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DNA-based detection methods are highly promising for risk assessment in the food sector, such as tracing the existence of food allergens. However, due to the complexity of food matrices, cumbersome protocols are often needed to isolate the DNA components, which hinder the achievement of rapid and on-site detection. Herein, an instant and multiple DNA extraction method was developed based on the poly(vinyl alcohol) microneedle (MN) patch. With simple press and peel-off operations within 1 min, samples suitable for DNA-based analysis such as polymerase chain reaction (PCR) could be collected. By further combining with the recombinase polymerase amplification assay, rapid screening of the allergenic risks in complex samples such as shrimp ball and cheesecake could be achieved within 30 min. The MN-based DNA extraction method not only was a potential alternative to the traditional DNA extraction method but provided a transformative approach in realizing rapid, on-site detection of foodborne hazards in collaborating with fast DNA-based assays.

Currently, there is a need to explore the effects of different types of protein-anthocyanin complexations, as well as the possible changes in the nutrition and allergenicity of the formed complexes. Here, we systematically investigated the covalent and non-covalent interactions between cyanidin-3-O-glucoside (C3G) and two major milk proteins, α-casein (α-CN) and β-lactoglobulin (β-LG). Fluorescence quenching data showed that, under non-covalent conditions, C3G quenched the fluorescence of the two proteins via a static process, with the interaction forces being revealed; for covalent products, decreased fluorescence intensities were observed with red shifts in the λmax. Multiple spectroscopic analyses implied that C3G-addition induced protein structural unfolding through transitions between the random coil and ordered secondary components. With a two-stage simulated gastrointestinal (GI) digestion model, it was seen that covalent complexes, not their non-covalent counterparts, showed reduced protein digestibility, ascribed to structural changes resulting in the unavailability of enzyme cleaving sites. The GI digests displayed prominent 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) radical cation-scavenging abilities (3.8-11.1 mM Trolox equivalents per mL digest), in contrast to the markedly reduced 1,1-diphenyl-2-picrylhydrazyl radical-scavenging capacities. Additionally, covalent protein-C3G complexes, but not their non-covalent counterparts, showed lower IgE-binding levels in comparison to the native control. This study provides new understanding for the development of anthocyanin-milk protein systems as functional ingredients with health-beneficial properties.

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.

Graphical abstract, Highlights • The role of pre-ultrasound on β-LG–phenolic binding at various pH was investigated. • Pre-ultrasound at 35% amplitude strengthened the binding affinity of EGCG/CA to β-LG. • Pre-ultrasound promoted changes in the protein spatial structure by phenolic binding. • Dimer/monomer form of β-LG distinctly affects the complex property under ultrasound. • Pre-ultrasound with EGCG binding improved foaming and emulsifying properties of β-LG., There is a need to understand the ultrasound-induced changes in the interactions between proteins and phenolic compounds at different pH. This study systematically explored the role of high-intensity ultrasound pre-treatment on the binding mechanisms of β-lactoglobulin (β-LG) to two common phenolic compounds, i.e., (−)-epigallocatechin-3-gallate (EGCG) and chlorogenic acid (CA) at neutral and acidic pH (pH 7.2 and 2.4). Tryptophan fluorescence revealed that compared to proteins sonicated at 20% and 50% amplitudes, 35%-amplitude ultrasound pre-treatment (ULG-35) strengthened the binding affinities of EGCG/CA to β-LG without altering the main interaction force. After phenolic addition, ULG-35 displayed a similar but a greater extent of protein secondary and tertiary structural changes than the native protein, ascribed to the ultrasound-driven hydrophobic stacking among interacted molecules. The dominant form of β-LG (dimer/monomer) played a crucial role in the conformational and interfacial properties of complexes, which can be explained by the distinct binding sites at different pH as unveiled by molecular docking. Combining pre-ultrasound with EGCG interaction notably increased the foaming and emulsifying properties of β-LG, providing a feasible way for the modification of bovine whey proteins. These results shed light on the understanding of protein–phenolic non-covalent binding under ultrasound and help to develop complex systems with desired functionality and delivery.

