The evaluation of mixed-layer emulsions stabilized by myofibrillar protein-chitosan complex for delivering astaxanthin: Fabrication, characterization, stability and in vitro digestibility.

Muscle protein based functional foods have been attracted great interests in novel food designing. Herein, myofibrillar protein (MP)-chitosan (CH) electrostatic complexes were employed to fabricate mixed-layer emulsions to protect and deliver astaxanthin. The MP/CH complex fabricated mixed-layer emulsions displayed higher stability against pH and temperature changes, exhibiting smaller droplet and homogenous distributions. After UV-light irradiation for 8 h, the mixed-layer emulsions had higher astaxanthin retention (69.11 %, 1:1 group). During storage, a lower degree of lipid oxidation, protein oxidation and higher astaxanthin retention were obtained, indicating desirable protections of mixed-layer emulsions. The vitro digestion reveled the mixed-layer emulsions could decrease the release of free fatty acids. Meanwhile, the bioaccessibility of astaxanthin was higher (30.43 %, 2:1 group) than monolayer emulsion. In all, the MP/CH prepared mixed-layer emulsions could protect and deliver fat-soluble bioactive compounds, and contributed to develop muscle protein based functional foods to meet the needs of slow and controlled release.

Plant-based meat analogues enhance the gastrointestinal motility function and appetite of mice by specific volatile compounds and peptides.

Eating behavior is critical for maintaining energy homeostasis. Previous studies have found that plant-based meat analogues increased diet intake in mice compared with animal meat under a free feeding mode, however the reasons were unclear. To explore the underlying mechanisms of plant-based meat analogues increasing diet intake, mice were fed animal or plant-based pork and beef analogue diets, respectively. Biochemical and histological analyses were performed to evaluate appetite-regulating hormones and gastrointestinal motility function. Peptiomics and GC-IMS were applied to identify key substances. We found that the intake of plant-based meat analogues significantly enhanced the gastrointestinal motility function of mice. The long-term intake (68 days) of plant-based meat analogues significantly increased the muscle layer thickness of the duodenum and jejunum of mice; the activity of gastrointestinal cells of Cajal were also promoted by upregulating the expression of c-kit related signals as compared to animal meat; plant-based meat analogues intake markedly enhanced the signal intensity of the intestinal neurotransmitter 5-hydroxytryptamine (5-HT) by upregulating the expression of 5-HT synthase and receptors but downregulating its transporter and catabolic enzyme in the intestine. Moreover, plant-based meat analogues intake significantly increased levels of appetite-stimulating factors in the peripheral or hypothalamus but reduced levels of appetite-suppressing factors compared with animal meat. Specific volatile compounds were significantly associated with appetite regulating factors. Among them, 7 substances such as linalool have a potential promoting effect on food intake. Besides, different digestive peptides in gastrointestinal tract may affect eating behavior mainly through the neuroactive ligand-receptor interaction pathway, exerting hormone-like effects or influencing endocrine cell secretion. These findings preliminarily clarified the mechanism of plant-based meat analogues promoting diet intake and provided a theoretical basis for a reasonable diet.

Effect of interfacial layer number on the storage stability and in vitro digestion of fish oil-loaded multilayer emulsions consisting of gelatin particle and polysaccharides.

The purpose of this study is to investigate the effects of the interfacial layer number on the storage stability and in vitro digestion of fish oil-loaded primary, secondary, tertiary, and quaternary multilayer emulsions stabilized by gelatin particle and polysaccharides (anionic alginate and cationic chitosan), prepared using a layer-by-layer electrostatic deposition technique. The results demonstrate that the emulsion creaming stability during the storage process and the emulsion droplet stability against the gastric phase are dependent on the interfacial layer number. But, the interfacial layer number in the multilayer emulsions has no obvious effects on the droplet stability against droplet coalescence during the storage process and against the small intestinal phases of gastrointestinal tract models. Moreover, it also has no obvious effect on the sustained free fatty acid release of multilayer emulsions. This study can advance the fundamental understanding of multilayer emulsions and promote their potential applications.

Effect of extraction methods on the structural characteristics, functional properties, and emulsion stabilization ability of Tilapia skin gelatins.

