Structural characteristics and emulsifying properties of linear dextrin/eicosapentaenoic acid composites: Effect of the degree of polymerization.

This work aimed at building functional emulsions based on the linear dextrins (LDs) emulsion system. The gradient polyethylene glycol (PEG) precipitaion method was used to fractionate LDs into fractions with different degrees of polymerization (DP). A package, and co-precipitation procedure of LDs, and eicosapentaenoic acid (EPA) was used to fabricate LDs-EPA composites. The gas chromatograph, Fourier transform infrared spectroscopy, X-ray diffraction and differential scanning calorimetry analyses affirmed the formation of the LDs-EPA composites. The sizes of these composites were 38.55 nm, 59.14 nm to 80.62 nm, respectively, and they had good amphiphilicity. Compared with LDs, these LDs-EPA composites stabilized Pickering emulsion had higher stability and antioxidant capacity. Their emulsifying ability was positively correlated with the DP values of LDs. Furthermore, the oxidation stability results showed that LDsF10-EPA emulsion had the lowest lipid hydroperoxide (LHs) content, malondioxide (MDA) content and hexal concentration, which were 138.75 mmol kg-1 oil, 15.50 mmol kg-1 oil and 3.83 µmol kg-1 oil, respectively. The study provided a new idea and application values for the application of LDs in emulsion.

A study on the catalytic domain of pork phospholipase A2: Enzymatic properties and hydrolysis characteristics of phosphatidylcholine and its hydroperoxide.

Endogenous phospholipase A2 (PLA2) plays an important role in phospholipids degradation during cured meat products manufacturing. The present study was undertaken to reveal more information about the endogenous PLA2 in muscles and its role in degradation of intramuscular phospholipids. With the catalytic domain of pork calcium-independent PLA2 (iPLA2cd), impacts of physic-chemical factors on the activity were investigated and substrate specificity of the enzyme were tested respectively. The optimum temperature and pH of pork iPLA2cd were 40 °C and 7.5, respectively. The iPLA2cd could be stimulated by adequate contents of NaCl and ATP, and inhibited by CaCl2 and NaNO2. For native phospholipids, the iPLA2cd was of a little higher affinity towards phosphatidylcholine (PC) than phosphatidylethanolamine (PE), phosphoserine (PS) and phosphatidylinositol (PI). The iPLA2cd could preferentially hydrolyze peroxidized PC over the native PC. The results would help better understand the degradation of phospholipids and the role played by endogenous enzymes during meat products manufacturing.

Preparation of carboxymethyl chitosan/double-formaldehyde cellulose based hydrogel loaded with ginger essential oil nanoemulsion for meat preservation.

An antibacterial nano-hydrogel (ginger essential oil nanoemulsion hydrogel, GEONH) based on Schiff base reaction was prepared using double-formaldehyde micro fibrillated cellulose (DAMFC) and carboxymethyl chitosan (CMCS) loaded with ginger essential oil nanoemulsion (GEON). It was found that when the mass ratio of DAMFC/CMCS/GEON was 1/9/270, the gel time, the water absorbency, gel strength, and morphology were the best. The results of X-ray diffraction and FT-IR confirmed that the aldehyde group on the DAMFC molecular chain formed a stable chemical crosslinking with the amino group on the CMCS molecular chain, resulting in a change in the crystal structure. GEONH showed excellent bactericidal activity against Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus. Simultaneously, the prepared GEONH decreased the total viable count, Malondialdehyde, and total sulfhydryl content and improved the taste in the storage of boiled salted duck. Therefore, GEONH film is a promising fresh-keeping packaging for storing meat products. Supplementary Information: The online version contains supplementary material available at 10.1007/s10068-023-01437-4.

Spectroscopy combined with spatiotemporal multiscale strategy to study the adsorption mechanism of soybean protein isolate with meat flavor compounds (furan): Differences in position and quantity of the methyl.

