Composition and nutritional qualities of edible tissues of Chinese mitten crab (Eriocheir sinensis) from Ya Lake over different months

Variability in Morphological Traits and Nutritional Profiles of Adult Eriocheir sinensis in Different Aquacultural Regions

Eriocheir sinensis is a species of significant economic importance in China's aquaculture industry. In order to investigate the variations in morphologic and nutritional profiles of farmed crabs across diverse farming regions, E. sinensis were collected from six aquafarms located in the primary cultivation areas in China. The findings revealed significant variations in specific morphological indices, but these are insufficient for clear regional distinction using PCA. Essential amino acid (EAA) levels varied by tissue and gender, with ovaries from the YY (Yongyan in Anhui province) group showing the highest levels, while the hepatopancreas in females from the JX (Jianxian in Jiangxi province) group had the lowest. The analysis of fatty acid contents revealed that muscles were rich in PUFAs, whereas MUFAs were dominant in the hepatopancreas and gonads. The fatty acid levels were significantly higher in ovaries than in testes, notably in the HZ (Huzhou in Zhejiang province), EZ (Ezhou in Hubei province), YY, and JX groups. Furthermore, the PCA based on proximate composition, amino acids, and fatty acids revealed distinct categorizations of E. sinensis from various regions. In conclusion, these findings highlight significant regional variations in the morphology and nutritional composition of farmed E. sinensis, suggesting the need for tailored aquaculture practices to optimize quality and output.

Edible portions of precooked blue swimming crab: Chemical composition and effect of chitooligosaccharide conjugate and high-pressure processing on microbial inactivation

Different edible portions including meat (lump, claw and backfin) and roe of blue swimming crab (Portunus pelagicus) were analyzed. Both meat and roe had high protein content, but a greater fat content was found in roe. All meats showed higher levels of polyunsaturated fatty acids than roe. Myosin heavy chain and actin constituted as key proteins in meat, but the protein pattern of roe was completely different. Glutamic acid/glutamine were dominant in lump meat, while leucine was prevalent in roe. Meats were fibrous, while roe had a granular structure. Moraxellaceae were dominant in both samples and roe had higher microbial diversity than lump meat. When chitooligosaccharide-catechin (COSC) conjugate and high-pressure processing (HPP) were applied for both lump meat and roe, COSC conjugate (200 ppm) reduced Vibrio spp., and HPP at 500 MPa eliminated all detectable bacteria in both samples. Developed method was promising for enhancing food safety and maintaining quality of precooked crab products.

Detection of Critical Parts of River Crab Based on Lightweight YOLOv7-SPSD

The removal of back armor marks the first stage in the comprehensive processing of river crabs. However, the current low level of mechanization undermines the effectiveness of this process. By integrating robotic systems with image recognition technology, the efficient removal of dorsal armor from river crabs is anticipated. This approach relies on the rapid identification and precise positioning of the processing location at the crab's tail, both of which are essential for optimal results. In this paper, we propose a lightweight deep learning model called YOLOv7-SPSD for detecting river crab tails. The goal is to accurately determine the processing location for the robotic removal of river crab back armor. We start by constructing a crab tail dataset and completing the data labeling process. To enhance the lightweight nature of the YOLOv7-tiny model, we incorporate the Slimneck module, PConv, and the SimAM attention mechanism. These additions help achieve an initial reduction in model size while preserving detection accuracy. Furthermore, we optimize the model by removing redundant parameters using the DepGraph pruning algorithm, which facilitates its application on edge devices. Experimental results show that the lightweight YOLOv7-SPSD model achieves a mean Average Precision (mAP) of 99.6% at a threshold of 0.5, an F1-score of 99.6%, and processes frames at a rate of 7.1 frames per second (FPS) on a CPU. Compared to YOLOv7-tiny, the improved model increases FPS by 2.7, reduces GFLOPS by 74.6%, decreases the number of parameters by 71.6%, and lowers its size by 8.1 MB. This study enhances the deployment of models in river crab processing equipment and introduces innovative concepts and methodologies for advancing intelligent river crab deep processing technology.

