Improved antioxidant activity and delivery of peppermint oil Pickering emulsion stabilized by resveratrol-grafted zein covalent conjugate/quaternary ammonium chitosan nanoparticles.

Novel nanoparticles (Z-R/H) were successfully fabricated by a resveratrol-grafted zein covalent conjugate (Z-R) combined with quaternary ammonium chitosan (HTCC), which were used as stabilizers to prepare peppermint oil (PO) Pickering emulsions with antioxidant activity. HTCC effectively adjusted wettability of Z-R conjugate, and three-phase contact angle of Z-R/H3:1 was moderate (95.01°). The influencing factors of Pickering emulsion formation, including volume fraction of PO, concentration of Z-R/H, and mass ratio of Z-R to HTCC, were evaluated by droplet size, ζ-potential, microscopic observation, and stability index analysis. Pickering emulsions stabilized by Z-R/H3:1 showed excellent physical stability under heat treatment. Z-R/H nanoparticles adsorbed on the oil-water interface yielded a dense filling layer as a physical barrier to improve the emulsion stability, which was validated by confocal laser-scanning microscopy. After 4 weeks of storage, retention rate of PO in Pickering emulsion stabilized by Z-R/H3:1 remained high (72.1 %). Electronic nose analysis showed that Z-R/H3:1-stabilized emulsion effectively prevented volatilization of PO aroma components. Additionally, PO and Z-R/H nanoparticles provided an additive antioxidant effect of Pickering emulsions against DPPH and ABTS free radicals. In summary, these novel Z-R/H nanoparticle offer promising applications as a stabilizer with great potential in preparing functional Pickering emulsions to improve essential oil delivery.

Comprehensive Screening for EPA/DHA-Structured Phospholipids in Aquatic Products by a Specific Precursor Ion Scanning-Based HILIC-MS/MS Method.

Comprehensive screening for functional substances from natural resources is always a hot research topic. Eicosapentaenoic acid- (EPA) and docosahexaenoic acid (DHA)-structured phospholipids (PLEPA/DHA) have versatile cardiovascular benefits as well as superior bioavailability. Herein, the abundance of PLEPA/DHA in 16 aquatic products was specifically and selectively screened using a recently developed precursor ion scan-driven hydrophilic interaction chromatography-mass spectrometry (PreIS-HILIC/MS) method with the fatty acyl moieties of EPA (m/z 301.6) and DHA (m/z 327.6) locked. The aim focused on the characteristics and differences in the varieties and contents of EPA/DHA-structured phosphatidylcholine (PCEPA/DHA) and EPA/DHA-structured phosphatidylethanolamine (PEEPA/DHA) molecular species. A total of 80 PLEPA/DHA molecules were identified in these natural sources, including 47 PCEPA/DHA and 33 PEEPA/DHA. After analysis, PC 16:0/20:5 and PC 16:0/22:6 are present in all aquatic products and at high levels. Antarctic krill was found to be the best resource of PLEPA/DHA in total (2574.69 µg·g-1), followed by mackerel (2330.11 µg·g-1), salmon (2109.91 µg·g-1), and Farrer's scallop (1883.59 µg·g-1), while abalone contained the lowest level of PLEPA/DHA (310.44 µg·g-1). Besides, sea cucumber and sea bass contained the highest contents of EPA-structured and DHA-structured ether phospholipids, respectively, which could be highly recommended as dietary sources of special functional phospholipids. Finally, the multiple discrepancies between the 16 aquatic products were revealed by multivariate statistical analysis. These findings improve the awareness of the composition and content of PLEPA/DHA contained in aquatic products, providing a reference for their integrated development.

Parallel generation of extra advanced glycation end-products during co-digestion of whey proteins and α-dicarbonyls in a simulated gastrointestinal model.

