In vitro digestion of curcumin-nanoemulsion-enriched dairy protein matrices: Impact of the type of gel structure on the bioaccessibility of curcumin

Soy protein isolate-xanthan gum complexes to stabilize Pickering emulsions for quercetin delivery

This study aimed to prepare soy protein isolate-xanthan gum complexes (SPI-XG) at pH 7.0 and as emulsifiers to prepare Pickering emulsions for delivering quercetin (Que). The results showed that SPI-XG exhibited a gel network structure in which protein particles were embedded. Fourier transform infrared spectroscopy (FTIR) and molecular docking elucidated that SPI-XG formed through hydrogen bonding, hydrophobic, and electrostatic interactions. Three-phase contact angle (θo/w) of SPI-XG approached 90° with biphasic wettability. SPI-XG adsorbed at the oil-water interface to form an interfacial layer with a gel network structure, which prevented droplet aggregation. Following in vitro simulated digestion, Que displayed higher bioaccessibility in SPI-XG stabilized Pickering emulsions (SPI-XG PEs) than SPI stabilized Pickering emulsions. In conclusion, SPI-XG PEs were a promising system for Que delivery.

Functionalized xanthohumol nanoemulsion: fabrication, characterization and bioavailability enhancement of bioactive compounds

BACKGROUND

Xanthohumol is an isopentadienyl flavonoid in hops, which have several pharmacological effects. However, due to the poor bioavailability of xanthohumol, it cannot be widely used.

RESULT

In this study, solvent extraction combined with preparative liquid chromatography was used to separate and purify xanthohumol in hop residue. And the purity, yield and recovery of xanthohumol was 983.0 ± 2.1 g kg-1, 921.61 ± 5.65 g kg-1, and 5.41 ± 0.07 g kg-1, respectively. Response surface methodology optimization revealed that 216.75 g kg-1 ethyl oleate, 574.1 g kg-1 polyoxyl-35 castor oil (EL35) and 209.15 g kg-1 polyethylene glycol 200 (PEG200) produced the xanthohumol nanoemulsion with a loading capacity of 85.40 ± 0.33 g kg-1, mean droplet diameter of 42.35 ± 0.06 nm, and zeta potential of -21.78 ± 0.18 mV.

CONCLUSION

Xanthohumol nanoemulsion has better relative stability. The relative oral bioavailability of xanthohumol nanoemulsion was increased by 1.76 times. These results provide a theoretical basis for the application of nanoemulsion containing xanthohumol in food and pharmaceutical industry. © 2024 Society of Chemical Industry.

Macronutrient digestion and polyphenol bioaccessibility in oat milk tea products: an in vitro gastrointestinal tract study

People are increasingly preparing milk tea using plant-based milks rather than cow's milk, e.g., vegans, those with lactose intolerance, and those with flavor preferences. However, adding plant-based milks to tea may impact the digestion, release, and bioaccessibility of nutrients and nutraceuticals in both the tea and milk. In this study, oat milk tea model systems (OMTMSs) containing different fat and tea polyphenol concentrations were used to explore the impact of tea on macronutrient digestion in oat milk, as well as the impact of oat milk matrix on the polyphenol bioaccessibility in the tea. An in vitro gastrointestinal model that mimics the mouth, stomach, and small intestine was used. Tea polyphenols (>0.25%) significantly reduced the glucose and free fatty acids released from oat milk after intestinal digestion. Tea polyphenols (>0.10%) also inhibited protein digestion in oat milk during gastric digestion but not during intestinal digestion. The bioaccessibility of the polyphenols in the tea depended on the fat content of oat milk, being higher for medium-fat (3.0%) and high-fat (5.8%) oat milk than low-fat (1.5%) oat milk. Liquid chromatography-tandem mass spectrometry (UPLC-ESI-MS/MS) analysis showed that lipids improved the tea polyphenol bioaccessibility by influencing the release of flavonoids and phenolic acids from the food matrices. These results provide important information about the impact of tea on the gastrointestinal fate of oat milk, and vice versa, which may be important for enhancing the healthiness of plant-based beverages.

