BACKGROUND Among various cooking methods, steaming is favored by many because it can cause less damage to nutrient components in muscle, retain the inherent food flavor, and reduce the generation of harmful substances. Steaming conditions are closely related to fish flavor, fat and protein oxidation, and digestibility. RESULTS The black carp steamed for 4 to 14 min was studied in this article based on sensory assessment, electronic tongue, free amino acids, adenosine triphosphate (ATP)‐related compounds, total nitrogen and non‐protein nitrogen to explore the effect of steaming time on the taste substances and protein degradation of pickled black carp. The experimental result showed that the meat steamed within 8 min tasted better, showing high tastiness. The sensory assessment score increased significantly to the maximum value of 82.33 at 6 min. The content of umami and sweet amino acids increased significantly to the maximum value of 1.6801 g kg–1 at 6 min. In the meantime, the IMP (inosine monophosphate) content was 1.9128 g kg–1, with its taste activity value (TAV) reaching 7.65, which proved that IMP affected the taste most. Furthermore, the total nitrogen content was 30.77 g kg–1, which meant protein degraded a great deal. Based on equivalent umami concentration (EUC) and its TAV, the meat tasted best at 6–8 min. The longer the steaming time, the faster the protein degradation and the more the flavor precursors. CONCLUSION The black carp pickled products (with a weight of 20 g, with the size of 3 cm × 3 cm × 2 cm) is suggested to be steamed for 6 to 8 min. This conclusion provides a theoretical basis for its better taste quality. © 2020 Society of Chemical Industry

This work describes the development and application of an electrochemical cell specifically designed for disposable screen printed carbon electrodes (SPCE) suitable for simultaneous electrochemiluminescence (ECL) and amperometric detection in sequential injection analysis. The flow system with facility for photomultiplier tube via a fiber optic facing the SPCE is user-friendly and makes the detection process very easy to operate. Instead of the need to constant deliver the chemiluminescence (CL) reagents to the reaction zone, sequential injection analysis allows a considerable reduction in the consumption of the sample and expensive CL reagents (such as Ru (bpy) 2þ 3 salts). The utility of the analyzer was demonstrated for the detection of oxalate based on the ECL reaction with Ru(bpy) 2þ 3 . Under optimized conditions, in the presence of 100 mM Ru(bpy) 2þ 3 , the linear ranges of peak current and ECL light intensity for oxalate distinctly varied from 10 mM to 5 mM and 0.1 mM to 100 mM, respectively. In other words, the linear detection can be covered over a four-order range with the combination of these two signals.

The research on the quality changes of grass carp during brine salting with 6%, 8%, and 10% salt additions was evaluated by chemical and physical indicators, as well as a sensory assessment and microbiological analysis. The NaCl content was proportional to salt addition and salting time. The increase of salt addition could lead to the increase of hardness and chewiness in which change trends were contrary to the pH within 24 hr. All K values were less than 10% during brine salting. The effect of 8% salt additions on free amino acids was relatively smaller. Higher levels of salt additions could inhibit bacterial growth. Combined with sensory assessment, equivalent umami concentration (EUC), and taste activity value (TAV) to analysis comprehensively, it was suggested that grass carp meat should be eaten at 4–8 hr of brine salting with 8% salt additions or processed for the next step, in which the grass carp meat had a better taste and quality.

Summary The aim of this study was to investigate the changes in physicochemical properties and myofibrillar protein properties of grass carp meat during brining and brine injection at 4 °C. The time reached equilibrium was 7 h in brining group and 5 h by injection, where the salt content was about 1.76%. The water content, water holding capacity and yield in injection group (86.59%, 9.18% and 110%, respectively) were higher than brining group (84.76%, 11.47%, and 108%, respectively) at equilibrium point significantly (P < 0.05). This was attributed to the more swollen filament lattices and disordered protein structure in injection group (P < 0.05). The myofibrillar protein structure was compared, including sulphydryl content, surface hydrophobicity, solubility, sodium dodecyl sulphate polyacrylamide gel electrophoresis pattern and secondary structure. The injection group presented the better quality of salted fish meat in shorter time.

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