Effects of dietary replacement of fish oil by vegetable oil on proximate composition and odor profile of hepatopancreas and gonad of Chinese mitten crab (Eriocheir sinensis)

Elucidation of key fatty aroma compound contributing to the hepatopancreas of Eriocheir sinensis using sensomics approach by GC-IMS and GC-MS-O

Aroma is one of the most noticeable characteristics when consuming Chinese mitten crab (Eriocheir sinensis) and is crucial for consumer satisfaction and the development of industry. In this study, we utilized fingerprints and the sensomics approach to analyze volatiles in the hepatopancreas of E. sinensis from Chongming and Taixing. GC-IMS indicated that the odor profile was dominated by pungent (-), buttery (+), and fruity (+) from Chongming and was more prone to alcoholic (-), solvent (-), and aldehydic (+) in Taixing. Moreover, PLS-DA modeling identified 2-acetylthiazole and toluene as the primary differential compounds. Subsequently, fifteen active-aroma compounds with FD values of >4 was recombined in an odorless matrix to simulate the odor profile of the hepatopancreas. Notably, removing methional may significantly decrease the intensity of the fatty and toasted odors. The findings reveal the odor profile of hepatopancreas and establish a theoretical foundation for subsequent studies on flavor.

Environmental salinity and dietary lipid nutrition strategy: Effects on flesh quality of the marine euryhaline crab Scylla paramamosain

The quality of crustaceans' flesh has direct impact on consumers' purchase choices, with water environment and dietary nutrition being effective ways to regulate flesh quality. The aim of present study was to investigate the impacts of water salinity (low, 4 and medium, 23) and dietary lipid source (fish oil and soybean oil) on nutritional values, texture, taste and odor of flesh of mud crab. While water salinity had no significant influence on nutritional values of crab flesh, crabs fed soybean oil displayed significantly lower contents of amino acids and n-3 PUFAs in muscle. However, crabs reared at low salinity showed reduced flesh hardness, chewiness and gumminess likely related to altered myofiber structure, that impacted muscle texture. Furthermore, low salinity and dietary soybean oil weakened umami taste and aroma characteristics of crab flesh associated with decreased contents of free amino acids, flavor nucleotides, inorganic ions and odor active compounds in flesh.

Key lipid molecules in hepatopancreas of Eriocheir sinensis: Identification and thermal oxidative degradation characteristics

The hepatopancreas of Eriocheir sinensis are the key parts that form its unique flavor. Lipids are important parts of hepatopancreas; hence, this study used UHPLC-Q E Orbitrap mass spectrometer to investigate the changes in the lipid composition of crabs formed from thermal oxidation system. The results demonstrated that key lipids in the hepatopancreas of female Chinese mitten crabs were phosphatidylethanolamine (PE) and free fatty acid (FFA) during the steaming process. The key fatty acids of PE were C18:1, C18:3, C20:3, C20:4, C20:5, and C22:6. The degradation rate of C24:0 in FFA was greater than the synthesis rate. Principal component analysis, partial least square analysis combined with hierarchical cluster analysis found that PE (16:0/20:5), PE (18:1/20:4), PE (16:0/22:6), PE (16:0/20:4), PE (16:0 /16:1), PE (16:0/18:2), PE (18:0/20:5), PE (18:0/22:6), PE (18:0/20:4), PE (16:0/18:1), PE (18:0/18:2), PE (18:0/22:5), and PE (18:0/18:1) were the key PE molecular species. Simulating thermal oxidation to understand the dynamic change mechanism of lipids is meaningful for processing of Chinese mitten crab products and catering to public sensory orientation. PRACTICAL APPLICATIONS: In this study, the UHPLC-Q E Orbitrap method was used to detect and analyze the molecular species changes of Eriocheir sinensis in the simulated thermal oxidation system, and systematically analyzed the law of changes. Based on these results, we can expand our understanding of the changing characteristics of the hepatopancreas and pancreas of the river crab and provide a direction for the formation mechanism of the aroma substances of E. sinensis during the heat treatment and the improvement of the quality of its products.

Effects of fish oil replacement by blending vegetable oils in fattening diets on nonvolatile taste substances of swimming crab (Portunus trituberculatus)

A 45-day fattening trial was conducted using iso-nitrogenous and iso-fatty fattening diets, among which 0%, 25%, 50%, 75%, and 100% of fish oil were, respectively, replaced by blending vegetable oils (canola oil: soybean oil = 1:1), recorded as Diet 1 ~ Diet 5, respectively. The results showed that the meat of crabs (150 ± 25 g) cultured by five fattening feed were distinguished effectively with the electronic tongue. The total free amino acids and taste nucleotides in the meat of crab cultured by Diet 1 were higher than others. The contents of betaine (taste activity value <1) and umami amino acids in the meat of Diet 3 were highest. The contents of sweet amino acids in the meat of crab cultured by Diet 5 was the highest among the different diet. The equivalent umami concentration of Diet 1 was the highest, suggesting that the umami taste is better. In conclusion, 50% of fish oil could be replaced by vegetable oil in fattening feeds. PRACTICAL APPLICATIONS: This paper provided technical support for blending vegetable oils instead of fish oil in fattening feed for swimming crab by using electronic tongue, automatic amino acid analysis, and high performance liquid chromatography to research the changes in the contents of free amino acids, nucleotides, and betaine in female meat of swimming crab, and the taste impacts were evaluated by taste activity values and equivalent umami concentration methods.