The interaction mechanism between soybean protein isolate (SPI) and furan flavor compounds with different structures is studied using spectroscopy, molecular docking, and MD simulation methods. The order of binding ability between SPI and furan flavor compounds is 2-acetylfuran>furfural>5-methylfurfural. The structural differences (position and quantity of methyl groups) of three furan flavor compounds are key factors leading to the different adsorption abilities of SPI for furan flavor compounds. The findings from spectroscopy analyses suggest that the interaction between SPI and furan flavor compounds involves both static and dynamic quenching mechanisms, with static quenching being the main factor. Molecular docking and MD simulations reveal the atomic-level mechanisms underlying the stable binding for SPI and furan flavor compounds at spatiotemporal multiscale. This study provides a theoretical framework for the production and adjustment of meat essence formula in the production of soybean protein-based meat products.

Effects of water-soluble and water-insoluble α-glucans produced in situ by Leuconostoc citreum SH12 on physicochemical properties of fermented soymilk and their structural analysis.

This study investigated the effect of in situ produced water-soluble α-glucan (LcWSG) and water-insoluble α-glucan (LcWIG) from Leuconostoc citreum SH12 on the physicochemical properties of fermented soymilk. α-Glucans produced by Leuc. citreum SH12 improved water-holding capacity, viscosity, viscoelasticity and texture of fermented soymilk. Gtf1365 and Gtf836 of the five putative glucansucrases were responsible for synthesizing LcWSG and LcWIG during soymilk fermentation, respectively. Co-fermentation of soymilk with Gtf1365 and Gtf836 and non-exopolysaccharide-producing Lactiplantibacillus plantarum D1031 indicated that LcWSG effectively hindered the whey separation of fermented soymilk by increasing viscosity, while LcWIG improved hardness, springiness and accelerated protein coagulation. Fermented soymilk gel formation was mainly based on hydrogen bonding and hydrophobic interactions, which were promoted by both LcWSG and LcWIG. LcWIG has a greater effect on α-helix to ß-sheet translation in fermented soymilk, causing more rapid protein aggregation and thicker cross-linked gel network. Structure-based exploration of LcWSG and LcWIG from Leuc. citreum SH12 revealed their distinct roles in the physicochemical properties of fermented soymilk due to their different ratio of α-1,6 and α-1,3 glucosidic linkages and various side chain length. This study may guide the application of the water-soluble and water-insoluble α-glucans in fermented plant protein foods for their quality improvement.

Constructing Protein-Scaffolded Multienzyme Assembly Enhances the Coupling Efficiency of the P450 System for Efficient Daidzein Biosynthesis from (2S)-Naringenin.

Daidzein is a major isoflavone compound with an immense pharmaceutical value. This study applied a novel P450 CYP82D26 which can biosynthesize daidzein from (2S)-naringenin. However, the recombinant P450 systems often suffer from low coupling efficiency, leading to an electron transfer efficiency decrease and harmful reactive oxygen species release, thereby compromising their stability and catalytic efficiency. To address these challenges, the SH3-GBD-PDZ (SGP) protein scaffold was applied to assemble a multienzyme system comprising CYP82D26, P450 reductase, and NADP+-dependent aldehyde reductase in desired stoichiometric ratios. Results showed that the coupling efficiency of the P450 system was significantly increased, primarily attributed to the channeling effect of NADPH resulting from the proximity of tethered enzymes and the electrostatic interactions between NADPH and SGP. Assembling this SGP-scaffolded assembly system in Escherichia coli yielded a titer of 240.5 mg/L daidzein with an 86% (2S)-naringenin conversion rate, which showed a 9-fold increase over the free enzymes of the P450 system. These results underscore the potential application of the SGP-scaffolded multienzyme system in enhancing the coupling and catalytic efficiency of the P450 system.

An innovative Pickering W/O/W nanoemulsion co-encapsulating hydrophilic lysozyme and hydrophobic Perilla leaf oil for extending shelf life of fish products.

