The processing of fish-pork sausage was optimized by single factor experiments and orthogonal array design methods. The results of single factor experiments showed that increasing the ratio of fish to pork obviously increased the content of free amino acids in sausage, and that the sausage with fish/pork ratio of 3:5 (m/m) had better texture characteristics and sensory quality. The moisture content was lower and the content of free amino acids was evidently higher in the sausage prepared by two-step heating at 90 and 100 ℃ than in the other groups. The sausage prepared by 20/60 min heating scored highest in sensory evaluation, having higher water-soluble protein content and better texture properties such as elasticity. The sausage with 10% added salt had the highest hardness. With an increase in salt content, the measured moisture content and pH tended to decrease. Using orthogonal array design and analysis of variance (ANOVA), the optimal processing conditions were obtained as follows: mass ratio of fish to pork 6:2, amount of salt added 8%, and 90 ℃/20 min and 100 ℃/60 min heating. The casing of the prepared sausage was complete, which was lustrous and grayish-red in color. The sausage had a homogenous and compact texture with good elasticity. It had a moderate umami and salty taste.

In order to explore the characteristic flavor compounds and to infer the possible main flavor precursors in irradiated pigeon meat, the changes of volatile compounds and lipid metabolites in irradiated pigeon meat were analyzed by headspace solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) and ultra-high performance liquid chromatography-tandem quadrupole time-of-flight high-resolution tandem mass spectrometry (UPLCT-riple-TOF MS/MS). The results showed that hydrocarbon and aldehydes were the major volatile components in pigeon meat. There were 10 key flavor components identified, among which, nonanal, (E)-2-hexenal, decanal, hexanal, (E)-2-octenal, (E,E)-2,4-nonadienal, octanal, 2,4-decadienal, and 1-octen-3-ol substances were derived from lipid oxidation, and nonanal aldehydes such as aldehydes, decanal, and hexanal may be generated by the decomposition of oleic and linoleic acids. Fatty acids (FA), AcylCarnitine, plasmenylPE, GlcCer_NDS, AcyGlcADG, lysoPC, Cer_BS, and lysoPS were identified as significantly differential lipid subclasses. Among the 30 lipid molecules with variable importance in the projection (VIP) scores higher than two, 6 contained oleic acid (C_18:1) and 10 contained linoleic acid (C_18:2). Oleic acid and linoleic acid, precursors for the formation of the characteristic flavor substances of pigeon meat, may be generated by the degradation of these 16 lipid molecules.

Chilled pigeon meat was irradiated with different doses of ⁶⁰Co-γ rays, and the effect of irradiation on the quality and lipid oxidation of chilled pigeon meat was investigated through the determination of biochemical and physicochemical indexes, volatile flavor components and microstructure observation. The results showed that with an increase in irradiation dose, the a* value, total volatile basic nitrogen (TVB-N) value, juice loss percentage, peroxide value (POV), thiobarbituric acid reactive substances (TBARS) value and acid value increased significantly (P < 0.05), and total bacterial number (TBN), L* value, b* value and texture parameters decreased significantly (P < 0.05); the diameter of muscle fibers decreased significantly (P < 0.05) and the gap between muscle fibers increased; and the contents of total, saturated and monounsaturated fatty acids increased significantly (P < 0.05), while the contents of polyunsaturated fatty acids decreased significantly (P < 0.05), indicating that irradiation treatment can promote the oxidative hydrolysis of lipids into free fatty acids and the decomposition of polyunsaturated fatty acids in pigeon meat. A total of 73 volatile components belonging to 8 chemical classes were detected in pigeon meat. Among them, hydrocarbons and aldehydes were most abundant, indicating that lipid oxidation has an important impact on the flavor of irradiated pigeon meat. The results of this study can provide a theoretical basis for the application of irradiation in the processing of livestock and poultry meat.

Tilapia fillets rinsed in ozone water were made into surimi, and the effects of ozone water concentration and rinsing time on the quality and in vitro digestive properties of surimi were investigated. Furthermore, the mechanism by which ozone water rinsing improved the quality of tilapia surimi was investigated by analyzing the degree of myofibrillar protein oxidation. The results showed that the whiteness, hardness and gumminess of surimi were significantly increased by ozone water rinsing (P < 0.05), and the surimi rinsed with 10 mg/L ozone water for 10 min had the best gel properties. With the increase in ozone water concentration and rinsing time, the thiobarbituric acid reactive substances (TBARS) value of surimi tended to increase, and the carbonyl content of myofibrillar proteins increased and the total sulfhydryl content gradually decreased. The sensory evaluation results showed that the best sensory quality was obtained by rinsing with 10 g/mL ozone water for 10 min. sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) showed that rinsing with 10–18 mg/L ozone water caused the proteins to cross-link and form small soluble aggregates, while ozone water at concentrations more than 18 mg/L caused the formation of large insoluble aggregates. According to Raman spectra, after rinsing with 10–18 mg/L ozone water, the secondary structure of myofibrillar proteins was gradually unfolded, and the α-helix was gradually converted to β-sheet and random coil. Ozone water rinsing increased the degree of hydrolysis of surimi during in vitro digestion, the highest being observed with 10 mg/mL ozone water rinsing for 10 min. The content of small peptides (100-1000 Da) after digestion was significantly higher than that of the other experimental groups (P < 0.05). In conclusion, moderate oxidation of myofibrillar proteins could improve the quality of tilapia surimi, and the surimi rinsed for 10 min in 10 mg/mL ozone water had the highest sensory quality and the best gel characteristics and in vitro digestive characteristics.

To investigate the effects of different irradiation treatments on the quality of black pepper beef during storage, a backpropagation-artificial neural network (BP-ANN) model for predicting various quality attributes of black pepper beef was developed based on physicochemical indicators. Irradiation at a dose of 3–4 kGy effectively delayed the loss of juice, lipid oxidation, and protein degradation in black pepper beef during storage, maintained its hardness and microstructure, and increased the contents of umami (Asp) and sweet (Gly, Ala and Ser) amino acids. The BP-ANN model was optimized with the juice loss, thiobarbituric acid reactive substances (TBARS) value, total volatile basic nitrogen (TVB-N) content, tropomyosin band intensity ratio, myosin heavy chain band intensity ratio, and total free amino acid content of irradiated black pepper beef as input variables. The ReLU function was used as the activation function, with 14 neurons in the hidden layer and 100 iterations. The results showed that the 6-14-6 BP-ANN model could predict the quality changes of irradiated black pepper beef well, and have great potential in predicting various qualities of irradiated meat products.