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

Abstract

To systematically study multi-stage countercurrent process for Antarctic krill protein extracting and to optimize the multi-stage countercurrent technology, the solubility of Antarctic krill proteins after multi-step dissolution was explored firstly; multi-step extraction was investigated; and then multi-stage countercurrent system for protein extraction was carried out. In single step extraction, krill-to-water ratio and pH were chosen as 1:10 and 12.5 respectively, in order to extract more protein. In the multi-step dissolution process, the protein solubility of aqueous solution at pH 12.5 was 33.0 ± 0.8 mg/mL. Multi-step cross-flow processing testified the feasibility of multi-stage countercurrent assumption. Three-stage countercurrent method using krill-to-water ratio 1:10 extracted, 95.1 ± 0.6% protein from krill, where almost the same water as previous works. The total recovery yield of 67.9 ± 1.6% was achieved after precipitation at pH 4.5.

Effects of ultrasound-assisted basic electrolyzed water (BEW) extraction on structural and functional properties of Antarctic krill (Euphausia superba) proteins

“…The mixture was centrifuged at 8000 g for 10 min, and then the pH of supernatant was adjusted to 4.5 by 3 M HCl [6] . The precipitated proteins were washed by 3-stage countercurrent method [7] , and then quick-frozen in liquid nitrogen. Afterwards, the protein samples were freeze-dried in a vacuum dryer (−76 °C, 1.3 × 10 −2 mbar) to remove water [21] .…”

“…The purity of krill proteins was determined by Kjeldahl method, and 6.25 was used as Kjeldahl nitrogen-to-protein conversion factor [7] . Protein yield of ultrasound-assisted BEW or DW were calculated by Eq.…”

“…At present, the frequently-used method for extracting plant or animal proteins is alkaline extraction [6] , [7] . During the whole process, a large amount of alkaline solution (NaOH, KOH, etc.)…”

Cryoprotective effect of three oligosaccharides on freezing–thawing induced krill mince: with emphasis on physicochemical changes and gelation properties

“…1d. Similar to previous studies, the fragment marked of krill corresponds to myosin heavy chain (MHC, ~210 kDa), paramyosin (~100 kDa), actin (~45 kDa), tropomyosin (~38 kDa), and myosin light chain (MLC, ~17 kDa) (Qi et al ., 2018; Zheng et al ., 2019). After 9‐FT, krill mince exhibited weakened bands of MHC, paramyosin, and MLC, indicating protein degradation of MPs, corresponding with decreased protein solubility.…”

From a Single-Stage to a Two-Stage Countercurrent Extraction of Lipids and Proteins from Full-Fat Chickpea Flour: Maximizing Process Extractability and Economic Feasibility

“…Countercurrent extraction approaches with the use of flammable solvents such as hexane have been widely used by the oil industry to reduce solvent use without a loss in the process extractability [23]. Because of increasingly restrictive environmental, safety, and consumer concerns regarding the use of flammable solvents such as hexane, this strategy has also been applied in the AEP and EAEP of soybeans, defatted sunflower seed meal, and Antarctic Krill [21,25,26]. Countercurrent extraction systems rely on contacting the freshest feed (starting material) with a richer extraction medium originating from a previous extraction, where the feed continues to be extracted until near-depleted feed contacts the fresh extraction medium.…”