One-step spraying of protein-anchored chitosan oligosaccharide antimicrobial coating for food preservation.

The persistent global issues of unsafe food and food waste continue to exist. Microbial contamination stands out as a major cause of losses in perishable foods like vegetables and fruits. Herein, we report a self-assembling coating based on disulfide bond cleavage-induced bovine serum albumin (BSA), where the antimicrobial activity of chitosan oligosaccharide (COS) is stably anchored in the coating by electrostatic interactions during the unfolding-aggregation phase of BSA. The intrinsic antimicrobial activity of COS, combined with the positively charged and hydrophobic regions enriched on the BSA coating, significantly disrupts the integrity of bacterial structures. Furthermore, the BSA@COS coating can easily adhere in situ to the grooves on the surface of strawberries through a simple one-step spraying process, extending the shelf life of strawberries and bananas by nearly three times. This makes it a potential economic alternative to current commercial antimicrobial coatings, offering a solution to the rampant global issue of food waste.

Analysis of volatiles from the thermal decomposition of Amadori rearrangement products in the cysteine-glucose Maillard reaction and density functional theory study.

The Amadori rearrangement products are an important flavor precursor in the Maillard reaction. Its thermal decomposition products usually contribute good flavors in foods. Therefore, investigating the thermal breakdown of Amadori products is significant for understanding the flavor forming mechanism in the Maillard reaction. In this study, volatiles from thermal decomposition of Amadori products in cysteine and glucose Maillard reaction was investigated by a thermal desorption cryo-trapping system combined with gas chromatography-mass spectrometry (GC-MS). A total of 60 volatiles were detected and identified. Meanwhile, the forming mechanism of 2-methylthiophene, a major decomposition product, was also investigated by using density functional theory. Seventeen reactions, 12 transition states, energy barrier and rate constant of each reaction were finally obtained. Results reveal that it is more likely for Amadori products of cysteine and glucose to undergo decomposition under neutral or weakly alkaline conditions.

Soy protein particles as stabilizers of heat-stable O/W emulsions with 20% protein content.

In response to the increasing demand for nutritionally rich foods, consumer preference for protein-enriched beverages has grown. However, heat-induced protein aggregation and gelation significantly hinders the production of high-protein drinks. In this study, oil-in-water (O/W) emulsions with exceptional thermal stability were formulated using modified soy protein particles (MSPs). These MSPs effectively resisted gel formation, even at a protein concentration of up to 20% (w/v). In contrast, emulsions prepared with untreated soy proteins (SPs) experienced pronounced gelation under identical conditions. The compact structure of MSPs, in comparison to SPs, imparted resistance to heat-induced denaturation and aggregation. Additionally, the emulsion displayed heightened heat processing insensitivity, due to the enhanced hydrophobicity of MSPs and their rapid adsorption at the oil-water interface, resulting in a denser, more elastic, and resilient interfacial film. These findings provide practical insights for the formulation of protein-rich milk alternatives, meeting the evolving market demands.

Highly Effective Nobiletin-MPN in Yeast Microcapsules for Targeted Modulation of Oxidative Stress, NLRP3 Inflammasome Activation, and Immune Responses in Ulcerative Colitis.

Inflammatory bowel disease (IBD) etiology is intricately linked to oxidative stress and inflammasome activation. Natural antioxidant nobiletin (NOB) contains excellent anti-inflammatory properties in alleviating intestinal injury. However, the insufficient water solubility and low bioavailability restrict its oral intervention for IBD. Herein, we constructed a highly efficient NOB-loaded yeast microcapsule (YM, NEFY) exhibiting marked therapeutic efficacy for dextran sulfate sodium (DSS)-induced ulcerative colitis (UC) at a low oral dose of NOB (20 mg/kg). We utilized the metal polyphenol network (MPN) formed by self-assembly of epigallocatechin gallate (EGCG) and FeCl3 as the intermediate carrier to improve the encapsulation efficiency (EE) of NOB by 4.2 times. These microcapsules effectively alleviated the inflammatory reaction and oxidative stress of RAW264.7 macrophages induced by lipopolysaccharide (LPS). In vivo, NEFY with biocompatibility enabled the intestinal enrichment of NOB through controlled gastrointestinal release and macrophage targeting. In addition, NEFY could inhibit NLRP3 inflammasome and balance the macrophage polarization, which favors the complete intestinal mucosal barrier and recovery of colitis. Based on the oral targeted delivery platform of YM, this work proposes a novel strategy for developing and utilizing the natural flavone NOB to intervene in intestinal inflammation-related diseases.

The gelling properties of fish gelatin as improved by ultrasound-assisted phosphorylation.

