contains highly active endogenous hydrolases, which are easy to autodissolve, resulting in a rapid decline in shrimp freshness. Therefore, it is necessary to carry out onboard processing in time after fishing to prepare frozen shrimp or shrimp powder. Antarctic krill powder has the characteristics of high freshness of raw materials, excellent product quality and low transportation cost. In recent years, its processing proportion has gradually increased, and it has become one of the main processing products of Antarctic krill. Antarctic krill powder is rich in protein, astaxanthin, phospholipids and other components. It is mainly used in the production of krill oil, krill peptide and other functional products, as well as the production and processing of animal feed. The full efficiency utilization and highvalue processing have become the focus of the industry.

This paper mainly searches the research and review articles on Antarctic krill powder in recent ten years, combined with patent examination and industrial research, understands the production technology and processing technology of Antarctic krill powder, expounds the main processing links, and summarizes the main research directions and research results of Antarctic krill powder. At present, the research on Antarctic krill powder mainly includes processing technology, nutritional quality and application, so this paper elaborates on these three aspects. Firstly, the advantages and disadvantages of different processing methods of whole krill powder and skimmed krill powder are introduced, and the process optimization of three key processing steps of cooking, separation and drying by different scholars is summarized. Secondly, the nutritional quality of whole fat krill powder is evaluated, mainly referring to its internal quality. The nutritional value includes the content of basic nutrients such as protein and lipid, the composition of amino acids and fatty acids, the content of minerals and other active substances. The safety is mainly to guide the fluorine content in krill powder, and the focus is to optimize the fluoride removal process. Finally, the application status of Antarctic krill powder is introduced, in which shrimp oil extraction and aquaculture are the traditional application directions, and the emerging field of highvalue utilization is the current research hotspot.

From the processing of Antarctic krill powder, cooking will denature and solidify Antarctic krill protein to a certain extent, and high temperature will inactivate endogenous enzymes, and kill heatresistant microorganisms. When heating at room temperature, the central temperature controlled between 5560℃, the quality of krill powder is the best. The purpose of separation is to realize solidliquid separation of cooked materials and improve the subsequent drying efficiency. This link mainly affects the conversion rate of shrimp powder. The content of protein, fat and minerals in shrimp powder obtained by twinscrew extrusion technology increases. Drying can remove excess water, but too high temperature will cause adverse effects such as oil oxidation. Freeze drying (-50℃), lowpower microwave drying (≤1 kW) and lowtemperature hot air drying (≤60℃) are three drying methods conducive to the production of Antarctic krill powder with high astaxanthin content.

From the quality characteristics of Antarctic krill powder, it has the characteristics of high protein and high fat, and shows good nutritional value. However, due to the influence of processing technology, the content of basic nutrients is different. The content of crude protein in the whole shrimp powder of Antarctic krill is the highest, which is 55%70%, followed by crude fat, which is basically in the range of 5%15%, ash content is 9%18%, and water content is 2%10%. The ash content of krill powder prepared after shelling reduces significantly, and the content of crude protein increases. The amino acid composition of the whole krill powder of Antarctic krill conforms to the ideal essential amino acid composition mode recommended by FAO/WHO (1973). The fatty acid composition is rich, it is also rich in EPA and DHA. Antarctic krill powder is rich in minerals, astaxanthin and other substances, of which the content of astaxanthin is in the range of 110140 mg·kg-1, and the content of minerals and chitin can reach 6%. The main factor affecting the safety of Antarctic krill powder is the content of fluorine. Enzymatic hydrolysis, calcium chloride method and hydrochloric acid multistage countercurrent extraction method are effective methods for defluorination of shrimp powder. During the storage of krill powder, lipid oxidation and enzymatic hydrolysis, astaxanthin and tocopherol oxidation can occur. Vacuum storage is conducive to improve the oxidative stability of krill powder. At the same time, adding antioxidant (VE) or deoxidizer (reduced iron powder) can improve the storage of Antarctic krill powder.

From the perspective of the application of Antarctic krill powder, it is mainly used in aquatic feed and highvalue utilization. Antarctic krill powder has high protein content and rich flavor amino acids, which plays a certain role in food attraction. It can be added to aquatic feed as a protein source, which can promote the growth performance of aquatic animals, but the promotion effect varies with the feeding objects. At the same time, it can also improve the muscle quality of aquatic animals, improve the meat flavor and muscle color. And it can promote the nonspecific immunity and antioxidant capacity of aquatic animals. Modern methods such as chemical reagent extraction and enzyme engineering are used to extract krill oil, astaxanthin and prepare active peptides. The highvalue utilization of Antarctic krill powder is mainly based on these aspects. At present, shrimp oil is mostly extracted by organic solvent extraction, enzymatic hydrolysis and subcritical fluid extraction, but the difference of extraction methods will affect the extraction efficiency and nutritional value. To overcome the problems of the current single extraction method and develop multidimensional combined extraction methods with high extraction efficiency, convenience and environmental protection is very necessary. Using krill powder as raw material, astaxanthin is extracted by organic solvent method, and its extraction process and production application still need to be further studied. Enzymatic hydrolysis is the main method to prepare Antarctic krill protein peptide, which has the advantages of high production efficiency, but it is easy to produce bitter taste, which restricts its popularization and application in food. Using the target microbial fermentation and biological enzymatic hydrolysis, while ensuring its degree of hydrolysis, the flavor of active peptides is improved by using microbial fermentation, which has gradually attracted the attention of the industry, and has good development potential and application prospects.

To sum up, Antarctic krill powder is rich in nutrition, but at present, China’s relevant production and processing equipment is backward, the product quality varies greatly, and the potential value of Antarctic krill powder has not been fully utilized. We should carry out targeted process optimization and systematic equipment upgrading, establish a standardized production system of shrimp powder, and focus on the research related to the highvalue utilization of Antarctic krill powder. This paper systematically expounds the production technology, nutritional quality and highvalue utilization of Antarctic krill powder, in order to provide reference for establishing the whole industrial chain technology system of Antarctic krill powder processing on board, processing on land and industrial application, extending the industrial chain and improving the added value.

Keywords: Antarctic krill powder; onboard processing; parameter optimization; nutritional quality; production applications