A Pickering water-in-oil-in-water nanoemulsion co-encapsulating lysozyme (LYS) and Perilla leaf oil (PO) was prepared using whey protein isolate-tannin acid conjugated nanoparticles (WPI-TA NPs) as emulsifiers, called LYS-PO-NE, and subsequently analyzed. The nano size and multiple phases was confirmed based on the results of confocal laser scanning microscope, scanning electron microscope, and droplet size analysis. LYS-PO-NE had high encapsulation efficiencies of 89.36 % (PO) and 43.91 % (LYS) and both could be released at a slow and continuous rate. The PO addition increased the droplet size, and the LYS addition delayed the release of PO. LYS-PO-NE also showed good storage, pH, thermal, and salt stability, and an effective combined bactericidal activity of LYS and PO against spoilage bacteria. Furthermore, the results of chilled salmon storage experiments indicated that LYS-PO-NE could extend the shelf life of chilled salmon to at least 6 days, demonstrating the potential in the shelf life for fish products.

Engineering Escherichia coli for cost-effective production of medium-chain fatty acids from soy whey using an optimized galactose-based autoinduction system.

Medium-chain fatty acids (MCFAs) are essential chemical feedstocks. Microbial production of MCFAs offers an attractive alternative to conventional methods, but the costly media and external inducers limit its practical application. To address this issue and make MCFA production more cost-effective, an E.coli platform was developed using soy whey as a medium and galactose as an autoinducer. We first designed an efficient, stringent, homogeneous, and robust galactose-based autoinduction system for the expression of pathway enzymes by rationally engineering the promoter of the galactose-proton symporter (GalP). Subsequently, the intracellular acetyl-CoA availability and NADH regeneration were enhanced to improve the reversal of the ß-oxidation cycle. The resulting strain yielded 8.20 g/L and 16.42 g/L MCFA in pH-controlled batch fermentation and fed-batch fermentation with glucose added using soy whey as medium, respectively. This study provided a cost-effective and promising platform for MCFA production, as well as future strain development for other value-added chemicals production.

Mushroom alcohol(1-octen-3-ol)and other 7 aroma compounds selected from Chinese dry-cured hams can enhance saltiness perception.

Reducing NaCl content in food while maintaining acceptability poses a significant challenge. Odor-induced saltiness enhancement (OISE) emerges as a promising solution. This study utilized gas chromatography-olfactory (GC-O) in conjunction with gas chromatography-mass spectrometry (GC-MS) to identify 37 key volatile compounds in three representative Chinese dry-cured hams. These compounds had an odor activity value (OAV) of ≥1 or a modification frequency (MF) of ≥30%. Subsequently, quantitative descriptive analysis (QDA) identified eight odorants associated with saltiness. These included 1-octen-3-ol, nonanal, heptanal, 2-methylbutanal, 3-methyl-butanal, benzaldehyde, octanal, and 2,6-dimethylpyrazine. Remarkably, these odorants significantly intensified saltiness (P < 0.05) when added to a low-concentration NaCl solution (0.3%), compared to zero or high concentrations (0.75% and 0.8%). As a result, traditional Chinese salty meat products offer a promising source of odorants for enhancing saltiness, compensating for reduced NaCl content through OISE.

Characterisation, slow-release, and antibacterial properties of carboxymethyl chitosan/inulin hydrogel film loaded with novel antilisterial durancin GL.

This paper reports the development of a hydrogel film with antibacterial activity and controlled release characteristics. Carboxymethyl chitosan (CMCS) is grafted onto durancin GL and inulin via a mediated reaction between N-hydroxysuccinimide and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride. Rheology tests, Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy, and lap shear tests confirmed the formation of a stable chemical cross-linking and excellent adhesion hydrogel with 4 % CMCS and 8 % inulin. The CMCS/inulin hydrogel film loaded with durancin GL appears transparent and uniform. FTIR spectroscopy results reveal the interaction mode among CMCS, inulin, durancin GL, and the hydrogel film structure. Cross-linking improved thermal stability and water-vapour barrier performance. The hydrophobicity of CMCS/inulin @Durancin GL increased under a durancin GL concentration of 0.036 g/30 mL, and the release of active substances is prolonged. In-vitro antibacterial capacity and salmon preservation experiments show that the addition of durancin GL enhanced the antibacterial activity of the hydrogel film. Therefore, CMCS/inulin@Durancin GL hydrogel films can be used as fresh-keeping packaging materials in practical applications.

