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To make full use of crayfish head and other by-products, explore the feasibility of crayfish head as food processing ingredients. In this paper, the head of crayfish cultured in rice fields in Guangxi were used as raw materials. The basic nutrients such as protein, fat, ash, amino acids and fatty acids in crayfish head were determined by national standards, the contents of flavor nucleotides and organic acids in crayfish head were determined by high performance liquid chromatograph. The overall taste and odor of fresh crayfish head were analyzed by electronic tongue and gas chromatography ion mobility spectrometry (GC-IMS). The results showed that: From the perspective of nutritional composition, crayfish head is rich in nutrients, which mainly consists of crude protein (10.92 g/100 g) and crude fat (9.05 g/100 g), and the fat contains phospholipid 4.67 mg/g. There were 17 kinds of amino acids in crayfish head, and the total content was 97.28 mg/g, among which there were 7 kinds of essential amino acids, accounting for 50.01% of the total amino acids. A total of 19 kinds of fatty acids (9 kinds of saturated fatty acids and 10 kinds of unsaturated fatty acids) were detected, and the unsaturated fatty acids contained 57.94%. In terms of flavor composition, amino acids, phospholipids and fatty acids were important flavor precursors. In addition, the total content of free amino acids in fresh crayfish head was 900.70 mg/100 g, and the fresh and sweet amino acids accounted for 39.88%. The flavor nucleotides and organic acids in the crayfish head also provided a richer taste. The umami response value of the electronic tongue of shrimp head was 13.55, indicating that the umami taste was obvious. A total of 23 volatile flavor compounds were identified in the crayfish head, including aldehydes, ketones and alcohols, etc., which had a certain aroma of oil, meat, similar to grass and fruit, and earthy smell. In general, crayfish head was nutritious and healthy, and contained rich flavor precursors and taste substances. It had certain potential and feasibility in the processing and utilization of crayfish head and the development of condiments.

In order to investigate the effects of temperature on the quality of Procambarus clarkiii during waterless preservation, the changes in survival rates, muscle flesh quality, and physiological indicators of Procambarus clarkiii were analyzed under different waterless storage temperatures. The results showed that the survival rates of Procambarus clarkii in those of 4~16 ℃ groups were 80%~90% after 72 h of waterless preservation, the 24 ℃ group dropped to 40%, and the 32 °C group had reached zero. The moisture content, water-holding capacity, muscle hardness, and elasticity of muscle decreased significantly with the increase in temperature and time (P

In this paper, Penaeus vannamei (PV), Penaeus monodon (PM) and Macrobrachium rosenbergii (MR) were used as the research object, through comparing the rheological properties, cooking yield, water holding capacity, texture properties and sensory characteristics of different varieties of shrimp surimi, to explore the quality differences of different raw materials varieties of shrimp surimi, in order to provide a theoretical basis for the selection of raw materials for shrimp products. The results showed that the meat yield of PV, PM and MR were 53.12%, 49.40% and 34.93% respectively. The storage modulus (G') of three varieties of shrimp surimi began to rise rapidly at about 40 ℃, reached the maximum at 65 ℃, and the G'max value of PV was the highest. After repeated freezing and thawing treatment, G' did not increase significantly during the temperature rised of shrimp, indicating that freezing would change the protein structure of shrimp and lead to a decline in gel quality. After freezing and thawing, the cooking yield and water retention rate of PV and PM shrimp surimi gel increased, while MR decreased. PV shrimp surimi gel had the best hardness and chewiness. The elasticity of PM gel was the best. Sensory evaluation showed that the tissue state and texture of PV and PM shrimp surimi gel were better than MR. After repeated freezing and thawing, the texture and sensory score of PV shrimp surimi gel were excellent. The crude protein contents of PV, PM and MR were 21.72, 19.30 and 17.23 g/100 g respectively, and the quality of PV and PM gel with lower water-soluble protein and higher salt soluble protein was better. The MR with highest water soluble protein content formed the worst gel, and the salt soluble protein content of three shrimp surimi decreased significantly after repeated freezing and thawing. In conclusion, the surimi of Penaeus vannamei has good taste, high meat yield and low cost, so it is suitable to be used as the raw material of prawn products.

Sensory evaluation, texture analyzer, low field-nuclear magnetic resonance (LF-NMR) and scanning electron microscope were used in this study for analyzing the changes of moisture, sensory quality, color, texture and microstructure of crayfish tail during frying, and the correlation between relaxation time and related indexes was analyzed. The results showed that: With the increasing of frying temperature and frying time, the moisture content decreased. LF-NMR imaging showed that the water was removed gradually from the outside to the inside. The peak area and relative proportion of relaxation time T22 decreased, which showed that the immobilized water was removed mainly during frying. With the decrease of water content of fried crayfish tail, the brightness of color (L* value) and the red value (a* value) decreased, and yellow value (b* value) rised, at the same time the hardness, elasticity and chewiness of crayfish meat increased gradually. Scanning electron microscope images showed that muscle fibers contracted and the gap became dense. The happiness and chewiness indexes of crayfish tail were best when the water content was 60.5%. At this point, the hardness was 24.55~25.64 N, the elasticity was 3.52~3.57 mm, the cohesion was 0.7 Ratio, and the chewiness was 54.6~56.5 mJ. Correlation analysis showed that, T22 was negatively correlated with hardness, elasticity, cohesiveness and chewiness (P

In order to improve the utilization rate of silkworm pupa resources and the added value of products, silkworm pupa peptides were prepared from silkworm pupa proteins by liquid fermentation of natto. The optimum fermentation conditions were determined by single-factor experiment and response surface methodology. The inflammatory model of RAW264.7 macrophages was established by lipopolysaccharide, and the anti-inflammatory activity of silkworm pupa peptides were studied in vitro. The results showed that the optimum fermentation conditions of silkworm pupa peptide were inoculation amount 5.0 mL, silkworm pupa protein addition amount 2.6 g, initial pH7.0, fermentation temperature 37 ℃ and fermentation time 35.4 h. Under these conditions, the yield of silkworm pupa peptide was 14.58%. Silkworm pupa peptides were nontoxic to RAW264.7 macrophages and had significant proliferation effect on cells (P