This study investigated the effects of ultrasound-assisted phosphorylation on gelling properties of fish gelatin (FG). Ultrasound-assisted phosphorylation (UP) for 60, 90, and 120 min resulted in >6.54% increase of phosphorylation degree and decreased zeta potential of FG. Atomic force microscopy revealed that UP-FGs showed larger aggregates than P-FGs (normal phosphorylation FGs). Low frequent-NMR and microstructure analysis revealed that phosphorylation enhanced water-binding capability of FG and improved the gel networks. However, UP60 had the highest gel strength (340 g), gelling (17.96 °C) and melting (26.54 °C) temperature while UP90 and UP120 showed slightly lower of them. FTIR analysis indicated thatß-sheet and triple helix content increased but random coil content decreased in phosphorylated FGs. Mass spectrometry demonstrated phosphate groups mainly bound to serine, threonine and tyrosine residues of FG and UP-FG exhibited more phosphorylation sites. The study showed that mild phosphorylation (UP60) could be applied to improve FG gel properties.

Constructing a strongly interacting Pea-Cod binary protein system by introducing metal cations toward enhanced gelling properties.

Developing prospective plant-animal binary protein systems with desirable nutritional and rheological properties stands as a significant and challenging pursuit within the food industry. Our understanding of the effect of adding salt on the aggregation behavior of food proteins is currently based on single model protein systems, however, this knowledge is rather limited following binary protein systems. Herein, various ionic strength settings are used to mitigate the repulsive forces between pea-cod mixed proteins during the thermal process, which further benefits the construction of a strengthened gel network. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) collectively demonstrated that larger heat-induced protein aggregates were formed, which increased in size with higher ionic strength. In the presence of 2.5 mM CaCl2 and 50 mM NaCl, the disulfide bonds significantly increased from 19.3 to 27.53 and 30.5 µM/g, respectively. Notably, similar aggregation behavior could be found when introducing 2.5 mM CaCl2 or 25 mM NaCl, due to the enhanced aggregation tendency by specific binding of Ca2+ to proteins. With relevance to the strengthened cross-links between protein molecules, salt endowed composite gels with preferable gelling properties, evidenced by increased storage modulus. Additionally, the gelling temperature of mixed proteins decreased below 50 °C at elevated ionic strength. Simultaneously, the proportion of network proteins in composite gels increased remarkably from 82.05 % to 93.61 % and 92.31 % upon adding 5.0 mM CaCl2 and 100 mM NaCl, respectively. The findings provide a valuable foundation for designing economically viable and health-oriented plant-animal binary protein systems.

Unveiling the critical pH values triggering the unfolding of soy 7S and 11S globulins and enhancing their encapsulation efficiency.

The pH-shifting process is an effective encapsulation method, and it is typically performed at extreme alkaline pH, which severely limits the application. In this study, we found that there were critical pH for the unfolding proteins during pH-shifting from 7 to 12, and upon the critical pH, physiochemical characteristics of protein greatly changed, leading to a sharp increase of encapsulation of hydrophobic actives. Firstly, the critical pH for ß-conglycinin (7S) or Glycinin (11S) unfolding was determined by multispectral technology. The critical pH for 7S and 11S were 10.5 and 10.3, respectively. The encapsulation efficiency (EE) obtained by ß-conglycinin-curcumin nanocomposite (7S-Cur) (88.80 %) and Glycinin-curcumin nanocomposite (11S-Cur) (88.38 %) at critical pH was significantly higher than that obtained by pH 7 (7S-Cur = 16.66 % and 11S-Cur = 15.78 %), and both values were close to EE obtained by at 12 (7S-Cur = 95.16 % and 11S-Cur = 94.63 %). The large-scale application of hydrophobic functional compounds will be enhanced by the experimental results.

Heat-induced agglomeration of water-soluble cod proteins toward gelled structures.

Cod proteins (CPs) have potential applications in designing desirable gel-based products, and this study aimed to unravel their heat-induced aggregation pattern and further probe the roles in protein gels. SDS-PAGE analysis indicated that high-precipitation-coefficient aggregates (HPCAs) of CPs aggregates were composed of considerable polymers of myosin heavy chains and actin, and their low-precipitation-coefficient aggregates (LPCAs) contained myosin light chains and tropomyosin. Studies from correlation analysis between the structure and aggregation kinetics revealed that the generation of ß-sheet and SS bonds were responsible for their spontaneous thermal aggregation induced by heating temperature and protein concentration, respectively. Additionally, as protein denaturation ratio increased, more and larger HPCAs were formed, which was evidenced driving the network formation of protein gels and resulting in higher storage modulus (G') values. These novel findings may be applicable to other animal proteins for better tailoring the manufacturing of muscle gel-based products.

