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The ameliorative effect of depolymerized sulfated polysaccharides from Eucheuma serra (DESP) on ovalbumin (OVA)-caused induced food allergy was investigated in this work. Results showed that OVA stimulated the secretion of allergy-related cytokines (OVA-specific IgE, mMCP-1, IgA, TNF-α) and led to diarrhea, intestinal epithelial damage, and intestinal microflora dysbiosis in sensitized mice. After the administration of DESP, however, the anaphylactic symptoms (shortness of breath, hypothermia, diarrhea), along with the allergy-related cytokines, were effectively suppressed. Moreover, the reduced intestinal inflammation was discovered in the DESP-treated group. Additionally, 16S rRNA sequencing of fecal samples was performed, and gene count and α-diversity analysis revealed that DESP improved microbial community richness. Taxonomic composition analysis showed that DESP modulated the proportion of Firmicutes and Bacteroidetes/Proteobacteria. Particularly, DESP increased probiotics (Lactobacillaceae, Bifidobacteriaceae and Prevotellaceae) and decreased pathogenic bacteria (Helicobacteraceae and Desulfovibrionaceae). These findings, therefore, suggest that DESP may ameliorate food allergy through the regulation of intestinal microbiota.

Dietary advanced glycation end products (dAGEs) are complex and heterogeneous compounds derived from nonenzymatic glycation reactions during industrial processing and home cooking. There is mounting evidence showing that dAGEs are closely associated with various chronic diseases, where the absorbed dAGEs fuel the biological AGEs pool to exhibit noxious effects on human health. Currently, due to the uncertain bioavailability and rapid renal clearance of dAGEs, the relationship between dAGEs and biological AGEs remains debatable. In this review, we provide the most updated information on dAGEs including their generation in processed foods, analytical and characterization techniques, metabolic fates, interaction with AGE receptors, implications on human health and reducing strategies. Available evidence demonstrating a relevance between dAGEs and food allergy is also included. AGEs are ubiquitous in foods and their contents largely depend on the reactivity of carbonyl and amino groups, along with surrounding condition mainly pH and heating procedures. Once being digested and absorbed into the circulation, two separate pathways can be involved in the deleterious effects of dAGEs: an AGE receptor-dependent way to stimulate cell signals, and an AGE receptor-independent way to dysregulate proteins via forming complexes. Inhibition of AGEs formation during food processing and reduction in the diet are two potent approaches to restrict health-hazardous dAGEs. To elucidate the biological role of dAGEs toward human health, the following significant perspectives are raised: molecular size and complexity of dAGEs; interactions between unabsorbed dAGEs and gut microbiota; and roles played by concomitant compounds in the heat-processed foods.

Backgrounds As one of the most important cereals, wheat (Triticum aestivum) can cause severe allergic reactions, such as baker's asthma, allergic rhinitis, and atopic dermatitis. A growing number of people are developing allergies to Chinese wheat; however, only a few wheat cultivars have been screened on allergenicity in China. Objective The aim of the present study was to assess the allergenicity of different Chinese wheat cultivars and characterize wheat allergen profiles of patients with allergic rhinitis. Methods We determined protein (soluble protein, gliadin, and glutenin) composition in Chinese wheat by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), and the immunoglobulin E (IgE) binding capacity by enzyme-linked immunosorbent assay (ELISA) and Western blot using 10 positive sera from wheat allergy patients. We identified 5 gel bands with significant IgE binding capacity using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Results Soluble protein, albumin, and globulin, showed the highest allergenicity, followed by gliadin, while glutenin only had slight allergenicity. In soluble protein, 5 protein bands with molecular weights of 27, 28, 53, 58, and 62 kDa showed very significant allergenicity. Meanwhile, the relative abundances of 28 kDa-protein and 58 kDa-protein were significantly positively correlated with the IgE-binding capacity of Chinese wheat cultivars, which were identified as rRNA N-glycosidase and β-amylase, respectively, among other proteins in those highly complex gel bands. Conclusion and clinical relevance 28 kDa-protein (rRNA N-glycosidase) and 58 kDa-protein (β-amylase) were speculated to be the main allergens of Chinese wheat causing baker's asthma and allergic rhinitis. These results provide new insights into the prevention and treatment of wheat allergy and the development of hypoallergenic wheat products, whose clinical significance is worth further evaluation.

Despite being the fastest growing sector, the modern aquaculture industry faces serious challenges such as the lack of protein source in feed, the susceptibility to pathogens, and deterioration in quality during culture and storage. Bacterial biomass is considered as a proper protein source for feed, and the beneficial bacterial species protect aquatic animals from infection or reduce spoilage of products. In this review, we summarized the application of beneficial bacteria to aquatic products, focusing mainly on the nutritional, anti-pathogenic, anti-spoilage and immunoregulatory functions of these bacteria. We then discussed the relationship between beneficial bacteria, intestinal microbiota and host immunity, and the recent progress and drawbacks of the technology.

Put was the main biogenic amine produced by Shewanella baltica. PL and PP were the main QS autoinducers of S. baltica. PL and PP displayed significant positive correlation with Put. DKPs and Put production and odc gene expression were inhibited by anthocyanins. Anthocyanins were proposed as new QSIs and seafood preservative candidates.

Transglutaminase (TG) is a major food processing enzyme that induces protein cross-linking. Tropomyosin (TM) is a major shellfish allergen that is responsible for at least 80% of the shrimp allergic incidents. The aim of this research was to investigate the effect of TG on TM allergenicity and reveal the involvement of TM structure alternation. After treated with TG for different time, the allergenicity of TM was assessed by indirect ELISA with shrimp allergic patients’ sera, and the structure of TM was characterized by circular dichroism (CD) spectroscopy, ultraviolet (UV) absorption spectroscopy and fluorescence spectroscopy. Results showed that the allergenicity slightly decreased at the early stage of reaction and dramatically decreased at the late stage, which is tightly correlated with the increment of β-turn content and UV absorption. In conclusion, TG modification is an effective and promising food processing method to eliminate TM allergenicity with significant prospect of industrial appli...

