Lutein encapsulation into dual-layered starch/zein gels using 3D food printing: Improved storage stability and in vitro bioaccessibility.

The ability of 3D printing to encapsulate, protect, and enhance lutein bioaccessibility was investigated under various printing conditions. A spiral-cube-shaped geometry was used to investigate the effects of printing parameters, namely zein concentration (Z; 20, 40, and 60 %) and printing speed (PS; 4, 8, 14, and 20 mm/s). Coaxial extrusion 3D printing was used with lutein-loaded zein as the internal flow material, and corn starch paste as the external flow material. The viscosities of the inks, microstructural properties, storage stability, and bioaccessibility of encapsulated lutein were determined. The sample printed with a zein concentration of 40 % at a printing speed of 14 mm/s (Z-40/PS-14) exhibited the best shape integrity. When lutein was entrapped in starch/zein gels (Z-40/PS-14), only 39 % of lutein degraded after 21 days at 25 °C, whereas 78 % degraded at the same time when crude lutein was studied. Similar improvements were also observed after storing at 50 °C for 21 days. Furthermore, after simulated digestion, the bioaccessibility of encapsulated lutein (9.8 %) was substantially higher than that of crude lutein (1.5 %). As a result, the developed delivery system using 3D printing could be an effective strategy for enhancing the chemical stability and bioaccessibility of bioactive compounds (BCs).

Comprehensive Analysis of Lutein and Loroxanthin in Scenedesmus obliquus: From Quantification to Isolation.

Carotenoids are hydrophobic pigments produced exclusively by plants, fungi, and specific microbes. Microalgae are well suited for the production of valuable carotenoids due to their rapid growth, efficient isoprenoid production pathway, and ability to store these compounds within their cells. The possible markets for bio-products range from feed additives in aquaculture and agriculture to pharmaceutical uses. The production of carotenoids in microalgae is affected by several environmental conditions, which can be utilized to enhance productivity. The current study focused on optimizing the extraction parameters (time, temperature, and extraction number) to maximize the yield of carotenoids. Additionally, the impact of various nitrogen sources (ammonia, nitrate, nitrite, and urea) on the production of lutein and loroxanthin in Scenedesmus obliquus was examined. To isolate the carotenoids, 0.20 g of biomass was added to 0.20 g of CaCO3 and 10.0 mL of ethanol solution containing 0.01% (w/v) pyrogallol. Subsequently, the extraction was performed using an ultrasonic bath for a duration of 10 min at a temperature of 30 °C. This was followed by a four-hour saponification process using a 10% methanolic KOH solution. The concentration of lutein and loroxanthin was measured using HPLC-DAD at 446 nm, with a flow rate of 1.0 mL/min using a Waters YMC C30 Carotenoid column (4.6 × 250 mm, 5 µm). The confirmation of carotenoids after their isolation using preparative chromatography was achieved using liquid chromatography-tandem mass spectrometry (LC-MS/MS) with an atmospheric pressure chemical ionization (APCI) probe and UV-vis spectroscopy. In summary, S. obliquus shows significant promise for the large-scale extraction of lutein and loroxanthin. The findings of this study provide strong support for the application of this technology to other species.

Stability protection of lutein emulsions by utilizing a functional conjugate of collagen and Lycium barbarum L. leaf flavonoid.

Lutein exhibits excellent functional activity making it useful in many fields. Nevertheless, its use is limited by its physical and chemical instability. Here, collagen and Lycium barbarum L. leaf flavonoids (LBLF) were used as emulsifiers, their structures were characterized, the properties of the complexes were evaluated, and their stabilizing effects on lutein emulsions were explored. According to the results, the encapsulation rate of the complex of collagen-LBLF was (68.67 ± 1.43) % and the drug loading was (6.92 ± 0.13) %. Collagen compounded LBLF with a changed structure and morphology, resulting in improved antioxidant capacity, better foaming and emulsification, and reduced hydrophobicity. In addition, the thiobarbituric acid value of collagen-LBLF stabilized lutein emulsion (0.0012 ± 0.00011) mg/kg was significantly lower than that of collagen stabilized lutein emulsion (0.0021 ± 0.00016)  mg/kg (P < 0.05), indicating that the composite stabilized lutein emulsion obtained higher stability. LBLF contributed a high free radical scavenging effect and inhibited lutein degradation during storage. During simulated digestion, collagen-LBLF effectively stabilized the emulsion and protected lutein from destruction, made it release more slowly, and benefited the bio-accessibility of lutein during the next utilization step. Based on the present study, improved storage and digestion stabilities of lutein wereachievedby the utilization of collagen-LBLF complex, which provides a new method for the preparation and application of composite functional emulsifiers.

