Effect of chitosan size on destabilization of oil/water emulsions stabilized by whey protein

Fucoidan alleviates the inhibition of protein digestion by chitosan and its oligosaccharides

Chitosan (CTS) and chitosan oligosaccharides (COS) have been widely applied in food industry due to their bioactivities and functions. However, CTS and COS with positive charges could interact with proteins, such as whey protein isolate (WPI), influencing their digestion. Interaction among CTS/COS, FUC, and WPI/enzymes was studied by spectroscopy, chromatography, and chemical methods in order to reveal the role of FUC in relieving the inhibition of protein digestibility by CTS/COS and demonstrate the action mechanisms. As shown by the results, the addition of FUC increased degree of hydrolysis (DH) and free protein in the mixture of CTS and WPI to 3.1-fold and 1.8-fold, respectively, while raise DH value and free protein in the mixture of COS and WPI to 6.7-fold and 1.2-fold, respectively. The interaction between amino, carboxyl, sulfate, and hydroxyl groups from carbohydrates and protein could be observed, and notably, FUC could interact with CTS/COS preferentially to prevent CTS/COS from combining with WPI. In addition, the addition of FUC could also relieve the combination of CTS to trypsin, increasing the fluorescence intensity and concentration of trypsin by 83.3 % and 4.8 %, respectively. Thus, the present study demonstrated that FUC could alleviate the inhibitory effect of CTS/COS on protein digestion.

Phycocyanin-chitosan complex stabilized emulsion: Preparation, characteristics, digestibility, and stability

Phycocyanin is a natural pigment protein with antioxidant, anti-tumor, and anti-inflammatory properties, but its relatively poor emulsibility limits its use in the food industry. In order to improve the emulsifying capacity of phycocyanin, a novel phycocyanin-chitosan complex was prepared, and the characteristics, digestibility, and stability of emulsion containing oil droplets stabilized by the complex were investigated. The results showed that the phycocyanin-chitosan complex had better stability and lower interfacial tension at pH 6.5 than phycocyanin, and it significantly improved the stability of emulsion and inhibited the aggregation of oil droplets. The phycocyanin-chitosan complex stabilized emulsion showed better physical stability, digestibility, and oxidation stability than the phycocyanin emulsion. The particle size of the phycocyanin-chitosan complex stabilized emulsion was very small (from 0.1 to 2 μm), and its absolute value of zeta potential was high. Overall, this study suggests that the phycocyanin-chitosan complex effectively improved the emulsifying capacity of phycocyanin.

Review on demulsification techniques for oil/water emulsion: Comparison of recyclable and irretrievable approaches

Since the establishment of the first global refinery in 1856, crude oil has remained one of the most lucrative natural resources worldwide. However, during the extraction process from reservoirs, crude oil gets contaminated with sediments, water, and other impurities. The presence of pressure, shear forces, and surface-active compounds in crude oil leads to the formation of unwanted oil/water emulsions. These emulsions can take the form of water-in-oil (W/O) emulsions, where water droplets disperse continuously in crude oil, or oil-in-water (O/W) emulsions, where crude oil droplets are suspended in water. To prevent the spread of water and inorganic salts, these emulsions need to be treated and eliminated. In existing literature, different demulsification procedures have shown varying outcomes in effectively treating oil/water emulsions. The observed discrepancies have been attributed to various factors such as temperature, salinity, pH, droplet size, and emulsifier concentrations. It is crucial to identify the most effective demulsification approach for oil/water separation while adhering to environmental regulations and minimizing costs for the petroleum sector. Therefore, this study aims to explore and review recent advancements in two popular demulsification techniques: chemical demulsification and magnetic nanoparticles-based (MNP) demulsification. The advantages and disadvantages of each technique are assessed, with the magnetic approach emerging as the most promising due to its desirable efficiency and compliance with environmental and economic concerns. The findings of this report are expected to have a significant impact on the overall process of separating oil and water, benefiting the oil and gas industry, as well as other relevant sectors in achieving the circular economy.

Chitosan and its oligosaccharide accelerate colonic motility and reverse serum metabolites in rats after excessive protein consumption

Excessive protein consumption (EPC) could increase the gastrointestinal burden and impair gut motility. The present study was designed to explore the improvement of chitosan (CTS) and chitosan oligosaccharide (COS) on colonic motility and serum metabolites in rats after EPC. The results of in vivo experiments fully proved that CTS and COS could improve gut motility and reverse the serum metabolites in rats as indicated by LC-MS/MS analysis, and the COS group even showed a better effect than the CTS group. Furthermore, short-chain fatty acids (SCFAs), which could promote gut motility, were also increased to alleviate EPC-induced constipation after supplementation with CTS or COS. In addition, CTS and COS could decrease the concentration of ammonia in serum and down-regulate the levels of H2S and indole. In summary, the present study revealed that CTS and COS could produce SCFAs, improve the colonic motility in rats, reverse the levels of valine, adenosine, cysteine, 1-methyladenosine, indole, and uracil, and enhance aminoacyl-tRNA biosynthesis and valine, leucine and isoleucine degradation. The present study provides novel insights into the potential roles of CTS and COS in alleviating the adverse effects of EPC.