The application of fish gelatins in emulsions has attracted much attention and their stabilization mechanisms remain unclear. This work explores the effect of extraction methods on the structural characteristics, functional properties, and emulsion application of Tilapia skin gelatins. The creaming stability of Tilapia skin gelatin-stabilized emulsions are dependent on gelatin secondary structure, gelatin fat-binding capacity, the presence of NaCl, and storage temperatures. The emulsion creaming velocities are: acetic acid-extracted gelatin (AAG) ≈ hot water-extracted gelatin (HWG) > pepsin enzyme-extracted gelatin (PEG). The emulsion creaming velocities in the presence of NaCl are: AAG < HWG ≈ PEG. The stability mechanisms are involved with a "protein secondary structure - molecular interaction - emulsion droplet structure - emulsion stability" route. This work provides useful information for understanding the relationships between the structural characteristics and emulsion stability of gelatins. The fish oil-loaded Tilapia skin gelatin-stabilized emulsions also show promising prospective applications in food beverages.

Electrosprayed Soft Capsules of Millimeter Size for Specifically Delivering Fish Oil/Nutrients to the Stomach and Intestines.

Contrasting to the traditional centimeter-sized soft capsules that are difficult to swallow or micro/nanometer-sized soft capsules that suffer from limited loading capacity for fish oil/nutrients and lowered stability, the millimeter-sized soft capsules with good enough stability could be a potential solution in solving these problems. Herein, we report millimeter-sized soft core-shell capsules of 0.42-1.85 mm with an inner diameter of 0.36-1.75 mm, for fish oil/nutrients, obtained through an electrospray approach upon optimization of different fabrication parameters such as applied voltage, sodium alginate concentration, shell/core feeding rate ratio, times of feeding rate, and types of coaxial needles. Further in vitro and in vivo studies reveal that the resulting soft capsules were apparently weakened and became mechanically destructive in the simulated small intestine solution and were totally destroyed in the simulated small intestine solution if they were first treated in the simulated stomach solution but not in the simulated stomach solution, which makes the millimeter-sized capsules useful as containers for specific delivery of fish oils and lipophilic nutrients to the stomach and intestines with excellent in vivo bioavailability (>90%). The whole fabrication approach is very facile with no complicated polymer modification and formulations involved, which endows the resulting soft capsules with broad application prospect in food and drug industries.

Gelatin molecular structures affect behaviors of fish oil-loaded traditional and Pickering emulsions.

As the differences of traditional and Pickering emulsions might have resulted from stabilizer structures, this study analyzes the effects of gelatin molecular structures (uncrosslinked molecules vs. crosslinked molecules) on the preparation, long-term storage, and dilution of fish oil-loaded traditional and Pickering emulsions. Both traditional and Pickering emulsions have three types of droplets with different sizes, and all the droplet sizes were exponentially decreased with the increase of stabilizer concentration. Pickering emulsions have slightly lower droplet sizes compared with traditional emulsions. Traditional emulsions have three different emulsion forms (liquid, redispersible emulsion gel, and unredispersible emulsion gel), whereas Pickering emulsions only have the liquid form. Emulsion creaming stability was dependent on stabilizer molecular structures and stabilizer concentrations. The two emulsions have similar and good dilution stability. This work demonstrates that gelatin molecular structures affect droplet size, emulsion forms, and creaming stability, but not droplet size types and emulsion dilution stability.

Fish oil-loaded emulsions stabilized by synergetic or competitive adsorption of gelatin and surfactants on oil/water interfaces.

The simultaneous application of proteins and surfactants for emulsion preparation and stabilization is a research hotspot in the field of emulsions, and their interfacial adsorption mechanisms remain unclear. In order to analyze the interaction mechanism of gelatin with low-molecular-weight surfactants, we mainly explored the preparation and storage of fish oil-loaded gelatin/surfactant-stabilized emulsions in this work. The results demonstrated that gelatin and four types of surfactants were synergetically (Span 80 and soybean lecithin) or competitively (Tween 80 and SDS) adsorbed on the oil/water interfaces in the emulsions. The adsorption behaviors affected emulsion stability (creaming, liquid-gel transformation, and droplet coalescence behaviors) and size distribution of emulsion droplets. These fish oil-loaded gelatin/surfactant-stabilized emulsions have the potential to reduce the disadvantages of fish oils and to provide multiple prospective applications in beverages, hard foods, and alkaline foods. It would also be beneficial to the basic understanding of protein/surfactant interfacial adsorption in emulsion formation.