Delivery of encapsulated bioactive compounds within food matrices to the digestive tract: recent trends and future perspectives

Encapsulation technologies have achieved encouraging results improving the stability, bioaccessibility and absorption of bioactive compounds post-consumption. There is a bulk of published research on the gastrointestinal behavior of encapsulated bioactive food materials alone using in vitro and in vivo digestion models, but an aspect often overlooked is the impact of the food structure, which is much more complex to unravel and still not well understood. This review focuses on discussing the recent findings in the application of encapsulated bioactive components in fabricated food matrices. Studies have suggested that the integration of encapsulated bioactive compounds has been proven to have an impact on the physicochemical characteristics of the finished product in addition to the protective effect of encapsulation on the fortified bioactive compound. These products containing bioactive compounds undergo further structural reorganization during digestion, impacting the release and emptying rates of fortified bioactive compounds. Thus, by manipulation of various food structures and matrices, the release and delivery of these bioactive compounds can be altered. This knowledge provides new opportunities for designing specialized foods for specific populations.

The impact of heat-set milk protein gel textures modified by pH on circulating amino acid appearance and gastric function in healthy female adults: a randomised controlled trial

Modification of dairy proteins during processing impacts structural assemblies, influencing textural and nutritional properties of dairy products, and release and availability of amino acids during digestion. By modifying only pH, acid heat-set bovine dairy gels with divergent textural properties were developed to alter protein digestion. In vitro assay confirmed faster digestion of protein from a firm gel (pH 5.65) versus a soft gel (pH 6.55). We hypothesised that firm gel (FIRM-G; pH 5.6) would result in greater indispensable amino acid (IAA) appearance in circulation over 5 h and corresponding differences in gastric myoelectrical activity relative to soft gel (SOFT-G; pH 6.2). In a randomised, single-blind cross-over trial, healthy females (n = 20) consumed 150 g of each gel; plasma amino acid appearance was assessed over 5 hours. Iso-nitrogenous, iso-caloric gels were prepared from identical mixtures of bovine milk and whey protein concentrates; providing 17.7 g (FIRM-G) and 18.9 g (SOFT-G) of protein per serving. Secondary outcomes included gastric myoelectrical activity measured by body surface gastric mapping, glycaemic, triglyceridaemic, and subjective appetite and digestive responses. Overall plasma IAA (area under the curve) did not differ between gels. However, plasma IAA concentrations were higher, and increased more rapidly over time after SOFT-G compared with FIRM-G (1455 ± 53 versus 1350 ± 62 μmol L-1 at 30 min, p = 0.024). Similarly, total, branched-chain and dispensable amino acids were higher at 30 min with SOFT-G than FIRM-G (total: 3939 ± 97 versus 3702 ± 127 μmol L-1, p = 0.014; branched-chain: 677 ± 30 versus 619 ± 34 μmol L-1, p = 0.047; dispensable: 2334 ± 53 versus 2210 ± 76 μmol L-1, p = 0.032). All other measured parameters were similar between gels. Peak postprandial aminoacidaemia was higher and faster following ingestion of SOFT-G. Customised plasma amino acid appearance from dairy is achievable by altering gel coagulum structure using pH during processing and may have minimal influence on related postprandial responses, with implications for targeting food design for optimal health. The Clinical Trial Registry number is ACTRN12622001418763 (https://www.anzctr.org.au) registered November 7, 2022.

Modulating in vitro digestion of whey protein cold-set emulsion gels via gel properties modification with gallic acid and EGCG

Gallic acid (GA) and epigallocatechin gallate (EGCG), cooperated at varied ratios (1:0, 3:1, 1:1, 1:3, and 0:1), were employed to modify gel properties of calcium induced-whey protein emulsion gel. The effects of GA/EGCG on emulsion morphology, as well as gel properties and in vitro digestive behavior of the emulsion gels were investigated. Compared with emulsions without phenolics, GA/EGCG induced slightly smaller particle size and stronger electrostatic repulsion between emulsion droplets. Moreover, GA/EGCG, notably at a ratio of 3:1, promoted electrostatic and hydrophobic interactions between protein molecules and the formation of a compact and filamentous gel microstructure, resulting in a remarkable increment in the gel strength (up to 106 %). Furthermore, in vitro oral digestion, dynamic gastric digestion (using an artificial gastric digestive system, AGDS), and intestinal digestion of the emulsion gels were simulated. Particle size and protein hydrolysis results revealed that GA/EGCG was prone to weaken the physical disintegration of gels, reduce protein hydrolysis, and enhance the stability of emulsified oil droplets during dynamic gastric digestion. As a consequence, delayed release of oil droplets was observed in the gels and more free fatty acids were released in the intestinal digestion, particularly in the gel with GA/EGCG (3:1). These findings would provide novel strategies for application of phenolic compounds in developing protein gel-based delivery systems.