Preparation and characterization of a novel absorbent pad based on polyvinyl alcohol/gellan gum/citric acid with incorporated Perilla leaf oil nanoemulsion for chilled chicken packaging.

A novel absorbent pad based on polyvinyl alcohol (PVA)/gellan gum/citric acid (CA) composite with incorporated Perilla leaf oil (PO) nanoemulsion was prepared and characterized. The esterification between PVA and CA and strong hydrogen bonds were detected. The PVA improved the tensile strength and elongation at break by 110% and 73%, respectively, whereas PO concentration ≤ 1.5 % (w/v) had little effect on the material properties. The CA and PO nanoemulsion loaded in the pads showed good antioxidant activity, and the pads with PO concentration ≥ 1.5 % (w/v) had effective antimicrobial activity against Escherichia coli and Staphylococcus aureus. The results of chilled chicken storage experiments indicated that the pad with 1.5% (w/v) PO nanoemulsion extended the shelf life of chicken to at least 9 days, demonstrating that the developed absorbent pads are potential materials for chilled chicken storage packing.

Novel PVA/carboxylated cellulose antimicrobial hydrogel grafted with curcumin and ε-polylysine for chilled chicken preservation.

PVA/CC/CUR/PL composite films containing curcumin (CUR) and ε-polylysine (PL) were prepared by casting and chemical grafting methods to address the threat to food spoilage. Morphological analysis showed that the grafting of CUR and PL resulted in a rough cross-section of the polymer matrix. Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analysis confirmed the grafting of CUR and PL into the polymer matrix via esterification and amidation reactions, respectively. Thermal weight loss analysis showed that grafting process positively improved the thermal stability. The PVA/CC/CUR/PL films exhibited strong bactericidal activity, reaching 99.0% and 99.8% for Pseudomonas lundensis and Shewanella putrefaciens, respectively. After 8 days of storage, the total number of colonies and the TVB-N content in the PVA/CC/CUR/PL group decreased by 1.51 lg CFU/g and 13.77 mg/100 g, respectively. Therefore, PVA/CC/CUR/PL films are considered as a promising bactericidal material with good mechanical properties, functionality, and other excellent characteristics.

Comparison of biochemical characteristics and gel properties of chicken myofibrillar protein affected by heme-iron and nonheme-iron oxidizing systems.

In this study, the effect of hemin and non-heme iron on the biochemical and gelling properties of chicken myofibrillar protein (MP) was compared. Results revealed that free radicals from hemin incubated MP were significantly higher than that in FeCl3 incubated samples (P < 0.05), and had higher ability to initiate protein oxidation. The carbonyl content, surface hydrophobicity, random coil increased with oxidant concentration, whereas the total sulfhydryl and α-helix content decreased in both oxidizing systems. The turbidity and particle size were increased after oxidant treatment, indicating oxidation promoted the cross-linking and aggregation of protein, and the degree of aggregation was higher in hemin treated MP compared with that incubated with FeCl3. The biochemical changes of MP resulted in an uneven and loose gel network structure, which significantly reduced the gel strength and water holding capacity (WHC) of the gel.

Lipidomics analysis of Sanhuang chicken during cold storage reveals possible molecular mechanism of lipid changes.

