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The effect of static magnetic field-assisted freezing (MF) at different temperatures (-35, -30, -25, and -20 °C) on the muscle quality of pacific white shrimp (Litopenaeus vannamei) was evaluated to investigate the possibility of energy saving by MF. The results showed that the -35 °C MF treatment increased the water-holding capacity of shrimp muscle, and maintained the wholeness of the microstructure compared to -35 °C immersion freezing (control group, IF). With the increase in freezing temperature in the MF treatments, the size of ice crystals gradually increased, and the sensory properties of shrimp decreased. The water-holding capacity, sensory properties, and water distribution of shrimp muscle subjected to MF at -25 °C were still no significantly different from those of the IF at -35 °C (P > 0.05). In summary, the utilization of MF enhanced the quality of frozen pacific white shrimp, which has the potential to provide energy saving benefits.

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Tropomyosin (TM) is a heat-stable protein that plays a crucial role as a major pan-allergen in crustacean shellfish. Despite the high thermal stability of the TM structure, its IgG/IgE binding ability, immunodetection, and in vitro digestibility can be negatively influenced by glycation during food processing, and the underlying mechanism remains unclear. In this study, TM was subjected to glycosylation using various sugars and temperatures. The resulting effects on IgG/IgE-binding capacity, immunodetection, and in vitro digestibility were analyzed, meanwhile, the structural alterations and modifications using spectroscopic and LC-MS/MS analysis were determined. Obtained results suggested that the IgG/IgE binding capacity of glycosylated TM, immunodetection recovery, and in vitro digestibility were significantly reduced depending on the degree of glycosylation, with the greatest reduction occurring in Rib-TM. These changes may be attributable to structural alterations and modifications that occur during glycosylation processing, which could mask or shield antigenic epitopes of TM (E3: 61-81, E5b: 142-162, and E5c: 157-183), subsequently reducing the immunodetection recognition and digestive enzyme degradation. Overall, these findings shed light on the detrimental impact of glycation on TMs potential allergenicity and digestibility immunodetection and provide insights into the structural changes and modifications induced by thermal processing.

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Despite the fact that tropomyosin (TM) has highly stable structural characteristics, thermal processing can adversely influence its immunodetection, and the mechanism involved has not been elucidated. Purified TM was heated at various temperatures, and then the IgG/IgE-binding capacity and immunodetection recovery were determined; meanwhile, the structural alterations were analyzed via spectroscopic and molecular dynamics simulation techniques. The obtained results demonstrated that heat-treated TM showed significantly increased IgG/IgE reactivity, confirmed by indirect ELISA and immunoblotting analysis, which might be attributed to the increased structural flexibility, and thus allowed TM to be recognized IgG/IgE easily. However, these structural alterations during thermal processing would contribute to the masking of some epitopes located in TM's surface due to the presence of curled or folded conformation with a considerable reduction of the solvent-accessible surface and radius of gyration, which primarily caused immunodetection recovery reduction in the sandwich ELISA (sELISA) test. The number of antigen binding sites might play a crucial role in a sandwich immunodetection system for sensitive and precise analysis in processed foods.

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Shrimps were first subjected to various thermal processing, then tropomyosin (TM) was purified and their structure, IgG/IgE-binding ability and detectability were evaluated for elucidating the mechanisms responsible for thermal-induced TM immunodetection recovery alterations. According to CD and FT-IR analysis, heat-treated shrimp TM had significantly reduced α-helix and ß-sheet contents with elevated random coil contents, contributing to an increase of 24.42%-62.22% in IgG/IgE reactivity as compared with raw shrimp TM. The exposure of hydrophobic residues and glycosylation occurred in various heated shrimps TM were confirmed by UV, intrinsic/extrinsic fluorescence spectrum and free amino group analysis, which caused some epitopes masking or modification, thereby inducing considerable TM recovery reduction (48.48%-90.44%). These results demonstrated that thermal-treated TMs with higher structural flexibility facilitated IgG/IgE recognition, however the lower number of epitopes within the thermal-treated TMs might cause considerable underestimation of recovery. The number of antigen binding sites might play a critical role in sandwich immunodetection.