Effect of peach gum polysaccharide on the rheological and 3D printing properties of gelatin-based functional gummy candy

Excellent 3D printing materials must exhibit good extrudability and supportability, but these two characteristics are often contradictory. In this study, peach gum polysaccharide (PGP) was added to gelatin to prepare a 3D-printed functional gummy candy encapsulating curcumin. Rheology tests indicated that adding PGP could effectively improve the apparent viscosity and thermal stability and consequently improve the 3D printability and supportability of the products. When PGP addition was 6 %, the printing accuracy was higher than 90 %. Texture and microstructure analysis further revealed that PGP addition promoting a dense gel structure formed and the water holding capacity and supportability of gel materials were enhanced. Furthermore, the in vitro gastrointestinal digestion tests showed that after 6 h of simulated gastrointestinal fluid digestion, the retention rate of curcumin was nearly 80 %. The above results indicated that the composite gel of PGP and gelatin is a good 3D printing base material for nutrient delivery.

Compartmentalization of lutein in simple and double emulsions containing protein nanoparticles: Effects on stability and bioaccessibility

Delivery systems designed through protein stabilized emulsions are promising for incorporating carotenoids in different products. Nevertheless, the versatility in structures of such systems raises questions regarding the effect of the bioactive compound localization on their bio-efficacy, in particular for double emulsions. In this context, the aims of this study were to determine the impact of the localization of lutein in different water/oil/water double emulsions versus a single oil/water emulsion on the stability and in vitro bioaccessibility of lutein, a lipophilic carotenoid. The inner aqueous phase, which contained whey protein isolate (WPI) nanoparticles obtained by desolvation, was emulsified in sunflower oil stabilized by polyglycerol polyricinoleate (PGPR). The primary emulsion was then emulsified in a continuous aqueous phase containing whey protein isolate (WPI) and xanthan gum, the latter to increase the viscosity of the outer phase and delay creaming. Lutein was incorporated using different strategies: (1) lutein entrapped by WPI nanoparticles within the inner water phase of a double emulsion (W-L/O/W); (2) lutein incorporated into the oil phase of the double emulsion (W/O-L/W); (3) lutein incorporated in the oil phase of a single emulsion (O-L/W). All systems contained similar whey protein concentrations, as well as all other stabilizers. W-L/O/W sample showed the lowest lutein stability against light exposure during storage, and the highest lutein bioaccessibility after in vitro digestion, for freshly made samples. Furthermore, the in vitro bioaccessibility of lutein incorporated into the single emulsion was considerably lower than those observed for the double emulsions. The results reinforce the importance of designing appropriate structures for delivering improved stability and bioaccessibility of bioactive compounds.

Novel Biphasic In Vitro Dissolution Method Correctly Predicts the Oral Bioavailability of Curcumin in Humans

In vitro dissolution methods correctly predicting in vivo bioavailability of compounds from complex mixtures are lacking. We therefore used data on the in vivo performance of bioavailability-improved curcumin formulations to implement an in vivo predictive dissolution method (BiPHa+). BiPHa+ was applied for the characterization of eight curcumin formulations previously studied in a strictly controlled pharmacokinetic human trial. During dissolution, the dissolved proportion of curcumin in the aqueous medium underwent a formulation-dependent reduction, whereas the proportion remained stable in the organic layer. Compared with conventional dissolution systems, BiPHa+ was superior in terms of in vivo-relevant formulation characterization. All formulations could be precisely categorized according to their bioavailability in humans. In vitro-in vivo relationships for each dissolution method were established, with BiPHa+ providing the highest degree of linearity (r2 = 0.9975). The BiPHa+ assay correctly predicted the bioavailability of curcuminoids from complex mixtures and provided mechanistic information about formulation-dependent release characteristics.