Celiac disease (CD) is a prevalent disorder with autoimmune features. Dietary exposure of wheat gluten (including gliadins and glutenins) to the small intestine activates the gluten-reactive CD4+ T cells and controls the disease development. While the human leukocyte antigen (HLA) is the single most important genetic factor of this polygenic disorder, HLA-DQ2 recognition of gluten is the major biological step among patients with CD. Gluten epitopes are often rich in Pro and share similar primary sequences. Here, we simulated the solution structures changes of a variety of gluten epitopes under different pH and temperatures, to mimic the fermentation and baking/cooking processes. Based on the crystal structure of HLA-DQ2, binding of differently processed gluten epitopes to DQ2 was studied in silico. This study revealed that heating and pH change during the fermentation process impact the solution structure of gluten epitope. However, binding of differently treated gluten epitope peptide (GEP) to HLA-DQ2 mainly depended on its primary amino acid sequence, especially acidic amino acid residues that play a pivotal role in their recognition by HLA-DQ2.

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.

Tropomyosin (TM), the predominant shellfish allergen, has induced severe food allergy worldwide, but efficient prevention and cure measures are limited nowadays. In the present study, we introduced an approach to eliminate Penaeus chinensis TM by Maillard reaction with reducing sugars including ribose, galacto-oligosaccharide (GOS) and chitosan-oligosaccharide (COS), which reduced the allergenicity by up to 60%. We also evaluated the conformational changes of TM during reaction by far-UV circular dichroism, and found the reaction-induced alternation from α-helix to β-sheet. We further determined the effect of Maillard reaction on TM allergenic epitopes to investigate the detailed mechanisms, and revealed the structure preference of different sugars. Correlation analysis with experimental data revealed that α-helix mediated the allergenicity elimination by Maillard reaction. There results provided theoretical foundations for the improvement and application of Maillard reaction in allergenic food processing.

The production of biogenic amines (BAs) set considerable obstacles in seafood preservation. However, the characteristic BAs and their roles in the spoilage profiles in large yellow croaker were still poorly understood. The BAs contents, free amino acids (FAAs) contents, aerobic bacterial count, sensory evaluation and several characteristic physicochemical indexes were monitored during storage at 4 °C. It's forcefully uncovered that the putrescine and cadaverine were the main BAs and the sum value of them could be used as a novel quality indicator instead of BAI. The reasonable limitation for unaccepted corruption was suggested be around 60 mg/kg. The regression model (r > 0.8, P < 0.05) at 4 °C indicated a significant correlation between the main BAs and total volatile basic nitrogen (TVB-N), protein hydrolysis index (P.I.%) as well as pH value, offering a new interpretation form for the physiochemical properties of BAs in aquatic products. Additionally, the evolution of FAAs show the predominant role of lysine, proline, histidine, glycine, and alanine during the whole storage and it can be concluded that BAs biosynthesis in large yellow croaker were moderately related with their precursor substance. This work provides a preliminary insight into the origin of BAs in large yellow croaker. PRACTICAL APPLICATION: It was proposed that the sum value of putrescine and cadaverine which were the main BAs can be used as a novel quality indicator instead of BAI in large yellow croaker. And the regression models of BAs and other physiochemical indexes provided a new perspective for comprehending the spoilage profiles involving BAs biosynthesis. The study may potentially contribute to improving the evaluation of seafood freshness and provide new target site for seafood preservation.

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...

Ovomucoid (OVM), known as the major allergen in egg white, has gained increasing concerns in industrialized countries. Here, we found the deglycosylation and Maillard reaction with galactooligosaccharide (GOS) and fructooligosaccharide (FOS) can induce conformational transformation of OVM from other structures (β-turn, strang, and random coils) to α-helix. We also introduced an approach to reduce the allergenicity of Gallus domesticus OVM by Maillard reaction with GOS and FOS. However, the OVM glycated by mannosan (MOS) and deglycosylated OVM exhibited higher allergenicity than native OVM. Therefore, GOS and FOS, especially GOS, could be applied in the reduction of the potential allergenicity of OVM through glycation. Furthermore, these findings may provide new insights into the development of hypoallergenic egg products. PRACTICAL APPLICATION: In this study, the allergenicity and conformation of OVM treated with deglycosylation and glycation (GOS, FOS, and MOS) were investigated. The results would provide a better understanding of the effects of deglycosylation and Maillard reaction with different reducing sugars on the molecular characteristics of OVM and further provide new insights into the development of hypoallergenic egg products.