Developing biopolymer-stabilized emulsions for improved stability and bioaccessibility of lutein.

Lutein is essential for infant visual and cognitive development but has low stability and solubility. This study aimed to enhance the stability and bioaccessibility of lutein using oil-in-water emulsions stabilized with biopolymers. Commercially available octenylsuccinylated (OS) starches, including capsule TA® (CTA), HI-CAP®100 (HC), and Purity Gum® 2000 (PG), along with gum Arabic (GA) variants Ticaloid acacia Max® (TAM), TICAmulsion® 3020 (TM), and pre-hydrate gum Arabic (PHGA), were chosen as emulsifiers. By screening the effect of biopolymer concentration and oil volume fraction (Φ), emulsions stabilized with CTA, HC, or TM at 20% and 30% (w/v) concentration and 70% Φ exhibited a gel-like structure and were selected for further assessments. After a week at 25 °C, emulsions stabilized by CTA and HC showed no significant change in droplet size, while TM emulsion exhibited a 1.58-fold increase. At 45 °C, all emulsions exhibited increase in droplet size. Lutein retention is higher in CTA emulsions at both storage temperatures than free lutein. In vitro bioaccessibility of all lutein emulsions was higher than that of free lutein. These findings highlight the superior stability and bioaccessibility of the lutein emulsion stabilized by OS starch, positioning it as a promising carrier to broaden lutein applications in infant foods.

The nature of carotenoid S* state and its role in the nonphotochemical quenching of plants.

In plants, light-harvesting complexes serve as antennas to collect and transfer the absorbed energy to reaction centers, but also regulate energy transport by dissipating the excitation energy of chlorophylls. This process, known as nonphotochemical quenching, seems to be activated by conformational changes within the light-harvesting complex, but the quenching mechanisms remain elusive. Recent spectroscopic measurements suggest the carotenoid S* dark state as the quencher of chlorophylls' excitation. By investigating lutein embedded in different conformations of CP29 (a minor antenna in plants) via nonadiabatic excited state dynamics simulations, we reveal that different conformations of the complex differently stabilize the lutein s-trans conformer with respect to the dominant s-cis one. We show that the s-trans conformer presents the spectroscopic signatures of the S* state and rationalize its ability to accept energy from the closest excited chlorophylls, providing thus a relationship between the complex's conformation and the nonphotochemical quenching.

The presence of free palmitic acid modulates the effects of lutein on structural and dynamic properties of lipid membranes.

Free fatty acids, like palmitic acid (PA), and xanthophyll pigments, like lutein (LUT) are the natural membrane compounds in plants. To study the effect of PA on LUT and their organization, a model membrane of 1,2-dimyristoyl-sn-glycerol-3-phosphocholine (DMPC) enriched with 2 mol% PA and 1 mol% LUT was formed. Molecular mechanisms underlying the interaction between these two compounds were examined with application of molecular spectroscopy techniques, e.g., visible spectroscopy, electron paramagnetic resonance and Fourier transform infrared. We determined the monomeric/dimeric organization of LUT in the membrane. We proved that the presence of PA in the lipid phase facilitated and stabilized the formation of LUT structures in the membrane. Lutein with PA did not form strong molecular aggregates like H- and J-structures. We presented the simplified model membrane that could be a suitable representation of the physiological process of de-esterification of PA from LUT appearing in natural biomembranes in humans.

Lipid composition and properties affect protein-mediated carotenoid uptake efficiency from membranes.