The impact of differently structured starch gels on the gastrointestinal fate of a curcumin-containing nanoemulsion

In this study, we focused on the in vitro gastrointestinal digestion of curcumin-nanoemulsion-loaded corn starch gels formed using starches with different amylose contents, i.e. waxy (WCS), normal (NCS) and high amylose (HACS) corn starches and their impact on the release and bioaccessibility of curcumin. Curcumin nanoemulsion (CNE) loading significantly increased the storage modulus of the WCS and NCS gels by interspersing in the gelatinized continuous phase, whereas it decreased in the HACS gel due to the formation of a weak network structure as a result of the incomplete gelatinized amylose granules. During the gastric digestion, the disintegration and emptying of the WCS + CNE gel from the stomach was the slowest compared to the other two gels. The changes in the stomach, influenced the emptying of total solids (HACS + CNE > NCS + CNE > WCS + CNE) into the gastric digesta, which further affected the rate of starch and lipid digestion during the intestinal phase. The HACS + CNE and NCS + CNE gels showed a higher and faster release of curcumin compared to the WCS + CNE gel that showed a slower and sustained release during the intestinal digestion. This study demonstrated that the oral-gastric digestion of these starch gels was more dependent on the gel structures rather than on the molecular properties of the starches. The dynamic gastric environment resulted in the formation of distinct gel structures, which significantly influenced the composition and microstructure of the emptied digesta, further affecting starch hydrolysis and curcumin bioaccessibility in the small intestine.

Enhancing Therapeutic Efficacy of Curcumin: Advances in Delivery Systems and Clinical Applications

Curcumin, a potent active compound found in turmeric and Curcuma xanthorrhiza oil, possesses a wide range of therapeutic properties, including antibacterial, anti-inflammatory, antioxidant, and wound healing activities. However, its clinical effectiveness is hindered by its low bioavailability and rapid elimination from the body. To overcome these limitations, researchers have explored innovative delivery systems for curcumin. Some promising approaches include solid lipid nanoparticles, nanomicelle gels, and transdermal formulations for topical drug delivery. In the field of dentistry, curcumin gels have shown effectiveness against oral disorders and periodontal diseases. Moreover, Pickering emulsions and floating in situ gelling systems have been developed to target gastrointestinal health. Furthermore, curcumin-based systems have demonstrated potential in wound healing and ocular medicine. In addition to its therapeutic applications, curcumin also finds use as a food dye, contraception aid, corrosion-resistant coating, and environmentally friendly stain. This paper primarily focuses on the development of gel compositions of curcumin to address the challenges associated with its clinical use.

Pickering emulsion stabilized by casein-caffeic acid covalent nanoparticles to enhance the bioavailability of curcumin in vitro and in vivo

BACKGROUND

In recent years, the design of food-grade Pickering emulsion delivery systems has become an effective strategy for improving the low bioavailability of bioactive substances. Protein-based Pickering emulsions have received extensive attention because of a high biocompatibility and loading capacity. The bioavailability of active substances is mainly evaluated by simulating in vitro gastrointestinal digestion. As a model organism for antioxidation and anti-aging, Caenorhabditis elegans can provide additional biological information for the in vivo utilization of active substances.

RESULTS

After the introduction of caffeic acid, the average particle size and Zeta potential of the casein-caffeic acid covalent complex nanoparticles (CCP) were 171.11 nm and - 37.73 mV, respectively. The three-phase contact angle was also increased to 89.8°. By using CCP to stabilize Pickering emulsion (CCE), the retention quantity of the embedded curcumin increased by 2.19-fold after 28 days. In the simulated gastric digestion, curcumin degradation in CCE was reduced by 61.84%, released slowly in the intestinal environment, and the final bioaccessibility was increased by 1.90-fold. In C. elegans, CCE significantly reduced ROS accumulation, increased SOD activity by 2.01-fold and CAT activity by 2.30-fold, decreased MDA content by 36.76%, prolonging the lifespan of nematodes by 13.33% under H₂ O₂ stimulation and improving bioavailability in vivo.

CONCLUSION

The results indictae that CCP-stabilized Pickering emulsion can efficiently implement the physiological activities of bioactive compounds in vitro digestion and C. elegans, and thus it can be regarded as a reliable delivery system for food and medicine. © 2023 Society of Chemical Industry.

