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Ultrasound-assisted phosphorylation of goose myofibrillar proteins: improving protein structure and functional properties

Zhou Y, Sun Y, Pan D, Xia Q, Zhou C

J Sci Food Agric, 2023 Aug 30;103(11):5412-5421.
PMID: 37038882 DOI: 10.1002/jsfa.12616

BACKGROUND: Goose meat is rough and embedded with dense connective tissue, impairing protein solubility. Therefore, to improve the functional properties of goose myofibrillar protein (GMP), ultrasound was used to assist the phosphorylation of GMP.
RESULTS: The fact that GMP attached covalently with the phosphate group of sodium tripolyphosphate (GMP-STP) was disclosed directly by Fourier transform infrared spectroscopy. Furthermore, ultrasound significantly improved the hydrophobicity and solubility of GMP-STP, which could be attributed to the conversion of α-helix to β-sheet, β-turns, and random coils by sonication. The spatial stabilization of the protein phosphorylation process was boosted by ultrasound, making the droplets more dispersed, and thus an improvement in the functional properties of GMP-STP was observed. Water-holding capacity, oil-binding capacity, and emulsifying and foaming properties were best at an ultrasound power of 400 W.
CONCLUSION: Ultrasound-assisted phosphorylation has great potential to modulate the structure-function relationship of proteins. © 2023 Society of Chemical Industry.
Fulltext Challenge-Hindrance Stressors and Academic Engagement Among Medical Postgraduates in China: A Moderated Mediation Model

Bao D, Mydin F, Surat S, Lyu Y, Pan D, Cheng Y

Psychol Res Behav Manag, 2024;17:1115-1128.
PMID: 38505350 DOI: 10.2147/PRBM.S448844

BACKGROUND: Improving academic engagement of medical postgraduates is crucial for enhancing the quality of learning and the development of medical education. Due to medical postgraduates face high levels of stress and rigorous demands, yet the mechanisms linking challenge-hindrance stressors to academic engagement in this context remain largely unexplored. This study aims to explore the comprehensive relationship between challenge-hindrance stressors and academic engagement among medical postgraduates in China.
METHODS: Data were collected from 437 medical postgraduates in China, to investigate their challenge-hindrance stressors, emotional exhaustion, learning, relaxation and academic engagement. Among these postgraduates, 40.3% were male and 59.7% were female, with the mean age of the participants being 25.71 years. Statistical procedures were conducted using Mplus 8.3, ensuring a robust analysis of the data collected.
RESULTS: Our study showed that both challenge and hindrance stressors are significantly positively correlated with emotional exhaustion among Chinese medical postgraduates, and emotional exhaustion is negatively associated with academic engagement. Emotional exhaustion mediates the relationship between challenge-hindrance stressors and academic engagement. Learning plays a protective role, moderating the challenge stressors and emotional exhaustion relationship and its indirect effect on academic engagement. However, relaxation was not identified as a significant moderating factor in this context.
CONCLUSION: Our findings not only revealed emotional exhaustion as a potential mechanism underlying the relationship between challenge-hindrance stressors and academic engagement but also validated the moderating role of learning in mitigating the adverse effects of challenge stressors on emotional exhaustion and academic engagement among Chinese medical postgraduates. This comprehensive insight into the complex dynamics between different stressors and academic engagement provides both theoretical and empirical evidence for medical universities. It underscores the importance of interventions to enhance academic engagement in stressful environments and serves as a valuable reference for the development of reasonable assessment systems. These contributions are crucial for fostering a supportive educational atmosphere and promoting the well-being of medical postgraduates.
Electrospun of functionalized mesoporous UiO-66 as the selective coating of solid phase microextraction Arrow for the determination of nine alkylphenols

Yang P, Zhu X, Lan H, Wu Y, Pan D

Mikrochim Acta, 2024 Mar 08;191(4):188.
PMID: 38457047 DOI: 10.1007/s00604-024-06248-w

