Abstract
Maintaining probiotic viability during tablet manufacturing and storage remains a critical challenge in functional food development. In this study, a double-layer microencapsulation system was developed using porous starch (PS) as the core carrier and cellulose derivatives (microcrystalline cellulose, MCC; hydroxypropyl cellulose, HPC; and hydroxypropyl methylcellulose, HPMC) as coating materials to enhance probiotic protection and tableting performance. Among the formulations, PS–HPMC presented the highest encapsulation efficiency, which was ascribed to the formation of a compact coating structure. The double-layer microcapsules significantly improved the stress resistance of Lactobacillus plantarum. In particular, the PS–HPMC system showed viability losses of 0.07 log CFU/g under acidic conditions and 1.97 log CFU/g under bile salt treatment, and it retained a survival rate of 44.09% after tablet compression. In vitro gastrointestinal digestion revealed a controlled release profile of probiotics, which followed the Korsmeyer–Peppas model. A viable count of 6.67 log CFU/g was maintained after digestion, demonstrating effective protection of probiotics during gastrointestinal transit. In addition, PS–HPMC tablets preserved 10.80 ± 0.02 log CFU/g after 30 days of storage at 4 °C, and the predicted shelf life based on the first-order kinetic model reached 202.6 days, indicating the double-layer structure enhanced storage stability and prolonged shelf life. The prepared tablets also exhibited satisfactory mechanical strength and disintegration properties. Overall, the cellulose-coated porous starch system effectively enhanced the viability and stability of probiotics in solid dosage forms, providing a promising strategy for the development of functional foods.
Introduction
Probiotics have garnered considerable attention for their potential health benefits, which encompass the enhancement of gut health, reinforcement of immune function, and prevention of diseases [1]. By safeguarding gastrointestinal health and modulating the host’s gut microbiota, probiotics can exert influence on metabolism and immunity [2]. When administered as live bacteria in adequate quantities, probiotics confer health advantages to individuals and can be utilized as dietary supplement. These beneficial effects have led to the development of various solid oral delivery systems for probiotics, including powders, capsules, and chewable tablets. Tablets, in particular, are highly valued for their convenience and superior physicochemical stability. Relative to alternative dosage forms, tablets offer several distinct advantages, such as precise unit-dose accuracy, simplified administration, high patient acceptability, and compatibility with high-throughput, cost-effective manufacturing. However, probiotics are susceptible to numerous factors encountered during food processing and storage, such as heat, oxygen, water activity, extreme pH conditions, bile salts, enzymes, and physiological environments in the body, all of which can impact their viability [3]. The elevated compression forces involved in tablet formulation introduce shear and thermal stress that can compromise probiotic viability. Consequently, there is an urgent imperative to develop effective protective strategies to enhance probiotic viability in tablet formulations.
Probiotic encapsulation technology protects viable cells by embedding them within a soft-matter matrix, which enhances storage stability and enables targeted release in the colon [4]. Among various biopolymers, porous starch (PS) is regarded as a promising encapsulation carrier owing to its excellent biocompatibility, safety, and low cost. Its porous architecture significantly enhances loading capacity and confers improved resistance to environmental stresses on probiotics. For instance, Zhu et al. [5] developed an ultrasound-precipitation method combined with mild gelatinization to prepare PS with controllable pore sizes by regulating the amylose to amylopectin ratio, which achieved a high encapsulation efficiency for Lactobacillus plantarum and notably improved heat resistance. Firdaus et al. [6] utilized arrowroot derived PS via enzymatic hydrolysis and spray drying, achieving an encapsulation efficiency of 85.39% for L. acidophilus and demonstrating satisfactory viability during low-temperature storage. Polysaccharide modification has been a promising strategy to enhance the physicochemical properties of PS. Shi et al. [7] designed chitosan-modified PS (CMPS) for oral mucosal probiotic delivery, which significantly enhanced mucoadhesion (47.96% retention after 30 min saliva rinsing) and storage stability. Cellulose, a natural polymer known for its abundance, biodegradability [8], and excellent compatibility with other polymers [9], has been widely employed in various areas. However, the strong hydrogen bonding in cellulose renders its native form water-insoluble, posing a practical challenge that should be addressed. Cellulose derivatives, such as Microcrystalline cellulose (MCC), hydroxypropyl cellulose (HPC), and hydroxypropyl methylcellulose (HPMC), are water soluble polymers valued for their gel-forming (hydrogel, cryogel, aerogel), film-forming, and cross-linking properties, have been extensively employed across diverse industries, ranging from food and cosmetics to pharmaceuticals and textiles. MCC utilized its high crystallinity and rigid particles to enhance the compressive strength and structural integrity of the composite. HPMC and HPC are common film formers in orally disintegrating tablets. HPMC is well known for its tablet/granule coating applications, whereas HPC, despite some film-coating use, functions mainly as a binder [10]. These cellulose derivatives exhibit significant potential in enhancing compressive strength, flexibility, and barrier properties owing to their exceptional compatibility [11]. Consequently, starch/cellulose composites offer a promising strategy for probiotic microencapsulation, capable of both increasing loading efficiency and shielding probiotics from harsh environmental conditions.
Despite the promising properties of porous starch and cellulose derivatives, little research has been devoted to their combined application in double-layer microencapsulation systems for probiotic delivery. The synergistic effects of PS and different cellulose derivatives on encapsulation efficiency, stress resistance and tableting behavior remain unclear. Therefore, this study developed a double-layer system using porous starch coated with MCC, HPC, and HPMC to improve probiotic stability. The structural characteristics, stress protection, tableting performance, and storage stability were systematically evaluated, providing insights into polysaccharide-based delivery systems for solid formulations.
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Materials
PS, MCC, HPC and HPMC were obtained from Wan bang Chemical Technology Co., Ltd. (Henan, China). The PS exhibited a specific surface area of 1.4985 m2/g and a pore volume of 0.0032 cm3/g as determined by BET analysis. All other chemicals utilized in this study were of food-grade quality. The Lactobacillus plantarum YZX21 strain was sourced from Zhong chuang Yike (Shanghai) Biotech Co., Ltd.
Guoqi Na, Minxin Zou, Lu Kong, Xiufa Hu, Xinnan Liu, Qingyu Yang, Double encapsulation with porous starch and cellulose: A strategy for enhanced probiotic protection in microcapsules and tablets, International Journal of Biological Macromolecules, Volume 370, 2026, 152959, ISSN 0141-8130, https://doi.org/10.1016/j.ijbiomac.2026.152959.
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