Prospect of Bioactive Curcumin Nanoemulsion as Effective Agency to Improve Milk Based Soft Cheese by Using Ultrasound Encapsulation Approach

The aim of this paper was to determine the effect of stabilized curcumin nanoemulsions (CUNE) as a food additive capable of directionally acting to inhibit molecules involved in dairy products' quality and digestibility, especially cheese. The objects were cheeses made from the milk of higher grades with addition of a CUNE and a control sample. The cheeses were studied using a scanning electron microscope (SEM) in terms of organoleptic properties, such as appearance, taste, and aroma. The results show that the addition of CUNEs improved the organoleptic properties compared to the control cheese by 150% and improved its shelf life. The SEM study shows that formulation with CUNE promotes the uniform distribution of porosity. The CUNE-based cheese shows a better sensory evaluation compared to the emulsion without curcumin. CUNE-processed cheese provided better antioxidant and antimicrobial analysis than the control sample and offers added value to the dairy sector.

Ultrasound-Assisted Stable Curcumin Nanoemulsion and Its Application in Bakery Product

The quality of the bread has been always an important issue and needs to be improved. Curcumin nanoemulsion provides an antioxidant and other nutritional value to the bakery products. Our aim was to determine the effect of curcumin nanoemulsions as a food additive on the quality and digestibility of breads. Curcumin nanoemulsion was stabilized by using Tween 80 and an ultrasound approach and its incorporation of curcumin nanoemulsion into bread formulation as the replacement of margarine. The objects of the study were the obtained bread from wheat flour, namely, control sample, CuNE containing sample, and raw curcumin containing bread sample. The results of the sensory evaluation of prototype bread suggest that curcumin nanoemulsion does affect organoleptic properties of bread. The result of antioxidant activity for curcumin nanoemulsion bread is higher (31.59%) compared to a control bread (20.59%). Also, in addition to a positive effect, there is an increase in the total strain and the elasticity of the crumb of bread compared to the control bread. SEM (scanning electron microscope) study shows that formulation with nanoemulsion promotes uniform distribution of fine pores (porosity).

The Impact of the Oil Phase Selection on Physicochemical Properties, Long-Term Stability, In Vitro Performance and Injectability of Curcumin-Loaded PEGylated Nanoemulsions

A nanotechnology-based approach to drug delivery presents one of the biggest trends in biomedical science that can provide increased active concentration, bioavailability, and safety compared to conventional drug-delivery systems. Nanoemulsions stand out amongst other nanocarriers for being biodegradable, biocompatible, and relatively easy to manufacture. For improved drug-delivery properties, longer circulation for the nanoemulsion droplets should be provided, to allow the active to reach the target site. One of the strategies used for this purpose is PEGylation. The aim of this research was assessing the impact of the oil phase selection, soybean or fish oil mixtures with medium chain triglycerides, on the physicochemical characteristics and injectability of curcumin-loaded PEGylated nanoemulsions. Electron paramagnetic resonance spectroscopy demonstrated the structural impact of the oil phase on the stabilizing layer of nanoemulsions, with a more pronounced stabilizing effect of curcumin observed in the fish oil nanoemulsion compared to the soybean oil one. The design of the experiment study, employed to simultaneously assess the impact of the oil phase, different PEGylated phospholipids and their concentrations, as well as the presence of curcumin, showed that not only the investigated factors alone, but also their interactions, had a significant influence on the critical quality attributes of the PEGylated nanoemulsions. Detailed physicochemical characterization of the NEs found all formulations were appropriate for parenteral administration and remained stable during two years of storage, with the preserved antioxidant activity demonstrated by DPPH and FRAP assays. In vitro release studies showed a more pronounced release of curcumin from the fish oil NEs compared to that from the soybean oil ones. The innovative in vitro injectability assessment, designed to mimic intravenous application, proved that all formulations tested in selected experimental setting could be employed in prospective in vivo studies. Overall, the current study shows the importance of oil phase selection when formulating PEGylated nanoemulsions.