Advanced glycation end-products (AGEs) are a group of heterogeneous compounds formed during the Maillard Reaction (MR) and have been proven to be detrimental to human health. In addition to thermally processed foods, the digestive tract may be an additional site for exogenous AGE formation since the MR would possibly occur between (oligo-)peptides, free amino acids, and reactive MR products (MRPs) such as α-dicarbonyl compounds (α-DCs) along the digestion. In this study, through establishing a simulated gastrointestinal (GI) model consisting of whey protein isolate (WPI) and two typical α-DCs, i.e., methylglyoxal (MGO) or glyoxal (GO), we first validated that co-digestion of WPI with α-DCs generated extra amounts of AGEs in a precursor-dependent manner, especially seen in the intestinal stage. At the end of GI digestion, the contents of total AGEs in WPI-MGO and WPI-GO systems were 4.3-242 and 2.5-73.6 times higher than those formed in the control system, respectively. Evaluation of the protein digestibility further showed that AGE formation along the digestion process slightly affected the digestibility of whey protein fractions. However, as sequenced and identified by high-resolution mass spectrometry, different types of AGE modifications were identified in peptides released from ß-lactoglobulin and α-lactalbumin in the final digests, as well as changes in peptide sequence motifs. This suggested that the glycated structures formed during co-digestion affected the action of digestive proteases toward whey proteins. Overall, these results highlight the GI tract as an additional source of exogenous AGEs and provide new insights into the biochemical consequences of MRPs in heat-processed foods.

Aromatic chloroosmacyclopentatrienes.

Aromatic metallacycles are of considerable current interest. Reported aromatic metallacycles are mainly those with carbon, nitrogen, oxygen and sulfur. In this work, we report the synthesis and characterization of aromatic chloroosmacyclopentatrienes, which represent the first structurally confirmed metallaaromatic with a chlorine atom in its framework. Single-crystal X-ray diffraction studies show that these planar chloroosmacyclopentatrienes possess a very short Os-ClC distance suggesting M=ClC bond character.

A DFT study of the endo-selectivity mechanism of the Diels-Alder reaction in lindenane dimeric sesquiterpene synthesis promoted by pyridines.

The lindenane dimeric sesquiterpenoids with versatile biological activities are accessible via biometric synthesis, in which the endo-selective Diels-Alder reaction plays an important role. To explore the endo-selectivity of the Diels-Alder reaction between lindenane sesquiterpenes promoted by pyridines, density functional theory (DFT) calculations were performed to explore the reaction mechanism between pyridines and D-A monomers. The calculations performed on the reaction pathways explain why pyridines can promote endo-selectivity via hydrogen bonding, and the hydrogen bond strength is a key factor driving the Diels-Alder reaction in major biochemical systems. These DFT-level insights will pave the way for designing better promoters for Diels-Alder reactions in biometric synthesis applications.

Highly biologically active and pH-sensitive collagen hydrolysate-chitosan film loaded with red cabbage extracts realizing dynamic visualization and preservation of shrimp freshness.

Accurate and efficient detection of food freshness is of great significance to guarantee food safety. Herein, pH sensitive colorimetric films with considerable biological activities have been prepared by combining red cabbage anthocyanin extracts (RCE) with collagen hydrolysate-chitosan (CH-CS) matrix film. The formation mechanism of CH-CS-RCE films was discussed by SEM, FT-IR and XRD, which showed that RCE was successfully fixed in CH-CS film through hydrogen bonding and electrostatic interaction. The CH-CS-RCE films exhibited good mechanical properties, high barrier ability, excellent thermal stability, significant antioxidant and antimicrobial activity, and especially sensitive response to pH and ammonia. Fickian diffusion was the main mechanism for the release of RCE from CH-CS-RCE films and such release mechanism facilitated the maintenance of functional features of films. During the storage of shrimps at 4 °C, CH-CS-RCE2% showed a remarkable preservation effect on shrimps, and their shelf life was prolonged from 2 d to 5 d. Furthermore, CH-CS-RCE2% provided a dynamic visual color switching to detect the freshness of shrimp, realizing real-time monitoring of freshness. Color information (RGB) extracted via smartphone APP was used to enhance the accuracy and universality of freshness indication. Thus, this multifunctional film has great potential in food preservation and freshness monitoring.