A solid-phase microextraction (SPME) Arrow and high-performance liquid chromatography-UV detector (HPLC-UV, detection at 225 nm) based method was developed for the selective determination of nine alkylphenols (APs) in milk. The functionalized mesoporous UiO-66 (4-meso-UiO-66) was utilized as the new coating material, which was synthesized by post-modification of pore-expanded UiO-66-NH2 by an esterification reaction with 4-pentylbenzoic acid. It was fully characterized by X-ray photoelectron spectroscopy (XPS), fourier transformation infrared spectrometry, nitrogen sorption-desorption test, scanning electron microscopy, transmission electron microscopy, and X-ray diffractometer. The characterization results showed the ester groups and benzene rings were introduced into the 4-meso-UiO-66, and the mesoporous structure was predominant in the 4-meso-UiO-66. The extraction mechanism of 4-meso-UiO-66 to APs is the synergistic effect of Zr-O electrostatic interaction and the size exclusion effect resulting from XPS, selectivity test, and nitrogen sorption-desorption test. The electrospinning technique was utilized to fabricate the 4-meso-UiO-66 coated SPME Arrow and polyacrylonitrile (PAN) was used as the adhesive. The mass rate of 4-meso-UiO-66 to PAN and the electrospinning time were evaluated. The extraction and desorption parameters were also studied. The linear range of this method was 0.2-1000 μg L-1 with a coefficient of determination greater than 0.9989 under the optimal conditions. The detection limits were 0.05-1 μg L-1, the inter-day and intra-day precision (RSD) were 2.8-11.5%, and the recovery was 83.6%-112%. The reusability study showed that the extraction performance of this new SPME Arrow could be maintained after 80 adsorption-desorption cycles. This method showed excellent applicability for the selective determination of APs in milk.
The relationship between challenge-hindrance stressors and innovative behavior among medical postgraduates in China: the mediation role of academic engagement and the moderating effect of relaxation

Bao D, Mydin F, Surat S, Lyu Y, Pan D, Cheng Y

Med Educ Online, 2024 Dec 31;29(1):2379110.
PMID: 39016967 DOI: 10.1080/10872981.2024.2379110

This study investigated the relationship between challenge-hindrance stressors and innovative behavior of medical postgraduates in China, examining the mediating role of academic engagement and the moderating effect of relaxation. Drawing from a sample of 437 medical postgraduates from three Chinese universities, our findings revealed that challenge stressors positively correlated with innovative behavior, while the direct relationship between hindrance stressors and innovative behavior was not statistically significant. Furthermore, academic engagement mediated the relationship between two types of stressors and innovative behavior. Challenge stressors enhanced academic engagement, which in turn fostered innovative behavior. Conversely, hindrance stressors were found to diminish academic engagement, which in turn indirectly limited innovative behavior. Additionally, relaxation was identified as a moderating factor that helped mitigate the negative effects of hindrance stressors on academic engagement and indirectly on innovative behavior. These results suggested that academic engagement as a mechanism played a pivotal role in determining how different stressors influenced innovative behavior, underscoring the need for stress management, particularly through relaxation techniques, to maintain high levels of academic engagement and innovative behavior. This study offers practical insights for medical education policymakers and educators in China, emphasizing the importance of balancing stressors and incorporating relaxation practices to enhance the innovative capabilities of medical postgraduates in demanding academic environments.
Research Progress of Nitrite Metabolism in Fermented Meat Products

Shen Q, Zeng X, Kong L, Sun X, Shi J, Wu Z, et al.

Foods, 2023 Apr 01;12(7).
PMID: 37048306 DOI: 10.3390/foods12071485

Nitrite is a common color and flavor enhancer in fermented meat products, but its secondary amines may transfer to the carcinogen N-nitrosamines. This review focuses on the sources, degradation, limitations, and alteration techniques of nitrite. The transition among NO3- and NO2-, NH4+, and N2 constitutes the balance of nitrogen. Exogenous addition is the most common source of nitrite in fermented meat products, but it can also be produced by contamination and endogenous microbial synthesis. While nitrite is degraded by acids, enzymes, and other metabolites produced by lactic acid bacteria (LAB), four nitrite reductase enzymes play a leading role. At a deeper level, nitrite metabolism is primarily regulated by the genes found in these bacteria. By incorporating antioxidants, chromogenic agents, bacteriostats, LAB, or non-thermal plasma sterilization, the amount of nitrite supplied can be decreased, or even eliminated. Finally, the aim of producing low-nitrite fermented meat products is expected to be achieved.
Nanocoating of lactic acid bacteria: properties, protection mechanisms, and future trends

Fan Q, Zeng X, Wu Z, Guo Y, Du Q, Tu M, et al.