Carotenoids are pigments of diverse functions ranging from coloration over light-harvesting to photoprotection. Yet, the number of carotenoid-binding proteins, which mobilize these pigments in physiological media, is limited, and the mechanisms of carotenoid mobilization are still not well understood. The same applies for the determinants of carotenoid uptake from membranes into carotenoproteins, especially regarding the dependence on the chemical properties of membrane lipids. Here, we investigate xanthophyll uptake capacity and kinetics of a paradigmatic carotenoid-binding protein, the homolog of the Orange Carotenoid Protein's C-terminal domain from Anabaena sp. PCC 7120 (AnaCTDH), using liposomes formed from defined lipid species and loaded with canthaxanthin (CAN) and echinenone (ECN), respectively. Phospholipids with different chain length and degree of saturation were investigated. The composition of carotenoid-loaded liposomes directly affected the incorporation yield and storage ratio of CAN and ECN as well as the rate of carotenoid uptake by AnaCTDH. Generally, saturated PC lipids were identified as unsuitable, and a high phase transition temperature of the lipids negatively affected the carotenoid incorporation and storage yield. For efficient carotenoid transfer, the velocity increases with increasing chain length or membrane thickness. An average transfer yield of 93 % and 43 % were obtained for the formation of AnaCTDH(CAN) and AnaCTDH(ECN) holoproteins, respectively. In summary, the most suitable lipids for the formation of AnaCTDH(CAN/ECN) holoproteins by carotenoid transfer from artificial liposomes are phosphatidylcholine (18:1) and phosphatidylglycerol (14:0). Thus, these two lipids provide the best conditions for further investigation of lipid-protein interaction and the carotenoid uptake process.

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.

Extraction, identification and application of gliadin from gluten: Impact of pH on physicochemical properties of unloaded- and lutein-loaded gliadin nanoparticles.

In the present study, high purity gliadin was extracted from gluten by the marginally modified Osborne method and the effect of different pHs in the aqueous ethanol on the physicochemical properties of unloaded gliadin nanoparticles (UGNs) and lutein-loaded gliadin nanoparticles (LGNs) was investigated. The results revealed that the formation of UGNs and LGNs at diverse pHs was driven by a conjunction of hydrogen bonding, electrostatic interactions and hydrophobic effects, but their dominant roles varied at different pHs. pH also significantly impacted the surface hydrophobicity, secondary structure and aromatic amino acid microenvironment of UGNs and LGNs. LGNs at pH 5.0 and at pH 9.0 exhibited better loading capacity and could reach 9.7884 ± 0.0006 % and 9.7360 ± 0.0017 %, respectively. These two samples also had greater photostability and thermal stability. Half-lives of LGNs at pH 5.0 were 2.185 h and 54.579 h, respectively. Half-lives of LGNs at pH 9.0 were 2.937 h and 49.159 h, respectively. LGNs at pH 5.0 and LGNs at pH 9.0 also had higher bioaccessibility of lutein, with 15.98 ± 0.04 % and 15.27 ± 0.03 %, respectively. These findings yielded precious inspirations for designing innovative lutein delivery system.

Physiological Significance of the Heterogeneous Distribution of Zeaxanthin and Lutein in the Retina of the Human Eye.

Zeaxanthin and lutein are xanthophyll pigments present in the human retina and particularly concentrated in its center referred to as the yellow spot (macula lutea). The fact that zeaxanthin, including its isomer meso-zeaxanthin, is concentrated in the central part of the retina, in contrast to lutein also present in the peripheral regions, raises questions about the possible physiological significance of such a heterogeneous distribution of macular xanthophylls. Here, we attempt to address this problem using resonance Raman spectroscopy and confocal imaging, with different laser lines selected to effectively distinguish the spectral contribution of lutein and zeaxanthin. Additionally, fluorescence lifetime imaging microscopy (FLIM) is used to solve the problem of xanthophyll localization in the axon membranes. The obtained results allow us to conclude that one of the key advantages of a particularly high concentration of zeaxanthin in the central part of the retina is the high efficiency of this pigment in the dynamic filtration of light with excessive intensity, potentially harmful for the photoreceptors.

