The study of pH-dependent complexation between gelatin and gum arabic by morphology evolution and conformational transition

Progress in Fabrication and Applications of Cholesteric Liquid Crystal Microcapsules

Liquid crystals (LCs) are well known for inherent responsiveness to external stimuli, such as light, thermal, magnetic, and electric fields. Cholesteric LCs are among the most fascinating, since they possess distinctive optical properties due to the helical molecular orientation. However, the good flow, easy contamination, and poor stability of small-molecule LCs limit their further applications, and microencapsulation as one of the most effective tools can evade these disadvantages. Microencapsulation can offer shell-core structure with LCs in the core can strengthen their stability, avoiding interference with the environment while maintaining the stimuli-responsiveness and optical properties. Here, we report recent progress in the fabrication and applications of cholesteric LC microcapsules (CLCMCs). We summarize general properties and basic principles, fabrication methods including interfacial polymerization, in-situ polymerization, complex coacervation, solvent evaporation, microfluidic and polymerization of reactive mesogens, and then give a comprehensive overview of their applications in various popular domains, including smart fabrics, smart sensor, smart displays, anti-counterfeiting, information encryption, biomedicine and actuators. Finally, we discuss the currently facing challenges and the potential development directions in this field.

Digestion behavior of a polysaccharide from Cyclina sinensis: An explanation for the discrepancy in its immunostimulatory activities in vitro and in vivo

Although numerous polysaccharides have demonstrated potential immunostimulatory activities in in vitro models, only a few of them successfully stimulate the immune system in vivo. In order to explore the possible reasons for the activity loss of polysaccharides in in vivo models, the immunostimulatory activities in vitro and in vivo and the digestion behavior of a polysaccharide from Cyclina sinensis (CSP) were investigated in the present study. CSP showed obvious immunostimulatory activity in a RAW 264.7 cell model. In in vitro experiment, CSP did not exhibit cytotoxicity at concentrations of ≤10 µg/ml, and significantly increased NO production at concentrations of 0.4-10 µg/ml, suggesting CSP processes immunostimulatory activity in vitro. Further investigation using simulated digestion model indicated that CSP could bind with the protein in the digestive fluids to form precipitate in both the stomach and small intestine, and it could be seriously degraded by amylase during the digestion in the small intestine. Furthermore, the in vivo immunostimulatory activity evaluation demonstrated CSP had no effect on immunosuppressed mice as indicated by the body weight, thymus and spleen indexes, and TNF-α, IL-1β, IL-6, and IL-10 mRNA expression. Thus, the present study indicates that the degradation and precipitation of CSP in the digestive tract are the possible reasons for the activity loss of CSP after digestion. PRACTICAL APPLICATION: Cyclina sinensis is the common aquatic shellfish in China and plays an important role in the marine aquaculture industry. Cyclina sinensis polysaccharide (CSP) is the main active component of C. sinensis. The structure characterization and immunostimulatory activity of a purified fraction of CSP (CSP-1) and the effect of digestion on CSP and its immunostimulatory activity were studied. The result of this study promotes the understanding of the nutritional function effects and provides a scientific reference for the rational development and high-value utilization of C. sinensis.

Recent advances in the development of bitter gourd seed oil: from chemical composition to potential applications

Non-conventional seed oils are being considered novelty foods due to the unique properties of their chemical constituents. Numerous such seed oils serve as nutritional and functional supplements, making them a point of interest for scholars. Bitter gourd (Momordica charantia L.) seed oil (BGSO) has been widely used in folk medicine worldwide for the treatment of different pathologies, such as diabetes, cancer, and several inflammatory diseases. Therefore, its nutritional and medicinal value has been extensively studied. Considering the potential use of BGSO, it is imperative to have a comprehensive understanding of this product to develop and use its biologically active ingredients in innovative food and pharmaceutical products. An extensive understanding of BGSO would also help improve the economic feasibility of the bitter gourd seed processing industry and help prevent environmental pollution associated with the raw waste produced during the processing of bitter gourd seeds. This review addresses the potential uses of BGSO in terms of food and pharmaceuticals industry perspectives and comprehensively summarizes the oil extraction process, chemical composition, biological activity, and the application prospects of BGSO in clinical medicine.

