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[Display omitted] • CaCl 2 improved the emulsification performance of shrimp MP. • CaCl 2 induced molecular stretching of shrimp MP. • CaCl 2 improved the rheology properties and gel strength of shrimp MP. • CaCl 2 improved the digestibility of MP gel. In this study, the effects of CaCl 2 (0, 25, 50, 75, and 100 mM) on the gelling and digestive properties of the myofibrillar protein (MP) in Litopenaeus vannamei were investigated. The results showed that increasing CaCl 2 concentration led to changes in the tertiary structure of MP. Specifically, compared with the control group, a 64.31 % increase in surface hydrophobicity and a 45.90 % decrease in the sulfhydryl group were observed after 100 mM CaCl 2 treatment. Correspondingly, the water holding capacity and strength of the MP gel increased by 24.46 % and 55.99 %, respectively. These changes were positively correlated with the rheological properties, microstructure pore size, and content of non-flowable water. The mechanical properties of MP gel were improved, and the microstructure became more compact with the increase in CaCl 2 concentration. Furthermore, the particle size of the digested MP gels decreased in the presence of CaCl 2 , which improved the digestion characteristics of MP gels. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate the effects of ultra-high pressure (UHP) on the physicochemical properties, gelling properties, and in vitro digestion characteristics of myofibrillar protein (MP) in Litopenaeus vannamei. The pressures were set at 0, 150, 300, 450, and 600 MPa, respectively. The α-helix structure gradually unfolded and transformed into β-sheet structure as the pressure increased from 0 to 600 MPa. Compared with the control group, the content of α-helix structure of the 600 MPa-treated MP samples decreased by 51.31%, and the content of β-sheet structure increased by a 1.34-fold. In addition, the UHP treatment enhanced the rheological properties of MP. The elastic modulus (G′) and viscous modulus (G″) of the 600 MPa-treated MP samples increased by 4.77-fold and 3.78-fold, respectively, compared with the control group (at frequencies up to 10 Hz). The gel properties of the MP also increased significantly after UHP treatment, e.g., the WHC of MP gel increased by 45.49% and the gel strength increased by a 5.99-fold when the pressure reached 600 Mpa, compared with the control group. The results of in vitro simulated digestion showed that UHP treatment led to the formation of more easily digestible MP gels. Compared with the control group, the 600 MPa-treated MP gel samples showed a 1.89-fold increase in digestibility and a 66.86% decrease in digestible particle size. [Display omitted] • Ultra-high pressure improved the emulsification performance of shrimp MP. • Ultra-high pressure induced molecular stretching of shrimp MP. • Ultra-high pressure improved the rheology properties of shrimp MP. • Ultra-high pressure enhanced the gel strength and WHC of shrimp MP. • Ultra-high pressure improved the digestibility of MP gel of Litopenaeus vannamei. [ABSTRACT FROM AUTHOR]

Protein gelation is an important functional characteristic of shrimp surimi products. The effects of structurally relevant natural phenolic compounds on the structure and functional properties of myofibrillar protein (MP) of the Penaeus vannamei were investigated. In the present study, phenolics improved the oxidative stability of MP, while leading to a decrease in the emulsification properties of MP. The carbonyl and free radical contents and fluorescence quantification of protein oxidation products showed that the addition of phenolic compounds could effectively prevent MP oxidation due to their antioxidant capacity derived from hydroxyl groups. In addition, phenolics could improve the rheological properties and gelling behavior of MP. Finally, the interactions between the substituents of MP and phenolic compounds were explored by molecular docking to elucidate the modification mechanism. Gallic acid (GA), quercetin (QT), and (−)-epigallocatechin-3-gallate (EGCG) interacted with MP mainly through hydrogen bonding to unfold the secondary structure of MP and reduce the surface hydrophobicity. Unlike GA and EGCG, QT interacted electrostatically with MP, maintaining the α-helical structure and leading to a slight increase in surface hydrophobicity. This study demonstrated the great potential of phenolic compounds as natural additives for the functional modification of shrimp surimi products. [Display omitted] • Structure of phenolic compounds affected their interaction with MP. • Hydrogen bond and electrostatic interactions were found in the interactions. • Phenolics affected the structure and functional properties of MP. • Effect of GA and EGCG on functional properties of MP differed from quercetin. [ABSTRACT FROM AUTHOR]

Konjac glucomannan (KGM) is commonly used as a texture enhancer due to its distinctive gelling properties. This study aimed to investigate the changes in gelling and digestive properties of myofibrillar protein (MP) in Litopenaeus vannamei when modified with varying KGM (1/40, 1/20, and 1/10 of the MP weight, respectively). The physicochemical properties of KGM-modified MP including secondary and tertiary structures, emulsibility, particle size, and protein aggregation were significantly affected. In contrast, the KGM treatment group (1/20 of MP weight, MK20) exhibited the highest storage modulus, loss modulus, and thermal stability of MP. This resulted in an improvement in the water holding capacity, the stability of the three-dimensional space network, and the strength of the heat-induced MP gels. In addition, the digestion behavior of MP gel could be regulated by modifying MP with KGM. When compared to control sample, the digestion rate and hydrolysis degree of MK20 increased by 16.63% and 1.32 times, respectively. However, it should be noted that excessive KGM could result in the formation of a viscous hydrogel that permeates with MP, causing a loose degradation structure and reducing sensitivity to digestive enzymes. The molecular docking results indicated that KGM interacted with MP through hydrogen bonding, primarily relying on its hydroxyl group. This interaction disrupted the α-spiral structure of MP and promoted the expansion of its structure, and ultimately affected the physicochemical properties of MP and its heat-induced gel. [Display omitted] • Hydroxyl of KGM modified the structure of MP by hydrogen bonding interactions. • KGM improved the emulsifying functional properties of MP. • KGM enhanced the mechanical properties and thermal stability of MP gels. • KGM promoted the digestive properties of MP gels. [ABSTRACT FROM AUTHOR]

Carbon source addition is an effective microbial management strategy for healthy shrimp growth, but bottleneck problems have emerged in production applications. Beneficial microalgae with functions of capturing carbon dioxide, generating oxygen, absorbing phosphate and recruiting specific bacteria could theoretically modify carbon source addition. However, the implementation effectiveness and underlying microecological mechanism of the combined addition of carbon sources and microalgae remain unknown. Here, we investigated the effects of modified glucose addition with the microalga Nannochloropsis oculata on water quality, shrimp health and rearing water bacterial community. Although purification of the water environment was not achieved, the combined addition of glucose and microalgae significantly improved the shrimp survival rate and immune responses and altered the rearing water bacterial community structure. Network topology analysis indicated that the combined addition limited positive interactions and increased the modularity of the network, which enhanced the bacterial community stability. Partial least squares path modeling (PLS-PM) analysis showed that the bacterial community structure indirectly affected the survival rate of shrimp through bacterial network topological features. Furthermore, comparison of the biomarkers identified by shrimp survival rate-discriminatory importance and the bacterial taxa in the co-occurrence network module related to shrimp survival rate revealed that Rhodobacteraceae taxa recruited by the combined addition of glucose and microalgae might play important roles in maintaining healthy status of shrimp. These results provide a basis for developing novel microbial management strategies for sustainable aquaculture. • The combined addition of glucose and N. oculata could improve immune responses in shrimp. • The combined addition could alter the rearing water bacterial community structure and network topology. • The bacterial community stability created by the combined addition could enhance shrimp health. • Rhodobacteraceae taxa recruited by the combined addition could maintain healthy status of shrimp. [ABSTRACT FROM AUTHOR]