Lipidomic profiles changes of the Sanhuang chicken breast meat during cold storage (4 °C) were analyzed using ultra-high performance liquid chromatography coupled with mass spectrometry (UHPLC-MS)-based lipidomic analysis. Total lipids content decreased 16.8% after storage. Triacylglycerol (TAG), phosphatidylcholine (PC) and phosphatidylethanolamine (PE) significantly decreased, while lysophosphatidylcholine (LPC) and lysophosphatidylethanolamine (LPE) increased. Particularly, there was a trend that TAGs with fatty acids of 16:0 and 18:1, and phospholipids containing 18:1, 18:2 and 20:4 were more likely to be downregulated. The increase in the ratio of lysophospholipids/phospholipids and the degree of lipid oxidation demonstrated oxidation and enzymatic hydrolysis are potentially responsible for the lipid transformation. Moreover, 12 lipid species (P < 0.05, VIP > 1, FC < 0.8 or >1.25) were identified to be associated with the spoilage of meat. Glycerophospholipid metabolism and linoleic acid metabolism were the key metabolic pathways involved in the lipid transformations of chilled chicken.

Case report: Urothelial carcinoma of the renal pelvis with trophoblastic differentiation: A rare case report and review of literature.

We report a rare case of urothelial carcinoma (UC) of the renal pelvis with trophoblastic differentiation that occurred in a 55-year-old male patient. The patient presented with gross hematuria and paroxysmal lumbago pain 5 months ago. The enhanced computed tomography (CT) scan demonstrated a large space occupying lesion in the left kidney and multiple retroperitoneal lymph node enlargements. Histologically, high-grade infiltrating urothelial carcinoma (HGUC) contained giant cells which were positive for beta-human chorionic gonadotropin (ß-hCG). Three weeks after resection, positron emission tomography and computed tomography (PET-CT) scan showed multiple nodules of metastasis in the left renal region, extensive systemic muscle, bone, lymph node, liver and bilateral lung metastases. The patient underwent bladder perfusion chemotherapy and gemcitabine combined with cisplatin chemotherapy regimens. This is the eighth documented case of UC of the renal pelvis with trophoblastic differentiation. Due to its rarity and extremely poor prognosis, it is important to clarify the characteristics of the disease and make an accurate and prompt diagnosis.

Fabrication of nitrogen-doped graphene quantum dots based fluorescent probe and its application for simultaneous, sensitive and selective detection of umami amino acids.

In this work, nitrogen-doped graphene quantum dots (N-GQDs) were synthesized by an efficient one-step hydrothermal using hydrated citric acid and urea as the carbon and nitrogen sources, respectively. The fluorescent quantum yield of the N-GQDs was up to 88.20 %, and the fluorescence lifetime was 12.29 ns. Based on the excellent fluorescence property, water-soluble and low cytotoxicity of N-GQDs, a novel fluorescent probe was fabricated and used for simultaneous detection of l-glutamic acid (l-Glu) and l-aspartic acid (l-Asp). Herein, Al3+ was used as a chelant agent for l-Glu shielding. The sensitive response of the probe towards l-Glu and l-Asp presented a wide concentration range with a low detection limit (S/N = 3). The fluorescent probe showed good selectivity, high stability and acceptable reproducibility in the application of l-Glu/l-Asp simultaneous detection in chicken soup. Meanwhile, the detection results of the fluorescent probe were correlated well with those obtained by amino acid analyzer.

Lipidomic profile changes of yellow-feathered chicken meat during thermal processing based on UPLC-ESI-MS approach.

In this work, ultra-performance liquid chromatography-electrospray ionization mass spectrometry (UPLC-ESI-MS) was applied to compare the lipidomics profile of chicken breast meat heated to various temperatures. A total of 445 lipids including phospholipids, diacylglycerols, triacylglycerols, glycoglycerolipids, and sphingolipids were detected in chicken muscle. Significant decreases in a list of characteristic unsaturated phospholipid species including phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol and phosphatidylinositol were identified after heating, suggesting the occurrence of lipid oxidation, while significant increases in characteristic lysophospholipid species were found with increasing heating temperature, which were mainly derived from hydrolysis of phospholipids. Moreover, ether phospholipid and neutral lipid species exhibited remarkable changes during the heating process, and monoalk(en)yl diacylglycerol was first identified in chicken meat. The findings could contribute to the improved understanding of key lipids and biochemical reactions engaged in the heating of meat products.

