BACKGROUND: The quality deterioration of Antarctic krill (Euphausia superba) after thermal processing limits its industrial application. This study sought to improve the texture characteristics of Antarctic krill after heat treatment through pre-soaking using L-lysine (Lys) solution and sodium tripolyphosphate (STPP). Moreover, the effects of Lys on heat-treated Antarctic krill were explored.RESULTS: Lys significantly reduced the cooking loss and improved the texture characteristics of Antarctic krill during heat treatment. The low-field nuclear magnetic resonance results showed that Lys reduced the water loss of Antarctic krill during heat treatment. Additionally, the surface hydrophobicity, Fourier transform infrared spectroscopy, and endogenous fluorescence spectroscopy results showed that Lys could inhibit the structural damage of Antarctic krill protein under the thermal denaturation condition and enhance the thermal stability of the protein. The scanning electron microscopy results showed that Lys could protect the structural integrity of Antarctic krill muscle fibers during heat treatment.CONCLUSION: The cooking loss in the Lys added groups was better than the sodium tripolyphosphate added group, and 2.0% Lys solution could minimize the cooking loss of Antarctic krill. The secondary and tertiary structures of the Antarctic krill protein were actively protected by Lys during heat treatment. Overall, the study will provide insights into the application of Lys in the food industry as a natural additive and an alternative to phosphate.

Antarctic krill (Euphausia superba) is an important source of biomass and high-quality protein. However, heat treatment of Antarctic krill negatively impacts its quality and compromises its utilization in the food industry. This study aimed to investigate the mechanisms underlying changes in Antarctic krill meat characteristics and physicochemical properties treated at different temperatures and holding times.Findings indicate that at higher temperatures and holding times, hardness and cooking loss of Antarctic krill meat increased dramatically. The low-eld nuclear magnetic resonance (LF-NMR) analysis revealed that the loss of immobile water increased, whereas SDS-PAGE analysis showed that the content of myosin heavy chain decreased signi cantly, and that protein degradation occurred. Fourier transform infrared spectroscopy (FT-IR) and intrinsic uorescence spectra indicated that α-helix motifs were transformed into β-sheets, and that more hydrophobic groups were exposed. The scanning electron microscopy (SEM) results showed that Antarctic krill meat formed corrugated folded regions after heat treatment without forming a three-dimensional water-entrapped structure, which led to signi cant water loss, resulting in rapid deterioration Antarctic krill meat. These results provide the basis for a deeper understanding of processing characteristics of Antarctic krill meat.

Summary The object of this study was a high‐protein Antarctic krill ball which was made of mixed shrimp surimi (Antarctic krill and white shrimp). The effects of four different exogenous additives on gel properties and spatial structure of mixed shrimp surimi systems during processing were investigated by texture profile analysis, low‐field nuclear magnetic resonance, magnetic resonance imaging, Fourier‐transform infrared spectroscopy, scanning electron microscopy and rheology analysis, according to product formulation and processing conditions. Different exogenous additives improved distinctly the mixed shrimp surimi system. The use of the four exogenous additives combined had a synergistic promotional effect. Acetylated distarch adipate, egg white powder and soy protein isolate played a vital role in producing high‐protein Antarctic krill balls. The relatively limited improvement of transglutaminase could be attributed to processing temperature and the presence of autolytic enzymes originated intrinsically from Antarctic krill surimi.

Antarctic krill (Euphausia Superba) has a high nutritional value; however, due to its autolysis characteristics and easy deterioration characteristics after heating, which leads to di culties in processing, canned Antarctic krill is one of the few products that exist. However, canned Antarctic krill have a rough taste, high hardness, and poor palatability. Therefore, there is a need to improve its quality.In recent years, the good performance of basic amino acids as a Phosphate-free additives in improving the product quality of foods has indicated their broad application prospect. The purpose of this study was to evaluate the effect of basic amino acid (L-arginine (Arg), L-lysine (Lys), and L-histidine (His)) pretreatment on enhancing the quality of canned Antarctic krill. Low-eld nuclear magnetic resonance, magnetic resonance imaging, and textural pro le analyses, color, scanning electron microscopy, thiobarbituric acid reaction substances (TBARS), pH, and sensory evaluation were used to determine the indices of krill meat at different pretreatment conditions and processing stages. The results showed that compared to the sodium tripolyphosphate pretreatment group, krill meat pretreated with Lys had a larger peak area of immobile water, higher pseudo-color image brightness after sterilization of krill meat, a more complete microstructure network. Additionally, it had the best water-holding capacity, lower hardness and TBARS values, and signi cantly higher a* values, indicating that Lys effectively improved the texture and color of krill, protecting the microstructure, and reducing the degree of oxidation. Sensory evaluation results showed that the Lys-treated canned Antarctic krill had a better avor and texture compared to other canned products. The results of this study suggest that Lys can provide a regulatory strategy for effectively enhancing the quality of canned Antarctic krill. common method of food preservation as it can be stored at room temperature for a long time, is easy to carry, transport, and store, saves the cooking process time, overcomes the seasonal and regional restrictions on the supply of food varieties, and is popular with consumers (Draszanowska et al. 2019).To improve the safety of canned food, the microorganisms in canned food need to be destroyed, which also extend the shelf life of the food. The best method is heat sterilization, but this process can lead to food browning (color changes), damage the avor, and reduce nutritional value (Muñoz et al. 2022).Canned Antarctic krill is one of the products exported to earn foreign exchange; however, its processing causes severe moisture loss, resulting in a tough texture, rough taste, and poor product quality. The main reason is that during the storage of raw Antarctic krill, the autolysis enzymes degrade the myo brillar protein, whereas it forms corrugated folded structures during thermal processing (Sun et al. 2022). Consequently, improving the taste, avor, and nutritional value of canned Antarctic krill is a practical issue that needs to be...

Heat treatment reduces the quality of Antarctic krill (Euphausia superba), thus greatly limiting its industrial application. Although L-Lys immersion pretreatment can effectively improve the quality of heat-treated Antarctic krill meat, the underlying mechanism is unclear. This study aimed to investigate the effect of different L-Lys concentrations (0, 25, 50, 100, and 200 mM) on the aggregation behavior and structure of Antarctic krill myofibrillar protein solution before and after heat treatment. Compared with the untreated group, L-Lys decreased the surface hydrophobicity and particle size of the heat-treated Antarctic krill protein by 2.38 times and 18.27 times while increasing the solubility by 3.59 times. Furthermore, L-Lys intervention inhibited the formation of disulfide bonds in myofibrillar protein of the heat-treated Antarctic krill, enhanced the intermolecular hydrogen bonding force, improved the orderliness of the secondary structure, and "exposed" the tyrosine residues of the protein molecule. As a result, the polarity of the microenvironment was enhanced while the tertiary structure of the protein was altered, thus inhibiting thermal aggregation behavior and improving the water-holding capacity and tenderness of heat-treated Antarctic krill. This study reveals the mechanism of L-Lys inhibition of thermal aggregation behavior of Antarctic krill myofibrillar protein. Our results provide insights into the development and utilization of Antarctic krill protein in the food industry.