Load phycocyanin to achieve in vivo imaging of casein-porous starch microgels induced by ultra-high-pressure homogenization

Phycocyanin from microalgae: A comprehensive review covering microalgal culture, phycocyanin sources and stability

As food safety continues to gain prominence, phycocyanin (PC) is increasingly favored by consumers as a natural blue pigment, which is extracted from microalgae and serves the dual function of promoting health and providing coloration. Spirulina-derived PC demonstrates exceptional stability within temperature ranges below 45 °C and under pH conditions between 5.5 and 6.0. However, its application is limited in scenarios involving high-temperature processing due to its sensitivity to heat and light. This comprehensive review provides insights into the efficient production of PC from microalgae, covers the metabolic engineering of microalgae to increase PC yields and discusses various strategies for enhancing its stability in food applications. In addition to the most widely used Spirulina, some red algae and Thermosynechococcus can serve as good source of PC. The genetic and metabolic manipulation of microalgae strains has shown promise in increasing PC yield and improving its quality. Delivery systems including nanoparticles, hydrogels, emulsions, and microcapsules offer a promising solution to protect and extend the shelf life of PC in food products, ensuring its vibrant color and health-promoting properties are preserved. This review highlights the importance of metabolic engineering, multi-omics applications, and innovative delivery systems in unlocking the full potential of this natural blue pigment in the realm of food applications, provides a complete overview of the entire process from production to commercialization of PC, including the extraction and purification.

Stability of high internal-phase emulsions prepared from phycocyanin and small-molecule sugars

BACKGROUND

The use of high internal-phase Pickering emulsions in the food industry is widespread due to their excellent stability and special rheological properties. Proteins are often used as food-grade Pickering stabilizers due to their safety and nutritious properties. Nowadays, the development and efficient utilization of novel proteins as Pickering stabilizers has become a new challenge.

RESULTS

Phycocyanin complexes with small-molecule sugars (SMS), formed as a result of non-thermal interactions, can serve as stabilizers for high internal-phase Pickering emulsions. The addition of SMS-enabled gel-like emulsions significantly reduced the amount of emulsifier used. When the SMS was sorbitol, the emulsion had excellent elastic properties and self-supporting ability and was stable during long-term storage, when subjected to centrifugation, and under different temperature conditions. The fluorescent property of phycocyanin was utilized to investigate the formation mechanism of the emulsion. Small-molecule sugars were able to form 'sugar-shell' structures on the surface of proteins to enhance the structural stability of proteins. Phycocyanin-SMS-stabilized emulsions provided superior protection for photosensitive and volatile substances. The retention rates of trans-resveratrol and n-hexane increased by 384.75% and 30.55%, respectively.

CONCLUSION

These findings will encourage the development of proteins that stabilize Pickering emulsions. They will also provide new ideas for protecting photosensitive and volatile substances. © 2023 Society of Chemical Industry.

Expanded porous-starch matrix as an alternative to porous starch granule: Present status, challenges, and future prospects

Exposing the hydrated-soft-starch matrix of intact grain or reconstituted flour dough to a high-temperature-short-time (HTST) leads to rapid vapor generation that facilitates high-pressure build-up in its elastic matrix linked to large deformation and expansion. The expanded starch matrix at high temperatures dries up quickly by flash vaporization of water, which causes loss of its structural flexibility and imparts a porous and rigid structure of the expanded porous starch matrix (EPSM). EPSM, with abundant pores in its construction, offers adsorptive effectiveness, solubility, swelling ability, mechanical strength, and thermal stability. It can be a sustainable and easy-to-construct alternative to porous starch (PS) in food and pharmaceutical applications. This review is a comparative study of PS and EPSM on their preparation methods, structure, and physicochemical properties, finding compatibility and addressing challenges in recommending EPSM as an alternative to PS in adsorbing, dispersing, stabilizing, and delivering active ingredients in a controlled and efficient way.