Food allergy is a severe food safety problem worldwide. Probiotics are effective in alleviating food allergy whereas antibiotics may exacerbate allergenic responses, but the knowledge on the interplay between them during food allergy is limited. In the present study, we investigate the activity of probiotic strain Lactobacillus casei (Lc) and antibiotic cocktail (Abx) on in a food allergy mouse model. The results showed that Lc relieved allergenic symptom and changed allergen-specific antibodies isotypes. Moreover, Lc upregulated chemokines in the spleen, and promoted regulatory CD103+ DC and IgA-producing B cell proliferation. In contrast, the application of Abx eliminated all these beneficial effects of Lc. Microbiota analysis revealed that the commensal genus Butyricicoccus was a critical mediator in the process. These results revealed the mechanisms of Lc and Abx interaction on food allergy and provided Butyricicoccus as a potential therapeutic target for food allergy.

To explore effect of the structural properties of porphyra haitanensis polysaccharide on its biological activity, degraded porphyra polysaccharides were separated and purified by Cellulose DEAE-52 and Sephadex G-100 chromatography, obtaining three purified components (P1, P2 and P3). All the three components were sulfate polysaccharides containing the repeating units of → 3) β-D-galactose (1 → 4) 3,6-anhydro-α-L-galactose (1 →, and → 3) β-D-galactose (1 → 4) α-L-galactose-6-S (1 →, and → 3) 6-O-methyl-β-D-galactose (1 → 4) 3,6-anhydro-α-L-galactose (1 →. The molecular weight of the three fractions was measured to be 300.3, 130.4 and 115.1 kDa, respectively. Their antioxidant activity was investigated by the determination of the free radical scavenging effect and ferric reducing power. It was found that P1, P2 and P3 possessed marked antioxidant activity. It was also found that they appreciably enhanced the proliferation, phagocytic ability and nitric oxide secretion in RAW264.7 cells. Lower molecular weight and higher sulfate content were beneficial to bioactivities of P. haitanensis polysaccharides. Overall, P2 and P3 possess superior immuno-modulatory activity to that of P1 and PHP. Thus, the current work will provide the basis for the better utilization of P. haitanensis to develop the related functional foods.

The degraded polysaccharides from Porphyra yezoensis (DPPY) prepared using the H2 O2 -Vc method under optimized conditions were isolated and purified by DEAE Cellulose-52, and Sephadex G-100, providing four pure components, namely, DPPY-0, DPPY-0.1, DPPY-0.3, and DPPY-0.5. Their relative molecular weights were measured to be 10.8, 10.7, 18.7, and 35.5 kDa, respectively. GC-MS analysis revealed that all the four fractions were mainly composed of galactose, together with a small portion of glucose, mannose, xylose, and rhamnose. Structural analysis revealed that the purified polysaccharides mainly possess a backbone of (1 → 3)-β-D-galactose (1 → 4)-3,6-anhydro-α-L-galactopyranose (G-A) units and (1 → 3)-β-D-galactose (1 → 4)-α-L-galactose-6-sulfate (G-L6S) units. They were found to promote the proliferation of RAW264.7 macrophages and enhance phagocytosis of the RAW264.7 cells. Antioxidant assays indicated that DPPY-0.5 possessed the most potent reducing power and free radical scavenging ability among the four purified polysaccharides. High sulfate content and proper molecular weight of these fractions are favorable to their immunomodulatory and antioxidant activities. PRACTICAL APPLICATIONS: Porphyra yezoensis, common economic red algae widely distributed in East Asian countries, contains a high content of polysaccharides with a variety of biological activities. However, P. yezoensis polysaccharide (PPY) has not been well utilized due to the relatively low biological activities and lack of understanding of its structure-activity relationship. Thus, it is necessary to improve the bioactivities and elucidate the structure-activity relationship of this polysaccharide for its practical use. In the present work, four purified fractions (DPPY-0, DPPY-0.1, DPPY-0.3, and DPPY-0.5) were isolated from the degraded P. yezoensis polysaccharide, and were investigated for their antioxidant and immunoregulatory activities. The results of the present work will lay a foundation for the application of the degraded P. yezoensis polysaccharide in the food industry as a functional food ingredient.

In this work, the preventive effect of depolymerized sulfated polysaccharides from Eucheuma serra (DESP) on bacterial diarrhea by regulating intestinal flora was investigated in vivo. Based on the enterotoxigenic Escherichia coli (ETEC)-infected mouse diarrhea model, DESP at doses ranging from 50 mg/kg to 200 mg/kg alleviated weight loss and decreased the diarrhea rate and diarrhea index. Serological tests showed that the levels of inflammation-related factors were effectively suppressed. Furthermore, the repaired intestinal mucosa was verified by morphology and pathological tissue section observations. Compared with the model group, the richness and diversity of the intestinal flora in the DESP group increased according to the 16S rRNA high-throughput sequencing of the gut microbiota. Specifically, Firmicutes and Actinobacteria increased, and Proteobacteria decreased after DESP administration. At the family level, DESP effectively improved the abundance of Lactobacillaceae, Bifidobacteriaceae, and Lachnospiraceae, while significantly inhibiting the growth of Enterobacteriaceae. Therefore, the antimicrobial diarrhea function of DESP may be related to the regulation of intestinal microbiota.

Unveiling specific interactions between nanoparticles (NPs) and proteins could benefit a better control of NPs' performance in recognition-based detection, imaging and drug delivery. Herein, we investigated the specific recognition between an aptamer modified gold nanoparticle (Apt-AuNP) and its target protein arginine kinase (AK) through a coffee-ring effect (CRE)-based approach. The evaporated droplets of the Apt-AuNP with AK featured a ring-disk-ring transition with elevated AK concentration and a disk pattern was found when the Apt was saturated by AK. Moreover, the AK concentration versus ring thickness curve below the saturation point was proved to fit in an exponential function, indicating the strong association between the Apt-AuNP and AK. In contrast, the ring thickness above the saturation point fitted in a Gompertz growth model that was similar with the Apt-AuNPs incubated with the nonspecific protein (bovine serum albumin, BSA), suggesting that AK was nonspecifically adsorbed onto the AuNPs. The impact of the specific NP-protein interaction on the translation of CRE into macroscopic patterns was further utilized to identify target food allergen AK by the Apt-AuNPs over nontarget allergens (tropomyosin, ovalbumin and β-lactoglobulin). This work provided new insight into the general NP-protein association process and demonstrated the feasibility of employing CRE as an effective tool to profile the specific interactions between NPs and proteins.