Crit Rev Food Sci Nutr, 2023 Jun 15.
PMID: 37318213 DOI: 10.1080/10408398.2023.2220803

Lactic acid bacteria (LAB) is a type of probiotic that may benefit intestinal health. Recent advances in nanoencapsulation provide an effective strategy to protect them from harsh conditions via surface functionalization coating techniques. Herein, the categories and features of applicable encapsulation methods are compared to highlight the significant role of nanoencapsulation. Commonly used food-grade biopolymers (polysaccharides and protein) and nanomaterials (nanocellulose and starch nanoparticles) are summarized along with their characteristics and advances to demonstrate enhanced combination effects in LAB co-encapsulation. Nanocoating for LAB provides an integrity dense or smooth layer attributed to the cross-linking and assembly of the protectant. The synergism of multiple chemical forces allows for the formation of subtle coatings, including electrostatic attractions, hydrophobic interactions, π-π, and metallic bonds. Multilayer shells have stable physical transition properties that could increase the space between the probiotic cells and the outer environment, thus delaying the microcapsules burst time in the gut. Probiotic delivery stability can be promoted by enhancing the thickness of the encapsulated layer and nanoparticle binding. Maintenance of benefits and minimization of nanotoxicity are desirable, and green synthesized nanoparticles are emerging. Future trends include optimized formulation, especially using biocompatible materials, protein or plant-based materials, and material modification.
TMT-labeled quantitative proteomic reveals the mechanism of proteolysis and taste improvement of dry-cured bacon with Staphylococcus co-inoculation

Zhou C, Wu X, Pan D, Xia Q, Sun Y, Geng F, et al.

Food Chem, 2024 Mar 15;436:137711.
PMID: 37839122 DOI: 10.1016/j.foodchem.2023.137711

To understand the mechanism of co-inoculation of Staphylococcus xylosus and Staphylococcus vitulinus (SX & SV) on structural protein degradation and taste enhancement of dry-cured bacon, protease activities, protein degradation, surface morphology of proteins and taste parameters of dry-cured bacon with Staphylococcus inoculation were investigated. The dry-cured bacon with co-inoculation of Staphylococcus xylosus and Staphylococcus vitulinus showed the best taste attributes. High residual activities in cathepsin B + L (more than 1.6-fold) and alanyl aminopeptidase (more than 1.4-fold) accelerated structural protein degradation in SX & SV. 32 down-regulated proteins were identified in SX & SV by TMT-labeled quantitative proteomic compared with control group; myosin and actin showed the most intense response to the accumulation of sweet and umami amino acids, and atomic force microscopy confirmed structural proteins breakdown by morphological changes. The accumulation of glutamic acid, alanine and lysine was mainly responsible for taste improvement of dry-cured bacon with Staphylococcus co-inoculation.
Effects of limited enzymatic hydrolysis and polysaccharide addition on the physicochemical properties of emulsions stabilized with duck myofibrillar protein under low-salt conditions

He S, Li M, Sun Y, Pan D, Zhou C, Lan H

Food Chem, 2024 Jan 01;430:137053.
PMID: 37549626 DOI: 10.1016/j.foodchem.2023.137053

This study aimed to investigate the role of hydrolysis and guar gum (GG) participation on the emulsification of the duck myofibrillar protein (MP) and the related stability of oil-in-water emulsion in low-salt condition. Emulsions were prepared using one of each or both treatments, and that prepared with trypsin hydrolysis and GG (T-GG) exhibited the highest stability. FTIR analysis confirmed the hydrogen bond interactions between the system components. T-GG treatment improved emulsion properties and decreased oil droplet size. Moreover, CLSM indicated that aggregation of T-GG oil droplets was prevented. Physical stability was assessed such as Turbiscan stability index, creaming index, and rheological properties. The adsorbed percentage for T-GG was the lowest. However, interfacial tension, droplet size, stability, and peroxide value analyses indicated that a denser interfacial membrane structure is formed with T-GG. Thus, T-GG treatment could be applied in the food industry, such as in nutrient delivery systems and fat mimetics.
Fulltext Investigation into the characteristic volatile flavor of old duck

Duan M, Xu L, Gu T, Sun Y, Xia Q, He J, et al.

