Vitamin D microencapsulation with probiotics (successful, but there are other ways)

Enhancing probiotic viability and vitamin D3 stability in co-microcapsules: Collaborative effects of W1/O/W2 double emulsion and HPMCP-fortified composite coating

Food Research InternationalVolume 235, 1 July 2026, https://doi.org/10.1016/j.foodres.2026.119104

Highlights* HPMCP-fortified W1/O/W2 microcapsules enable co-delivery of probiotics and vitD3.* W/O/W enhances probiotic survival by ∼1 log CFU/g vs O/W after heat drying.* HPMCP exhibits lowest inactivation rate for probiotics and vitD3 during storage.* HPMCP facilitates pH-responsive release in the gastrointestinal tract.* HPMCP-fortified W/O/W has lowest probiotic loss and highest vitD3 bioaccessibility.

Traditional spray-dried microencapsulation systems often exhibit limited thermal protection during drying process, inadequate barrier functionality throughout storage, and suboptimal control over gastrointestinal release.

To address these limitations, the present study developed a spray-dried microencapsulation platform using a W1/O/W2 double emulsion combined with a hypromellose phthalate (HPMCP)-enhanced composite coating to co-deliver the probiotic Lactiplantibacillus plantarum JYLP-326 and vitamin D3 (vitD3). First, the physicochemical properties of the composite coating materials and the resulting microcapsules were systematically characterized using various experimental and simulation methods. Subsequently, the influences of W1/O/W2 architecture and HPMCP incorporation on microcapsule performance were comprehensively investigated. The W1/O/W2 structure was found to be crucial in protecting probiotics during spray drying, attributable to the energy-absorbing and thermal-insulating properties of the intermediate lipid phase. In contrast, HPMCP integration was more effective in enhancing storage stability and facilitating pH-responsive release during simulated digestion, mechanistically attributed to a reinforced barrier network, higher glass transition temperature, and increased hydrophobicity. Compared to formulations lacking either W1/O/W2 structure or HPMCP, the combined W1/O/W2-HS microcapsules showed the highest probiotic viability after drying (93.6 ± 1.7%), lowest probiotic inactivation (0.39 ± 0.04 log CFU g−1), and greatest vitD3 bioaccessibility (71.5 ± 1.2%) post-digestion. They also demonstrated the lowest inactivation rates during storage (−0.060 log CFU g−1 day−1 for probiotics and −0.305% day−1 for vitD3). This study highlights how rational emulsion architecture and wall material design can address processing and storage challenges, offering an industrially scalable and effective strategy for co-encapsulating nutrients with diverse chemical properties.

Introduction

Numerous natural food resources, including various probiotics and vitamins, are garnering increasing attention due to their disease-preventive and health-promoting properties (Harahap & Suliburska, 2021, Harahap et al., 2022, Harahap & Suliburska, 2023). These bioactive components are generally intolerant to oxygen, heat, and acidic environments, which considerably restricts their application in functional foods. As global demand for functional foods continues to rise, the effective delivery of sensitive ingredients has become a significant challenge in food science (Espinoza-Espinoza et al., 2024; Xie et al., 2023). Microencapsulation technology, which utilizes polymeric wall materials to create a physical barrier, can effectively protect core components from adverse external factors, providing a viable solution to this issue (Castillo-Barzola et al., 2025; Cui et al., 2023). Spray drying is a prevalent industrial technique for producing microencapsulated products because of its simplicity, cost-effectiveness, and high processing efficiency. However, exposure to elevated temperatures during spray drying can significantly compromise the stability and bioactivity of sensitive ingredients (Dumitrașcu et al., 2021; Wang et al., 2021).

In recent years, lipid-based microcapsules have increasingly attracted the interest of researchers (Phumsombat et al., 2024). Lipid materials not only provide typical hydrophobic physical barriers but also serve as thermal protectants, reducing heat damage to sensitive ingredients during drying. For lipid-based microcapsules, establishing an optimal emulsion system before initiating the drying process is crucial to achieving effective integration of the core and wall materials, thereby forming a stable microcapsule structure. The W1/O/W2 double emulsion is a promising lipid-based emulsion system. Unlike conventional emulsification systems, such as aqueous or oil-in-water (O/W) emulsions, hydrophilic substances in W1/O/W2 emulsions are dispersed in the internal aqueous phase (W1) and fully surrounded by the oily phase (O); the O phase can then encapsulate lipophilic components in the external aqueous phase (W2) (Kumar et al., 2022; Saffarionpour & Diosady, 2021). Consequently, W1/O/W2 double emulsions offer significant advantages for the simultaneous and efficient encapsulation of both hydrophilic and lipophilic compounds (Li et al., 2025). To date, there are few reports on using double emulsion systems to encapsulate probiotics followed by spray drying. Yin et al. (2024) used solid fat as the oil phase in W1/O/W2 emulsions to encapsulate L. rhamnosus GG, demonstrating that the oil phase significantly protects probiotics, enhancing their viability during drying and storage. However, clear leakage of probiotics from the original W1 phase to W2 was observed during the preparation process, which may reduce encapsulation efficiency (Coelho et al., 2022). Similar phenomena have also been frequently observed in studies of W1/O/W2 emulsions for embedding small-molecule compounds (He et al., 2024; Hu et al., 2022).

