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

Tandem Mass Tag-based proteomic analysis of protein changes in superchilled crayfish (Procambarus clarkii) presoaked with carrageenan oligosaccharides

To assess the effectiveness of carrageenan oligosaccharides (COs) in enhancing superchilling storage of crayfish, the physicochemical features of muscle and protein abundance in the refrigerated sample (RS), superchilled sample (SS) and COs soaked superchilled sample (CS) were evaluated. Microstructural and SDS-PAGE analyses suggested that CS exhibited fewer pores, with a microstructure and protein subunits distribution more similar to RS. Tandem Mass Tags quantitative proteomic analysis revealed 66 up-regulated differentially abundant proteins (DAPs) in the CS vs. SS batch, including myosin light chain 2, neural cadherin, integrin beta, lectin-like protein, toll-1, reticulon-1, and moesin/ezrin/radixin homolog 1, which facilitate cells adhesion and maintain membrane/cytoskeleton integrity. Eukaryotic Clusters of Orthologous Groups results confirmed that COs treatment increased the stability of crayfish myofibrillar proteins by up-regulating DAPs, which were concentrated in functional categories such as "posttranslation modification, protein turnover, chaperones", "signal transduction mechanisms", "energy production and conversion", and "cytoskeleton".

Cryoprotective Effects of Carrageenan Oligosaccharides on Crayfish (Procambarus clarkii) during Superchilling

Cryoprotectants are widely used to protect muscle tissue from ice crystal damage during the aquatic products freezing process, but traditional phosphate cryoprotectants may cause an imbalance in the calcium-to-phosphorus ratio for the human body. This study evaluated the effects of carrageenan oligosaccharides (CRGO) on quality deterioration and protein hydrolysis of crayfish (Procambarus clarkii) during superchilling. The physical-chemical analyses showed that CRGO treatments could significantly (p < 0.05) inhibit the increase of pH values, TVB-N, total viable counts, and thawing loss, and improve the water holding capacity and the proportion of immobilized water, which indicated that CRGO treatment effectively delayed the quality deterioration of crayfish. The myofibrillar protein structural results demonstrated that the increase of the disulfide bond, carbonyl content, S₀-ANS, and the decrease of total sulfhydryl content were suppressed significantly (p < 0.05) in CRGO treatment groups. Furthermore, SDS-PAGE results showed that the band intensity of myosin heavy chain and actin in CRGO treatment groups were stronger than in the control. Overall, the application of CRGO to crayfish might maintain better quality and stable protein structure during the superchilling process, and CRGO has the potential to replace phosphate as a novel cryoprotectant for aquatic products.

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

The mainstream adoption of chickpea proteins and lipids requires a thorough understanding of the impact of critical extraction parameters (enzyme use, reaction time, and solids-to-liquid ratio—SLR) and modes of extraction (single-stage extraction—SSE and countercurrent extraction—CCE) on the simultaneous extraction of lipids and proteins from full-fat chickpea flour and economic process feasibility. A kinetics study revealed that 68.5% oil and 87% protein extraction yields can be achieved using 0.5% protease at pH 9.0, 50 °C, 60 min, and 1:10 SLR, highlighting the role of proteolysis and an adequate incubation time on overall extractability. An increased gradient concentration between the matrix and aqueous media solutes at a lower SLR (1:15), and reduced slurry viscosity increased oil and protein extractability to 80 and 91%, respectively. The high-water usage in the SSE was addressed by the development of a two-stage CCE that reduced water usage by 47% while increasing oil and protein extractability to ~96%. Higher extractability and reduced water usage in the two-stage CCE resulted in a higher net gross profit, thus outweighing its higher operating costs. The results presented herein further widen the scope of bioprocessing standards for full-fat chickpea flour and add to the elucidation of the impact of key processing conditions on the extractability and economic feasibility of the production of chickpea ingredients for subsequent food/nutraceutical applications.

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

A novel protein extraction method of ultrasound-assisted basic electrolyzed water (BEW) was proposed, and its effects on the structural and functional properties of Antarctic krill proteins were investigated. Results showed that BEW reduced 30.9% (w/w) NaOH consumption for the extraction of krill proteins, and its negative redox potential (-800 ~ -900 mV) protected the active groups (carbonyl, free sulfhydryl, etc.) of the proteins from oxidation compared to deionized water (DW). Moreover, the ultrasound-assisted BEW increased the extraction yield (9.4%), improved the solubility (8.5%), reduced the particle size (57 nm), favored the transition of α-helix and β-turn to β-sheet, promoted the surface hydrophobicity and disulfide bonds formation of krill proteins when compared to BEW without ultrasound. These changes contributed to the enhanced foam capacity, foam stability and emulsifying capacity of the krill proteins. Notably, all the physicochemical, structural and functional properties of the krill proteins were comparable to those extracted by the traditional ultrasound-assisted DW. This study suggests that the ultrasound-assisted BEW can be a potential candidate to extract proteins, especially offering an alternative way to produce marine proteins with high nutritional quality.