Food Chem X, 2023 Dec 30;20:100899.
PMID: 38144818 DOI: 10.1016/j.fochx.2023.100899

In order to explore the characteristic aroma flavor and its formation mechanism of old ducks, two ages (30 days and 60 days) of young ducks and three ages of old ducks (300 days, 900 days, and 1500 days) were selected and studied. An electronic nose was applied to evaluate the overall aroma flavor, and the result showed significant differences between the five duck samples. By gas chromatography-mass spectrometry (GC-MS), forty-eight volatile flavor compounds were detected, including seven aldehydes, six esters, five alcohols, five nitrogen compounds, twenty-one hydrocarbons, and four others. Among these compounds, twelve components, such as hexanal and dimethyl anthranilate, were considered as the characteristic flavor compounds along with duck aging. Furthermore, correlation analysis indicated that meat's unsaturated free fatty acids, especially linoleic acid (C18:2), were responsible for the duck's characteristic flavor formation. These data contribute to the flavor research and identification of old ducks.
Recent Advances on Antimicrobial Peptides from Milk: Molecular Properties, Mechanisms, and Applications

Wang Z, Xu J, Zeng X, Du Q, Lan H, Zhang J, et al.

J Agric Food Chem, 2024 Jan 10;72(1):80-93.
PMID: 38152984 DOI: 10.1021/acs.jafc.3c07217

Traditional antibiotics are facing a tremendous challenge due to increased antimicrobial resistance; hence, there is an urgent need to find novel antibiotic alternatives. Milk protein-derived antimicrobial peptides (AMPs) are currently attracting substantial attention considering that they showcase an extensive spectrum of antimicrobial activities, with slower development of antimicrobial resistance and safety of raw materials. This review summarizes the molecular properties, and activity mechanisms and highlights the applications and limitations of AMPs derived from milk proteins comprehensively. Also the analytical technologies, especially bioinformatics methodologies, applied in the process of screening, identification, and mechanism illustration of AMPs were underlined. This review will give some ideas for further research and broadening of the applications of milk protein-derived AMPs in the food field.
Legume protein fermented by lactic acid bacteria: Specific enzymatic hydrolysis, protein composition, structure, and functional properties

Du Q, Li H, Tu M, Wu Z, Zhang T, Liu J, et al.

Colloids Surf B Biointerfaces, 2024 Jun;238:113929.
PMID: 38677155 DOI: 10.1016/j.colsurfb.2024.113929

In recent years, with increasing emphasis on healthy, green, and sustainable consumption concepts, plant-based foods have gained popularity among consumers. As widely sourced plant-based raw materials, legume proteins are considered sustainable and renewable alternatives to animal proteins. However, legume proteins have limited functional properties, which hinder their application in food products. LAB fermentation is a relatively natural processing method that is safer than chemical/physical modification methods and can enrich the functional properties of legume proteins through biodegradation and modification. Therefore, changes in legume protein composition, structure, and functional properties and their related mechanisms during LAB fermentation are described. In addition, the specific enzymatic hydrolysis mechanisms of different LAB proteolytic systems on legume proteins are also focused in this review. The unique proteolytic systems of different LAB induce specific enzymatic hydrolysis of legume proteins, resulting in the production of hydrolysates with diverse functional properties, including solubility, emulsibility, gelability, and foamability, which are determined by the composition (peptide/amino acid) and structure (secondary/tertiary) of legume proteins after LAB fermentation. The correlation between LAB-specific enzymatic hydrolysis, protein composition and structure, and protein functional properties will assist in selecting legume protein raw materials and LAB strains for legume plant-based food products and expand the application of legume proteins in the food industry.
Fulltext Screening of a potential probiotic Lactiplantibacillus plantarum NUC08 and its synergistic effects with yogurt starter

Cai Z, Guo Y, Zheng Q, Liu Z, Zhong G, Zeng L, et al.

J Dairy Sci, 2024 May;107(5):2760-2773.
PMID: 38135047 DOI: 10.3168/jds.2023-24113

