Extracting Protein from Antarctic Krill (Euphausia superba)

Abstract

AcknowledgmentsWe would like to acknowledge the financial support which provided by the NSFC (Natural Science Foundation of China) project (No. 31101380, Topic: study on solubilisation mechanism of fish muscle protein on alkalized conditions by ammonia), Shangdong Province Young and Middle-Aged Scientists Research Awards Fund (No. BS2010SW038, Topic: study on protein recovery from marine processing wastewater using pressurized acid precipitation technology) and PCSIRT (Program for Changjiang Scholars and Innovative Research Team in University). ABSTRACTThe isoelectric solubilization/precipitation (ISP) process was applied to Antarctic krill protein extraction. The solubility of Antarctic krill proteins and their fluoride content was studied between pH1.00-13.75. Previous krill protein extraction conditions using ISP were improved.Excess fluoride in Antarctic krill was removed using a water-washing method according to its Downloaded by [New York University] at 16:57 01 June 2015 A c c e p t e d M a n u s c r i p t 2 solubility. To save water, a multi-stage countercurrent system was used to optimize the ISP method. The results showed that the solubility of Antarctic krill proteins reached a minimum at pH 4.5 and a maximum at pH 13.5, while the concentration of dissolved fluoride was relatively unchanged (16.78-20.50 mg/L), with pH 2.00-13.50. Water-washing 4 times could reduce fluoride 98.14±0.01% from krill with about a 5.14±0.21% protein loss. The reduction allows krill protein to meet the Chinese National Standard (GB 2762-2005) for fluoride. Meanwhile, the 4-stage countercurrent system achieved almost the same high fluoride removal rate (98.58±0.01 %) using only 1/4 of the water.

Low oil emulsion gel stabilized by defatted Antarctic krill (Euphausia superba) protein using high-intensity ultrasound

“…The zeta potential of emulsion gels stabilized by different concentrations of dAKP is illustrated in Fig. 2 h. According to the report [33] , the isoelectric point (pI) of Antarctic krill protein is around pH 4.5. The zeta potential values of the emulsion gels stabilized by different concentration proteins at pH 4.5 in this study were between +6 mV and +17 mV.…”

Multi-stage countercurrent process for extracting protein from Antarctic Krill (Euphausia superba)

“…Then the mixture was homogenized (1000 rpm, 30 s, ETS-2, Yi Tong Electronics Ltd., Hangzhou, China) at 4°C. The homogenate's pH was adjusted to 12.5 according to the procedures reported by Qi et al (2016) (PHS-3C pH meter, INESA Scientific Instrument Co. Ltd., Shanghai, China) using 10 mol/L NaOH of 4°C. Finally, additional water of 4°C was added to final volumes of 200, 160, 120 and 80 mL, respectively (i.e.…”

“…The supernatants from the above experiment or similar samples were obtained following the procedures described in the above section. They were adjusted to pH 4.5 using 5 mol/L HCl and centrifuged immediately at 70009g at 4°C, and then the precipitated protein was washed by 3-stage countercurrent method reported by Qi et al (2016) so as to assure that fluoride level was lower than 2 mg/kg. Then protein content was determined using Kjeldahl method, and recovery yield was calculated.…”

“…So far, isoelectric solubilization/precipitation (ISP) process has been widely applied to extract protein (Chen and Jaczynski 2007;Taskaya et al 2009; Vareltzis and Undeland 2012;Barac et al 2015), and also used as a suitable method to extract the krill protein (Chen et al 2009;Wang et al 2011;Qi et al 2016). Chen et al (2009) paid more attention to application properties and chemical composition of extracted protein, where operation conditions were set referring to ISP extraction condition of other aquatic protein.…”

“…Wang et al (2011) tried to optimize extraction conditions, and found that two extraction steps could improve the yield of extracted protein obviously, and applied two-step washing after isoelectric precipitation to remove fluoride. As to remove fluoride, Qi et al (2016) chosed multi-stage countercurrent system instead at acid condition and saved water consumption.…”