Improvement of physicochemical properties of lycopene by the self-assembly encapsulation of recombinant ferritin GF1 from oyster (Crassostrea gigas).

BACKGROUND: Lycopene (LYC), a carotenoid found in abundance in ripe red fruits, exhibits higher singlet oxygen quenching activity than other carotenoids. However, the stability of LYC is extremely poor due to its high double-bond content. In this paper, a nano-encapsulation strategy based on highly stable marine-derived ferritin GF1 nanocages was used to improve the thermal stability and oxidation resistance of LYC, thereby boosting its functional effectiveness and industrial applicability. RESULTS: The preparation of GF1-LYC nanoparticles benefited from the pH-responsive reversible self-assembly of GF1 to capture LYC molecules into GF1 cavities with a LYC-to-protein ratio of 51 to 1. After the encapsulation of the LYC, the reassembled GF1 nanocages maintained intact morphology and good monodispersity. The GF1-LYC nanoparticles incorporated the characteristic LYC peaks in spectrograms, and their powder form contained the crystalline form of LYC. Molecular docking revealed that LYC bound with the inner triple-axis channel areas of GF1, interacting with VAL139, LYS72, LYS65, TYR69, PHE129, HIS133, HIS62, and TYR134 amino acids through hydrophobic bonds. Fourier transform infrared spectroscopy also demonstrated the bonding of GF1 and LYC. In comparison with free LYC, GF1 reduced the thermal degradation of encapsulated LYC at 37 °C significantly and maintained the 2,2-Diphenyl-1-picrylhydrazyl (DPPH)-scavenging ability of LYC. CONCLUSION: As expected, the water solubility, thermal stability, and antioxidant capacity of encapsulated LYC from GF1-LYC nanoparticles was notably improved in comparison with free LYC, indicating that the shell-like marine ferritin nanoplatform might enhance the stable delivery of LYC and promote its utilization in the field of food nutrition and in other industries. © 2023 Society of Chemical Industry.

Microfluidized hemp protein isolate: an effective stabilizer for high-internal-phase emulsions with improved oxidative stability.

BACKGROUND: Hemp protein isolates (HPIs), which provide a well-balanced profile of essential amino acids comparable to other high-quality proteins, have recently garnered significant attention. However, the underutilized functional attributes of HPIs have constrained their potential commercial applications within the food and agriculture field. This study advocates the utilization of dynamic-high-pressure-microfluidization (DHPM) for the production of stable high-internal-phase emulsions (HIPEs), offering an efficient approach to fully exploit the potential of HPI resources. RESULTS: The findings underscore the effectiveness of DHPM in producing HPI as a stabilizing agent for HIPEs with augmented antioxidant activity. Microfluidized HPI exhibited consistent adsorption and anchoring at the oil-water interface, resulting in the formation of a dense and compact layer. Concurrently, the compression of droplets within HIPEs gave rise to a polyhedral framework, conferring viscoelastic properties and a quasi-solid behavior to the emulsion. Remarkably, HIPEs stabilized by microfluidized HPI demonstrated superior oxidative and storage stability, attributable to the establishment of an antioxidative barrier by microfluidized HPI particles. CONCLUSION: This study presents an appealing approach for transforming liquid oils into solid-like fats using HPI particles, all without the need for surfactants. HIPEs stabilized by microfluidized HPI particles hold promise as emerging food ingredients for the development of emulsion-based formulations with enhanced oxidative stability, thereby finding application in the food and agricultural industries. © 2023 Society of Chemical Industry.

Theory and protocol of dual mode unity solid-phase microextraction.

The solid-phase microextraction (SPME) bias problem limits comprehensive analysis of volatile compounds in real samples. The study introduces dual mode unity solid-phase microextraction (DMU-SPME) as a novel SPME mode to achieve balanced extraction of both volatile and low-volatile compounds. The DMU-SPME method exhibits excellent linearity (R2 ≥ 0.994), low quantitation limits (0.12-240 µg/L), and notable stability (relative standard deviations below 20 % for both intra-day and inter-day analyses). In practical application to soy sauce, the DMU-SPME method identified a total of 107 compounds, encompassing all those detected by both headspace solid-phase microextraction (HS-SPME) and direct immersion solid-phase microextraction (DI-SPME). Theoretical insights indicate that DMU-SPME is less influenced by Kfs0 and Kfs in comparison to HS/DI-SPME, rendering it suitable for complex matrices containing both volatile and low-volatile compounds. In conclusion, DMU-SPME emerges as a highly effective extraction mode for analyzing volatile and low-volatile compounds in food, medical, and environmental samples.

