The hypoallergenic of Maillard reaction product of Mactra quadrangularis crude extract (Mactra-Xyl) has been confirmed, its ability to induce oral tolerance remains unclear. In this study, Mactra-Xyl appeared light-yellow, exhibited increased responses to aromatic compounds and organic sulfides, and its biological safety was favorable. In bone marrow-derived dendritic cells (BMDCs) model in vitro, Mactra-Xyl was found to significantly reduce BMDCs maturation compared to Mactra while increasing IL-10 and TGF-β secretion, suggesting the induction of tolerogenic DCs. In a BALB/c mice food allergy model, Mactra-Xyl administration significantly reduced serum levels of specific IgE, mast cell protease, and IL-4 compared to Mactra group. Conversely, it increased specific IgG2a, Treg cells, IFN-γ, and TGF-β cytokines, thereby modulating the Th1/Th2 immune balance and alleviating allergic responses. These findings could provide a theoretical basis for developing functional foods to mitigate clam allergies.

In this study, xylose and arabinose were subjected separately to Maillard reaction with a crude extract of Mactra veneriformis under dry-heating conditions. The immunoreactivity and digestion properties of the Maillard reaction products (MRPs) were analyzed, finding that the Maillard reaction could reduce the immunoreactivity of allergens derived from Mactra veneriformis, increase the continuous digestion rate of the crude extract in simulated gastrointestinal fluid, and reduce the particle diameter of the digestion products. After that, TM in the MRPs was separated and purified, and its structural characteristics and immunoreactivity were analyzed. The results showed that the α-helix content of TM decreased and the β-sheet, β-turn, and random coil contents increased after the Maillard reaction, the surface hydrophobicity increased, and the spatial structure changed, which eventually led to a reduction in the immunoreactivity of TM. This study provides a theoretical basis for the development of hypoallergenic clam products.

Crustacean products are popular for its rich nutritional value, despite causing serious allergy symptoms. The presence of allergens is one of the main factors restricting the further development of the consumer market of crustacean products. The Maillard reaction widely exists in the processing and storage of aquatic products and can affect the allergenicity of foods. This review systematically introduces readers to the Maillard reaction, and summarizes the recent progress in research on the structure and epitopes of crustacean allergens. More importantly, it reviews the changes in the allergenicity of crustacean allergens after Maillard reaction and the underlying mechanism. It is our hope that this paper will provide a reference for controlling and reducing the allergenicity of crustacean products by Maillard reaction.

To compare the allergenicity of native arginine kinase (nAK) and recombinant AK (rAK) from Scylla paramamosain and to identify the predominant allergenic domain of AK, AK was divided into 4 fragments: AK-E1 (amino acid (AA) 1–92), AK-E2 (AA 87–187), AK-E3 (AA 172–265), and AK-E4 (AA 276–357) based on the distribution of epitopes and the spatial structure of the AK molecule. The four recombinant fragments were expressed in the prokaryotic system Escherichia coli, and then nAK, rAK, and the recombinant fragments were purified. The allergenicity of recombinant proteins were evaluated using BALB/c mice. The results showed that the levels of specific antibodies in the serum and the secretion of Th2 type cytokines by the splenocytes of mice sensitized with rAK significantly increased, but the immunogenicity of rAK was weaker than that of nAK. Among the 4 fragments of AK, AK-E2 had the strongest immunogenicity. Meanwhile, rAK could stimulate RBL-2H3 cells to release β-hexokinase, but it was less effective than nAK. Among the 4 expressed fragments, AK-E2 and AK-E4 had a stronger stimulating effect on effector cells. In conclusion, the rAK expressed in the prokaryotic system showed weaker immunogenicity than nAK, and among the 4 fragments of AK, AA 87–187 has the strongest immunogenicity while AA 276–357 has the strongest immunoreactivity.

Oyster, as a common aquatic food, play an important role in shellfish allergy. In this study, 2 tropomyosin (TM) isoforms TM-α and TM-β (TM-α/-β) in Alectryonella plicatula were identified. The sequences of 852 bp encoding 284 amino acids of TM-α/-β and 2 recombinant proteins were obtained, respectively. There were 12 amino acid differences between TM-α/-β. The results of immunological experiments indicated that TM-β had stronger immunobinding activity and immunoreactivity than those of TM-α. Structural analysis showed that TM-β had more α-helix and higher surface hydrophobicity than TM-α. Sequences and epitopes alignment with shellfish TMs revealed that amino acids of TM-β were more frequently recognized as IgE epitopes in other shellfish TMs than TM-α. Differences in structure and sequence account for the higher immunological activity of TM-β compared to TM-α. These findings provide a theoretical basis for enriching the understanding of shellfish TM and accurate diagnosis of allergic components.

In recent years, the allergy rate of oysters has surged, and daily food processing methods make it hard to reduce heat resistance and digestive allergy such as tropomyosin (TM). In this study, the Maillard reaction with xylose significantly reduced the IgE binding capacity of Alectryonella plicatula food matrix (AFM), that reduced by (77.81 ± 2.68)%. The study found the Maillard reaction changes the structure of the AFM, in which the content of α-helix decreased by (24.64 ± 1.46)%. Structural transformation further explains why the Maillard reaction alters the immunobinding activity of AFM. In addition, the Maillard reaction reduces the digestive stability of the AFM and makes TM in the A. plicatula food matrix Maillard reaction products (AFM-MRPs) more easily digested. Based on the above research, 10 amino acids on the 7 IgE epitopes of TM were modified. This result indicates that the Maillard reaction reduces the immunobinding activity of the AFM by changing the structure and modifying the amino acids on the epitope.

Bacteria contamination in Auricularia auricular culture bags reduces yield and increases the risk of food safety. In this study, 5 species of bacteria, mainly gram-positive bacteria including three species of Bacillus spp., Arthrobacter arilaitensis and Staphylococcus warneri, were isolated and identified from bacteria-contaminated A. auricular culture bags. An in silico predicted antimicrobial peptide from the β-1,3-glucan-binding protein sequence of Penaeus vannamei, designated PvGBP2 (FLKLGRKSRYGMLKL), was screened and its antibacterial effect and mechanism of action on the isolated Bacillus spp. explored. The minimal inhibitory concentrations (MIC) of PvGBP2 on Bacillus spp. were 15.6–31.25 μg/mL. Peptide PvGBP2 could inhibit Bacillus subtilis in A. auricular culture bags to maintain growth and yield of A. auricular. Transmission electron microscopy (TEM) revealed that PvGBP2 kills bacteria by perforating the cell wall, destroying membrane integrity and resulting in the leakage of intracellular solutes. In addition, PvGBP2 inhibits biofilm formation by B. subtilis by 90.6% at 1 × MIC. Thus, peptide PvGBP2 could be potentially applied as an antibacterial agent to control bacterial infection of A. auricular cultivation and the spread of foodborne pathogens.