Pickering emulsions stabilized by Chlorella pyrenoidosa protein-chitosan complex for lutein encapsulation

Lutein has many physiological functions like antioxidation, anti-cancer, and anti-inflammation, which presents good potential in the development of functional food for eye protection. However, the hydrophobicity and harsh environment factors during digestive absorption process will greatly reduce lutein bioavailability. In this study, Chlorella pyrenoidosa protein-chitosan complex stabilized Pickering emulsions were prepared, and lutein was encapsulated into corn oil droplets to increase its stability and bioavailability in gastrointestinal digestion. The interaction between Chlorella pyrenoidosa protein (CP) and chitosan (CS), and the effect of chitosan concentration on the emulsifying ability of the complex and emulsion stability were studied. With the increase of CS concentration from 0% to 0.8%, the emulsion droplet size obviously decreased, and the emulsion stability and viscosity increased significantly. In particular, when the concentration was 0.8%, the emulsion system was stable at 80 °C and 400 mM sodium chloride. After ultraviolet irradiation for 48 h, the retention rate of lutein encapsulated in Pickering emulsions was 54.33%, which was significantly higher than that (30.67%) of lutein dissolved in corn oil. The retention rate of lutein in Pickering emulsions stabilized by CP-CS complex was significantly higher than that in Pickering emulsions stabilized by CP only and corn oil after heating at 90 °C for 8 h. The results of simulated gastrointestinal digestion showed that the bioavailability of lutein encapsulated in Pickering emulsions stabilized by CP-CS complex reached 44.83%. These results explored the high-value utilization of Chlorella pyrenoidosa and provided new insights into the preparation of Pickering emulsions and the protection for lutein.

Microfluidics-based production of chitosan-gellan nanocomplexes encapsulating caffeine

Electrostatic complexes produced by interactions between polysaccharides have promising applications in the medical, pharmaceutical and food fields. In this light, for the development of such particles, microfluidics emerges as a promising technique in which processes occur at a strict laminar flow regime, allowing diffusion-dominated transport and particle formation in highly-controlled conditions. As a proof of concept, we compared bulk versus microfluidic (different devices simulating a range of residence times) processes for the production of electrostatic complexes of gellan with either chitosan (molecular weight ∼ 28 kDa) or hydrolyzed chitosan (molecular weight ∼ 3 kDa). Regardless of the process, polysaccharide solutions (pH 4.5) were mixed in pre-defined concentrations (polysaccharide ratios) to form electrostatic complexes that were used to encapsulate caffeine. These complexes were characterized by zeta potential measurements and particle size distribution. Overall, microfluidics produced complexes with improved characteristics such as lower polydispersity index (PDI ∼ 0.1) and mean size (∼200 nm) when compared to the conventional bulk process (PDI ∼ 0.3 and mean size ∼ 400 nm). Moreover, hydrolyzed chitosan (HC) contributed to an even smaller size and PDI value of the complexes. Such outcome is associated with the lower molecular weight and higher solubility of HC when comparing to conventional chitosan, which in turn improves electrostatic complexation. Caffeine could also be encapsulated in all complexes, but the highest encapsulation efficiency was achieved using microfluidics (70%) and with the geometry that provided a longer residence time. Therefore, we were able to demonstrate that microfluidics is clearly an effective strategy for generating electrostatic complexes with improved properties. Ultimately, this technique demonstrated a high potential for the production of vehicles of bioactive compounds.

Modulating properties of polysaccharides nanocomplexes from enzymatic hydrolysis of chitosan

Synthesis of nanocomplexes is a simple and low-cost technique for the production of encapsulation systems aiming industrial applications, based on the interaction of at least two oppositely charged molecules. Gellan gum (anionic) is a water-soluble biopolymer resistant to stomach pH conditions, therefore an interesting alternative as an encapsulating matrix. Chitosan (cationic) is also widely used due to its biocompatibility and mucoadhesive properties, although its low water solubility is an important step to be overcome for the production of the complexes. To improve this property, many techniques have been employed, but most of them use unsustainable techniques and chemical agents. The enzymatic hydrolysis of chitosan using proteases emerges as an alternative to these drawbacks and, therefore, this study aimed to evaluate the electrostatic nanocomplexation of native (C) or hydrolyzed (HC) chitosan (by porcine pepsin protease) with gellan gum (G). Polysaccharides and nanocomplexes formed with different G:C or G:HC ratio were evaluated by zeta potential measurements, particle size distribution, X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Transmission Electron Microscopy (STEM), intrinsic viscosity and turbidity analyses. Chitosan hydrolysis allowed the formation of a smaller (445.3 nm in pH 4.5) and more soluble structure (3 kDa), which positively influenced the formation of the complexes. The ratios G:HC of 7:3 and 8:2 formed complexes with lower values of zeta potential (13.9 mV and -5.0 mV, respectively), particle size (635.8 nm and 533.6 nm, respectively) and polydispersity (0.28 and 0.23) compared to complexes formed with native chitosan. Overall, our results show that enzymatic hydrolysis of chitosan favored the formation of electrostatic complexes with reduced size and low polydispersity, which can be used as efficient encapsulating matrices for improved targeted delivery and controlled release of bioactive compounds.