Preparation of acid-driven magnetically imprinted micromotors and selective loading of phycocyanin

Phycocyanin, a macromolecular protein known for its robust fluorescence, proves to be highly suitable for verifying the successful deposition of imprinted layers. In this study, an acid-propelled magnetic micromotor was successfully fabricated by utilizing surface imprinting and self-propelled nanomotor technology to achieve selective loading and capture of targets such as phycocyanin for future applications in environmental monitoring and precision drug delivery in vivo. This micromotor features a distinct recognition layer achieved through a template electrodeposition method. The outermost imprint layer of the micromotor was meticulously crafted using poly(3,4-ethylenedioxythiophene)/poly(sodium-4-styrenesulfonate) in the presence of a template, while the Pt layer serves as the supportive foundation, the Ni layer acts as the magnetic guidance component, and the innermost layer consists of metal Zn. In acidic environments, the Zn reacts to generate bubbles, which propels the micromotor's motion. The micromotor was comprehensively characterized using techniques such as scanning electron microscopy. Findings highlight the exceptional self-propulsion of the Zn-based micromotor, which is a fusion of molecular imprinting and micromotor technologies. This innovative design achieves an impressive maximum velocity of approximately 100 μm s-1, as well as commendable magnetic steering performance. Furthermore, the micromotor demonstrates the ability to imprint target protein through the imprint layer, enabling selective recognition and capture for transport of specific phycocyanin. In vitro cytotoxicity tests have also demonstrated that the micromotors are non-toxic to cells. This breakthrough concept offers a novel avenue for realizing targeted capture and transport of specific nutrients within the human gastric environment.

Physicochemical, structural and in vitro gastrointestinal tract release properties of ι-carrageenan/sodium caseinate synbiotic microgels produced by double-crosslinking with calcium ions and transglutaminase

The aim of this study was to develop ι-carrageenan (ιC)/sodium caseinate (NaCas) synbiotic microgels loading Lacticasebacillus paracasei produced by double-crosslinking with calcium ions and different concentrations (0, 5, 10, and 15 U/g protein) of transglutaminase (TGase). The synbiotic microgels were coated/filled with pectic oligosaccharide (POS). Field emission scanning electron microscope (FE-SEM) and X-ray diffraction (XRD) analyses indicated that L. paracasei was successfully microencapsulated in synbiotic microgels. In Fourier transform infrared (FT-IR) analysis, the new formation of covalent and ionic crosslinking was observed in double-crosslinked synbiotic microgels. The encapsulation efficiency of L. paracasei was significantly increased from 87.82 to 97.68 % by increasing the concentration of TGase from 0 to 15 U/g protein, respectively. After exposure to simulated gastric fluid for 2 h and simulated intestinal fluid for 4 h, the survival rate of L. paracasei was significantly increased as the concentration of TGase increased.

Development, application and future trends of starch-based delivery systems for nutraceuticals: A review

As a natural biopolymer, starch is ideally adapted as an encapsulant material for nutraceutical delivery systems due to its unique nature of extensive sources, versatility and high biocompatibility. This review offers an outline of recent advances in the development of starch-based delivery systems. The structure and functional properties of starch in encapsulating and delivering bioactive ingredients are first introduced. Structural modification of starch improves the functionalities and extends the applications of starch in novel delivery systems. Then, various nutraceutical delivery systems are systematically summarized, which include porous starch, starch particle, amylose inclusion complex, cyclodextrin, gel, edible film and emulsion. Next, the delivery process of nutraceuticals is discussed in two parts: digestion and release. Intestinal digestion plays an important role during the whole digestion process of starch-based delivery systems. Moreover, controlled release of bioactives can be achieved by porous starch, starch-bioactive complexation and core-shell structure. Finally, the challenges of the existing starch-based delivery systems are deliberated, and the directions for future research are pointed out. Composite delivery carriers, co-delivery, intelligent delivery, delivery in real food systems, and reuse of agricultural wastes may be the research trends for starch-based delivery systems in the future.

Fluorescence and antioxidant activity of heterologous expression of phycocyanin and allophycocyanin from Arthrospira platensis

