A gas chromatography-mass spectrometric (GC-MS) method was developed for the detection of volatile flavor compounds in dry-cured blunt snout bream. Analytical conditions such as extraction temperature, solid-phase microextraction (SPME) probe, headspace vial, chromatographic column, and extraction techniquewere optimized based on the peak area of identified compounds (hexanal, heptanal, octanal, nonanal, 1-penten-3-ol, 1-pentanol, hexanol and 1-octen-3-ol). The results showed that a total of 85 volatile compounds were detected in dry-cured fish. More volatile compounds were extracted at 90 ℃ than at 40 ℃, indicating that more volatile compounds were produced by thermal reaction. Divinylbenzene-carboxen polydimethylsiloxane (DVB/CAR/PDMS) fiber could better adsorb volatile compounds from dry cured fish. Twenty-mL short headspace vials provided better adsorption efficiency for volatile compounds, but the adsorption efficiency was lower than that of tall headspace vials. The volatile compounds in dry-salted fish were separated better on a polar column with good reproducibility. More aldehydes and alcohols were detected using a DB-WAX column, more acids and esters were detected using an HP-INNOWAX column, and more hydrocarbons were separated using a DB-1 column with weak polarity. The results of headspace solid phase microextraction (HS-SPME), stir bar sorptive extraction (SBSE) or dynamic headspace extraction (DHS) combined with gas chromatography-mass spectrometry (GC-MS) showed that DHS extracted the most volatile compounds, SBSE extracted the least volatile compounds, and SPME provided the most efficient and rapid extraction of volatile flavor compounds. SPME and DHS were more suitable for the extraction of volatile compounds from dry-cured fish.

The flavor differences of crawfish meat cooked by three different methods, namely, deep frying (90, 120, 150, and 180 s), air frying (5, 10, 15 and 20 min) and boiling (150 s) were analyzed by electronic nose, electronic tongue and gas chromatography-mass spectrometry (GC-MS). The quality changes of cooked crawfish meat were evaluated in terms of physicochemical indicators such as basic chemical composition, texture, color, thiobarbituric acid reactive substances (TBARs) value. The results showed that the electronic nose and electronic tongue could well distinguish crawfish meat cooked by different methods, and principal component analysis (PCA) showed a clearer discrimination crawfish meat with increased cooking time. Eight and 16 flavor substances were detected in fresh and boiled crawfish meat, respectively; 18, 18, 16, and 19 in deep fried crawfish meat, respectively; and 19, 20, 20, and 16 in air fried crawfish meat, respectively. Pyrazines were significantly more abundant in air fried crawfish meat than in crawfish meat cooked by the other two methods. With cooking time, the moisture content in crawfish meat gradually decreased, the fat content and hardness in deep-fried and air-fried crawfish meat gradually increased, and the springiness increased first and then decreased. The quality of cooked crawfish meat varied among different cooking methods, and the sensory evaluation results showed that the quality of crawfish meat air fried for 15 min was best.

In order to explore the effect of irradiation dose on the quality and flavor of crayfish roe from crayfish processing wastewater, changes in safety indexes such as total bacterial count, coliform group, and heavy metal content were analyzed after ⁶⁰Co-γ ray irradiation at different doses (2, 4, 6, and 8 kGy). Meanwhile, the flavor characteristics were evaluated by the combined use of electronic nose and gas chromatography-mass spectrometry (GC-MS). The results showed that irradiation doses ≥ 4 kGy had better inhibitory effects on the total bacterial count and coliform group, and the heavy metal content in the treated sample met the national standard. The results from the electronic nose showed significant differences in the flavor of crayfish roe treated with four different irradiation doses, and the response values for nitrogen-containing oxides and sulfur-containing compounds increased with irradiation dose. The sample treated with a dose of 6 kGy had the highest amount of volatile flavor compounds (19), the predominant ones being aldehydes, alcohols, and heterocycles. The 4 and 6 kGy irradiation groups were more acceptable in sensory evaluation. In general, 6 kGy irradiation was superior to the other doses in terms of safety and flavor.

A composite emulsion was created by incorporating 4% (m/m) soybean protein isolate and 25% (m/m) soybean oil into a mixture containing 0.5% (m/m) chitosan and 1% (m/m) thymol. By comparing changes in total volatile basic nitrogen content, aerobic bacteria count, pH, biogenic amines content, volatile components, and microbial species in fish meat after storage at different times, the study explored the impact of composite emulsions on the quality of largemouth bass fillets during storage. Our results show that this composite emulsion effectively delayed the increase in total volatile basic nitrogen content, aerobic bacterial count, putrescine, cadaverine, and histamine contents of largemouth bass fillets during storage at 10 °C, extending the shelf life to 16 days. The primary spoilage compounds observed during the storage of largemouth bass fillets were isopentyl butyrate-M, 3-methylpentanoic acid, 4-methyl-2-pentanone, 4-methylthiazole, ethyl 2-methylbutyrate, and 2-butanol-D. Furthermore, the addition of the emulsion during storage effectively reduced the relative abundance of Aeromonas and Citrobacter, while also decreasing the generation of isoamyl butyrate-M and 2-methylbutyraldehyde-M. In conclusion, the combination of chitosan and thymol coating not only delayed the deterioration of largemouth bass fillet quality during storage but also inhibited the growth of spoilage bacteria and reduced the production of volatile spoilage compounds. Therefore, this study can provide valuable reference for the preservation of largemouth bass and the application of low temperature logistics and transportation for aquatic products.

