Plant-based meat alternatives are developed to address consumer demands and sustainability of future food supply, and the market has grown exponentially in recent years. Although progresses have been ...made to construct plant protein-based fibers organoleptically comparable to a whole-muscle cut, it remains challenging to reproduce the hierarchical organization of muscle tissue known to contribute to the overall sensory profile. For now, the market strategies are largely focused on restructured or formed meat mimeticks.
Literature search and supermarket surveys are conducted to identify processing technologies, product formulations, and the chemistry and functionality of various additives applied in meat alternatives production. Comparisons are made between muscle and legume proteins to elucidate disparities in macroscopic aggregation properties that may be greatly diminished through fabrication and ingredient innovation. Due to the highly formulated and processed nature, the nutrition, health, and safety of plant-based meat alternatives are analyzed.
Thermoextrusion is found to be the principal reconstructuring technique for meat-like fiber synthesis from plant proteins. Soy and pea proteins, gluten, and polysaccharides are the major building blocks. Through physicochemical interactions, plant proteins are able to aggregate into particles and anisotropic fibrils to impart meat-like texture and mouthfeel. Vegetable oil blends and spices are used to modify the texture and flavor; pigments are added to impart color; vitamins, minerals, antioxidants, and antimicrobials are incorporated to boost nutrition and improve shelf-life. Opportunities exist to overcome technology obstacles and nutrition and safety challenges in further developing the alternatives market.
•The plant-based meat alternative market expands rapidly to meet consumer demands.•Legume (soy, pea, and others) proteins are the main building blocks of meat analogues.•Technological barriers, product quality, safety, and cost remain significant hurdles.•Protein functionality and chemical roles of various additives are analyzed.•Plant-based meatless products are a diet option, not to replace regular meat.
Fresh and processed meats offer numerous nutritional and health benefits and provide unique eating satisfaction in the lifestyle of the modern society. However, consumption of red meat including ...processed products is subjected to increasing scrutiny due to the health risks associated with cytotoxins that potentially could be generated during meat preparation. Evidence from recent studies suggests free radical pathways as a plausible mechanism for toxin formation, and antioxidants have shown promise to mitigate process-generated chemical hazards. The present review discusses the involvements of lipid and protein oxidation in meat quality, nutrition, safety, and organoleptic properties; animal production and meat processing strategies which incorporate natural antioxidants to enhance the nutritional and health benefits of meat; and the application of mixed or purified natural antioxidants to eliminate or minimize the formation of carcinogens for chemical safety of cooked and processed meats.
•Lipid and protein oxidation is a common phenomenon in processed meat.•Chemical toxins are formed at high temperature cooking and in nitrite cured meat.•Natural phenolic antioxidants can inhibit oxidation and toxin formation.•Antioxidant ingredient strategies can feasibly promote muscle food safety.
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•Effect of reducing agents on oat protein functionality is investigated.•Cysteine effectively dissociates oat protein complexes via SS bond breakage.•Disruption of SS bonds leads to ...partial opening of oat protein structure.•Treatment of cysteine enhances oat globulin emulsifying properties.
Disulfide bonds play an essential structural role but may hinder the molecular flexibility and functionality of proteins. The present study investigated the effect of disulfide cleavage on emulsifying activity of oat protein isolate (OPI). Four reducing agents tested (dithiothreitol, ascorbic acid, cysteine, and sodium bisulfite) except ascorbic acid disrupted inter-subunit SS bonds of OPI (up to 90 %) in a dose-dependent manner. Emulsification properties were measured specifically on cysteine-modified OPI, and the results showed increased emulsifying activity up to 37 % after subunit dissociation, which exposed hydrophobic groups and loosened the structure. In particular, emulsions formed by cysteine-treated OPI (1.7 to 6.7 mM/mg protein) displayed a superior interfacial protein coverage (0.170 m2/mg compared to 0.092 m2/mg for control) and reduced emulsion particle size (from 4722 to 2238 nm). The application of cysteine as a structure-modifying food additive can broaden the utilization of oat protein in emulsion-based food products.
