Effect of tea polyphenols on chitosan packaging for food preservation: Physicochemical properties, bioactivity, and nutrition.

Chitosan packaging has been widely studied for food preservation, the application of which is expanded by the incorporation of tea polyphenols. This paper reviews the influence of tea polyphenols incorporation on chitosan-based packaging from the perspectives of physicochemical properties, bioactivity used for food preservation, and nutritional value. The physicochemical properties included optical properties, mechanical properties, water solubility, moisture content, and water vapor barrier property, concluding that the addition of tea polyphenols improved the opacity, water solubility, and water vapor barrier property of chitosan packaging, and the mechanical properties and water content were decreased. The bioactivity used for food preservation, that is antioxidant and antimicrobial properties, is enhanced by tea polyphenols, improving the preservation of food like meat, fruits, and vegetables. In the future, efforts will be needed to improve the mechanical properties of composite film and adjust the formula of tea polyphenols/chitosan composite film to apply to different foods. Besides, the identification and development of high nutritional value tea polyphenol/chitosan composite film is a valuable but challenging task. This review is expected to scientifically guide the application of tea polyphenols in chitosan packaging.

Efficient Utilization of Tea Resources through Encapsulation: Dual Perspectives from Core Material to Wall Material.

With the high production and consumption of tea around the world, efficient utilization of tea byproducts (tea pruning, tea residues after production, and drinking) is the focus of improving the economy of the tea industry. This review comprehensively discusses the efficient utilization of tea resources by encapsulation from the dual perspectives of core material and wall material. The core material is mainly tea polyphenols, followed by tea oils. The encapsulation system for tea polyphenols includes microcapsules, nanoparticles, emulsions, gels, conjugates, metal-organic frameworks, liposomes, and nanofibers. In addition, it is also diversified for the encapsulation of tea oils. Tea resources as wall materials refer to tea saponins, tea polyphenols, tea proteins, and tea polysaccharides. The application of the tea-based delivery system widely involves functionally fortified food, meat preservation, film, medical treatment, wastewater treatment, and plant protection. In the future, the coencapsulation of tea resources as core materials and other functional ingredients, the precise targeting of these tea resources, and the wide application of tea resources in wall materials need to be focused on. In conclusion, the described technofunctional properties and future research challenges in this review should be followed.

The encapsulation strategy to improve the survival of probiotics for food application: From rough multicellular to single-cell surface engineering and microbial mediation.

The application of probiotics is limited by the loss of survival due to food processing, storage, and gastrointestinal tract. Encapsulation is a key technology for overcoming these challenges. The review focuses on the latest progress in probiotic encapsulation since 2020, especially precision engineering on microbial surfaces and microbial-mediated role. Currently, the encapsulation materials include polysaccharides and proteins, followed by lipids, which is a traditional mainstream trend, while novel plant extracts and polyphenols are on the rise. Other natural materials and processing by-products are also involved. The encapsulation types are divided into rough multicellular encapsulation, precise single-cell encapsulation, and microbial-mediated encapsulation. Recent emerging techniques include cryomilling, 3D printing, spray-drying with a three-fluid coaxial nozzle, and microfluidic. Encapsulated probiotics applied in food is an upward trend in which "classic probiotic foods" (yogurt, cheese, butter, chocolate, etc.) are dominated, supplemented by "novel probiotic foods" (tea, peanut butter, and various dry-based foods). Future efforts mainly include the effect of novel encapsulation materials on probiotics in the gut, encapsulation strategy oriented by microbial enthusiasm and precise encapsulation, development of novel techniques that consider both cost and efficiency, and co-encapsulation of multiple strains. In conclusion, encapsulation provides a strong impetus for the food application of probiotics.

Development of pH-driven zein/tea saponin composite nanoparticles for encapsulation and oral delivery of curcumin.

The purpose of this paper was to overcome the challenges of curcumin by zein/tea saponin composite nanoparticles (Z/TSNPs) without any organic reagents and high-energy equipment. The spherical Z/TSNPs exhibited good physical stability, the conditions of which included pH at 5.0-8.0, heating at 80 ℃, ionic strength within 100 mM, and storage at 25 ℃ for 30 days. Meanwhile, Z/TSNPs showed excellent redispersibility. Z/TSNPs were used to encapsulate and deliver curcumin (Cur-Z/TSNPs), showing encapsulation efficiency and loading capacity of 83.73% and 22.33%, respectively. Cur-Z/TSNPs exhibited good chemical stability during storage, and the effect of light on Cur-Z/TSNPs was smaller than that of free curcumin. Furthermore, Cur-Z/TSNPs improved the solubilization and bioaccessibility of curcumin about 290 and 5 times, respectively. Besides, the encapsulation changed the crystalline state of curcumin to amorphous, and the pH-driven mechanism was probably related to hydrogen bonding, hydrophobic and electrostatic interactions.

Selective, highly efficient extraction of Cr(III), Pb(II) and Fe(III) from complex water environment with a tea residue derived porous gel adsorbent.

A novel macroporous (~150 µm) double network hydrogel (TR/PAA) was prepared from tea residue and acrylic acid, and its performance was systematically evaluated. The static adsorption experiments showed that gel exhibited high selectivity and adsorption capacity, ultrafast kinetics (~10 min) for Cr(III), Pb(II) and Fe(III). The adsorption behavior showed heterogeneous and chemisorption process adsorption capacities of 206.19, 253.16, and 94.88 mg g-1 for Cr(III), Pb(II) and Fe(III), respectively. In pluralistic systems, TR/PAA showed the adsorption order of Fe(III) > Cr(III) > Pb(II). Mechanism studies confirm that nitrogen and oxygen-containing functional groups play a major role in the adsorption process. In the fixed-bed column experiments, the treatment volume of simulated wastewater reached 1400 bed volumes (BV) (21.6 L), producing only 7 BV (323 mL) eluent. This work provides a new avenue for the combination of TR/PAA reuse and heavy metal removal, which is expected to be applied in actual wastewater treatment.