This study aims to identify lactic acid bacteria (LAB) isolates possessing physiological characteristics suitable for use as probiotics in yogurt fermentation. Following acid and bile salt tolerance tests, Lactiplantibacillus plantarum (NUC08 and NUC101), Lacticaseibacillus rhamnosus (NUC55 and NUC201), and Lacticaseibacillus paracasei (NUC159, NUC216, and NUC351) were shortlisted based on intraspecies distribution for further evaluation. Their physiological probiotic properties, including transit tolerance, adhesion, autoaggregation, surface hydrophobicity, biofilm formation, and antibacterial activity, were assessed. Principal component analysis indicated that Lactiplantibacillus plantarum NUC08 was the preferred choice among the evaluated strains. Subsequent investigations revealed that co-culturing Lactiplantibacillus plantarum NUC08 with 2 yogurt starter strains resulted in a cooperative and synergistic effect, enhancing the growth of mixed strains and increasing their tolerance to simulated gastric and intestinal conditions. Additionally, when Vibrio harveyi bioluminescent reporter strain was used, the 3 cocultured strains cooperated to induce the activity of a quorum sensing (QS) molecule autoinducer-2 (AI-2), hinting a potential connection between phenotypic traits and QS in the cocultured strains. Importantly, LAB viable counts were significantly higher in yogurt co-fermented with Lactiplantibacillus plantarum NUC08, consistently throughout the storage period. In conclusion, the study demonstrates that the probiotic strain Lactiplantibacillus plantarum NUC08 can be employed in synergy with yogurt starter strains, affirming its potential for use in the development of functional fermented dairy products.
Fulltext Combining thermosonication microstress and pineapple peel extract addition to achieve quality and post-acidification control in yogurt fermentation

Zhang X, Zheng Y, Zhou C, Cao J, Zhang Y, Wu Z, et al.

Ultrason Sonochem, 2024 May;105:106857.
PMID: 38552299 DOI: 10.1016/j.ultsonch.2024.106857

This work investigated the effects of the combined use of thermosonication-preconditioned lactic acid bacteria (LAB) with the addition of ultrasound-assisted pineapple peel extracts (UU group) on the post-acidification potential, physicochemical and functional qualities of yogurt products, aimed at achieving prolonged preservation and enhancing functional attributes. Accordingly, the physical-chemical features, adhesion properties, and sensory profiles, acidification kinetics, the contents of major organic acids, and antioxidant activities of the differentially processed yogurts during refrigeration were characterized. Following a 14-day chilled storage process, UU group exhibited acidity levels of 0.5-2 oT lower than the control group and a higher lactose content of 0.07 mg/ml as well as unmodified adhesion potential, indicating that the proposed combination method efficiently inhibited post-acidification and delayed lactose metabolism without leading to significant impairment of the probiotic properties. The results of physicochemical analysis showed no significant changes in viscosity, hardness, and color of yogurt. Furthermore, the total phenolic content of UU-treated samples was 98 μg/mL, 1.78 times higher than that of the control, corresponding with the significantly lower IC50 values of DPPH and ABTS radical scavenging activities of the UU group than those of the control group. Observations by fluorescence inverted microscopy demonstrated the obvious adhesion phenomenon with no significant difference found among differentially prepared yogurts. The results of targeted metabolomics indicated the proposed combination strategy significantly modified the microbial metabolism, leading to the delayed utilization of lactose and the inhibited conversion into glucose during post-fermentation, as well as the decreased lactic acid production and a notable shift towards the formation of relatively weak acids such as succinic acid and citric acid. This study confirmed the feasibility of thermosonication-preconditioned LAB inocula, in combination with the use of natural active components from fruit processing byproducts, to alleviate post-acidification in yogurt and to enhance its antioxidant activities as well as simultaneously maintaining sensory features.
Fulltext Effect and potential mechanism of nitrite reductase B on nitrite degradation by Limosilactobacillus fermentum RC4

Fan Q, Xia C, Zeng X, Wu Z, Guo Y, Du Q, et al.

Curr Res Food Sci, 2024;8:100749.
PMID: 38694558 DOI: 10.1016/j.crfs.2024.100749

Nitrite has the potential risk of hypoxic poisoning or cancer in pickled food. In our previous study, Limosilactobacillus fermentum (L. fermentum) RC4 is effective in nitrite degradation by producing nitrite reductase B (NirB). To investigate the detailed mechanism from the genome, response, and regulation of NirB, the whole-genome sequence of L. fermentum RC4 was analyzed, the L. fermentum-EGFP-nirB with enhanced green fluorescent protein (EGFP) labeled the nitrite reductase large subunit nirB, and the recombined L. fermentum-NirB with overexpression NirB strain was conducted. The key genes within the dominant metabolism pathways may be involved in stress tolerance to regulate the degrading process. The green fluorescence density of EGFP indicated that NirB activity has a threshold and peaked under 300 mg/L nitrite concentration. NirB overexpressed in L. fermentum RC4 boosted the enzyme activity by 39.6% and the degradation rate by 10.5%, when fermented in 300 mg/L for 40 h, compared to the control group. RNA-seq detected 248 differential genes mainly enriched in carbohydrate, amino acid, and energy metabolism. The ackA gene for pyruvate metabolism and the mtnN gene for cysteine metabolism were up-regulated. NirB regulates these genes to produce acid and improve stress resistance for L. fermentum RC4 to accelerate nitrite degradation.
New clues for postbiotics to improve host health: a review from the perspective of function and mechanisms

