摘要：为评价焦亚硫酸钠在南极磷虾(Euphausia superba)黑变控制中的效果并对处理工艺进行优化，本研究检测了南极磷虾经不同浓度的焦亚硫酸钠溶液和浸泡时间处理后二氧化硫(SO₂)残留量和酚氧化酶(PO)活力变化，并对其在冷藏和冻藏过程中的黑变情况进行了观察分析。结果显示，焦亚硫酸钠处理能够有效抑制南极磷虾PO活性，其中，1 g/L焦亚硫酸钠溶液浸泡300 s和2 g/L焦亚硫酸钠溶液浸泡30 s后，PO相对酶活分别为21.2%和34.5%，同时，虾体内的SO₂残留量分别为0.094 g/kg和0.096 g/kg，符合GB 2760中SO₂残留量≤0.1 g/kg的限量要求。与对照组相比，焦亚硫酸钠处理延缓了南极磷虾在冷藏和冻藏过程中的黑变进程，且2 g/L焦亚硫酸钠溶液浸泡30 s处理组的防黑效果更好。

Abstract: Antarctic krill (Euphausia superba) is a vital species in the Antarctic ecosystem, boasting substantial reserves and high nutritional value. It has emerged as a significant commercial fishery resource in the Southern Ocean. However, because of its exceptionally high autolytic enzyme activity, it is susceptible to autolysis and blackening during processing, storage, and transportation, resulting in a decline in the sensory quality and nutritional value of raw materials. Shrimp melanosis is caused by a series of enzymatic reactions mediated by phenoloxidase (PO) within the body. PO facilitates the oxidation of phenolic substances, leading to the formation of highly unstable quinone compounds, which further react to produce melanin. The accumulation of melanin significantly affects the appearance of Antarctic krill, thereby reducing its commercial value. On account of their cost-effectiveness and potent anti-blackening effects, sulfites are commonly used as shrimp anti-black agents. Sodium metabisulfite is one of the compounds whose use is allowed for shrimp preservation under GB 2760-2014 regulations. It not only inhibits PO activity, but also reduces quinone compounds to prevent blackening. However, excessive sulfite use can lead to discomfort and health issues such as gastrointestinal problems, liver disturbances, dyspnea, vomiting, diarrhea, and headaches. Therefore, GB 2760-2014 regulations stipulate that the residual SO₂ content should not exceed 0.1 g/kg. Currently, the use of sodium metabisulfite in production is widespread but lacks standardized requirements, with limited guidance available on how to regulate its usage. Therefore, to assess the impact of sodium metabisulfite on blackening control in Antarctic krill and refine the treatment process, experiments were conducted to measure the changes in SO₂ residue and PO activity in Antarctic krill subjected to various concentrations of sodium metabisulfite solutions and soaking times. Furthermore, observations and analyses were conducted to monitor the blackening of Antarctic krill during cold storage and frozen storage. The results demonstrated a positive correlation between the SO₂ residue in Antarctic krill and the concentration of sodium metabisulfite solution. A concentration of 1 g/L sodium metabisulfite solution resulted in a SO₂ residue of 0.065 g/kg in Antarctic krill, which is below the national standard limit of 0.1 g/kg. However, treatment with a 2 g/L solution led to a SO₂ residue of 0.166 g/kg in shrimp, exceeding the national standard limit. Treatment with a 3 g/L solution resulted in a SO₂ residue of 0.254 g/kg in shrimp, which significantly surpassed the national standard limit. Consequently, we recommended using 1 g/L or 2 g/L sodium metabisulfite solutions to prevent blackening in Antarctic krill while maintaining the SO₂ residue below 0.1 g/kg. Under these conditions, the treatment time for a 1 g/L sodium pyrosulfite solution could be extended to 300 s, with a relative PO activity of 21.2%. For a 2.0 g/L sodium pyrosulfite solution, a treatment time of 30 s was suitable, yielding a relative PO activity of 34.5%. During storage, the control group exhibited noticeable blackening after storage at 4 ℃ for 24 h and frozen storage for 6 months, predominantly in the head, chest, abdomen, and tail sections, and slight variations were observed in the blackening process among individuals. Compared with the control group, the sodium metabisulfite treatment group displayed significantly lower blackening scores during storage (P < 0.05). Specifically, the 1 g/L sodium metabisulfite solution with 300 s treatment group and the 2 g/L sodium metabisulfite solution with 30 s treatment group showed obvious blackening at 48 h and 72 h of cold storage, respectively, and after 12 months of frozen storage, indicating that higher concentrations of sodium metabisulfite solution during treatment led to a better control effect on the blackening of Antarctic krill during storage. Notably, PO activity is just one of the factors influencing the melanosis process. Although the 1 g/L sodium metabisulfite solution with treatment for 300 s could better inhibit PO activity, the anti-blackening effect of this group was not as pronounced as that of the 2 g/L sodium metabisulfite solution with treatment for 30 s during storage. In summary, soaking in 1 g/L sodium metabisulfite solution for 300 s and 2 g/L sodium metabisulfite solution for 30 s resulted in relative PO enzyme activities of 21.2% and 34.5%, respectively. Simultaneously, the SO₂ residues in shrimp were measured at 0.094 g/kg and 0.096 g/kg, respectively, meeting the GB 2760-2014 limit of SO₂ residue not exceeding 0.1 g/kg. Compared with the control group, sodium metabisulfite treatment effectively delayed the blackening process of Antarctic krill during cold storage and frozen storage, with the 2 g/L sodium metabisulfite solution soaking for 30 s exhibiting superior anti-blackening effects. This suggests that a high concentration of sodium metabisulfite solution and a short treatment period had a better blackening inhibition effect. These findings offer a theoretical foundation and technical guidance for maintaining the quality of Antarctic krill during storage and transportation.