Pseudomonas fluorescens is a specific spoilage bacteria in seafood, which has the ability to maintain growth and reproduction at low temperatures. There are some functional proteins in Pseudomonas fluorescens to defense the harm of cold to its life activities. Hence, disrupting this defense mechanism may be a good way to control food spoilage. In this study, we screened the food ingredients database to search for potential cold defense mechanism inhibitors of P. fluorescens PF08 by using virtual screening. From the screening results, we found a compound with inhibitory activity — l -phenylalanine. Moreover, the effects of l -phenylalanine on the cold defense mechanism were determined. l -phenylalanine is difficult to inhibit bacterial growth at room temperature. However, it significantly inhibits the growth ability of Pseudomonas fluorescens PF08 and the production of biofilm at 4 °C. In addition, we also found that l -phenylalanine can compress RpoS and Algk, which undoubtedly interferes with the function of proteins.

Shewanella baltica, one of the dominant spoilers of seafoods, can synthesize putrescine from ornithine under acidic conditions, which could result in food spoilage and health problems. We identified three regulatory enzymes (SpeC, SpeF, and PotE) in the ornithine decarboxylation (ODC) pathway of S. baltica by searching the NCBI database and exploring their functional roles through gene knock-out technology. The ornithine decarboxylase SpeC is an auxiliary adjustor of the ODC system, whereas the ornithine-putrescine transporter SpeE and ornithine decarboxylase SpeF participate in the production of extracellular putrescine. Exogenous addition of ornithine and putrescine promotes the extracellular secretion of putrescine by upregulating the expression of speF and potE. The putrescine biosynthesis and alkalization of cytoplasm is enhanced at weak acidic pH compared with neutral pH, especially at pH 6.0. The maximum upregulation of ODC genes and the optimum decarboxylation activity of SpeF are achieved in a weak acidic environment (pH 6.0), suggesting that the ODC pathway plays an important role in putrescine production and the cytoplasmic acid counteraction of S. baltica. This study contributes to a wider understanding of spoilage mechanisms in food systems and provides theoretical support for developing novel seafood preservation methods. HIGHLIGHTS

Arginine kinase (AK) is one of the most important allergens in shrimp products. Herein, a novel immunoassay for quantitation of AK was developed using the antibody modified gold nanoparticle (AuNP) and quantum dot (QD). When the first antibody modified AuNP (AuNP-Ab1) was bridged by AK with the secondary antibody modified QD (QD-Ab2), fluorescence resonance energy transfer (FRET) would occur between the AuNP and QD, which led to a decrease in fluorescent signals. The decrease in fluorescence intensity was found to correlate linearly with the log of AK concentration in the range of 1.0 × 10-6-1.0 × 10-3 mg/mL (R2 = 0.9909) and the detection limit was 0.11 ng/mL. The immunoassay was further proved to have encouraging specificity, precision and accuracy. Compared with existing methods, this study provided a promising approach to develop a highly sensitive and selective detection method for AK in shrimp related food samples.

Porphyra haitanensis polysaccharide (CPH) was degraded by pectinase to improve its biological activities. Box-Behnken response surface design was used to optimize the hydrolysis conditions. The molecular weight of CPH and the degraded P. haitanensis polysaccharide (DCPH) were measured to be 524 and 217 kDa, respectively. GC-MS spectrometry results showed that CPH and DCPH were mainly composed of galactose. In vitro antioxidant assays indicated that DCPH possessed improved radical scavenging activity and ferric iron reducing power when compared to those of CPH. In H2 O2 -treated RAW264.7 cells, DCPH was also found to be more effective in reducing the generation of malondialdehyde and reactive oxygen species than CPH. The immunomodulatory assays demonstrated that DCPH possessed superior activities in enhancing the proliferation, phagocytosis, and NO secretion in a RAW264.7 macrophage cell model to those of CPH. PRACTICAL APPLICATIONS: Polysaccharide is the most abundant bioactive component of an edible red algae Porphyra haitanensis. However, the use of CPH is limited due to its relatively low biological activities. Thus, in order to fully utilize P. haitanensis, it is necessary to enhance the biological activities of CPH for its practical use. An efficient and practical method to enhance the bioactivities of P. haitanensis polysaccharide has been developed in the present work. The DCPH prepared in this work could have potential applications in food and medicinal areas.

Shewanella baltica is the specific spoilage microorganism of Pseudosciaena crocea during low-temperature storage. Exploring the correlation between cold adaptability and spoilage potential may provide a new perspective for prolonging shelf life of aquatic products. In the present study, we investigated the synthesis pathway of unsaturated fatty acid (UFA) responsible for regulating cold adaptability in Shewanella baltica and its effect on spoilage potential. FabR and FadR, as key regulators of membrane unsaturated fatty acids synthesis pathway, were identified in S. baltica. FabR was significantly down-regulated at 4 °C compared to at 30 °C, yet FadR displayed the opposite results. By overexpressing fabR and fadR genes at 4 °C, we found that FabR and FadR had negative and positive effects on UFA content and membrane fluidity as well as spoilage potential, respectively. These data indicated that FabR and FadR functioned collectively to increase the membrane fluidity for better cold adaptability at low temperature, resulting in the maintenance of spoilage potential of S. baltica.

Large yellow croaker (Pseudosciaena crocea) is a popular and nutritious but also highly perishable fish species, with Shewanella baltica being the primary spoilage bacteria during low-temperature storage. Clarifying the factors promoting spoilage will facilitate efforts to predict and control the shelf life of foods. This study focused on spoilage-related genes in two Shewanella baltica strains with different spoilage potentials. Using whole genome sequencing and alignment, three distinguishing genes (torT, cysM and trxB) were identified. Further protein sequence comparison and protein structure modeling revealed possible motifs responsible for the spoilage activity. Moreover, diketopiperazine (DKP) quorum sensing (QS) signaling molecules regulated biofilm formation and spoilage gene expression, indicating a relationship between the QS system, biofilm formation and spoilage potential. Our results suggest that DKPs and spoilage genes are potential targets for developing novel food antiseptics, as well as new markers for fish product spoilage.