Co-encapsulation of L-ascorbic acid and quercetin by gelatin/sodium carboxymethyl cellulose coacervates using different interlayer oils

A two-step emulsification prior to complex coacervation was employed to develop a co-encapsulation technology of hydrophilic and hydrophobic components for nutrition enhancement. Processing parameters of mononuclear ellipse-like microcapsules using gelatin and sodium carboxymethyl cellulose as wall materials were evaluated. The particle size and morphology of microcapsules and the encapsulation efficiency of L-ascorbic acid were significantly affected by the water-oil phase ratio and total biopolymer concentration. The L-ascorbic acid and quercetin co-encapsulated microcapsules with an average size of 65.26 µm showed good physical and chemical stability. The encapsulation efficiencies of L-ascorbic acid and quercetin were 69.91% and 88.21%, respectively. To predict the potential of functional lipids as hydrophobic carriers, microcapsules using soybean oil, olive oil, fish oil, and conjugated linoleic acid as interlayer oils were developed. The encapsulation efficiencies of hydrophobic compounds carried by different oils were similarly high (88.21-93.08%), whereas, hydrophilic ones carried by conjugated linoleic acid had the lowest encapsulation efficiency (32.54%). The interface tension results indicated that the interfacial stability was impaired by a competitive relation between conjugated linoleic acid and hydrophobic emulsifier at the interface, due to their structural similarity. These results provided the guidance for improving the quality of interlayer oils from microcapsules.

Utilization of chickpea protein isolate and Persian gum for microencapsulation of licorice root extract towards its incorporation into functional foods

This study aimed at the fabrication of licorice extract (LE)-loaded microparticles by complex coacervation, using chickpea protein isolate (CPI) and soluble fraction of Persian gum (SFPG). The LE-loaded microparticles with the highest encapsulation efficiency (97.87%) and loading capacity (11.35%) were obtained at pH 3 and CPI: SFPG ratio, core: coating ratio, and polymer concentration of 2, 1.5, and 2, respectively. The LE-loaded microparticles (2-15 μm) possessed heterogeneous microstructure, and the Fourier-transform infrared spectroscopy data confirmed the pronounced effect of electrostatic interactions and hydrogen bonding. The thermostability, amorphous structure, and color of the LE-loaded microparticles were significantly enhanced, compared to free LE. The sensory evaluation of the model beverages containing LE-loaded microparticles revealed that the microencapsulation was able to mask the bitter aftertaste and color of the extract. Thus, the results of this research confirm the potential of CPI-SFPG complex coacervates for the efficient delivery of glycyrrhizin via incorporation into functional food products.

Characterization of soy protein isolate/Flammulina velutipes polysaccharide hydrogel and its immunostimulatory effects on RAW264.7 cells

Soy protein isolate (SPI) is a nutritional commercial product, while the poor solubility and gelling restricts its applications for functional foods. To surmount the challenge presented by this poor solubility, the gelling polysaccharide shows potential in ameliorating SPI. In this study, SPI/Flammulina velutipes polysaccharide (FVP) hydrogels were prepared under four mixing ratios (32:1, 20:1,15:1 and 10:1, w/w) at both pH6.5 and pH3.5, respectively. The stability of hydrogels and its immunostimulatory impact on RAW264.7 cells were assessed. Initial results revealed that water holding capacity increased when increasing the mixing ratios, likely to be the results of enhanced electrostatic interaction between SPI and FVP. The addition of FVP contributed to the improved swelling ratio and lowered the degradation ratio. Such structure feature was shown to be favorable for hydrogels to culture cells. More importantly, SPI/FVP hydrogels demonstrated no cytotoxic effect on cell metabolic activity. The culture of SPI/FVP hydrogels enhanced the immunostimulatory capacity in RAW264.7 cells by increasing phagocytosis and inducing the production of pro-inflammatory cytokines. The performances of the hydrogels made at pH3.5 were superior to those prepared at pH6.5. Our results suggested SPI/FVP hydrogels may provide application potential for the development of functional foods.

Eugenol nanocapsules embedded with gelatin-chitosan for chilled pork preservation

Chilled pork is widely consumed in China. However, various contaminants during storage directly lead to a decline in the quality of chilled pork products. An extract of natural plant sources, eugenol (Eug) exerts good antibacterial and antioxidant effects. Nanometerization was used in this study to improve the insoluble and volatile characteristics of Eug. Eug nanocapsules embedded with gelatin/chitosan (Eug-Gel-CS NPs) were used to preserve chilled pork. Results indicated that Eug-Gel-CS NPs could effectively inhibit increases in the pH, total volatile basic nitrogen (TVB-N), and thiobarbituric acid-reactive substances (TBARS) of chilled pork than that of the Eug group (p < 0.05). The L* and a* values of the Eug-Gel-CS NPs group were significantly higher than those of the Eug and gelatin-chitosan (CS-Gel) groups (p < 0.05). The total number of colonies (TBC) showed that the storage period of the Eug-Gel-CS NPs group could be extended to 15 d, which was significantly different from that of the CK group (8 d) (p < 0.05). The Eug-Gel-CS NPs also effectively delayed the decline in the water- holding capacity (WHC), springiness, and cohesiveness of the chilled pork. Therefore, Eug-Gel-CS NPs exert good antiseptic, antibacterial, and antioxidative effects on preserved chilled pork.