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Objective: This study aimed to evaluate the combination of hairy eggplant (Solanum ferox) and bitter ginger (Zingiber zerumbet) on the production performance and hematological parameters of whiteleg shrimp (Litopenaeus vannamei). Materials and Methods: Four treatments were formulated in the test feed, where P1 (control + commercial vitamin C); P2 (120 ml/l combination of S. ferox and Z. zerumbet); P3 (100 ml/l); and P4 (80 ml/l) 6,000 post-larvae shrimp with an average initial weight of 0.2 gm were randomly stocked in four groups, with three replications per treatment, and 500 were stocked in each pond with a total of 12 pounds. Results: Based on the results, there were significant differences in production performance (survival, absolute weight growth, specific growth rate, and feed conversion ratio). Biologically, the best performance was found in the P3 treatment (100 ml/l). In this treatment, the total number of hemocytes and the number of hyaline hemocytes were much higher, and this was not the case in the control treatment (P1), where the number of semi-granular and granular cells was significantly higher than the treatment group (p < 0.05). Conclusions: This study confirmed that supplementation of 100 ml/l of S. ferox and Z. zerumbet could improve the production performance and hemato-immunological parameters of whiteleg shrimp, with functional potential to be developed in phytobiotic-based commercial diets for shrimp.

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The effects of six kinds of thermal processing on soluble protein recovery, potential allergenicity, in vitro digestibility and structural characteristics of shrimp soluble proteins were evaluated. Obtained results confirmed soluble protein recovery and IgG/IgE reactivity of shrimp soluble extracts were markedly suppressed by various thermal treatments with enhanced digestibility depended on the extent and type of heating applied, which correlated well with the structural alterations and modification. The maximum reduction of IgG/IgE-binding capacity and digestive stability were observed in the autoclaved shrimps because of unfolding of protein and hydrophobic residues exposed. Notably, tropomyosin (TM) and sarcoplasmic calcium-binding protein (SCP) were still IgG/IgE-reactive in various heat-processed shrimps, even higher IgG reactivity were found in heat-treated shrimps TM according to TM antiserum western-blotting and indirect ELISA results. Shrimp TM and SCP maintains its IgE/IgG-binding capacity after various cooking methods, thus most probably initiating allergic sensitization to both raw and cooked shrimps.

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Three trials were conducted to comprehensively evaluate the application of chitooligosaccharides (COSs) different dosages, molecular weights (MW) and degrees of deacetylation (DD) as a feed additive for Pacific white shrimp (Litopenaeus vannamei). In trial 1, COSs (3 KDa and 85% DD) at four different dosages (0.05%, 0.1%, 0.15% and 0.2%) were added to feed to investigate the appropriate dosages. The survival ratio (SR) of the shrimps was not significantly different (P > 0.05) between the control and treatment groups. The shrimps fed with 0.1% COSs supplementation exhibited the highest wet body weight (FBW), specific growth ratio (SGR), and weight gain (WG) and the lowest feed conversion ratio (FCR). In trial 2, COSs with different MW (85% DD and 0.1% dosage) were tested. Except for the group treated with the 12 KDa COSs, all shrimps fed with COSs had remarkably higher (P < 0.05) FBW, WG, and SGR and lower FCR (P < 0.05) than the control group, and shrimps fed with the 1 KDa COSs showed most positive effects. In trial 3, COSs with different DD (MW of 1 KDa and 0.1% dosage) were further studied. The different DD were DD5, DD25, DD50, DD75, and DD95. Shrimps fed COSs-supplemented diets of DD75 or DD95 exhibited higher (P < 0.05) FBW, WG and SGR and lower FCR than the other groups. The DD95 group had the highest FBW, WG and SGR and the lowest FCR, but there were no significant differences (P > 0.05) between the DD75 and DD95 groups. Moreover, for COSs supplementation, especially for the DD75 and DD95 groups, the antioxidant parameters were significantly different from those of the other groups. Furthermore, groups fed diets with COSs supplementation had higher (P < 0.05) trypsin activity than those fed control diets. In addition, immune and antioxidant gene expression and the morphology of the hepatopancreas were affected by the DD of COSs. Therefore, the additive dosages, molecular weights and degrees of deacetylation of COSs significantly affected the growth performance of the shrimps; therefore, it is particularly important to determine the optimum parameters of COSs.