Large yellow croaker (Pseudosciaena crocea) is a cultivated fish of great economic importance and abundant nutritional value. However, due to its high protein and water contents, it is susceptible to decomposition, leading to considerable economic loss and adverse effects on consumer health. Here, we assessed the function of the bacterial strain Bacillus coagulans L1208 (Bcoa) in preserving large yellow croaker during storage at 4°C and found that Bcoa elongates the shelf-life significantly. Further investigations showed that Bcoa prolongs the storage time mainly by suppressing the growth of spoilage bacteria. Moreover, a novel bacteriocin, designated as Coagulin L1208 and produced by Bcoa, was purified and identified by N-terminal sequencing. Finally, the activity of Coagulin L1208 for suppressing spoilage bacteria during the preservation of large yellow croaker was assessed. Our results reveal the mechanism by which Bcoa aids the preservation of large yellow croaker and identify Coagulin L1208 as a potential novel antiseptic.

Protein glycation and formation of advanced glycation end-products (AGEs) impose threats to the human health. This study firstly investigated the inhibition of Chinese bayberry (Myrica rubra) phenolics on AGEs formation through mechanistic analysis. Four common Chinese bayberry cultivars were selected to prepare phenolic-rich extracts (CBEs) and characterized for phenolic composition, and their anti-AGE properties were evaluated in multiple in vitro systems. Total sixteen phenolics were quantified in CBEs by UPLC-ESI-MS/MS. CBEs reduced total and specific fluorescent AGEs formation in various simulating models, and protected the protein from structural modification, oxidation, and cross-linking. Mechanistic analysis unveiled that scavenging of free radicals, inactivation of transition metals, interaction with protein to form complexes, and trapping of reactive α-dicarbonyls to form adducts underlain the mechanisms of the anti-glycative actions of CBEs. Chinese bayberry fruits, especially the cultivars Biqi and Wuzi, may be a promising dietary strategy to mitigate AGEs load in the human body.

Alcalase hydrolysis of soybean proteins was shown effective in degrading epitopes, but with a significant loss of tastes and functional properties. In this study, the combined use of controlled Alcalase hydrolysis and transglutaminase (TGase)-cross-linking was used to produce hypoallergenic soybean protein hydrolysates (SPHs) with improved flavor and techno-functional properties. Through establishing the kinetic model of heterogeneous enzymatic processes, SPHs with different degrees of hydrolysis (2.5–10.0%) were obtained and polymerized by TGase to yield products with various peptide components. Results showed that post-hydrolysis cross-linking rearranged the (poly)peptides in SPHs via glutaminyl modifications. Following TGase-treatments, due to the masking of bitter-active peptides and free amino acids, the bitterness of SPHs was significantly reduced with a slight improvement in the overall flavor. Furthermore, TGase–cross-linking rescued multiple techno-functionalities of SPHs, particularly their emulsifying and foaming properties. Using sera from soybean-allergic individuals, it was evidenced that TGase-addition did not generate neoallergens and the residual allergenicity of SPHs was not distinctly affected. The final products maintained 44–71% reduction in the IgE-binding levels in comparison to the unhydrolyzed protein. Combining limited Alcalase hydrolysis with TGase–cross-linking provides a feasible way to produce hypoallergenic soybean ingredients with desired flavor and functional attributes.

Marine red algae are rich sources of sulfated polysaccharides as bioactive ingredients and hydrocolloid molecules. In this study, sulfated polysaccharides (YGAP, EGAP, and NGAP) were extracted from Gelidium amansiis that were harvested from three different sea areas of China. Characterization of these polysaccharides shows that they contain 3.7–4.0% sulfate and are mainly composed of galactose, glucose, fucose, arabinose, and mannose. The FT-IR and 13C NMR analysis indicate that the sulfated polysaccharides are agar-type galactans containing 3,6 anhydro-α- l -galactopyranose and β- d -galactopyranose residues. By using various in vitro models, all sulfated polysaccharides, particularly EGAP, exhibit the ability to scavenge O2•– and OH· radicals and reducing power. Additionally, in a glucose-glycated BSA system, the polysaccharides show an inhibitory effect on protein glycation and formation of specific advanced glycation end-product. Their anti-glycative property is attributed to their anti-oxidant activity and trapping capacity of methylglyoxal. Given that these polysaccharides possess agar-like structures, they were used to prepare bioactive films and expectedly, transparent and homogeneous films were obtained. The films display high water barrier properties with retained antioxidant and anti-glycation activities as above. These results expand the current knowledge of G. amansiis polysaccharides as nutraceuticals and hydrocolloids, which would benefit their applications in the food industry.

Cyclic diguanylate (c-di-GMP) is a second messenger involved in the regulation of various physiological processes in bacteria. However, its function in spoilage bacteria has not yet been addressed. Here, we studied the function of a tandem GGDEF-EAL domain protein, Sbal_3235, in the spoilage bacterium Shewanella baltica OS155. The deletion of sbal_3235 significantly reduced the c-di-GMP level, biofilm formation, and exopolysaccharide, trimethylamine (TMA), and putrescine production; sbal_3235 deletion also downregulated the expression of the torS and speF genes and affected membrane fatty acid composition. Site-directed mutagenesis in conserved GGDEF and EAL motifs abolished diguanylate cyclase (DGC) and phosphodiesterase (PDE) activity, respectively. These data indicate that Sbal_3235 is an essential contributor to the c-di-GMP pool with bifunctional DGC and PDE activity, which is involved in the biofilm formation and spoilage activity of S. baltica OS155. Our findings expand the biochemical role of c-di-GMP and uncover its link to spoilage activities, providing novel targets for food quality and safety controlling.

Tropomyosin (TM) is the major allergen in shellfish, which causes severe food allergy worldwide and shows wide cross-reactivity in different species. Transglutaminase (TG) and tyrosinase (Tyr) are protein modification enzymes that catalyze substrate cross-linking and change protein structures and properties. The aim of this work was to investigate the effect of TG and Tyr on TM. After TG/Tyr treatment, the cross-linking and protein structural change were observed by SDS-PAGE, scanning electron microscopy and circular dichroism. Furthermore, ELISA and mast cell degranulation assay with allergic sera demonstrated the allergenicity reduction after treatment. An in vivo TM-sensitization mouse model showed that both TG and Tyr treatments reduced the IgE-induction capacity of TM but maintained the IgG-induction ability, making the treated TM a potential hypoallergen. Moreover, TG-but-not-Tyr-treated TM promoted regulatory T cell proliferation and thus may facilitate the establishment of oral tolerance. This work provided an effective method to reduce TM allergenicity and produce hypoallergens, which has broad application prospects in low allergenic food production and allergen-specific immunotherapy.