Modulation of Fabrication and Nutraceutical Delivery Performance of Ovalbumin-Stabilized Oleogel-Based Nanoemulsions via Complexation with Gum Arabic

Protein–polysaccharide complexes, which involve Maillard-type protein–polysaccharide conjugates and electrostatic protein–polysaccharide complexes, have the potential to stabilize oleogel-based nanoemulsions for nutraceutical delivery. Here, ovalbumin (OVA) and gum arabic (GA) were used to prepare OVA–GA conjugate (OGC) and OVA–GA mixture (OGM), followed by the fabrication of astaxanthin-loaded oleogel-based nanoemulsions. Carnauba wax (5% w/w) and rice bran oil were mixed to prepare food-grade oleogel. The successful preparation of OGC was verified by means of SDS-PAGE analysis and free amino groups determination. OGC endowed oleogel-based nanoemulsions with smaller emulsion droplets and higher stability during 30-day storage, implying more outstanding emulsifying capability than OGM. Both OGC-stabilized nanoemulsions and OGM-stabilized nanoemulsions could enhance the extent of lipolysis and the bioaccessibility of astaxanthin compared with oleogel. Meanwhile, OGC exhibited significantly better than OGM, which indicated that OGC-stabilized oleogel-based nanoemulsions possessed more desirable nutraceutical delivery performance than OGM-stabilized oleogel-based nanoemulsions. This study may fill a gap in the influence of different protein–polysaccharide complexes on oleogel-based nanoemulsions and contribute to deeper insights about novel oleogel-based nanoemulsions for their applications in the food industry.

Impact of Recombined Milk Systems on Gastrointestinal Fate of Curcumin Nanoemulsion

Milk powder is an important ingredient in various foods and pediatric formulations. The textural and digestion properties of the formulations depend on the preheat treatment of the milk powder during manufacture. Thus, it is interesting to know how these modifications can influence on the release of fortified bioactive compounds during digestion with a milk matrix. In this study, a curcumin nanoemulsion was incorporated into milks reconstituted from low-heat, medium-heat and high-heat skim milk powders (SMPs) and the milks were subjected to semi dynamic in vitro digestion. All the recombined milk systems formed a curd under gastric conditions, which reduced the gastric emptying of protein and curcumin-loaded oil droplets. Because of the formation of heat-induced casein/whey protein complexes, the open fragmented curd formed by the high-heat-treated reconstituted powder resulted in higher protein and oil droplets emptying to the intestine and higher curcumin bioaccessibility. This study provides useful information for how protein ingredients can govern the fate of added health-promoting compounds during digestion.

Food Structure and Nutrition Interface: New Perspectives in Designing Healthy and Sustainable Foods

The increasing world population, impact of food production on climate change, and ongoing issues with diet-related diseases (e.g., malnutrition and obesity) are global major challenges. Recent advances in how food structure impacts the extent and kinetics of uptake of nutrients and its consequent effects on the physiological outcomes are beginning to shift our understanding of nutrition. This understanding is important to designing future foods that provide optimum nutrient bioavailability and deliver healthy outcomes. We discuss perspectives and scientific challenges in understanding the complex relationship between food structure/matrix modification during the digestion process and the absorption of nutrients as well as designing food structures with more sustainable materials.

Influence of Proteins on the Absorption of Lipophilic Vitamins, Carotenoids and Curcumin - A Review

While proteins have been widely used to encapsulate, protect, and regulate the release of bioactive food compounds, little is known about the influence of co-consumed proteins on the absorption of lipophilic constituents following digestion, such as vitamins (A, D, E, K), carotenoids, and curcumin. Their bioavailability is often low and very variable, depending on the food matrix and host factors. Some proteins can act as emulsifiers during digestion. Their liberated peptides have amphiphilic properties that can facilitate the absorption of microconstituents, by improving their transition from lipid droplets into mixed micelles. Contrarily, the less well digested proteins could negatively impinge on enzymatic accessibility to the lipid droplets, slowing down their processing into mixed micelles and entrapping apolar food compounds. Interactions with mixed micelles and proteins are also plausible, as shown earlier for drugs. This review focuses on the ability of proteins to act as effective emulsifiers of lipophilic vitamins, carotenoids, and curcumin during digestion. The functional properties of proteins, their chemical interactions with enzymes and food constituents during gastro-intestinal digestion, potentials and limitations for their use as emulsifiers are emphasized and data from human, animal, and in vitro trials are summarized.