An intrinsic dual-emitting fluorescence sensing toward tetracycline with self-calibration model based on luminescent lanthanide-functionalized metal-organic frameworks.

A novel ratiometric fluorescence sensor based on lanthanide-functionalized metal-organic frameworks (Ag+/Eu3+@UiO-66(COOH)2, AEUC) with intrinsic dual-emitting bands was fabricated to determine tetracycline (TC) residues by exploiting (UiO-66-(COOH)2, UC) as reference units, Eu3+as recognition units and Ag+ as fluorescence enhancer. Benefiting from specific binding sites and functional adsorbent channels of AEUC, efficient capture and specific recognize toward TC could be achieved, remarkably enhancing the reliability. The synergistic effect of inner filter effect (IFE) and photoinduced electron transfer (PET) process between TC and AEUC was verified, enabling the detection limit and quantification limit of established strategy reaching as 12.8 nmol/L and 38.6 nmol/L and conspicuous fluorescence color gradation from red to blue. Given its portability, point-of-care sensing platform and nanoprobe-immobilized test-paper-based measurement allowing for on-site qualitative identification and semi-quantitative assay of TC was devised for sensing visualization and has been successfully applied in foodstuff samples, providing prospect in the field of smart devices for visual monitoring of TC.

Ultrasensitive multicolor electrochromic sensor built on closed bipolar electrode: Application in the visual detection of Pseudomonas aeruginosa.

Pseudomonas aeruginosa (P. aeruginosa) is an opportunistic infection-causing pathogen that threatens human health. Accordingly, a rapid and ultrasensitive analytical method is required urgently. Herein, an ultrasensitive multicolor electrochromic sensing platform was established on the basis of a closed bipolar electrode (BPE). Prussian blue (PB), the blue spot that can be easily electrodeposited, was selected as an electrochromic indicator at the closed BPE cathode. Integrating with the anodic emitter, Ru(bpy)32+, which emitted optical red light, visualized multicolor electrochromism was achieved on closed BPE. Particularly, physical separation between the positive and negative poles of the closed BPE greatly prevented mutual interference between Ru(bpy)32+ and PB. Consequently, the sensitivity and accuracy of the proposed biosensor considerably improved. Notably, owing to magnetic-separation technology, the closed BPE surface required no modification. Without any complex pretreatment, the entire experiment time could be greatly shortened because the PA@MBs completely captured P. aeruginosa in food matrix within only 20 min. By comparing the visual electrochromic colors, ultrasensitive screening of P. aeruginosa was accomplished within 1-108 CFU mL-1. Combining the merits of closed BPE, electrochemiluminescence (ECL), and electrochromic, this strategy provided an accurate and intrinsic way for visual detection of P. aeruginosa, as well as great potential in measuring other pathogens.

Inactivation of Clostridium perfringens C1 Spores by the Combination of Mild Heat and Lactic Acid.

Clostridium perfringens is a major pathogen causing foodborne illnesses. In this experiment, the inactivation effects of heat and lactic acid (LA) treatments on C. perfringens spores was investigated. Heat treatment (80 °C, 90 °C and 100 °C), LA (0.5% and 1%), and combined LA and heat treatments for 30 and 60 min were performed. Residual spore counts showed that the count of C. perfringens spores was below the detection limit within 30 min of treatment with 1% LA and heat treatment at 90 °C. Scanning electron microscopy and confocal scanning laser microscopy results showed that the surface morphology of the spores was severely disrupted by the co-treatment. The particle size of the spores was reduced to 202 nm and the zeta potential to −3.66 mv. The inner core of the spores was disrupted and the co-treatment resulted in the release of 77% of the nuclear contents 2,6-pyridinedicarboxylic acid. In addition, the hydrophobicity of spores was as low as 11% after co-treatment with LA relative to the control, indicating that the outer layer of spores was severely disrupted. Thus, synergistic heating and LA treatment were effective in inactivating C. perfringens spores.