Enhancing viability of Lactobacillus plantarum encapsulated by alginate-gelatin hydrogel beads during gastrointestinal digestion, storage and in the mimic beverage systems.

To improve the viability of Lactobacillus plantarum (P) during digestion and storage, the probiotics were encapsulated by alginate (ALG) and alginate-gelatin (ALG-GE) hydrogels beads. ALG-P-GE showed much better physicochemical properties than ALG-P. The scanning electron microscopy (SEM) results validated the incorporation of bacterial cells into the beads. ALG-P-GE exhibited good encapsulation efficiency of 97.7 %, and the storage and thermal stability of probiotic were increased by 15 % and 8 %, respectively, when comparing with ALG-P. ALG-P-GE beads could protect the probiotics from inactivation in simulated gastric fluid and then release it in simulated intestinal fluid. The protective mechanism of ALG-GE for probiotics was further studied by fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and found that ALG and GE can form gel network through hydrogen bonding and electrostatic interactions. In the mimic beverage systems, ALG-P-GE beads could protect the encapsulated probiotics and increase its viability. The storage, thermal, and digestion stability of encapsulated probiotic were significantly increased and showed high viability in the mimic beverage systems. ALG-P-GE beads have great potential for the protection and delivery of probiotics in food systems.

Chain-locked precursor ion scanning based HPLC-MS/MS for in-depth molecular analysis of lipase-catalyzed transesterification of structured phospholipids containing ω-3 fatty acyl chains.

Lipase-catalyzed transesterification of structured phospholipids (sPLs) is a hot topic, but the structural variation of the fatty acyl chains in intact phospholipids at the molecular level remains unclear to date. The present study explored the detailed characteristics of synthesized phospholipids through high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) in precursor ion scan mode. The optimal conditions were in-depth inspected and determined for the reaction system, including phospholipase A1 as catalyst, 15% lipase loading, and 1% water content. The sPLs enriched with EPA/DHA were structurally and quantitatively characterized by focusing on the fragments of m/z 301.6 (eicosapentaenoic acid, EPA) and m/z 327.6 (docosahexaenoic acid, DHA), and the results were statistically analyzed using partial least squares discriminant analysis and clustered heatmap hierarchical clustering analysis. PC 38:6 (18:1/20:5), PC 38:7 (18:2/20:5), PC o-40:6 (o-18:0/22:6), and PE 40:8 (18:2/22:6) etc. were revealed as the main variables that were active in the reaction.

Fabrication of Antioxidant Pickering Emulsion Based on Resveratrol-Grafted Zein Conjugates: Enhancing the Physical and Oxidative Stability.

Lipid oxidation is still a major problem complicating the development of food emulsions. In this study, an antioxidant Pickering emulsion stabilized by resveratrol-grafted zein (Z-R) conjugates and pectin (P) complex particles was prepared. The hydrophilic pectin successfully adjusted the wettability of Z-R; when the mass ratio of Z-R to P was 2:1 (Z-R/P2:1), the three-phase contact angle was 90.68°, and the wettability of the particles was close to neutral. Rheological analysis showed that the emulsion formed an elastic gel structure. FTIR spectra indicated that there was a hydrogen bond and electrostatic interaction between Z-R and P. The disappearance of characteristic infrared peaks of corn oil was due to a dense protective film formed on the surface of oil drops by Z-R/P2:1 particles, which was confirmed by confocal laser scanning microscopy. The emulsion stabilized by Z-R/P2:1 had excellent physical stability at a wide range of pH values (4-9), salt ion concentrations (0.04-0.15 mol·L-1) and storage times (0-30 days). The anti-lipid oxidation ability of the emulsion was outstanding; after storage for 14 days at room temperature, the MDA content in the emulsion was only 123.85 µmol/kg oil. In conclusion, the Z-R/P2:1 particles prepared in this study can effectively stabilize a Pickering emulsion and expand the usability of the method for constructing antioxidant Pickering emulsions.

