Ferment Antarctic Krill And The By-products By Microorganism For The Comprehensive Utilization

Antarctic krill(Euphausia superba),a kind of plankton in the Southern Ocean, belongs to Euphausiidae, Crustacea and Arthropoda. Antarctic krill is characterized by the rich biological storage, wide resource distributing and high nutritional value, which is of great explored potentiality and utilized value. Traditionally, chemical methods were used to develop the Antarctic krill in industries. However, there are many problems existing in chemical processes, such as a large amount of the low yields, high cost and also environmental pollution. Alternatively, with its advantages in environmental compatibility, low cost and reproducibility, conversion of Antarctic krill by microorganism become more and more popular in recent years.Twelve kinds of strains were isolated from deep sea mud by using Antarctic krill powder as the sole carbon/nitrogen source. According to the morphological characteristics, a series of physiological and biochemical tests and the16S rDNA (or18S rDNA) gene sequence analysis, these strains were identified and named as Bacillus cereus OKF001, Bacillus licheniformis OKF002, Bacillus amyloliquefaciens OKF003, Bacillus subtilis OKF004, Bacillus meqaterium OKF005, Shewanella baltica OKF006, Psychrobacter aquimaris OKF007, Klebsiella peumoniae OKF008, Macrococcus caseolyticus OKF009, Aeromonas veronii OKF010, Acinetobacter sp. OKF011, Saccharomyces cerevisiae OKF012, respectively.These12kinds of strains were used to ferment cheap carbon/nitrogen source of Antarctic krill pen powder. Then we investigated the bioconversion of Antarctic krill powder for the production of bioactive compounds. Finally, the amino acid compositions were analyzed by automatic amino acid analyzer. The total content of amino acids was2160.20mg/L in the fermented liquor from M. caseolyticus OKF009, while that of essential amino acids was1025.64mg/L, which was47.48%of the total amino acid. The phenolic substances and free amino acid were abundant in the supernatants and were heavily involved in the antioxidant property. What’s more, four enzyme activities (protease activity, chitinase activity, amylase activity and lipase activity) were detected in the culture supernatants. This is the first report of utilizing the isolated microorganism to ferment Antarctic krill powder. It turned out that the conversion technology could be applied to the High-value utilization of the Antarctic krill.Four food-grade microorganism, Aspergillus oryzae, Streptococcus thermophilus, Saccharomyces cerevisiae and Bacillus licheniformis, were selected to ferment Antarctic krill juice and without any nutrient supplementation. And highly trained and experienced panelists who were familiar with sensory tests were selected to perform sensory analysis. It was found that the fermented Antarctic krill juice were bright in color, excellent in mouth feel and taste delicious. In view of the result of sensory evaluation, organic acid and free amino acid were researched. The highest content of organic acids was existed in the Antarctic krill juice fermented by B. licheniformis (3044.0mg/100mL). However, the free amino acid in A. oryzae was reached to1519.45mg/100mL. Above all, these fermented juice were with distinctive features. This research demonstrated that the technological advantage of using Antarctic krill juice as a substrate for fermentation since it will avoid the environmental pollution. Besides, the Antarctic krill juice from fermentation was useful to enhance the nutrition and flavor. This research would contribute to the development of a condiment with health care function.Traditionally, soy sauce was produced by using bean cake and bran as raw materials. This study was designed to produce Antarctic krill sauce, bean cake, bran and powdered Antarctic krill were used as raw materials, by adopting low-salt solid-state fermentation. Then the optimal conditions of process koji were explored. The optimal conditions were determined to30%of Antarctic krill powder,100%of water and react for48h. In this condition, the soy sauce koji was optimum in the protease activity, the content of amino acid and reducing sugar. And the Antarctic krill sauce was superior to the soy sauce produced by traditional brewing technology in sensory evaluation, organic acid and free amino acid analysis. The only weak point here was that the amino nitrogen in the Antarctic krill sauce was lower compared with of the sold in market (≧0.5g/100mL) for being short of the concentration processes.