The spoilage potential and biofilm formation of Shewanella baltica are reported to be regulated by Quorum sensing (QS) system from the phenotype point of view, but the specific mechanism is not fully understood. In the present study, the QS autoinducers were detected by UHPLC-MS/MS, cell density-dependent luxR-type genes were obtained through autoregulation experiments among a series of candidates in S. baltica OS155 (The SSO of large yellow croaker). The direct interaction between cyclo-(L-Pro-L-Phe) (PP) and LuxR01 as well as LuxR02 proteins was revealed via in vitro binding assay. Deletion of luxR-type genes (luxR01 and luxR02) impaired spoilage potential and biofilm formation of S. baltica OS155 in various degrees. Transcriptional analysis and qRT-PCR validation showed that spoilage and biofilm-related genes torS, speF, and pomA were down-regulated in luxR01 and luxR02 deletion strains. In addition, exogenous PP promoted spoilage potential and biofilm formation, which could be attenuated by luxR01 or luxR02 deletion. Our results revealed an explicit QS system employing PP as autoinducer and two orphan LuxRs as receptors which positively regulated spoilage capacity and biofilm formation via transcriptional regulation of corresponding genes in S. baltica OS155, which provides potential specific targets for seafood preservation involving QS system.

Background: Shrimp tropomyosin (TM) is a major food allergen that may cause serious allergic responses, lactic acid-producing bacteria (LAPB) are believed to alleviate food allergy, but the mechanisms have not been fully clarified. The aim of this work is to investigate the mechanisms of LAPB in ameliorating food allergy-induced intestinal mucosal disorders and to investigate whether or not these disorders occur by the regulation of gut microbiota and metabolism. Methods: A TM allergy BALB/c mouse model was established, and two LAPB strains, Bifidobacterium longum (Bi) and Bacillus coagulans (Bc), were used for oral treatment in sensitized mice. The allergic mucosal disorders were assessed by histological analysis and ELISAs. Additionally, microbiota and metabolic modifications were determined by 16S rRNA gene amplicon sequencing and GC-TOF-MS, respectively. Results: YSPB administration suppressed TM-induced intestinal mucosal disorders, restored allergenic Th2 cell over-polarization and dysbiosis, and regulated gut arginine and proline metabolism pathways. Statistical analysis suggested the metabolites aspartate and arginine, as well as several commensal flora groups, to be the critical mediators in the process. Conclusions: These data demonstrated the correlation between allergic mucosal disorder, T cell subtype differentiation, gut microbiota composition and intestinal metabolism especially the arginine and proline metabolism pathways. We also revealed the significant effects of LAPB in ameliorating food allergy and maintaining the mucosal ecosystem. This study confirmed the efficiency of LAPB in relieving food allergy, provided Bi and Bc as the potential treatment approaches, and suggested amino acid metabolism pathways might be the novel targets for potential clinical applications. Keywords: Animal models, Food allergy, Gut microbiota, Metabolism, Probiotics

Food allergy represents an important issue in the field of food safety in industrialized countries because of the severity of allergenic reactions for affected persons even with small amounts of food. Recently, the food industries and legislative and regulatory agencies in different countries have formulated new regulations about displaying food allergen on food labels. Therefore, consumer protection and food labeling require reliable detection and quantification methods of allergens in food products. Several analytical approaches, with the ability of quantifying and detecting traces of allergenic ingredients, which target either the allergenic proteins or allergen markers (peptide fragment or gene segment) have been developed. The most popular methods for allergen detection can be mainly divided into two large groups: the protein-based approaches and the DNA-based approaches. Protein-based methods include enzyme-linked immunosorbent assays (ELISA), MS methods, and biosensors. On the basis of the amplification of specific DNA fragments, DNA-based methods can trace the potential presence of culprit allergen, which include polymerase chain reaction (PCR) and real-time PCR. In this chapter, we present the advances about specific and highly sensitive analytical methods in the field of food allergens detection, which can avoid the influence by the presence of matrix components.

In recent years, with the improvement of food production and industrialization as well as the development of transgenic technology and the popularization of genetically modified food, the incidence of food allergic diseases is on the rise and has become a common chronic disease that endangers people’s physical and mental health, especially those of children’s. The World Health Organization (WHO) has listed food allergy as the sixth problem affecting people’s health, and the research on food allergen has become one of the public issues of global concern. This chapter will discuss multiple allergens in the “big eight” categories of food allergens. Biochemical characteristics associated with food allergens like the presence of multiple, linear IgE-binding epitopes seem to predominate among food allergens, more so than common structural features. Here, the recent studies on the identification of structure and potential epitopes of food allergens are also presented. Due to the high sequence homology and structural similarity of food allergens in different species, especially the major allergens, cross-reactivity is common; therefore a comprehensive introduction to the cross-reactivity among different origins of allergens is also reviewed.

Chemically diverse bioactive compounds with numerous health benefits have been taken more seriously. Food allergic inflammation mediated by several types of immune cells can also be affected by the naturally occurring bioactive compounds. Various compounds show immunomodulating effects, including polyphenols, polysaccharides, vitamins, peptides, fatty acids, amino acids, minerals, as well as prebiotics. Some components boost immune responses, resulting in host defense against infection, whereas others suppress immune responses, thus inhibiting allergy and inflammation. A variety of food components act on the varying immune cells, and the effects are mainly mediated via the intestinal immune system, as well as the intestinal microbiota. This chapter focuses on anti-allergic agents derived from microorganisms, plants (phytochemicals), animals, and marine algae and presents an overview of their potential application in functional foods for the treatment of allergic disorders. The molecular mechanisms and scientific validity of some bioactive natural compounds in the treatment of food allergies will also be explored.

The gastrointestinal tract is colonized with an enormous number of microorganisms, which play a critical role in shaping the development and function of host innate as well as adaptive immune responses. Evidence from both epidemiologic investigations and experiments in animal models indicates that abnormalities in microbiota composition (dysbiosis) can influence the development of allergic disorders via effects on immune function. Correction of these abnormalities by the use of probiotics or prebiotics, therefore, could have therapeutic or preventive potential. Probiotics can have positive effects on health that contribute to nutrition, modulation of inflammatory and hypersensitivity responses, and prevention of intestinal infections. This chapter will review developments in our understanding of the gut microbiota and probiotics in relation to food allergies.