Carotenoids Composition of Green Algae Caulerpa racemosa and Their Antidiabetic, Anti-Obesity, Antioxidant, and Anti-Inflammatory Properties.

Green alga Caulerpa racemosa is an underexploited species of macroalgae, even though it is characterized by a green color that indicates an abundance of bioactive pigments, such as chlorophyll and possibly xanthophyll. Unlike chlorophyll, which has been well explored, the composition of the carotenoids of C. racemosa and its biological activities have not been reported. Therefore, this study aims to look at the carotenoid profile and composition of C. racemose and determine their biological activities, which include antidiabetic, anti-obesity, anti-oxidative, anti-inflammatory, and cytotoxicity in vitro. The detected carotenoids were all xanthophylls, which included fucoxanthin, lutein, astaxanthin, canthaxanthin, zeaxanthin, ß-carotene, and ß-cryptoxanthin based on orbitrap-mass spectrometry (MS) and a rapid ultra-high performance liquid chromatography (UHPLC) diode array detector. Of the seven carotenoids observed, it should be highlighted that ß-carotene and canthaxanthin were the two most dominant carotenoids present in C. racemosa. Interestingly, the carotenoid extract of C. racemosa has good biological activity in inhibiting α-glucosidase, α-amylase, DPPH and ABTS, and the TNF-α and mTOR, as well as upregulating the AMPK, which makes it a drug candidate or functional antidiabetic food, a very promising anti-obesity and anti-inflammatory. More interestingly, the cytotoxicity value of the carotenoid extract of C. racemosa shows a level of safety in normal cells, which makes it a potential for the further development of nutraceuticals and pharmaceuticals.

In Vitro α-Amylase and α-Glucosidase Inhibitory Effects, Antioxidant Activities, and Lutein Content of Nine Different Cultivars of Marigold Flowers (Tagetes spp.).

Marigolds (Tagetes spp.) are major sources of bioactive compounds. The flowers are used to treat a variety of illnesses and have both antioxidant and antidiabetic effects. However, marigolds exhibit a wide range of genetic variations. Because of this, both the bioactive compounds and biological activities of the plants differ between cultivars. In the present study, nine marigold cultivars grown in Thailand were evaluated for their bioactive compound content, as well as for their antioxidant and antidiabetic activities, using spectrophotometric methods. The results showed that the Sara Orange cultivar possessed the highest total carotenoid content (431.63 mg/100 g). However, Nata 001 (NT1) had the highest amount of total phenolic compounds (161.17 mg GAE/g), flavonoids (20.05 mg QE/g), and lutein (7.83 mg/g), respectively. NT1 exhibited strong activities against the DPPH radical and ABTS radical cation, and had the highest FRAP value as well. Moreover, NT1 demonstrated the most significant (p < 0.05) α-amylase and α-glucosidase inhibitory effects (IC50 values of 2.57 and 3.12 mg/mL, respectively). The nine marigold cultivars had reasonable correlations between lutein content and the capacity to inhibit α-amylase and α-glucosidase activities. Hence, NT1 may be a good source of lutein; it may also be beneficial in both functional food production and medical applications.

Lutein-stachyose (LS) amphiphilic oligosaccharide derivatives improve the oral bioavailability of lutein.

A new amphiphilic oligosaccharide derivative, based on lutein modification onto the OH position of stachyose with facile and mild esterification, was prepared and used to improve the oral bioavailability of lutein. The structures of lutein-stachyose derivative (LS) were confirmed by Fourier transform infrared spectroscopy and hydrogen-1 nuclear magnetic resonance, indicating that one stachyose is connected to one lutein through succinic acid. The critical micelle concentration of LS was approximately 6.86 ± 0.24 mg/mL, corresponding to the free lutein concentration of approximately 2.96 mg/mL. LS has better digestive stability and free radical scavenging ability, and it could inhibit the degradation of lutein in the gastrointestinal tract. Importantly, LS is nontoxic to cells and zebrafish embryos. In terms of oral bioavailability in rats, the AUC0-12h values of LS were 2.26 times higher than those of free lutein. Therefore, stachyose modification is a promising strategy for improving the oral bioavailability of fat-soluble lutein.