Phycocyanin and allophycocyanin are important active substances in Arthrospira platensis, because of their fluorescent characteristic and antioxidant capacity. In order to solve the problem of insufficient production and inconvenient modification of natural protein, recombinant expression was performed and the fluorescence activity and antioxidant activity was analyzed to meet the demand for phycocyanin and allophycocyanin. A total of seven recombinant strains were constructed in this study, including individual phycocyanin or allophycocyanin, co-expression of phycocyanin-allophycocyanin, and their co-expression with chromophore, and the expression strain for individual chromophore. Different molecular weights of phycocyanin and allophycocyanin were detected in the recombinant strains, which indicated the different polymers expressed. Through mass spectrometry identification, phycocyanin and allophycocyanin may form a dimer of 66 kDa and a polymer of 300 kDa. The results of fluorescence detection showed that phycocyanin and allophycocyanin combined with phycocyanobilin to show fluorescence activity. The fluorescence peak of recombinant phycocyanin was mainly concentrated at 640 nm, which was similar to natural phycocyanin, the fluorescence peak of purified recombinant allophycocyanin was at about 642 nm. The fluorescence peak of the co-expressed recombinant phycocyanin-allophycocyanin is located at 640 nm, and the fluorescence intensity is between the recombinant phycocyanin and the recombinant allophycocyanin. After purification, the fluorescence peak of the recombinant phycocyanin is more concentrated and the fluorescence intensity is higher, which is about 1.3 times of recombinant phycocyanin-allophycocyanin, 2.8 times of recombinant allophycocyanin, indicating that phycocyanin may be more suitable to be used as fluorescence probe in medicine. The antioxidant capacity was measured by using total antioxidant capacity (T-AOC) and DPPH (2,2'-diphenyl-1-triphenylhydrazino) free radical scavenging method, and the recombinant phycobiliprotein showed antioxidant activity. Phycocyanobilin also has certain antioxidant activity and could enhance the antioxidant activity of phycobiliprotein to a certain extent. Recombinant phycocyanin-allophycocyanin polymer has stronger T-AOC, which is about 1.17-2.25 times that of the other five recombinant proteins. And recombinant phycocyanin has stronger DPPH antioxidant activity, which is about 1.2-2.5 times that of the other five recombinant proteins. This study laid the foundation for the application of recombinant phycocyanin and allophycocyanin in medical detection and drug development.

Promoting adsorption performance and mechanical strength in composite porous gel film

Starch is widely used to prepare biodegradable films due to its superior biocompatibility, low immunogenicity, and renewability. In this work, a novel K⁺/carrageenan porous-starch/casein gel film with high oil absorption was prepared using modified porous starch. Optimal gel stability and uniformity were obtained when adding 10 mg/mL k-carrageenan and 2 mg/mL K⁺ to 2 mg/mL microgels, with significantly reduced crystallinity and elasticity and increased tensile strength. The concentration of k-carrageenan was the main factor affecting gel strength and the hydrophilic and mechanical properties of the film. In addition, the film-forming solution showed excellent fluidity and spreading typical of non-Newtonian fluids. The film also exhibited a highly porous structure, as visualized by SEM and AFM, in line with a cumulative oil absorption rate of 87.5 % within 20 min, which was significantly higher than that obtained with glutinous rice starch. In conclusion, reinforcement of starch-based microgels as described in this study can maximize the film's adsorption performance and mechanical properties, with promising applications in skin care and beauty products.

Progress of Microencapsulated Phycocyanin in Food and Pharma Industries: A Review

Phycocyanin is a blue fluorescent protein with multi-bioactive functions. However, the multi-bioactivities and spectral stability of phycocyanin are susceptible to external environmental conditions, which limit its wide application. Here, the structure, properties, and biological activity of phycocyanin were discussed. This review highlights the significance of the microcapsules' wall materials which commonly protect phycocyanin from environmental interference and summarizes the current preparation principles and characteristics of microcapsules in food and pharma industries, including spray drying, electrospinning, electrospraying, liposome delivery, sharp-hole coagulation baths, and ion gelation. Moreover, the major technical challenge and corresponding countermeasures of phycocyanin microencapsulation are also appraised, providing insights for the broader application of phycocyanin.

Preparation of starch-based functional food nano-microcapsule delivery system and its controlled release characteristics

Most of the functional substances in food are absorbed in the small intestine, but before entering the small intestine, the strong acid and enzymes in the stomach limit the amount that can reach the small intestine. Therefore, in this paper, to develop a delivery system for functional food ingredients, maintain the biological activity of the ingredients, and deliver them to the target digestive organs, preparation of starch-based functional food nano-microcapsule delivery system and its controlled release characteristics were reviewed. Embedding unstable food active ingredients in starch-based nano-microcapsules can give the core material excellent stability and certain functional effects. Starch-based wall materials refer to a type of natural polymer material that uses starch or its derivatives to coat fat-soluble components with its hydrophobic cavities. The preparation methods of starch-based wall materials mainly include spray drying, extrusion, freeze drying, ultra-high pressure, coagulation, fluidized bed coating, molecular inclusion, chemical, and enzymic methods. The controlled release of functional food can be achieved by preparing starch-based nano-microcapsules to encapsulate the active agents. It has been reported that that compared with traditional embedding agents such as gelatin, acacia gum, and xanthan gum, starch-based functional food nano-microcapsule delivery system had many good properties, including improving antioxidant capacity, bioavailability, probiotics, and concealing bad flavors. From this review, we can learn which method should be chosen to prepare starch-based functional food nano-microcapsule delivery system and understand the mechanism of controlled release.