Our purpose was to investigate the main bacterial microbiota and volatile profiles in the Chinese traditional dry-cured product—Jinhua ham during different processing stages and to analyze the role of the main microbiota in the formation of characteristic flavor. We determined the microbiota of Jinhua ham by using 16 S high throughput sequencing, and found that Staphylococcus constituted the predominant microbiota throughout the flavor formation process. Based on the volatile profiles of Jinhua dry-cured products from 11 different processing via SPME-GC-MS analysis, Aldehydes were the main groups of volatiles, with the most abundant ones being hexanal (13.89%) and nonanal (3.96%). To further investigate the relationship between predominant microbiota and the major volatile compounds in Jinhua ham, we screened and isolated genus Staphylococcus with high protease and lipase activities. The main Staphylococcus isolates, S. saprophyticus (53.4%) and S. equorum (31.0%) are related to the yields of aldehydes by producing hexanal, nonanal, benzaldehyde, and phenylacetaldehyde, indicating their contributions on the formation of characteristic flavor substances in Jinhua ham.

Essential oils have attracted increasing attentions due to their broad-spectrum antimicrobial activities and generally recognized as safe (GRAS) regulatory status. However, their low-solubility in water and reduced effectiveness in food matrices limit the commercial application in food industry. In this study, we used ultrasonic emulsification, medium-chain triacylglycerol (MCT) and phosphate-buffered saline (PBS) to formulate a highly stable and water-dispersible litsea cubeba essential oil (LCEO) nanoemulsions. After emulsification, a minimizing droplet size of LCEO nanoemulsions was achieved at approximately 100 nm in diameter, resulting in an increase in the water solubility and better stability at 4 °C and 25 °C. Furthermore, the bioactivities (antibacterial, antioxidant and antibiofilm properties) of LCEO nanoemulsions were greatly improved after emulsification, suggesting that nano-emulsification is beneficial for the value development of various essential oils and the LCEO nanoemulsions could be used as a novel food preservative for controlling bacterial growth and preventing oxidative deterioration in foods.

Scope Hippo signaling is a crucial pathway in innate immune responses, but the relationship between food allergy and Hippo pathway was unknown. The aim of this work was to investigate the regulation of food allergy by Hippo pathway and reveal the molecular mechanisms. Methods and results Two food allergens tropomyosin and ovalbumin were used to challenge a mouse model and CMT93 intestinal epithelia cell model. The allergic responses and the activation of Hippo pathway were tested in these models. In the mouse model, both allergens trigged significant allergic responses, and Hippo pathway was suppressed after allergen challenge. In CMT93, both allergens upregulated the expression of allergic cytokines TSLP, IL-25 and IL-33. In TAZ KD CMT93, the Hippo pathway was blocked, and the expression of allergenic cytokines were also suppressed. Conclusions Both in vivo and in vitro data demonstrated that the two food allergens suppressed Hippo pathway by downregulating TAZ expression, resulting in intestinal epithelia instability, and finally leading to hypersensitivity reactions. These findings provided potential therapeutic targets and molecular markers for food allergy, and provide dietary guidelines for allergenic individuals. This article is protected by copyright. All rights reserved.

Shellfish allergy is a crucial public health problem and a severe food safety issue, resulting in an urgent need for an accurate, simple and sensitive method to detect the shellfish allergens in complex food systems. Herein, we have desighed an “on-off-on” fluorescence aptasensor based on fluorescence resonance energy transfer (FRET) using prepared carboxyl groups functionalized CQDs (cCQDs) and graphene oxide (GO) for the detection and quantification of the major shellfish allergen arginine kinase (AK). The FRET aptasensor allowed for the sensitive detection of AK in the range of 0.001–10 μg/mL with the limit of detection (LOD) of 0.14 ng/mL (S/N = 3), and the limit of quantitation (LOQ) of 0.27 ng/mL (S/N = 10). This reliable, accurate and specific aptasensor with user-friendly operation may provide new perspectives in the application of fluorescence technologies for food allergens detection in the field of food safety.

In the present study, chitosan nanoparticles were prepared, characterized and used to evaluate the embryonic toxicology on zebrafish (Danio rerio). The average particle size of chitosan nanoparticles was 84.86nm. The increased mortality and decreased hatching rate was found in the zebrafish embryo exposure to normal chitosan particles and chitosan nanoparticles with the increased addition concentration. At 120h post-fertilization (hpf), the rate of mortality were 25.0 and 44.4% in the groups treated with chitosan nanoparticles and normal chitosan particles at 250mg/L, respectively. At 72hpf, the hatching rate in the groups treated with normal chitosan particles were lower (P

Scope Shellfish allergy is an important cause of food allergy, and tropomyosin (TM) is the major allergen within shellfish. Probiotics are safe bacteria that benefit host health and nutrition and is proposed as a novel approach for treating immunological diseases, including food allergies. Methods and results The probiotic strain Lactobacillus casei Zhang (LcZ) isolated from koumiss is investigated for its capacity to modulate food allergy induced by TM in BALB/c mice. Oral administration of LcZ attenuated allergy symptoms and intestinal epithelial damage. Furthermore, flow cytometry, real-time quantitative PCR, and ELISA demonstrated that LcZ administration altered the development and function of dendritic cells (DCs), T cells, and B cells, finally resulting in the change of TM-specific antibody isotypes into a tolerogenic pattern. Moreover, an in vitro spleen cell culture model reveals that LcZ directly modulates regulatory tolerogenic DC and T cell development, dependent on the activation of the nuclear factor kappa B (NF-κB) signaling pathway. Conclusion This work indicates the ability of LcZ to alleviate TM-induced food allergy and demonstrates the involvement of the tolerogenic immune cells and NF-κB signaling pathway, indicating LcZ to be a potential immunomodulator and immunotherapy assistor.