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.

Biogenic amines (BAs) are not only well-known indicators for food freshness but can cause serious harm to the body after excessive consumption, which makes the determination of its content in food of great significance. In this work, a simple and convenient method for colorimetric detection of BAs was developed based on the sensitivity of the polymerization of dopamine to the presence of BAs on the surface of gold nanoparticles (AuNPs). Taking histamine as a representative, the system exhibited a distinct color change from wine red to black among the amine concentration of 1–100 μg/mL with the detection limit of 2.8 μg/mL. The detection system also exhibited sensitivity to other common kinds of BAs, such as putrescine, cadaverine, spermine, spermidine, tyramine, and tryptamine. Moreover, the proposed method showed encouraging performance in visual detection of the freshness of real samples, which provided a new approach for food quality and freshness evaluation.

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.

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.

Tropomyosin (TM), a major allergen in shellfish, has raised increasing concern in industrialized countries and resulted in an urgent need for accurate, simple, and sensitive methods for tracing its presence in food products. Herein, we proposed a sandwich biosensor that employed the rationally imprinted magnetic particles and aptamer modified carbon dots for the detection of TM in seafood products. The multi-point initiated polydopamine was employed as molecular imprinting polymer on magnetic particles, which was subjected to antifouling surface modification to achieve efficient separation of TM. By taking the aptamer modified carbon dots as signal probes, a sandwich assay was achieved with the limit of detection (LOD) being 30.76 ng mL−1 (S/N = 3). The proposed method not only possessed excellent specificity towards TM but exhibited great accuracy. The sandwich biosensor was further used to quantitatively analyze TM in five shrimp and five shrimp processed products, which proved that the proposed biosensor could detect TM in commercial samples and had a great application prospect.

Dietary proteins and phenolic compounds are commonly co-existing components that readily interact with each other to yield complexes in a wide range of food systems. The formed complexes play a critical role in the physiochemical characteristics of both reacting molecules, thereby impacting nutritional and quality profiles of related products. In this review, we provided the most updated knowledge on dietary protein-phenolic interactions related with food science and human nutrition, including their mechanisms of complexation, analytical technologies, and alterations in the functionality and nutraceutical properties of both reacting partners. Their potential applications in the industries regarding stability during food processing and storage, impacts on product quality, and fabrication of novel delivery systems for liable bioactives were also discussed. The interactions between dietary proteins and phenolics, either via non-covalent or covalent processes, are ubiquitous in food systems and are closely associated with chemical structures of both compounds and the surrounding conditions, mainly temperature, pH, and the presence of phenolic oxidases. Albeit in different ways, such intermolecular associations induced changes in protein conformational structures, which subsequently impacted their techno-functional properties, digestibility, and allergenic potentials; in turn, the bioaccessibility/bioavailability and health-protecting features of interacted phenolics were modified to various extents, as noticed by in vitro and in vivo evidence. Largely depending on the interaction molecules and preparation steps, those influences can be either favorable or unfavorable in different systems and therefore can be tailored to develop food products and nutraceuticals with maximized functionality and quality attributes.

Currently, there has been a surge of interest in revealing the interactions between plasma and food matrices. In this study, we investigated the impacts of atmospheric cold plasma (ACP) treatment on the structural, physicochemical and allergenic characteristics of soybean protein isolate (SPI). SPI dispersions were subjected to ACP treatments at different frequencies (80 to 100 Hz) and durations (1 to 10 min) to investigate the effects of exposing conditions. Results showed that ACP induced reactive oxygen species-mediated oxidation of soy proteins, resulting in modifications in the secondary and ternary structures of SPI. As a consequence, functional properties of SPI, such as emulsifying (56 to 168%, compared with control) and foaming properties (60 to 194%) were influenced by varying degrees. In addition, under certain circumstance (120 Hz, 5 min), the IgE-binding level of SPI was decreased by up to 75%, when compared to the control. Moderate treatment yielded products with improved functionality and reduced allergenicity, while extensive exposure induced a loss of vendibility due to protein aggregation. PRACTICAL APPLICATION: In this study, we demonstrated for the first time, that plasma species reacted with soybean proteins, resulting in spatial structural changes which are closely related with protein functionality and allergenicity. ACP interacts with macromolecules in aqueous systems and thus can be an alternative and promising nonthermal approach in modifying soybean proteins, whereas the exact role of different processing parameters needs to be well-elaborated.

