An environmental friendly process for Antarctic krill (Euphausia superba) utilization using fermentation technology.

Antarctic krill was efficiently fermented by Bacillus subtilis OKF04 after the optimization of fermentation conditions. Bio-active substances were detected in fermentation broth, including polypeptides (9.5 g/L), phenols (1.1 g/L), polysaccharides (200.8 mg/L), and free amino acids (3469.4 mg/L). The fermentation broth was found to be rich in essential amino acids and non-protein amino acids, particularly methionine, leucine, lysine, and taurine. The fermentation broth was separated into 4 fractions: AKF-I (<1 kDa), AKF-II (1–3 kDa), AKF-III (3–5 kDa), and AKF-IV (>5 kDa), using membrane ultrafiltration. Antioxidative properties of the fermentation broth fractions were investigated, using DPPH (2, 2-diphenyl-1-picryl-hydrazyl-hydrate) scavenging activity, metal chelating activity and reducing capacity. The results showed that AKF-I and AKF-II had higher antioxidant activities than other fractions and the entire fermentation broth. These results indicate that bio-active substrates could be effectively and cleanly produced using fermentation of Antarctic krill by B. subtilis , and the antioxidant activity (DPPH scavenging activity, metal chelating activity and reducing capacity) of the fermentation broth is enhanced by ultrafiltration. [ABSTRACT FROM AUTHOR]