Fish has been recognized as one of the “Big-Eight” allergenic food sources with parvalbumin (PV) being one of the major allergens. Here, we report a novel immunomagnetic beads-derived enzyme-linked immunosorbent assay (ELISA) method which employs antibody functionalized graphene oxide (GO) and gold nanoparticles (AuNPs) to amplify the detection signal of PV. The GO and AuNPs are modified with monoclonal antibody (mAb) and HRP-labeled secondary antibody respectively to detect the PV captured by amino-functionalized magnetic beads. With the amplification effect of the antibody modified GO and AuNPs, the proposed ELISA could selectively detect PV with a detection limit as low as 4.29 ng/mL when using pure PV. Moreover, the recovery rates are found to range from 89.82% to 115.37% in the spiked samples. The feasibility in real-world fish sample analysis further shows that the proposed immunomagnetic beads-derived ELISA is a highly promising approach for PV detection and pave a new way for food safety analysis.

Tropomyosin (TM) and arginine kinase (AK) are known as two major allergens in seafood. For the first time, we demonstrate a newly developed ion-exchange chromatography coupled with dynamic coating capillary electrophoresis (IEC-DCCE) method to simultaneously analyze the TM and AK in shellfish. First, we have optimized the procedure of IEC for simple enrichment of TM and AK crude extract. By using 30 mM borate-borax at pH 9.0 with 0.3% (v/v) Tween-20 as a dynamic coating modifier for capillary electrophoresis (CE) separation, the migration time, separation efficiency and electrophoretic resolution greatly improved. The limits of detection (LOD) were 1.2 μg mL−1 for AK and 1.1 μg mL−1 for TM (S/N = 3), and the limits of quantification (LOQ) were 4.0 μg mL−1 for AK and 3.7 μg mL−1 for TM (S/N = 10). The recovery of AK ranged from 91.5 to 106.1%, while that of TM ranged from 94.0 to 109.5%. We also found that only when the concentrations of AK and TM were above LOD reported here, these proteins can stimulate human mast cell (LAD2) degranulation. Finally, the use of IEC-DCCE to analyze fresh shellfish samples highlights the applicability of this method for the simultaneous detection of these allergens in complex food systems.

Chinese shrimp ( Penaeus chinensis) is widely cultured and consumed in Asia but is also a major food allergen locally. Although they may be the foundation for preventing and treating allergies, the allergenic epitopes of the major allergens tropomyosin (TM) and arginine kinase (AK) in Penaeus chinensis have not been identified. Here, we applied Immunoinfo-CB (immunoinformatics coupled with competitive-binding strategy) to address the point. Potential allergenic epitopes of TM and AK were predicted by multiple immunoinformatics tools, followed by validating with inhibitory dot-blot assay, indirect competition ELISA, and mast cell degranulation assay. Furthermore, critical amino acids in allergenic epitopes were also identified by Immunoinfo-CB. Our findings provide new insight into allergenic epitopes and critical amino acids of TM and AK responsible for the anaphylactic response. The Immunoinfo-CB therefore offers promises for characterization of IgE-binding epitopes that might be used as new targets for immunotherapy of food allergy.

Shellfish is one of the major allergen sources worldwide, and tropomyosin (Tm) is the predominant allergic protein in shellfish. Probiotics has been appreciated for its beneficial effects on the host, including anti-allergic and anti-inflammatory effects, although the underlying mechanisms were not fully understood. In this study, oral administration of probiotic strain Bifidobacterium infantis 14.518 (Binf) effectively suppressed Tm-induced allergic response in a mouse model by both preventive and therapeutic strategies. Further results showed that Binf stimulated dendritic cells (DCs) maturation and CD103+ tolerogenic DCs accumulation in gut-associated lymphoid tissue, which subsequently induced regulatory T cells differentiation for suppressing Th2-biased response. We also found that Binf regulates the alterations of gut microbiota composition. Specifically, the increase of Dorea and decrease of Ralstonia is highly correlated with Th2/Treg ratio and may contribute to alleviating Tm-induced allergic responses. Our findings provide molecular insight into the application of Binf in alleviating food allergy and even gut immune homeostasis.

The effect of chitosan coatings on quality changes of shrimp, Litopenaeus vannamei, was studied during a 10-day storage at 4 °C. Groups of treatment 1 (T-1), treatment 2 (T-2), and control were treated with carboxymethyl chitosan, chitosan nanoparticle, and deionized water, respectively. The lowest pH values (P

Envelope protein VP28 has been suggested as a candidate vaccine component to evoke a better protection against white spot syndrome virus (WSSV). We have reported that Bacillus subtilis spores harbouring VP28 (rVP28-bs) can specifically protect shrimp against WSSV. However, the mechanism that supports the production of unique molecules induced by rVP28-bs to trigger specific immunity is originally unknown. It has recently been suggested that Dscam (Down syndrome cell adhesion molecule) plays an essential role in the alternative adaptive immunity of invertebrates. In this study, we compared the diversity of Litopenaeus vannamei Dscam (LvDscam) variable regions by different antigens immunization. A total of 13, 15 and 11 expressed alternative sequences were identified for N-terminal Ig2, N-terminal Ig3 and the entire Ig7 domain, respectively. More than half of the unique variants (16 out of 22) were found in the Ig2/Ig3 domains. Further analysis of the interaction between VP28 and unique Ig2/Ig3 variants was confirmed by both yeast two-hybrid and GST pull-down approach. We also found that the percentage of haemocytes phagocytosing WSSV was significantly higher (P < 0.001) in the shrimp injected with control-siRNA (43.8 � 2.2) than those with Dscam-siRNA (11.3 � 5.4) in the rVP28-bs groups. With Dscam-siRNA injection, survivorship significantly decreased (P < 0.001) in the rVP28-bs group after WSSV challenge. Our data suggested that LvDscam-mediated pathway may be involved in the specific immune response of shrimp against WSSV induced by rVP28-bs.

The freshness of Pacific white shrimp (Litopenaeus vannamei) stored for 0, 2, 4, 6, 8, and 10 days under vacuumpacking at 4°C was assessed by physicochemical, sensory, and microbiological methods. Thiobarbituric acid, total volatile basic nitrogen, pH, total viable counts, and K values increased significantly (P < 0.05) with the storage time, whereas the texture profile indexes decreased significantly (P < 0.05). Furthermore, a proteomic approach of 2-dimensional gel electrophoresis coupled with MALDI-TOF/TOF identification was used to analyze the differentially expressed muscle proteins at the different storage times. All of the 3 identified proteins (arginine kinase, phosphopyruvate hydratase, and actin T2, which were involved in muscle energy metabolism, glycolytic pathway in adenosine triphosphate generation, and organization of myofibril, respectively) were downregulated with the increase of storage time. Quantitative reverse transcription—polymerase chain reaction showed that messenger RNA ...