Intestinal proline is a potential anti-allergy factor for allergy diagnosis and therapy.

Allergy has become a public health problem worldwide, but effective diagnostic and therapeutic approaches are limited currently. Amino acids are essential macronutrients that potentially participated in the allergy process. This work aimed to investigate whether amino acids can be applied as a mediator for allergy diagnosis and therapy. Two cohort studies were performed to investigate the correlation between fecal amino acids and allergy responses, and a spleen cell model was used to validate the role of amino acids in regulating allergy. In a cohort study with 193 volunteers, fecal proline was found to be negatively correlated with serum IgE, and detailed data analysis revealed that people with high-IgE-mediated allergy had decreased odds of high intestinal proline. In another cohort study with distinct allergic and non-allergic individuals, proline concentration was significantly lower in the allergic group. Daily diet and metagenomics analysis showed that the proline intake and microbiota amino acid metabolism were not significantly different, implying that the body's proline metabolism might be different between allergic and non-allergic individuals. Furthermore, the spleen cell model demonstrated that proline specifically targeted Th2 and Treg activity. Overall, this work revealed a tight correlation between gut proline and serum IgE, indicating proline as a promising biomarker and a potential therapeutic method for allergic diseases.

Preparation of alginate-whey protein isolate and alginate-pectin-whey protein isolate composites for protection and delivery of Lactobacillus plantarum.

Probiotics are sensitive to external conditions, resulting in low survival rates after being ingested or during food production, transportation and storage. In order to improve the survival rate of Lactobacillus plantarum (LP) during gastrointestinal digestion, storage, and freeze-drying, alginate-whey protein isolate (ALG-WPI) and alginate-pectin-whey protein isolate (ALG-PEC-WPI) composites were employed to encapsulate LP. The encapsulation efficiency of ALG-WPI-LP and ALG-PEC-WPI-LP beads both reached more than 99 %. Scanning electron microscopy (SEM) indicated that dense and rough aggregates were formed on the surface of both composites, and attached LP cells could be observed inside the beads. The ALG-WPI and ALG-PEC-WPI composites can protect the viability of LP in simulated gastric fluid (SGF) and release the probiotics in simulated intestinal fluid (SIF). The storage stability of LP at 4 °C was improved by about 15 % in comparison with bare LP and the survival rates of LP in ALG-WPI-LP and ALG-PEC-WPI-LP powders after freeze-drying were increased by 65.37 % and 72.06 %, respectively. The formation mechanism of ALG-WPI and ALG-PEC-WPI composites was further explored by fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and thermogravimetric analysis (TGA). The ALG-WPI and ALG-PEC-WPI composites have great potential to protect and deliver probiotics in food systems.

Encapsulation of EGCG by Zein-Gum Arabic Complex Nanoparticles and In Vitro Simulated Digestion of Complex Nanoparticles.

Epigallocatechin gallate (EGCG) has many excellent qualities such as its antitumor, antiradiation and anti-oxidation properties, but its application is limited because its oral bioavailability is low and stability is poor. In this paper, zein and gum arabic (GA) were used as wall materials to prepare Zein-GA complex nanoparticles for encapsulating and protecting the EGCG. The particle size of Zein-GA-EGCG complex nanoparticles ranged from 128.03-221.23 nm, and the EGCG encapsulation efficiency reached a maximum of 75.23% when the mass ratio of zein to GA was 1:1. The FTIR and XRD results illustrated that the components of the Zein-GA-EGCG complex nanoparticles interacted by electrostatic, hydrogen bonding, and hydrophobic interactions. The EGCG release rate of Zein-GA-EGCG nanoparticles (16.42%) was lower than that of Zein-EGCG (25.52%) during gastric digestion, and a large amount of EGCG was released during intestinal digestion, suggesting that the Zein-GA-EGCG nanoparticles could achieve the sustained release of EGCG during in vitro digestion. Hence, using Zein-GA complexes to encapsulate EGCG effectively increased the encapsulation efficiency of EGCG and realized the purpose of sustained release during simulated gastrointestinal digestion.