Comparison of Body Characteristics, Carotenoid Composition, and Nutritional Quality of Chinese Mitten Crab (Eriocheir sinensis) with Different Hepatopancreas Redness

In this study, we investigated the body characteristics, carotenoid composition, and nutritional quality of Eriocheir sinensis with different hepatopancreas redness (a*). We distributed the crabs into two groups based on the hepatopancreas a* values and compared their body characteristics, chroma, carotenoid composition, and protein, lipid, total sugar, amino acid, and fatty acid content via paired t-test. The results revealed that the relationships between hepatopancreas a* values and crab quality are sex specific. In female crabs, the differences in nutritional characteristics were evident mainly in the hepatopancreases and ovaries. In the redder hepatopancreases, the content of zeaxanthin and β-carotene increased, and the levels of C22:6n3 and C20:5n3 decreased (p < 0.05). In the ovaries, the content of astaxanthin, canthaxanthin, β-carotene, umami, and sweet amino acids were lower in the redder hepatopancreas crabs (p < 0.05). In male crabs, there were positive relationships between hepatopancreas a* and amino acid and fatty acid content. The content of leucine, arginine, and total umami amino acids in muscles and of unsaturated fatty acids and n-6 polyunsaturated fatty acids in hepatopancreases and testicles increased with increasing hepatopancreas a* values (p < 0.05). Therefore, the redder the hepatopancreas, the higher the nutritional quality of male crabs.

Correlation of Taste Components with Consumer Preferences and Emotions in Chinese Mitten Crabs (Eriocheir sinensis): The Use of Artificial Neural Network Model

This study took a consumer sensory perspective to investigate the relationship between taste components and consumers’ preferences and emotions. Abdomen meat (M), hepatopancreas (H), and gonads (G) of Chinese mitten crabs, one from Chongming, the Jianghai 21 variety (C-JH), and two from Taixing, the Jianghai 21 (T-JH) and Yangtze II varieties (T-CJ), were used to evaluate flavor quality. The results indicated that in the abdomen meat, differences in taste components were mainly shown in the content of sweet amino acids, bitter amino acids, K+, and Ca2+; M-C-JH had the highest EUC value of 9.01 g/100 g. In the hepatopancreas, bitter amino acids were all significantly higher in H-C-JH (569.52 mg/100 g) than in the other groups (p < 0.05). In the gonads, the umami amino acid content was significantly higher in G-T-JH than in the other groups (p < 0.05) (EUC values: G-T-JH > G-C-JH > G-T-CJ). Consumer sensory responses showed that different edible parts of the crab evoked different emotions, with crab meat being closely associated with positive emotions and more complex emotional expressions for the hepatopancreas and gonads. In comparison, consumers were more emotionally positive when consuming Yangtze II crab. H-C-JH evoked negative emotions due to high bitter taste intensities. Multifactor analysis (MFA) showed arginine, alanine, glycine, proline, K+, and Ca2+ were found to have a positive correlation with consumer preference; an artificial neural network model with three neurons was built with good correlation (R2 = 0.98). This study can provide a theoretical foundation for the breeding of Chinese mitten crabs, new insights into the river crab industry, and the consumer market.

Fattening in Saline and Alkaline Water Improves the Color, Nutritional and Taste Quality of Adult Chinese Mitten Crab Eriocheir sinensis

The majority of pond-reared Chinese mitten crab (Eriocheir sinensis) grow and fatten in freshwater. Previous studies illustrated that E. sinensis cultured in saline-alkaline water in outdoor environments showed a higher quality than that cultured in freshwater. However, it is still unclear whether salinity or alkalinity has an important positive effect on the quality of E. sinensis. This study aimed to investigate the gonadal development, edible yield, coloration, and nutritional and flavor quality of E. sinensis fattening in saline and alkaline water indoors. Results showed that there were no significant changes observed in gonadosomatic index (GSI) and other edible parameters among freshwater (FW), saline water (SW), and alkaline water (AW) during the 55-day fattening period (p > 0.05). Significantly higher a* and b* values of freeze-dried female carapace were observed fattening in SW and AW compared with that of FW (p < 0.05). The crude protein in gonad and male muscle, moisture in female muscle, and crude lipid in male muscle increased significantly from FW to SW and AW (p < 0.05). Better nutritional and flavor values were also detected in male hepatopancreas and muscles. In conclusion, numerous advantages of fattening in SW and AW were observed, including the improvement of carotenoid accumulation in freeze-dried carapace, DHA, EPA, total essential free amino acids (∑EFAA), total free amino acids (∑FAA), and total umami values (∑TUV) contents in male hepatopancreas and muscle.