Preparation and characterization of tea polyphenol composite microspheres encapsulated using sodium alginate and crosslinked starch

As promising regulators of human health, tea polyphenols (TP) possess the ability to alleviate intestinal dysbiosis and restore balance in the co-metabolic processes of host-intestinal flora. However, these polyphenols are sensitive to potential destruction throughout the digestive process, limiting their ultimate bioavailability. To facilitate controlled TP release within the gastrointestinal tract, TP-loaded composite microspheres were prepared using sodium alginate (SA) and crosslinked corn starch (CP). The prepared microspheres were characterized via Fourier transform infrared spectroscopy (FTIR), differential scanning calorimeter synchronous thermal analyzer (DSC-TGA), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The properties of these microspheres were additionally examined through swelling assays, in vitro simulated release assays, and in vitro batch fermentation experiments. The outcome revealed that the prepared SA-crosslinked porous starch TP microspheres (CPMS) exhibited a significantly improved TP loading capacity (430.26 ± 16.71 mg/g). In vitro release assays demonstrated that the levels of TP release from CPMS in simulated colon fluid (325.05 ± 3.97 mg/mL) were significantly higher than that in simulated gastric fluid. In summary, the CPMS microspheres prepared herein can effectively achieve an improved TP loading, while exhibiting pH-responsive properties, and can effectively regulate the homeostatic balance of the intestinal microbiota.