Real-Time Profiling and Distinction of Lipids from Different Mammalian Milks Using Rapid Evaporative Ionization Mass Spectrometry Combined with Chemometric Analysis.

The price of mammalian milk from different animal species varies greatly due to differences in their yield and nutritional value. Therefore, the authenticity of dairy products has become a hotspot issue in the market due to the replacement or partial admixture of high-cost milk with its low-cost analog. Herein, four common commercial varieties of milk, including goat milk, buffalo milk, Holstein cow milk, and Jersey cow milk, were successfully profiled and differentiated from each other by rapid evaporative ionization mass spectrometry (REIMS) combined with chemometric analysis. This method was developed as a real-time lipid fingerprinting technique. Moreover, the established chemometric algorithms based on multivariate statistical methods mainly involved principal component analysis, orthogonal partial least squares-discriminant analysis, and linear discriminant analysis as the screening and verifying tools to provide insights into the distinctive molecules constituting the four varieties of milk. The ions with m/z 229.1800, 243.1976, 257.2112, 285.2443, 299.2596, 313.2746, 341.3057, 355.2863, 383.3174, 411.3488, 439.3822, 551.5051, 577.5200, 628.5547, 656.5884, 661.5455, 682.6015, and 684.6146 were selected as potential classified markers. The results of the present work suggest that the proposed method could serve as a reference for recognizing dairy fraudulence related to animal species and expand the application field of REIMS technology.

Insight into the effect of ultrasound treatment on the rheological properties of myofibrillar proteins based on the changes in their tertiary structure.

This was the first study to perform correlation analysis to determine the relationships between tertiary structural and rheological properties of the myofibrillar proteins (MPs) under ultrasound treatment (UT, frequency 20 kHz, power 500 W, intensity 30 %) for 0, 2, 4, 6, 8, and 10 min. The objectives of this study were to 1) characterize the changes of the small and large deformation rheological properties of MPs based on the tertiary structural changes; 2) determine relationships of rheological property, tertiary structural changes, and UT time. The results showed that UT could enhance the structural rigidity and the resistance of the system to permanent deformation observed in rheological tests. Besides, UT could unfold MPs, expose more hydrophobic amino acid residues to increase the surface hydrophobicity (S0-BPB), destroy disulfide bonds to increase the content of reactive sulfhydryl content (R-SH). The correlation analysis showed that the rheological properties of MPs could be improved by UT with a longer treatment time (0-10 min), while inevitably and significantly changing the tertiary structure of MPs (p < 0.05). These findings suggested that UT might be effective in the food-processing industry to change the structure of proteins and improve rheological properties.

Insight into the molecular mechanism of texture improvement of sturgeon fillets treated by low temperature vacuum heating technology using label-free quantitative proteomics.

Label-free quantitative proteomics and weighted protein co-expression network (WPCNA) strategy was used to determine the molecular mechanisms about how did the low temperature vacuum heating (LTVH) improve the texture quality of sturgeon fillets compared to traditional cooking (TC). Results showed that LTVH can reduce the accumulation of lactate and malondialdehyde (MDA) in sturgeon fillets, and decrease the degradation of myofibrillar protein. 594 proteins were identified, 26 and 10 key differentially abundant proteins (KDAPs) were observed in LTVH50-15 vs TC100-15 and LTVH60-15 vs TC100-15 groups, respectively. Most of KDAPs were structural proteins, metabolic enzymes, and oxidoreductase enzymes. They were primarily implicated in the structures of myofibrillar proteins and cytoskeleton, glycolysis/gluconeogenesis and oxidative phosphorylation pathways. In contrast to TC, LTVH can better preserve the structure of myofibrillar proteins and cytoskeleton, reduce lactate accumulation induced by glycolysis/gluconeogenesis, and limit the oxidative damage caused by oxidative phosphorylation, thereby improving the texture of sturgeon fillets.