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Mitochondrial uncoupling proteins (UCP) transport protons from the intermembrane space to the mitochondrial matrix uncoupling oxidative phosphorylation. In mammals, these proteins have been implicated in several cellular functions ranging from thermoregulation to antioxidant defense. In contrast, their invertebrate homologs have been much less studied despite the great diversity of species. In this study, two transcripts encoding mitochondrial uncoupling proteins were, for the first time, characterized in crustaceans. The white shrimp Litopenaeus vannamei transcript LvUCP4 is expressed in all tested shrimp tissues/organs, and its cDNA includes a coding region of 954 bp long which encodes a deduced protein 318 residues long and a predicted molecular weight of 35.3 kDa. The coding region of LvUCP5 transcript is 906 bp long, encodes a protein of 302 residues with a calculated molecular weight of 33.17 kDa. Both proteins share homology with insect UCPs, their predicted structures show the conserved motifs of the mitochondrial carrier proteins and were confirmed to be located in the mitochondria through a Western blot analysis. The genic expression of LvUCP4 and LvUCP5 was evaluated in shrimp at oxidative stress conditions and results were compared to some antioxidant enzymes to infer about their antioxidant role. LvUCP4 and LvUCP5 genes expression did not change during hypoxia/re-oxygenation, and no coordinated responses were detected with antioxidant enzymes at the transcriptional level. Results confirmed UCPs as the first uncoupling mechanism reported in this species, but their role in the oxidative stress response remains to be confirmed.

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Using thermal processing (TP) treatment (100 ℃, 1-8 min) as a control, the effects of high hydrostatic pressure (HHP, 200-500 MPa, 2.5-20 min) on the microbiological and biochemical characteristics of white shrimp Litopenaeus vannamei were investigated. The results showed that the efficiency of polyphenol oxidase (PPO) inactivation and log reduction of total plate count (TPC) by HHP treatment were all significantly lower than by TP treatment (p < 0.05). The rate of inactivation for TPC and PPO all increased with the increase of HHP pressure and holding time (p < 0.05). The inactivation of PPO was in accordance with a first-order kinetics with the HHP treating time. Hardness of HHP-treated samples at the pressure of 300-500 MPa was higher than TP-treated samples, while the yield loss of HHP treatment was significantly lower than with TP treatment (p < 0.05), long time and high pressure of HHP treatment turned the appearance of shrimps slightly pink.

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The envelope protein VP28 of white spot syndrome virus (WSSV) is considered a candidate antigen for use in a potential vaccine to this important shrimp pathogen (the cause of white spot syndrome, WSS). Here, we used spores of Bacillus subtilis to display VP28 on the spore surface. Trials were conducted to evaluate their ability to protect shrimps against WSSV infection. The gene cotB-vp28 was integrated into the chromosome of the laboratory strain B. subtilis PY79, and expression of CotB-VP28 was detected by Western blotting and immunofluorescence. Expression of CotB-VP28 was equivalent to 1000 molecules per spore. PY79 and CotB-VP28 spores were mixed with pellets for feeding of whiteleg shrimps (Litopenaeus vannamei), followed by WSSV challenge. Superoxidase dismutase (SOD), phenoloxidase activities and mortality rates of the two shrimp groups were evaluated. Groups fed with PY79 and CotB-VP28 spores at day 7 had increased SOD activities of 29% and increased phenoloxidase activities of 15% and 33%, respectively, compared to those of the control group. Fourteen days postchallenge, 35% of vaccinated shrimps had died compared to 49% of those fed naked spores (PY79) and 66% untreated, unchallenged animals. These data suggest that spores expressing VP28 have potential as a prophylactic treatment of WSS.

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