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

Cow's milk protein allergy, which occurs in approximately 5-10% of the population of infants and children, has become an important public food safety problem. As a major allergen in cow's milk, the most abundant protein casein (CN) is considered to be potent in inducing food allergy. In recent years, ultrasound treatment has played a significant role in the field of colloidal particulate system. In this study, we found that ultrasound treatment dramatically decreased the diameter of a CN particle to less than 100 nm in the presence of Tween 80, producing colloidal casein (c-CN) with high transparency. The electrophoretic and transmission electron microscopy analysis showed that the advanced protein structure of CN changed significantly. In addition, the enzyme-linked immunosorbent assay with allergic sera showed that the immunoglobulin-E-binding capacity of c-CN was significantly decreased. In the meantime, the LAD2 mast cell line degranulation assay demonstrated that ultrasound treatment made CN hypoallergenic. The colloidal and hypoallergenic properties of c-CN were stably maintained for more than 30 days. Likewise, the allergenicity of fresh whole milk also decreased after ultrasound treatment. This work provided an effective way to reduce the allergenicity of milk allergen, which could be beneficial to the production of hypoallergenic cow's milk.

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.

An authenticity-based method was developed to detect economically motivated adulteration (EMA) in milk. To achieve this goal, 46 peptides released from trypsin digested milk proteins were identified and marker peptides were further selected based on their digestibility and stability characteristics to allow further quantifications of the milk proteins in the original samples using an isotope-dilution ultra-performance liquid chromatography tandem triple quadrupole mass spectrometry (UPLC-TQMS). Furthermore, to detect EMA in milk samples, 22 authentic milk powder samples were analyzed using the isotope-dilution UPLC-TQMS, and an authenticity threshold value --70.26 g/100 g as the content of all five major milk proteins to total protein—was established to evaluate milk samples with high adulteration risks. Finally, the threshold value was validated using soy protein adulterated milk samples. Results showed that the reported authenticity-based method was sensitive enough to detect the tampering of milk samples with as little as 10 % soy protein added. It is clear that this newly developed authenticity-based detection method is a powerful tool to detect unknown adulteration risks in milk samples.

Major royal jelly protein 1 (MRJP1) is the most abundant protein in royal jelly (RJ), and the level of MRJP1 has been suggested as a promising parameter for standardization and evaluation of RJ authenticity in quality. Here, a quantitative method was developed for the quantification of MRJP1 in RJ based on a signature peptide and a stable isotope-labeled internal standard peptide FFDYDFGSDER*(R*, 13C6, 15N4) by ultraperformance liquid chromatography–tandem mass spectrometry. Recoveries of the established method ranged from 85.33 to 95.80%, and both the intra- and interday precision were RSD < 4.97%. Quantification results showed that content of MRJP1 in fresh RJ was 41.96–55.01 mg/g. Abnormal levels of MRJP1 were found in three commercial RJs and implied that these samples were of low quality and might be adulterated. Results of the present work suggested that the developed method could be successfully applied to quantify MRJP1 in RJ and also could evaluate the quality of RJ.

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.

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.

Serving as the predominant site for food digestion and nutrition absorption, the gastrointestinal tract separates the inner environment of the human body from the outer environment by epithelial barrier. The highly selective barrier favors fluxes of nutrients but limits host contact with the massive intraluminal load of dietary antigens and microbes. Under normal physiological conditions, controllable small amounts of food-derived antigens and microorganisms transport through the barrier with proper processing, inducting a homeostatic immune response and resulting in immune tolerance to dietary antigens. Conversely, primary or secondary intestinal barrier defects can lead to excessive entrance of lumen macromolecules, contributing to the pathogenesis of a wide range of human diseases including food allergy and inflammatory bowel disease (IBD). Consequently, the intestinal barrier dysfunction could be a promising target for treating food allergy; however, limited mechanical researches and practical applications are available nowadays, and far more investigations are required for reliable clinical practices.