Covalent Organic Framework-Incorporated Nanofibrous Membrane as an Intelligent Platform for Wound Dressing

Covalent organic frameworks (COFs) possess fascinating features that have sparked increasing interest as drug carriers in biomedical applications. However, the promising properties of COFs in wound healing have rarely been reported. Herein, a facile one-pot method is reported to prepare a curcumin-loaded COF (CUR@COF) by the condensation reaction and the Schiff base reaction and to further incorporate CUR@COF into polycaprolactone (PCL) nanofibrous membranes (CUR@COF/PCL NFMs) through electrospinning to develop a pH-triggered drug release platform for wound dressing. CUR@COF has a high CUR loading capacity of 27.68%, and CUR@COF/PCL NFMs exhibit increased thermal stability, improved mechanical properties, good biocompatibility, and enhanced antibacterial and antioxidant activities. More importantly, CUR@COF-based membranes show a pH-responsive CUR release profile by protonation under acidic conditions, suggesting the promotion of CUR release from membranes under an acidic extracellular microenvironment. The histopathological analysis and immunofluorescence staining of an in vivo skin defect model indicate that CUR@COF/PCL NFMs can accelerate wound healing and skin regeneration by reducing the expression of inflammatory factors (TNF-α) and enhancing the expression of angiogenesis (VEGF). This work provides a new strategy by employing COF-based drug-encapsulated nanocomposites for wound dressing applications.

In-vitro digestion models: a critical review for human and fish and a protocol for in-vitro digestion in fish

Digestive systems in human, animals, and fish are biological reactors and membranes to digest food and extract nutrients. Therefore, static and dynamic models of in-vitro digestion systems are developed to study e.g. novel food and feed before in-vivo studies. Such models are well developed for human, but not to the same extent for animals and fish. On the other hand, recent advances in aquaculture nutrition have created several potential fish meal replacements, and the assessment of their nutrient digestibility is critical in the application as a fish meal replacement. Using an in-vitro method, the assessment of an ingredient digestibility could be faster and less expensive compared to using an in-vivo experiment. An in-vitro method has been widely used to assess food nutrient digestibility for humans; however, its application for fish is still in the early stages. Both the human and fish as monogastric vertebrates share similar gastrointestinal systems; thus, the concept from the application for humans could be applied for fish. This review aims to improve the in-vitro digestion protocol for fish by adapting the concept from then study for humans, summarizing the current available in-vitro digestion model developed for human and fish in-vitro digestion study, identifying challenges specifically for fish required to be tackled and suggesting an engineering approach to adapt the human in-vitro gastrointestinal model to fish. Protocols to conduct in-vitro digestion study for fish are then proposed.

Nanoencapsulated curcumin emulsion utilizing milk cream as a potential vehicle by microfluidization: Bioaccessibility, cytotoxicity and physico-functional properties

Curcumin loaded milk cream emulsion was microfluidized at different pressures (50-200 MPa) and passes (1-4) using a full-factorial experimental design. Ultrasonicated and microfluidized emulsion was evaluated for particle size, morphological characteristics, antioxidant activity, rheological properties, bioaccessibility and cytotoxicity. Significant reduction was observed in the average particle size (358.2 nm) after microfluidization at 100 MPa/2nd pass. Transmission electron micrographs of the control (homogenized) and microfluidized (100 MPa/2nd pass) samples showed uniform distribution of fat globules in the microfluidized sample with partially dissolved curcumin particles (50-150 nm). Encapsulation efficiency of microfluidized emulsion was found to be significantly higher (97.88%) after processing as compared to control (91.21%). Two-fold (100%) increase in the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity and 25% increase in ferric-reducing antioxidant power (FRAP) was observed for microfluidized emulsions over control. Infrared spectrums of the emulsion exhibited shift in high intensity peaks indicating bond cleavage after microfluidization. After characterization, emulsions were subjected to in vitro digestion (oral, gastric and intestinal phase) to evaluate its bioaccessibility which was found to be remarkably increased by 30% after microfluidization. For assessing processing induced safety of the formulation, in vitro cytotoxicity of the microfluidized nanocurcumin emulsion was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay on HepG2 cells, wherein high % of cell viability (>93%) was seen even at a dose as high as 900 µg/mL revealing no toxic effect of the processing technique (microfluidization). This study highlights the efficacy of microfluidization as a technique and that of milk cream as an inexpensive, yet potential vehicle for generating stable and bio-accessible nano-curcumin emulsion.