Razor clam is a major cultivated shellfish of great economic importance and high nutritional value. Due to high corruptible potential, razor clam is generally preserved by controlled freezing-point storage (CFPS). Here, we applied isobaric tags for relative and absolute quantification (iTRAQ) labeling to investigate the biochemical mechanism of cold stress adaption in razor clam during CFPS. In total, 369 proteins were quantified, and 27 of them were identified as differentially expressed proteins during CFPS, mostly involved in energy metabolism process, DNA duplication and protein synthesis, and stress response, specifically, MAPK is the predominant pathway. Further qPCR results revealed H2A and S6K 2 alpha to be the critical post-transcriptionally regulated genes. Our results provided proteomics information with respect to the biochemical mechanism of cold stress adaption in razor clam, shed light on the further elongation of razor clams storage period, and help clarify the novel mechanisms of cold tolerance.

Bacteria communicate with one another using chemical signal molecules called autoinducers, and the most prevalent autoinducers used by Gram-negative bacteria are N-acylated homoserine lactones (AHLs). However, AHLs are hardly detected in Shewanella baltica, the specific spoilage organism of Pseudosciaena crocea. In this study, we applied ultrahigh-performance liquid chromatography coupled to triple quadrupole tandem mass spectrometry to determine AHLs. This method enabled the quantification of up to 11 AHLs within 5.6 min with excellent sensitivity (ng/mL level) and linearity (r2 > 0.99), which further detected 9 AHLs produced by S. baltica. Furthermore, by using a biofilm formation assay and statistical analysis, the biofilm-inducing activity of AHL in S. baltica was first revealed. Our results elucidated the physiological role of AHL in S. baltica and provided a satisfactory method to detect AHLs and a statistical model to predict food spoilage properties.

The beneficial effects of probiotics have been described in allergic sensitization and diseases; however, many questions remain unanswered, such as characteristics of the most effective strains in modulation of allergic responses and how orally administered probiotics affect the systemic immune system. In the present work, oral administration of five lactic acid bacteria strains showed variable effects on protection against the allergic reaction in a mouse model of food allergy to shrimp tropomyosin (ST). The most effective anti-allergic strain, Bacillus coagulans 09.712 (Bc), greatly improved epithelial barrier function and increased lymphocytes proliferation. Moreover, Bc suppresses ST sensitization by altering Th1/Th2/Treg balance as a result of strong induction of CD4+Foxp3+Tregs in combination with IL-10 producing. Bc-specific induction of CD4+Foxp3+ Tregs also suppresses Th17 pro-inflammatory response in this mouse model. Finally, the intake of Bc suppresses mTOR activation and thus the phosphorylation of downstream factors. Inhibition of mTOR signaling by Bc further results in FOXP3 up-regulation and GATA-3 down-regulation, which, in turn, facilitate to control Th2-predominant and Th17 pro-inflammatory responses caused by ST. Our work provides further characterization of the anti-allergic effects of probiotic LAB strains, and identifies new targets for preventive and curative treatment of food allergies.

Food Spoilage Microorganisms: Ecology and Control focuses on the occurrence, outbreak, consequences, control, and evaluation of spoilage microorganisms in food, providing the necessary basic knowledge of food spoilage ecology and control so as to ensure food safety, especially in developing countries where food hygiene in storage requires special care. The first part of the book looks at spoilage microorganisms in plant origin foods, such as cereals, beans, fruits, and vegetables, and the second part tackles the spoilage microorganisms in animal origin foods like meat, poultry, seafood, powdered milk, and egg products. In each chapter, the taxonomy of spoilage microorganisms, spoilage characteristics, consequences and possible mechanisms, and specific methods for detection and evaluation are discussed based on the basis surface introduction. The control, prevention, and management options for spoilage microorganisms are also presented. In addition, opportunities and challenges are summarized and predicted in the last part of each chapter.

Crowding, as a result of high stocking densities in aquaculture, can affect the physiological state and flesh quality of aquatic animals. To better understand the mechanism of response to crowding stress in Chinese shrimp (Fenneropenaeus chinensis), two-dimensional gel electrophoresis (2-DE) coupled with matrix-assisted laser desorption/ionization time-of-flight/time-of-flight (MALDI-TOF/TOF) mass spectrometry (MS) identification were used to analyze differentially expressed muscle proteins between shrimp under crowded and non-crowded conditions. Spots corresponding to 34 differentially expressed proteins were found. Further MALDI-TOF/TOF analysis indicated that three of the enhanced proteins, 14-3-3-like protein, actin T2 and pyruvate kinase 3, were involved in myogenic signaling, muscle cytoskeleton and carbohydrate catabolism, respectively. Moreover, quantitative RT-PCR showed that mRNA levels of 14-3-3-like protein and pyruvate kinase 3 were up-regulated after a 2-h crowding stress, whereas actin T2 showed down-regulation. The alterations of protein expression observed in the muscle may cause flesh quality decline of shrimp after crowding stress.

The present study was to evaluate two slaughter processing methods (ice water immersion (T-1) and individual beheaded (T-2)) on whiteleg shrimp quality farmed in freshwater culture systems using attenuated total reflection infrared (ATR-IR) technology. In addition, the corresponding physical, chemical and microbial properties of shrimp samples were also determined. No significant differences were observed in pH, total volatile basic nitrogen (TVB-N), thiobarbutiric acid (TBA) and K value as well as the contents of moisture, crude protein, crude fat and ash between groups of T-1 and T-2. However, significantly higher springiness and chewiness (P0.05) were observed in T-1 as compared to those of T-2. As for the result of total viable counts (TVC), significantly lower value (P0.05) was shown in T-1 than that of T-2, indicating that the quality and shelf life of whiteleg shrimp killed by ice water immersion could be improved and prolonged. Furthermore, all the samples were successfully divided into two categories regarding the two slaughter methods by principal component analysis (PCA) according to the infrared spectra. By analysis of the regression coefficients of PLS-DA, it can be supposed that the quality differences of whiteleg shrimp with different slaughter processing are largely caused by structural changes of their protein and fat. All together, our results indicated that the springiness and chewiness of whiteleg shrimp with different processing could be correctly distinguished using infrared spectroscopy.