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In order to determine the optimal method for drying Apostichopus japonicus gonads, the effects of four drying methods, namely, hot air drying, cold air drying, microwave drying and vacuum freezing drying, on the lipid composition, lipid stability and fatty acid nutritional value of A. japonicus gonads were analyzed and compared. The results showed that the contents of total lipids, phospholipids, triglycerides and astaxanthin reduced to different degrees after drying treatments. The peroxide value (POV) significantly reduced, and the thiobarbituric acid reactive substances (TBARS) value significantly increased (P < 0.05). In terms of fatty acid nutritional values, the atherogenic and thrombogenic indices decreased to different degrees after drying treatments, and the hypocholesterolemic/hypercholesterolemic indices increased significantly (P < 0.05). The results of electronic nose analysis showed significant differences in odor characteristics among dried samples obtained using different drying methods. Gas chromatography-ion mobility spectrometry (GC-IMS) identified 28 volatile substances from fresh and dried samples, among which, 2,5-dimethyl pyrazine was detected only in microwave-dried samples, while pentanal and ethyl acetate were odor-active substances unique to cold air-dried samples. In conclusion, vacuum freeze drying effectively slowed down the rate of lipid oxidation, but the samples were relatively bland in odor. Hot air, cold air and microwave drying all promoted lipid oxidation, but improved the nutritional value of fatty acids and enriched the odor characteristics of the samples. The results of this study could provide a theoretical basis for the processing and utilization of A. japonicus gonads.

Accurately grasping the comprehensive cost-benefit and influencing factors of various marine development projects is of great significance to the promotion of high-quality marine development. This work screened and constructed the performance audit evaluation index system of comprehensive cost-benefit of marine development projects from the four aspects including society, economy, resources, and environment. The entropy weight set pair analysis (SPA) was used to audit and evaluate the comprehensive cost-benefit of 15 marine development projects during the construction and operation period. The back propagation (BP) neural network model was used to test the results. The main influencing factors were analyzed by the grey relational analysis (GRA) model. It was found that the comprehensive cost-benefit performance audit evaluation index of the six projects of marine protected area and offshore wind power were higher than the other nine projects of mariculture, sewage dumping, and port industry. The main influencing factors were economic net income, loss of wetland ecological service value, environmental pollution prevention and control cost, new addition employment rate, etc. The countermeasures suggestions were put forward.

In order to explore the mechanism of flavor differences, the effect of two cooking methods, namely steaming and microwaving on the lipid composition, the degree of lipid oxidation and hydrolysis, and volatile substances in Penaeus vannamei was studied. The results showed that the contents of total lipids as well as phospholipids, triglycerides, and free fatty acids in P. vannamei were significantly reduced after cooking (P < 0.05). The lipid composition differed between steamed and microwaved shrimp. Microwaved shrimp had higher phospholipid contents but lower free fatty acid contents than the steamed one. The content of saturated fatty acids decreased markedly whereas the content of unsaturated fatty acids increased significantly after cooking (P < 0.05), which may be related to the hydrolysis of phospholipids. Steaming and microwave heating accelerated the oxidation and hydrolysis of lipids, resulting in a significant increase in acid value and thiobarbituric acid reactive substances (TBARS) value (P < 0.05). The results of electronic nose analysis showed that the odor characteristics of fresh, steamed and microwaved shrimp were significantly different, and the odor of fresh shrimp changed more after microwave heating. Twenty-five volatile substances were isolated and identified from shrimp meat using gas chromatography-ion mobility spectrometry (GC-IMS). Among these compounds, 2,3-glutaraldehyde, 2-butanone, 2-methyl butyraldehyde, hexanal, 1-octen-3-one and glutaraldehyde were the major flavor substances in cooked shrimp meat and their contents were higher in the microwaved sample. Pearson correlation analysis showed that oxidative hydrolysis of lipids made an essential contribution to the flavor formation of cooked shrimp and the free fatty acids C14:0, C15:0, C16:1, C18:1n9c, C18:2n6c and C18:3n3 were closely related to the formation of the characteristic odors of shrimp meat.

The comprehensive benefit evaluation of marine resources developmental model is of great significance to choose the appropriate types of marine resources development and promote the intensive utilization and sustainable development of marine resources. This article examined five types of marine resources development, such as marine protected areas, mariculture, offshore wind power, sewage dumping, and land reclamation, and constructed a three-level evaluation index system for the comprehensive benefits of marine resources development. The projection pursuit clustering model was used to evaluate and analyze the comprehensive benefits and main influencing factors of 15 marine resources development projects in Jiangsu Province, China. It was found that the comprehensive benefit projection values of marine protected areas and offshore wind power are higher. The projection value of comprehensive benefit of land reclamation is the lowest. The main influencing factors include but not limited to the change rate of total output of aquatic products, contradiction between management and marine use, negative impact on residents’ lives, etc. The research results have important guiding significance for promoting the rational development and utilization of marine resources and the high-quality development of the oceans.

Shaped cathode electrochemical machining is often used to process array microgrooves on difficult-to-machine materials because of its great flexibility. Unlike the single-groove structure, the current density distribution varies greatly during machining of array microgrooves, which is mainly dependent on the sheet cathode array offset (SCAO). This study establishes and validates a mathematical model based on SCAO for the stray-current density, U, and ton. Then the end gap and side gap are modeled. Next, through simulation, the current density distribution at various SCAO is examined. It has been discovered that when the SCAO grows, the current density distribution becomes more uniform, and the stray-current density becomes milder. The array microgrooves having high quality and high density can be fabricated at a SCAO of 1.4 mm. Additionally, the experiments show that quality and efficiency can be ensured under the optimal parameters. [ABSTRACT FROM AUTHOR]