Genipin-crosslinked O-carboxymethyl chitosan–gum Arabic coacervate as a pH-sensitive delivery system and microstructure characterization

The possibility of genipin-crosslinked O-carboxymethyl chitosan–gum Arabic coacervate as a pH-sensitive delivery vehicle was investigated. O-carboxymethyl chitosan–gum Arabic coacervates separated in pH 3.0, 4.5, and 6.0 were crosslinked by genipin for different durations and the crosslinked products were subjected to crosslinking degree, swelling behavior, bovine serum albumin release profile, and microstructure characterization. Genipin-crosslinking greatly improved the stability of the coacervates against the simulated gastric solution and created certain pH-sensitivity. The coacervates displayed higher swelling ratios in the simulated gastric solution than in the simulated intestine and colon solutions; meanwhile, the coacervates prepared in pH 4.5 and 6.0 swelled more severely than the complex separated in pH 3.0. Nevertheless, the bovine serum albumin release in the simulated gastric solution from the microcapsules prepared in pH 6.0 was much lower than those prepared in pH 4.5 and 3.0, whose cumulative release percentages in the three simulated solutions were 17.14%, 55.23%, and 79.79%, respectively, in crosslinking duration 2 h. X-ray diffraction, scanning electron microscopy, and transmission electron microscopy analysis revealed that genipin-crosslinking improved the regularity and compactness of coacervate structure, whereas confocal laser scanning microscopy observation indicated that O-carboxymethyl chitosan content was possibly the major reason for the different swelling and bovine serum albumin release behavior of the coacervates. It was concluded that the genipin-crosslinked O-carboxymethyl chitosan–gum Arabic coacervate was a potential intestine-targeted delivery system and its delivery performance could be tailored by varying the crosslinking degree and coacervation acidity.

A review of the preparation and application of flavour and essential oils microcapsules based on complex coacervation technology

This paper briefly introduces the preparation and application of flavour and essential oils microcapsules based on complex coacervation technology. The conventional encapsulating agents of oppositely charged proteins and polysaccharides that are used for microencapsulation of flavours and essential oils are reviewed along with the recent advances in complex coacervation methods. Proteins extracted from animal-derived products (gelatin, whey proteins, silk fibroin) and from vegetables (soy proteins, pea proteins), and polysaccharides such as gum Arabic, pectin, chitosan, agar, alginate, carrageenan and sodium carboxymethyl cellulose are described in depth. In recent decades, flavour and essential oils microcapsules have found numerous potential practical applications in food, textiles, agriculturals and pharmaceuticals. In this paper, the different coating materials and their application are discussed in detail. Consequently, the information obtained allows criteria to be established for selecting a method for the preparation of microcapsules according to their advantages, limitations and behaviours as carriers of flavours and essential oils.

Carboxymethyl cellulose-gelatin-silica nanohybrid: an efficient carrier matrix for alpha amylase

Carboxymethyl cellulose (CMC)-gelatin (G) dual templated polymerization of tetramethoxysilane (TMOS) furnished an efficient hybrid carrier support for alpha amylase. The material has been characterized using FTIR, XRD SEM, TGA and BET studies. The amylase was immobilized at the presynthesized hybrid support by adsorption and the immobilized enzyme was used to optimize the conditions for soluble starch hydrolysis. The immobilization did not change the optimum working pH (pH 5) and temperature (40°C) of the enzymatic reaction. The kinetic parameters of the immobilized (Km=9.970mgmL(-1); Vmax=66.23mgmL(-1)min(-1)) and free amylase (KM=4.0509mgmL(-1), Vmax=4.2909mgmL(-1)min(-1)) indicated that the immobilization has enhanced the catalytic function of diastase alpha amylase. The immobilized enzyme showed higher shelf life as compared to the free enzyme in solution and it could be reused for seven consecutive cycles where 85% of the initial activity was exhibited even in the last cycle. The present material is as efficient as our previously reported material CMC-AgNps-Si.