Summary Objective To determine whether autophagy contributes to the pathogenesis of degenerative disc disease (DDD) or retards the intervertebral disc (IVD) degeneration, and investigate the possible ...relationship between compression-induced autophagy and intracellular reactive oxygen species (ROS) in nucleus pulposus (NP) cells in vitro. Methods The autophagosome and autophagy-related markers were used to explore the role of autophagy in rat NP cells under compressive stress, which were measured directly by electronic microscopy, monodansylcadaverine (MDC) staining, immunofluorescence, western blot, and indirectly by analyzing the impact of pharmacological inhibitors of autophagy such as 3-methyladenine (3-MA) and chloroquine (CQ). And the relationship between autophagy and apoptosis was investigated by Annexin-V/propidium iodide (PI)-fluorescein staining. In addition, ROS were measured to determine whether these factors are responsible for the development of compression-induced autophagy. Results Our results indicated that rat NP cells activated autophagy in response to the same strong apoptotic stimuli that triggered apoptosis by compression. Autophagy and apoptosis were interconnected and coordinated in rat NP cells exposed to compression stimuli. Compression-induced autophagy was closely related to intracellular ROS production. Conclusions Enhanced degradation of damaged components of NP cells by autophagy may be a crucial survival response against mechanical overload, and extensive autophagy may trigger autophagic cell death. Regulating autophagy and reducing the generation of intracellular ROS may retard IVD degeneration.
Graphene is an atomically thin plasmonic medium that supports highly confined plasmon polaritons, or nano-light, with very low loss. Electronic properties of graphene can be drastically altered when ...it is laid upon another graphene layer, resulting in a moiré superlattice. The relative twist angle between the two layers is a key tuning parameter of the interlayer coupling in thus-obtained twisted bilayer graphene (TBG). We studied the propagation of plasmon polaritons in TBG by infrared nano-imaging. We discovered that the atomic reconstruction occurring at small twist angles transforms the TBG into a natural plasmon photonic crystal for propagating nano-light. This discovery points to a pathway for controlling nano-light by exploiting quantum properties of graphene and other atomically layered van der Waals materials, eliminating the need for arduous top-down nanofabrication.
Lithium ion batteries with lithium nickel cobalt manganese oxide (NCM) cathode were characterized by extensive cycling (>2000 cycles), discharge rate test, hybrid pulse power characterization test ...(HPPC), and electrochemical impedance spectroscopy (EIS). The crystal structure, morphology and particle size of cathode materials were characterized by X-ray diffraction and scanning electron microscopy (SEM). It was demonstrated that the rate performance and cycle life of battery are closely related to the cathode material composition and electrode design. With proper selection of cathode composition and electrode design, the lithium ion battery cell achieved close to 3500 cycles with 85% capacity retention at 1C current.
•Characterized lithium ion batteries under extensive cycling (>3000 cycles).•Achieved long cycle life (>3000 cycles) with LiNi1−x−yCoxMnyO2 cathode.•Importance of cathode composition and electrode design for long cycle life.•Possible capacity fade mechanisms were discussed.
Protein oxidation, a phenomenon that was not well recognized previously but now better understood, is a complex chemical process occurring ubiquitously in food systems and can be induced by ...processing treatments as well. While early research concentrated on muscle protein oxidation, later investigations included plant, milk, and egg proteins. The process of protein oxidation involves both radicals and nonradicals, and amino acid side chain groups are usually the site of initial oxidant attack which generates protein carbonyls, disulfide, dityrosine, and protein radicals. The ensuing alteration of protein conformational structures and formation of protein polymers and aggregates can result in significant changes in solubility and functionality, such as gelation, emulsification, foaming, and water-holding. Oxidant dose-dependent effects have been widely reported, i.e., mild-to-moderate oxidation may enhance the functionality while strong oxidation leads to insolubilization and functionality losses. Therefore, controlling the extent of protein oxidation in both animal and plant protein foods through oxidative and antioxidative strategies has been of wide interest in model system as well in
studies. This review presents a historical perspective of food protein oxidation research and provides an inclusive discussion of the impact of chemical and enzymatic oxidation on functional properties of meat, legume, cereal, dairy, and egg proteins based on the literature reports published in recent decades.