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.

Food allergy has risen as a worldwide food safety concern due to the increasing prevalence over the last decades. It’s in urgent need to develop straight yet sensitive detection methods for food allergens to help people avoid the potential risks imposed by food allergy. Here, we developed a dual-mode aptasensor that gave both colorimetric and fluorescent readouts in response to parvalbumin (PV), a major allergen in fish. The aptasensor was constructed by hybridizing the aptamer modified gold nanoparticles (AuNP-APT), the complementary short chain modified gold nanoparticles (AuNP-CS1) and the fluorescent dye-labeled complementary short chain (FAM-CS2). The presence of PV led to disassembly of the aptasensor through competitive interaction between APT and PV, which resulted in a change in the solution color of the AuNPs and a recovery of the once quenched fluorescence signals of FAM-CS2. The aptasensor exhibited a colorimetric response in the PV concentration range of 2.5–20 μg/mL and a linear fluorescent response in the PV concentration range of 2.38–40 μg/mL. Moreover, the aptasensor showed encouraging specificity, precision, accuracy as well as efficiency in real fish sample detection, which held great potential in recognition and analysis of food allergens.

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

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.

Arginine Kinases (AK), known as the major allergen in shellfish, has gained increasing concerns in industrialized countries. Here, we proposed a simple but accurate analytical immunoassay that employed gold nanoparticles (AuNPs) and magnetic beads (MBs) for tracing and quantification of AK in shellfish. The limit of detection (LOD) was 3.91 ng ml−1 (S/N = 3), while the limit of quantitation (LOQ) was 13.04 ng ml−1 (S/N = 10), respectively. Moreover, promising recoveries (94.6%–106.8%) were obtained for the determination of AK in foodstuffs, indicating the good accuracy of this method. Furthermore, the results demonstrated that this method is capable of quantification of AK from nine different shellfish species. Therefore, the double-enhanced immunoassay with simple sample preparation procedures and user-friendly operation showed high applicability for allergen detection in shellfish related foodstuffs and production lines. Furthermore, the developed method can be employed to identify the adulteration of shellfish products using AK as biomarker due to the less conserved sequences of AK in phylogenetically different species.

Tropomyosin (TM), known as the major allergen in seafood, has been increasing concerns in industrialized countries. We proposed a simple, rapid and accurate analytical method using surface plasmon resonance (SPR) sensor with gold patterned biochips for detection and quantification of TM in shellfish. The limit of detection (LOD) was 1.0 μg mL−1 (S/N = 3), while the limit of quantitation (LOQ) was 2.5 μg mL−1 (S/N = 10). Moreover, the satisfactory recoveries (92.0–108.0%) was obtained for TM detection in food samples, showing the good accuracy of this method. Furthermore, the results also demonstrated that this developed method is suitable for the determination of TM from different shellfish species within 3 min. Therefore, the developed SPR sensor with gold patterned biochips will have positive significance on the rapid and accurate detection allergens in shellfish foodstuffs, related products and their production lines in the future.

A biosensor based on a chiral assembly of polymer of gold nanoparticle (AuNP) trimers was developed for the detection and quantification of the major shellfish allergen tropomyosin (TROP). TROP and anti-TROP monoclonal antibodies (mAb) were immobilized on 20 nm and 30 nm 16-mercaptohexadecanoic acid (16-MHDA) functionalized AuNPs to assemble a trimer, which has a Circular dichroism (CD) signal. The free TROP from samples was quantified as an inhibitor for the formation of the AuNP trimer. The AuNP trimer-based biosensor allowed for the selective determination of TROP in the range of 0.1–15 ng mL−1 with the limit of detection (LOD) of 21 pg mL−1 (S/N = 3) and the limit of quantitation (LOQ) of 70 pg mL−1 (S/N = 10). The use of a AuNP trimer-based biosensor with simple sample preparation functions with specificity and accuracy; this highlights its applicability for the detection of allergens in shellfish products, related products and their production lines. Furthermore, based on the less conserved sequences of TROP in phylogenetically different species, this biosensor is currently being used to identify the adulteration of shellfish products using TROP as biomarker.

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.

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

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 ...

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.