Construction of Manganese-Based Oyster (Crassostrea gigas) Ferritin Nanozyme with Catalase-like Enzyme Activity.

MnO2 is a nanozyme that inhibits the decomposition of hydrogen peroxide (H2O2) into a hydroxyl radical (OH•), thus preventing its conversion into reactive oxygen species (ROS). Oyster ferritin (GF1) is a macromolecular protein that provides uniform size and high stability and serves as an excellent template for the biomineralization of nanozyme. This study presents a unique method in which MnO2 is grown in situ in the GF1 cavity, yielding a structurally stable ferritin-based nanozyme (GF1@Mn). GF1@Mn is demonstrated to be stable at 80 °C and pH 4-8, exhibiting a higher affinity with H2O2 than many other catalases (CAT) with a Michaelis constant (Km) of 25.45 mmol/L. In vitro experiments have demonstrated the potential of GF1@Mn to enhance cell survival by reducing nitric oxide (NO) production while mitigating macrophage damage from ROS. The findings are essential to developing ferritin-based nanozymes and hold great potential for applications in functional food development.

Determination of the critical pH for unfolding water-soluble cod protein and its effect on encapsulation capacities.

Hydrophobic polyphenols, with a variety of physiological activities, are often practically limited due to their low water solubility and chemical instability, among which curcumin (Cur) is a representative hydrophobic polyphenol. To improve Cur, the cod protein (CP)-Cur composite particles (CP-Cur) were successfully prepared using the pH-shift method, but this pH-shift method (7-12-7) required a higher pH, which limited application and increased cost. The critical pH of CP structure unfolding during pH-shift and its encapsulation effect on Cur were investigated in this paper. During the pH-shift process, the critical pH of the structural unfolding of CP was pH 10, and the degree of protein structure unfolding was higher, which was attributed to the increasing electrostatic repulsion, and the weakened hydrogen bond and hydrophobic interaction. The encapsulation efficiency of CP-Cur formed after pH 10-shift was higher than that formed after pH 9.8-shift, which increased by 22.17 %. At pH 9.8, the binding sites in CP reached saturation at the molar ratio of 10, while at pH 10 and 10.2, the binding sites in CP both reached saturation at the molar ratio of 14, also indicating that the protein treated with critical pH could bind more Cur. The binding between Cur and CP was mostly hydrophobic interaction, accompanied by hydrogen bonding and electrostatic interactions. The above results verified the necessity of critical pH in the experiment, indicating that critical pH could indeed improve the encapsulation effect and obtain a higher encapsulation efficiency. This work will help improve the large-scale application of hydrophobic functional substances in production.

The freeze-thaw stability of flavor high internal phase emulsion and its application to flavor preservation and 3D printing.

Volatilization of flavor substances may reduce consumers' perception of flavor, and the research on preservation of flavor substances by high internal phase emulsions (HIPEs) under freeze-thaw conditions is still blank. Herein, flavor HIPEs prepared by adding more than 15% litsea cubeba oil in the oil phase could be used as food-grade 3D printing inks, and showed better stability after 5 freeze-thaw cycles, which could be interpreted as the reduced ice crystal formation, more stable interface layer, and more flexible gel-like network structure resulting from the protein binding to flavor substances. The constructed HIPEs system in this study could preserve the encapsulated flavor substances perfectly after 5 freeze-thaw cycles. Overall, this study contributes a food-grade 3D printing ink, and provides a new method for the preservation of flavor substances under freezing conditions and expands the application range of flavor HIPEs in food industry.

Density functional theory studies on the oleic acid thermal oxidation into volatile compounds.

Oleic acid oxidation is one of the main sources of food flavor compounds. Volatile profiling was investigated using thermal desorption cryo-trapping combined with gas chromatography-mass spectrometry to analyze the volatile composition of oleic acid oxidation. A total of 43 volatile compounds, including aldehydes (11), ketones (2), alcohols (5), furans (2), acids (8), ester (12) and alkane (3) were identified from oleic acid during heating. Then, density functional theory (DFT) was applied to analyze the oxidative mechanism of oleic acid during heating. A total of 30 reactions were obtained and grouped into the peroxide (ROOH), alkoxy radical (RO•), and peroxide radical (ROO•) pathways. The structures of intermediates, transition states (TS), and products in each reaction were also determined. Results show that the branch chemical reactions were the key reactions in different reaction pathway. Moreover, the reaction priority of the thermal oxidation reaction of oleic acid was the peroxide radical mechanism > the peroxide mechanism > the alkoxy radical mechanism.