Structural unfolding of soy protein isolate (SPI) as induced by holding (0, 0.5, 1, 2, and 4 h) in acidic (pH 1.5−3.5) and alkaline (pH 10.0−12.0) pH solutions, followed by refolding (1 h) at pH 7.0, ...was analyzed. Changes in emulsifying properties of treated SPI were then examined. The pH-shifting treatments resulted in a substantial increase in protein surface hydrophobicity, intrinsic tryptophan fluorescence intensity, and disulfide-mediated aggregation, along with the exposure of tyrosine. After the pH-shifting processes, soy protein adopted a molten globule-like conformation that largely maintained the original secondary structure and overall compactness but lost some tertiary structure. These structural modifications, consequently, led to markedly improved emulsifying activity of SPI as well as the emulsion stability.
The interface modulation between perovskite and carrier-transport layers via an appropriate chemical bond is an effective way to achieve the promoted carrier extraction and the reduced charge ...recombination for high-efficiency perovskite solar cells (PSCs). Here, a multifunctional material potassium hexafluorophosphate (KPF6) is employed as an effective interface material between SnO2 quantum dots (QDs) and perovskite. At perovskite side, KPF6 could react with perovskite through the strong hydrogen bonds between PF6− group and organic cations, which could re-orientate or redistribute the organic cation groups. Meanwhile, KPF6 could react with SnO2 QD through the strong ionic bonds between PF6− group and Sn4+/Sn2+ at the SnO2 QD side, which could passivate the interface defects to suppress the non-radiative recombination for the improved electron-transferring. Consequently, a champion PCE over 21% comes from the PSCs with 0.5 mg/ml KPF6 treated the SnO2 QD/perovskite interface, and the devices maintain ~90% of initial PCEs after 720-h storage in dry air.
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•KPF6 is used as an effective interface modification material in PSCs.•KPF6 could re-orientate the organic cation groups at perovskite side.•KPF6 could passivate the interface defects at SnO2 QD side.•K+ could digest the A-site shallow defects.•The KPF6 based PSC achieve a PCE over 21%.
It has been reported that irisin regulated exercise-mediated adipocyte browning; however, the systematical effects of irisin on the metabolism of glucose and lipid in diabetes are largely unknown. In ...the present study, we investigated the role and underlying mechanism of irisin in glucose utilization and lipid metabolism in diabetic mice.
A mouse model of diabetes was established by feeding C57BL/6 mice with high-fat diet. The diabetic mice were then treated with irisin. To mimic type 2 diabetes in vitro, myocytes and hepatocytes were cultured in a medium of high glucose and high fat. Glucose uptake, fatty acid oxidation and the expression of related protein were evaluated.
Irisin improved glucose tolerance and glucose uptake as evidenced by increased (18)F-FDG accumulation and GLUT4 translocation in diabetic skeletal muscle. Irisin also increased glucose uptake in myocytes cultured in high glucose/high fatty acid medium. In contrast, irisin reduced the expression of PEPCK and G6Pase, which are involved in gluconeogenesis, in diabetic liver. Consistently, irisin reduced fat weight and serum total cholesterol and triglyceride levels in diabetic mice, but increased acetyl coenzyme A carboxylase-β phosphorylation in muscle tissue and uncoupling protein 1 expression in fat tissue. In addition, irisin increased the oxidation of fatty acid in myocytes. Knockdown of the adenosine monophosphate (AMP)-activated protein kinase (AMPK) attenuated the effects of irisin on glucose uptake and fatty acid β-oxidation in myocytes. Similarly, inhibition of AMPK by a specific inhibitor reduced the effects of irisin on PEPCK and G6Pase expression in hepatocytes.
Our results suggest that irisin has an essential role in glucose utilization and lipid metabolism, and irisin is a promising pharmacological target for the treatment of diabetes and its complications.
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