Currently, the selection and incorporation of protective materials represent the primary strategies for improving the encapsulation efficiency of W1/O/W2 emulsions and the subsequent spray-dried microcapsules. The integration of suitable polymeric materials within the W2 phase not only inhibits the outward migration of internal components and offers concurrent protection for both the W1 and O phases, but also modifies the surface characteristics of the microcapsules, thereby conferring customized release properties during digestion (Boostani & Jafari, 2021; Coimbra et al., 2021). Zhu et al. (2024) and He et al. (2023) utilized fucoidan-chitosan nanogels and chitosan-alginate self-assembly technology, respectively, to construct protective hydrogel networks on the outer layer of W1/O/W2 emulsions for improved viability during pasteurization and targeted intestinal delivery of probiotics. Hua et al. (2024) employed ovalbumin fibril/pectin complexes as the external phase stabilizer to develop bilayer-stabilized W1/O/W2 emulsions, successfully achieving the targeted release of curcumin and Lactobacillus plantarum in the small intestine and colon, respectively. However, the high viscosity of resulting emulsion, the complexity of the processes and the limited availability of specific materials involved in these studies have, to some extent, restricted their translation to food industrial applications.

Hydroxypropyl methylcellulose phthalate (HPMCP), used as an enteric coating material, is well-known for its remarkable pH-dependent solubility and film-forming properties (Kämäräinen et al., 2024; Nogami et al., 2021). Its solubility profile renders it insoluble in acidic environments (pH 1.2–3.0), thereby forming a protective barrier, while it rapidly dissolves in neutral environments (pH 5.0–7.0), facilitating targeted release and effectively fulfilling the delivery requirements of acid-sensitive components. Additionally, HPMCP's exceptional film-forming ability contributes to the formation of a dense network of wall material, thus enhancing the product's storage stability. Compared to other enteric materials, HPMCP exhibits relatively lower viscosity and cost-effectiveness, providing flexibility and economic advantages for industrial applications (Kalmer et al., 2023). Notably, HPMCP is among the few water-soluble enteric materials that can be prepared without using organic solvents, a critical feature for preserving probiotic viability. Despite these numerous advantages, research on the application of HPMCP in emulsion embedding systems and its interactions with other food-grade polymers remains limited.

To overcome the limitations of conventional emulsions regarding complete encapsulation and targeted release, and to explore the application potential of HPMCP in nutrients-encapsulated double emulsions, this study developed a novel solid microcapsule based on W1/O/W2 double emulsions, incorporating HPMCP into the W2 to enhance wall material properties, for the co-encapsulation of Lactiplantibacillus plantarum JYLP-326 and vitamin D3 (vitD3). The main aim of the research to examine the effects of the W1/O/W2 structure and HPMCP incorporation on probiotic viability, encapsulation efficiency, microstructure, storage stability, in vitro release, and bioaccessibility of co-encapsulated powders, for providing new strategies and a theoretical basis for developing efficient, targeted co-delivery systems for probiotics and vitamins.

Section snippets

Materials

The probiotic strain L. plantarum JYLP-326 was provided by Zhongke Jiayi Biotechnology Co., Ltd. (Weifang, Shandong, China). The strain was identified by 16S rRNA gene sequencing before use, and its stock cultures were stored at −80 °C in MRS broth containing 20% (v/v) glycerol. VitD3 (cholecalciferol, 98% purity) was purchased from Sigma-Aldrich (Shanghai, China). Octenyl succinic anhydride-modified starch (OSA-starch, HI-CAP 100®) and Hypromellose phthalate (HPMCP, HP-50) were purchased from FTIR analysis . . . .

To evaluate the influence of HPMCP incorporation on intermolecular interactions, the infrared spectra of the composite Film-HS, which comprises OSA-starch and HPMCP, were analyzed and compared with those of the individual HPMCP film (Film-H) and the OSA-starch film (Film-S) (Fig. 1A). The infrared spectrum of Film-HS did not exhibit any new absorption peaks compared to Film-H and Film-S, indicating the absence of covalent interactions between OSA-starch and HPMCP molecules. Further analysis . . .

Conclusion

This study explored a delivery platform that integrates the structural advantages of W1/O/W2 double emulsions with the functional properties of HPMCP-fortified wall materials for the co-encapsulation of L. plantarum and vitD3. The incorporation of HPMCP facilitated rapid film formation, enhanced hydrophobicity and Tg, reduced water vapor permeability, and strengthened intermolecular interactions. This dense matrix formed an effective barrier against moisture, oxygen, and gastric acid, thereby . . .

Note: Can accomplish the same thing by taking gut-friendly Vitamin D and time-release/gut-friendly Probiotics separately

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