Yan R, Zeng X, Shen J, Wu Z, Guo Y, Du Q, et al.

J Sci Food Agric, 2024 Aug 30;104(11):6376-6387.
PMID: 38450745 DOI: 10.1002/jsfa.13444

Strain activity and stability severely limit the beneficial effects of probiotics in modulating host health. Postbiotics have emerged as a promising alternative as they can provide similar or even enhanced efficacy to probiotics, even under inactivated conditions. This review introduces the ingredients, preparation, and identification techniques of postbiotics, focusing on the comparison of the advantages and limitations between probiotics and postbiotics based on their mechanisms and applications. Inactivation treatment is the most significant difference between postbiotics and probiotics. We highlight the use of emerging technologies to inactivate probiotics, optimize process conditions to maintain the activity of postbiotics, or scale up their production. Postbiotics have high stability which can overcome unfavorable factors, such as easy inactivation and difficult colonization of probiotics after entering the intestine, and are rapidly activated, allowing continuous and rapid optimization of the intestinal microecological environment. They provide unique mechanisms, and multiple targets act on the gut-organ axis, co-providing new clues for the study of the biological functions of postbiotics. We summarize the mechanisms of action of inactivated lactic acid bacteria, highlighting that the NF-κB and MAPK pathways can be used as immune targeting pathways for postbiotic modulation of host health. Generally, we believe that as the classification, composition, and efficacy mechanism of postbiotics become clearer they will be more widely used in food, medicine, and other fields, greatly enriching the dimensions of food innovation. © 2024 Society of Chemical Industry.
Fulltext Effects and improvement mechanisms of ultrasonic pretreatment on the quality of fermented skim milk

Yu H, Cheng X, Li H, Du Q, Zeng X, Wu Z, et al.

Ultrason Sonochem, 2024 Jun 15;108:106958.
PMID: 38889569 DOI: 10.1016/j.ultsonch.2024.106958

Fermented skim milk is an ideal food for consumers such as diabetic and obese patients, but its low-fat content affects its texture and viscosity. In this study, we developed an effective pretreatment method for fermented skim milk using low-frequency ultrasound (US), and investigated the molecular mechanism of the corresponding quality improvement. The skim milk samples were treated by optimal ultrasonication conditions (336 W power for 7 min at 3 °C), which improved the viscosity, water-holding capacity, sensory attributes, texture, and microstructure of fermented skim milk (P
Preparation of modified chitosan-based nano-TiO2-nisin composite packaging film and preservation mechanism applied to chilled pork

Yan R, Liu M, Zeng X, Du Q, Wu Z, Guo Y, et al.

Int J Biol Macromol, 2024 Apr 25;269(Pt 1):131873.
PMID: 38677699 DOI: 10.1016/j.ijbiomac.2024.131873

Here, we developed a nano-TiO2-nisin-modified chitosan composite packaging film and investigated its properties and antibacterial activity, as well as its effect on chilled pork preservation time. The results indicated that the preservation time of chilled pork coated with a nano-TiO2-nisin-modified chitosan film (including 0.7 g/L nano-TiO2, irradiated with ultraviolet light for 40 min, and dried for 6 h) followed by modified atmosphere packaging (50% CO2 + 50% N2) increased from 7 to 20 days at 4 °C. Both nano-TiO2 and nisin enhanced the mechanical strength of the chitosan film, and nisin promoted nano-TiO2 dispersion and compatibility in chitosan. Treatment with 0.4 g/L nano-TiO2 for 60 min considerably inhibited spoilage bacteria, particularly Acinetobacter johnnii XBB1 (A. johnnii XBB1). As nano-TiO2 concentration and photocatalytic time increased, K+, Ca2+, and Mg2+ leakage in A. johnnii XBB1 increased but Na+/K+-ATPase and Ca2+/Mg2+-ATPase activities decreased. In A. johnnii XBB1, TiO2 significantly downregulated the expression of putrefaction-related genes such as cysM and inhibited cell self-regulation and membrane wall system repair. Therefore, our nano-TiO2-nisin-modified chitosan film could extend the shelf life without the addition of any chemical preservatives, demonstrating great potential for application in food preservation.
Structure and regulatory mechanisms of food-derived peptides in inflammatory bowel disease: A review

Qiu W, Wang Z, Liu Q, Du Q, Zeng X, Wu Z, et al.