Facilitating Pro-survival Mitophagy for Alleviating Parkinson's Disease via Sequence-Targeted Lycopene Nanodots.

The pathogenesis of Parkinson's disease is closely linked to impaired mitochondrial function and abnormal mitophagy. Biocompatible natural antioxidants effectively protect dopaminergic neurons. However, the main challenge in using natural antioxidants for Parkinson's disease therapy is creating a delivery platform to achieve neuron-targeted enrichment. Herein, we synthesized rationally sequence-targeted lycopene nanodots using recombinant human H-ferritin nanocages with lycopene loading into the cavity and lipophilic triphenylphosphonium (TPP) coupling on the outer surface. The nanodots allow for the neural enrichment and mitochondrial regulation of lycopene through blood-brain barrier transcytosis and neuronal mitochondria-targeting capability. These anti-ROS nanodots protect neuronal mitochondrial function and promote PINK1/Parkin-mediated mitophagy in MPTP toxicity-induced neurons in vivo and in vitro, which favors the secretory efflux of pathogenic α-synuclein and the survival of dopaminergic neurons. Moreover, these nanodots restore the Parkinson-like motor symptoms in Parkinson's model mice. This noninvasive sequence-targeted delivery strategy with excellent biocompatibility for pro-survival mitophagy-mediated pathology alleviation makes it a promising approach for treating and preventing Parkinson's disease.

Deep exploration of lipid oxidation into flavor compounds: A density functional theory study on (E)-2-decenal thermal oxidative reaction.

Unsaturated fatty aldehydes are the main products of fatty acid oxidation, and could be further oxidized to form volatile compounds with shorter carbon chains. Therefore, studying the oxidation of unsaturated fatty aldehydes is an important way to reveal the mechanism of food flavor formation during heating. In this study, volatile profiling of (E)-2-decenal during heating was firstly investigated by using thermal-desorption cryo-trapping combined with gas chromatography-mass spectrometry (GC-MS). A total of 38 volatile compounds were detected. Then, twenty-one reactions in the heating process of (E)-2-decenal were obtained by using density functional theory (DFT) calculations, and grouped into three oxidation pathways, namely, peroxide pathway, peroxyl radical pathway and alkoxy radical pathway. Meanwhile, the priority of these three pathways was the alkoxy radical reaction pathway > peroxide pathway > peroxyl radical reaction pathway. Moreover, the calculated results agreed well with the experimental results.

Soy protein particles with enhanced anti-aggregation behaviors under various heating temperatures, pH, and ionic strengths.

Protein-containing food products are frequently heated during processing to passivate anti-nutritional components. However, heating also contributes to protein aggregation and gelation, which limits its application in protein-based aqueous systems. In this study, heat-stable soy protein particles (SPPs) were fabricated by preheating at 120 °C for 30 min and at 0.5% (w/v) protein concentration. Compared to untreated soy proteins (SPs), SPPs exhibited a higher denaturation ratio, stronger conformational rigidity, compacter colloidal structure, and higher surface charge. The aggregation state of SPs and SPPs at various heating conditions (temperatures, pH, ionic strength, and types) was analyzed by dynamic light scattering, atomic force microscopy, and cryo-scanning electron microscopy. SPPs showed less increase in particle size and greater anti-aggregation ability than SPs. When heated in the presence of salt ions (Na+, Ca2+) or at acidic conditions, both SPs and SPPs formed larger spherical particles, but the size increase rate of SPPs was significantly lower than SPs. These findings provide theoretical information for preparing heat-stable SPPs. Furthermore, the development of SPPs is conducive to designing protein-enriched ingredients for producing innovative foods.

Identification and characterisation of taste-enhancing peptides from oysters (Crassostrea gigas) via the Maillard reaction.

Oysters, which are flavourful edible marine products, have been utilised to produce Maillard reaction products (MRPs), which contribute to saltiness enhancement. Here, the molecular weight distribution, free amino acids, and taste characteristics of MRPs were analysed, while ultraviolet light was used to observe the Maillard reaction. Both thermal degradation and cross-linking reactions occur during the Maillard reaction. When the Maillard reaction time was 90 min, the saltiness, umami, and richness of the MRPs peaked, however bitterness reached its lowest value. Moreover, at an MRP concentration of 1.5 mg/mL, salts were reduced by 35.71% in a 3 mg/mL sodium chloride solution without reducing saltiness, based on sensory evaluation. Glycation sites of the MRPs, which are crucial for saltiness enhancement and derived from a variety of protein sources, were determined using nano-HPLC-MS/MS analysis. Our study establishes the foundation for preparing salt-enhancing peptides, accelerating the popularisation of oyster-derived flavouring agents.