Preparation of zein-lecithin-EGCG complex nanoparticles stabilized peppermint oil emulsions: Physicochemical properties, stability and intelligent sensory analysis.

Peppermint oil emulsions were prepared by using zein-lecithin-EGCG (Z-L/E) complex nanoparticles as emulsifiers. The preparation conditions of emulsions were optimized via measuring the particle size, surface tension and stability of emulsions, and peppermint oil of 3% (particle size = 375 nm, polydispersity index (PDI) = 0.45), the zein:lecithin ratio of 4:1 (w/w) (particle size = 396 nm), and the zein:EGCG ratio of 10:1 (w/w) (surface tension = 47.32 N/m) was the optimal condition. The rapid stability analysis showed that the instability mechanism of emulsions was ascribed to creaming and stratification, and the stability mechanism of emulsions was explored, indicating that the complex nanoparticles adsorbed on the surface of oil droplets to give Pickering emulsions. Electronic tongue experiments showed that the Z-E/L4:1 stabilized emulsion was distinguished from the other three samples due to its good stability. The electronic nose experiment could distinguish the emulsions with different droplet sizes.

Divergent Total Syntheses of (-)-Crinipellins Facilitated by a HAT-Initiated Dowd-Beckwith Rearrangement.

A hydrogen atom transfer (HAT)-initiated Dowd-Beckwith rearrangement reaction was developed, which enables the efficient assembly of diversely functionalized polyquinane frameworks. By incorporation of an iridium-catalyzed regio- and enantioselective hydrogenation and a diastereocontrolled ODI-[5+2] cycloaddition/pinacol rearrangement cascade reaction, the asymmetric total syntheses of eight tetraquinane natural products, including (-)-crinipellins A-F and (-)-dihydrocrinipellins A and B, have been achieved in a concise and divergent manner.

Nanoengineered on-demand drug delivery system improves efficacy of pharmacotherapy for epilepsy.

Long-term pharmacotherapy, serving as the main therapeutic approach for epilepsy prophylaxis, has suffered from limited efficacy and potential side effects because of the blood-brain barrier (BBB) and untimely medication. Here, we reported a nanoengineered drug delivery system for synergistic brain-targeting delivery and on-demand drug release of antiepileptic drugs (AEDs). The dopamine-pyrrole hybrid system can improve delivery efficiency through a combination of receptor-mediated transcytosis and BBB disruption­enabled transport induced by photothermal conversion of near-infrared light. Incorporation of polydopamine endowed the delivery system with enhanced conductivity and sensitivity, giving sustained (2 hours) and rapid (30 s) drug release in response to epileptiform discharges. Acute, continuous, and spontaneous seizure models validated that the delivery system could inhibit seizures upon epileptiform abnormalities, treated by one-fifth of the conventional dosage. Complemented with satisfactory biosafety results, this "smart" modality is promising to be an effective and safe strategy to improve the therapeutic index of AEDs for epilepsy.

The fabrication of novel zein and resveratrol covalent conjugates: Enhanced thermal stability, emulsifying and antioxidant properties.

Novel zein and resveratrol conjugates were fabricated by alkaline and free radical grafting reactions. The grafting efficiency and total phenolic content of alkaline treated conjugates were slightly higher than those of free radical grafting. Compared to native and alkaline treated zein, the sulfhydryl contents of conjugates were obviously decreased, confirming that nucleophilic addition of resveratrol to sulfhydryl group of zein formed stable CS covalent bonds. The conformation changes of zein modified by resveratrol were revealed by fourier transform infrared spectroscopy and fluorescence spectroscopy. Moreover, covalent modification changed isoelectric point of zein from 6.5 to 5.4 (alkaline) or 5.6 (free radical grafting), and broadening the pH application range of zein. It was worth mentioning that the conjugates showed much higher thermal stability, antioxidant activity, and emulsify activity than those of native zein. This study provides an effective way for the design of novel delivery systems to encapsulate bioactive substances.