This study systematically investigated lipid metabolic alterations during the dry-curing processing of Wuchang fish (Megalobrama amblycephala) using ultra-performance liquid chromatography-tandem mass spectrometry coupled with an in-house lipidomics database. A total of 1 370 lipid species were identified, classified into six major categories (fatty acids, glycerolipids (GL), glycerophospholipids (GP), prenol lipids, sphingolipids, and sterol lipids) and 41 subclasses. Orthogonal partial least squares-discriminant analysis revealed significant lipidomic divergence among three processing stages (fresh fish (CK), curing for 2 days (Y2), and drying for 2 days (G2)), with GL dominating the lipid profile and GP exhibiting marked depletion during salting. The lipid oxidation index elucidated competing effects of lipid hydrolysis (substrate depletion) and oxidation (metabolite generation), revealing that lipoxygenase-driven conversion of polyunsaturated fatty acids (PUFAs) to volatile aldehydes and alcohols predominated during salting, while reduced water activity in air-drying triggered PUFAs autoxidation and oxylipins accumulation. Post-processing nutritional enhancement was evident, with essential fatty acids (eicosapentaenoic acid, docosahexaenoic acid, linoleic acid, and oleic acid) significantly enriched in air-dried fish, constituting 18.869% of total free fatty acids, a substantial increase from 13.414% in fresh samples. This work provides critical insights into flavor formation mechanisms and quality control strategies for traditional dry-cured fish products.

The free amino acids, flavor nucleotides, organic acids and inorganic salts in cooked crayfish were qualitatively and quantitatively analyzed by high performance liquid chromatography (HPLC) and ultraviolet (UV) spectrophotometry. The taste profile was determined by taste activity value (TAV) and sensory evaluation, and the taste-active components were identified by omission and addition tests. The results showed that a total of 17 free amino acids and three taste nucleotides were detected in cooked crayfish. Among all taste components tested, the content of Arg (935.19 mg/100 g) was the highest, accounting for 35.95% of the total free amino acids, followed by K⁺ (817.63 mg/100 g) and adenosine monophosphate (AMP, 778.09 mg/100 g). Arg, Glu, Ala, His, Val, Gly, Asp, AMP, guanosine monophosphate, lactic acid, succinic acid, Na⁺, and K⁺ had TAV greater than 1, which may be potential taste-active components in cooked crayfish. Sensory profiling analysis and recombination, addition and omission tests showed that free amino acids and nucleotides were the main contributors to crayfish taste, and organic acids and some inorganic salt ions were auxiliary umami enhancers. The main taste characteristics of the hot aqueous extract of cooked crayfish were umami and kokumi, and its key taste components were Glu, Gly, Val, Ile, Leu, Phe, Arg, His, Ala, Tyr, AMP, lactic acid, Na⁺, K⁺ and PO₄^3-.

To investigate the effect of sterilization on the quality of crayfish hepatopancreas, hepatopancreas samples from whole crayfish and hepatopancreas irradiated with ⁶⁰Co γ-ray (6 kGy) and non-irradiated hepatopancreas were evaluated for color, browning index, 5-hydroxymethylfurfural (5-HMF) content, peroxide value (POV), thiobarbituric acid reactive substances (TBARS) value, total phenol content, and pyrrole content. The results showed that there was no significant difference in whiteness between the irradiated whole crayfish group and the non-sterilized group (P > 0.05), but the former had significantly higher brightness (L^*) and significantly lower redness (a^*) value compared to the latter (P < 0.05). After irradiation, the absorbance at 294 nm and browning degree of crayfish hepatopancreas increased, but the fluorescence intensity and 5-HMF content decreased, indicating that irradiation could trigger the Maillard reaction but then decompose the reaction products. The POV, TBARs value, pyrrole content, and total phenol content of both irradiated groups were higher than those of the non-sterilized group. Notably, a significant increase in these parameters was observed for the irradiated whole crayfish group (P < 0.05) indicating a higher degree of oxidation. Overall, irradiation can maintain the color of crayfish hepatopancreas well, but also promote the Maillard reaction and lipid oxidation, especially for whole crayfish.

This study employed four thermal processing methods to cook crayfish meat, including hot-water steaming (HS), hot-water boiling, cold-water steaming (CS), and cold-water boiling (CB). The results indicated that the four thermal treatments had varying effects on the nutritional composition, texture, microstructure, and color of the crayfish meat, as well as significant differences in the retention of volatile flavor compounds. Specifically, the cooking loss in the CB group (12.79%) was significantly higher than in the other three groups, but the retention of mineral elements was lower. Microstructural observations revealed that boiling caused more severe damage to the muscle fiber structure compared to steaming, while CB significantly increased the hardness and chewiness of the crayfish meat. The T₂₂ signal intensity of the CB group was significantly lower than that of the other groups, indicating the greatest loss of immobile water in this treatment, while CS better retained moisture in the muscle fibers. Moreover, different cooking methods led to variations in the retention of volatile flavor compounds in the crayfish meat. Among the four methods, HS was most effective in retaining volatile flavor compounds. Overall, steaming treatments were more beneficial for preserving the nutritional components and maintaining better texture of the crayfish meat, while boiling treatments were more conducive to retaining the flavor compounds. Our findings provide valuable insights for selecting thermal processing methods for crayfish and offer useful information for the development of crayfish products.