Food Sci Nutr, 2024 Sep;12(9):6055-6069.
PMID: 39554349 DOI: 10.1002/fsn3.4228

The number of patients with inflammatory bowel disease (IBD) is increasing worldwide. Since IBD is a chronic disease that seriously affects patients' life quality, preventing and alleviating IBD with natural and less side effect substances has become a research hotspot. Food-derived bioactive peptides have been an attractive research focus due to their high efficiency and low toxicity. This paper comprehensively summarizes food-derived peptides with intestinal health effects, focusing on peptide sequences with IBD-regulatory effects and emphasizing the effects of their structure and physicochemical properties such as peptide length, amino acid composition, and net charge on their function. We also analyzed its regulatory mechanisms, mainly in 5 aspects: modulating the intestinal microbiota, decreasing intestinal epithelial permeability, increasing antioxidant ability, regulating the expression of inflammatory cytokines, and targeting signaling pathways. This review will help establish novel, efficient screening methods for IBD-regulatory peptides and contribute to further research and discovery of them.
Unlocking the molecular modifications of plasma-activated water-induced oxidation through redox proteomics: In the case of duck myofibrillar protein (Anas platyrhynchos)

Rao W, Ju S, Sun Y, Xia Q, Zhou C, He J, et al.

Food Chem, 2024 Nov 15;458:140173.
PMID: 38943955 DOI: 10.1016/j.foodchem.2024.140173

Plasma-activated water (PAW) contains multiple active species that alter the structure of myofibrillar protein (MP) to enhance their gel properties. This work investigated the impact of PAW on the oxidation of cysteine in MP by label-free quantitative proteomics. PAW treatment caused the oxidation of 8241 cysteine sites on 2815 proteins, and structural proteins such as nebulin, myosin XVIIIB, myosin XVIIIA, and myosin heavy chain were susceptible to oxidation by PAW. Bioinformatics analysis, including Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway, subcellular localization, and STRING analysis, indicated that these proteins with differential oxidation sites were mainly derived from the cytoplasm and membrane, and were involved in multiple GO terms and KEGG pathways. This is one of the first reports of the redox proteomic changes induced by PAW treatment, and the results are useful for understanding the possible mechanism of PAW-induced oxidation of MP.
Penicillin binding proteins-based immunoassay for the selective and quantitative determination of beta-lactam antibiotics

Liu R, Lan H, Yan S, Huang L, Pan D, Wu Y

Enzyme Microb Technol, 2024 Sep 04;181:110507.
PMID: 39241682 DOI: 10.1016/j.enzmictec.2024.110507

An immunoassay method based on penicillin-binding protein (PBP) was developed for the quantitative determination of 10 kinds of beta-lactam antibiotics (BLAs). First, two kinds of PBPs, which are named PBP1a and PBP2x, were expressed and purified, and they were characterized by SDS-PAGE and western blotting analysis. Then, the binding activity of PBP1a and PBP2x to template BLAs, cefquinome (CEFQ) and ampicillin (AMP), was determined. The effect of the buffer solution system, e.g., pH, ion concentration, and organic solvent, on the immune interaction efficiency between PBPs and BLAs was also evaluated. In the end, the PBP-based immunoassay method was developed and validated for the detection of 10 kinds of BLAs. Under optimal conditions, PBPs exhibited high binding affinity to BLAs. In addition, this method showed a high sensitivity for the detection of 10 kinds of BLAs with the limits of detection from 0.21 to 9.12 ng/mL, which are much lower than their corresponding maximum residual limit of European Union (4-100 ng/mL). Moreover, the developed PBP-immunoassay was employed for BLA detection from milk samples, and satisfactory recoveries (68.9-101.3 %) were obtained.

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