Lutein Isomers: Preparation, Separation, Structure Elucidation, and Occurrence in 20 Medicinal Plants.

Lutein and its cis-isomers occur in a lot of plants, including a variety of flowers. In this study, lutein isomers were produced via iodine-catalyzed isomerization, and four cis-isomers (9Z-, 9'Z-, 13Z-, and 13Z') were isolated by means of column chromatography and semipreparative HPLC. The structures of the 9'Z- and 13'Z-isomers were elucidated via NMR measurements. These compounds were used as standards for the HPLC-DAD-MS determination of the carotenoid composition of the flowers of 20 plant species, in which lutein and its geometrical isomers are the main components. The flowers showed great variation in their cis- and trans-lutein content, and also in the presence or absence of other carotenoids, such as violaxanthin, neoxanthin, ß-cryptoxanthin, and ß-carotene. Some of the investigated flowers were found to be rich sources of lutein without zeaxanthin.

Polygalacturonase treatment affects carotenoid absorption from veggie juice.

The present study was conducted to investigate the effects of polygalacturonase (PG) treatment on carotenoid absorption upon digestion of HPH-treated combined peach and carrot juice (CJ) with or without the presence of lipids. Results showed that PG treatment reduced median particle diameter (D50) and viscosity of CJ, and increased total carotenoid bioaccessibility by 41%. In the presence of emulsion, the bioaccessibility of carotenoids was higher and it was not significantly affected by PG treatment. Xanthophylls (lutein and zeaxanthin) had higher bioaccessibility than the more lipophilic carotenes (ß-carotene and α-carotene); also, uptake in Caco-2 cells and transport of lutein and zeaxanthin were higher than for ß-carotene and α-carotene. Individual carotenoids bioaccessibility was negatively correlated with their transport. All together data showed digestion and absorption processes were two independent processes: factors improving carotenoid bioaccessibility did not necessarily affect their bioavailability.

Biodegradable film based on cress seed mucilage, modified with lutein, maltodextrin and alumina nanoparticles: Physicochemical properties and lutein controlled release.

In this study, maltodextrin (MDex), lutein pigment (Lut) and alumina (Al) were used to modify biodegradable film based on cress seed mucilage (Muc/MDex/Lut/Al). Central composite design (CCD) was used to study the effects of MDex, Lut and Al on the physical and chemical properties of the mucilage based film. The physicochemical, mechanical, antimicrobial and structural properties of the films were studied by various techniques such as FTIR, SEM, and XRD and TGA. The release of lutein from the film was investigated at 25 °C for 15 days. The results showed that lutein, alumina and maltodextrin increased the film thickness and lutein decreased the solubility and moisture content of the film. Maltodextrin improved the mechanical properties of the film and lutein reduced the film's flexibility. Lutein greatly increased its antioxidant properties, but alumina slightly increased its antioxidant properties. Lutein, alumina and maltodextrin improved the antibacterial properties of the film. Muc/MDex/Lut/Al film showed 26 ± 0.5 and 23 ± 0.8 mm non-growth halo against to Staphylococcus aureus and Escherichia coli, respectively. Maltodextrin filled the surface cracks, but lutein increased the surface cracks of mucilage film. The amorphous structure of the pure cress seed mucilage film was confirmed by XRD, which the alumina and lutein gave crystalline properties in the film. Maltodextrin and alumina increased the thermal stability of the film. The release results showed that the release rate of lutein depends on the structure of the film and by changing the structure of the film, the release rate can be purposefully controlled according to the required release rate.

Raman Spectroscopy of Carotenoid Compounds for Clinical Applications-A Review.

Carotenoid compounds are ubiquitous in nature, providing the characteristic colouring of many algae, bacteria, fruits and vegetables. They are a critical component of the human diet and play a key role in human nutrition, health and disease. Therefore, the clinical importance of qualitative and quantitative carotene content analysis is increasingly recognised. In this review, the structural and optical properties of carotenoid compounds are reviewed, differentiating between those of carotenes and xanthophylls. The strong non-resonant and resonant Raman spectroscopic signatures of carotenoids are described, and advances in the use of Raman spectroscopy to identify carotenoids in biological environments are reviewed. Focus is drawn to applications in nutritional analysis, optometry and serology, based on in vitro and ex vivo measurements in skin, retina and blood, and progress towards establishing the technique in a clinical environment, as well as challenges and future perspectives, are explored.

Silkworm carotenoprotein as an efficient carotenoid extractor, solubilizer and transporter.

Found in many organisms, water-soluble carotenoproteins are prospective antioxidant nanocarriers for biomedical applications. Yet, the toolkit of characterized carotenoproteins is rather limited: such proteins are either too specific binders of only few different carotenoids, or their ability to transfer carotenoids to various acceptor systems is unknown. Here, by focusing on a recently characterized recombinant ~27-kDa Carotenoid-Binding Protein from Bombyx mori (BmCBP) [Slonimskiy et al., International Journal of Biological Macromolecules 214 (2022): 664-671], we analyze its carotenoid-binding repertoire and potential as a carotenoid delivery module. We show that BmCBP forms productive complexes with both hydroxyl- and ketocarotenoids - lutein, zeaxanthin, astaxanthin, canthaxanthin and a smaller antioxidant, aporhodoxanthinone, but not with ß-carotene or retinal, which defines its broad ligand specificity toward xanthophylls valuable to human health. Moreover, the His-tagged BmCBP apoform is capable of cost-efficient and scalable enrichment of xanthophylls from various crude methanolic herbal extracts. Upon carotenoid binding, BmCBP remains monomeric and shows a remarkable ability to dynamically shuttle carotenoids to biological membrane models and to unrelated carotenoproteins, which in particular makes from the cyanobacterial Orange Carotenoid Protein a blue-light controlled photoswitch. Furthermore, administration of BmCBP loaded by zeaxanthin stimulates fibroblast growth, which is attractive for cell- and tissue-based assays.

Structural basis for the carotenoid binding and transport function of a START domain.

STARD3, a steroidogenic acute regulatory lipid transfer protein, was identified as a key xanthophyll-binding protein in the human retina. STARD3 and its homologs in invertebrates are known to bind and transport carotenoids, but this lacks structural elucidation. Here, we report high-resolution crystal structures of the apo- and zeaxanthin (ZEA)-bound carotenoid-binding protein from silkworm Bombyx mori (BmCBP). Having a STARD3-like fold, BmCBP features novel elements, including the Ω1-loop that, in the apoform, is uniquely fixed on the α4-helix by an R173-D279 salt bridge. We exploit absorbance, Raman and dichroism spectroscopy, and calorimetry to describe how ZEA and BmCBP mutually affect each other in the complex. We identify key carotenoid-binding residues, confirm their roles by ZEA-binding capacity and X-ray structures of BmCBP mutants, and also demonstrate that markedly different carotenoid-binding capacities of BmCBP and human STARD3 stem from differences in the structural organization of their carotenoid-binding cavity.

Lutein encapsulated in whey protein and citric acid potato starch ester: Construction and characterization of microcapsules.

The poor water solubility and stability of lutein limit its application in industry. Microencapsulation technology is an excellent strategy to solve these problems. This study used citric acid esterified potato starch and whey protein as an emulsifier to prepare oil-in-water lutein emulsion, and microcapsules were constructed by spray drying technology. The effects of different component proportions on microcapsules' microstructure, physical and chemical properties, and storage stability were analyzed. Citrate esterified potato starch had good emulsifying properties, and when compounded with whey protein, the encapsulation efficiency (EE) of microcapsules increased, and the embedding effect of lutein improved. After microencapsulation, the solubility of lutein increased significantly, reaching over 49.71 %, and gradually raised with more whey protein content. Furthermore, the high proportion of whey protein helped improve microcapsules' EE and thermal properties, with the maximum EE reaching 89.36 %. The glass transition temperatures of microcapsules were all higher than room temperature, which indicated that they keep a stable state under general storage conditions. The experimental results of this study may provide a reference for applying lutein in food and other fields.