Metal ion-mediated modulation of morphology, physicochemical properties, and digestibility of type 3 resistant starch microparticle.

Short-chain glucan (SCG) derived from debranched amylopectin has emerged as a promising candidate for the production of resistant starch particle (RSP) due to its controllable self-assembly features. Here, we investigated the effect of metal cations with different valencies and concentrations on the morphology, physicochemical properties, and digestibility of RSP formed by the self-assembly of SCG. The effect of cations on the formation of RSP followed the valency in the following order: Na+, Ka+, Mg2+, Ca2+, Fe3+, and Al3+, of which 10 mM trivalent cations increased the particle size of RSP over 2 µm and considerably decreased the crystallinity by 49.5 % ~ 50.9 %, which were significantly different from that of mono- and divalent ones. Importantly, RSP formed with divalent cations switched the surface charge from -18.6 mV to 12.9 mV, which significantly increased the RS level, indicating that metal cations would be useful for regulating physicochemical properties and digestibility of RSP.

Impact of solvent polarity on the morphology, physicochemical properties, and digestibility of A-type resistant starch particles.

Resistant starch particles (RSP) formed by antisolvent precipitation method has attracted much attention as a functional food ingredient having beneficial effects on obesity and diabetes. However, the effect of solvent polarity on the physicochemical properties and digestibility of RSP remains unclear. Here, n-propanol, isopropanol, acetone, and ethanol were employed as antisolvents to prepare RSP. The width and length of the resulting RSP decreased from 0.87 µm to 0.59 µm and from 2.56 µm to 1.31 µm, respectively, upon increasing the solvent polarity, while dramatically decreasing their crystallinity and the gelatinization enthalpy from 80.5% to 62.3% and from 67.9 ± 14.4 J/g to 41.5 ± 8.3 J/g, respectively, suggesting that solvent polarity is critical factor determining morphology, crystallinity, and thermostability of RSP. Furthermore, the level of resistant starch in RSP was found to be inversely proportional to the degree of solvent polarity, which would provide a useful means for modulating the digestibility of RSP.

Facile preparation of highly uniform type 3 resistant starch nanoparticles.

Resistant starch (RS) has emerged as a promising functional food ingredient. To improve the textural and sensory characteristics of RS, there need to be an effective approach to produce RS with well-defined size and shape. Here, we present a facile approach for the synthesis of highly uniform resistant starch nanoparticles (RSNP) based on recrystallization of short-chain glucan (SCG) originated from debranched starch. We found that the ratio of SCG to partially debranched amylopectin was a key parameter in regulating the morphology, size, and crystallinity of the nanoparticles, which enable us to prepare highly uniform RSNP with an average diameter of around 150 nm, while showing a good colloidal stability over a broad range of pH (2-10). Moreover, the in-vitro digestibility and RS content of RSNP was not affected over the ten successive cycles of assembly and disassembly, which would provide useful insights for the development of RS-based functional food ingredients.

Mn(II)-Mediated Self-Assembly of Tea Polysaccharide Nanoparticles and Their Functional Role in Mice with Type 2 Diabetes.

Tea polysaccharide (TPS) is a bioactive compound that has attracted increasing attention for its health effect on regulating the metabolism of glucose and lipid. Moreover, due to their good biocompatibility and biodegradability, TPS-based nanoparticles have emerged as effective nanocarriers for the delivery of bioactive molecules. In this study, we developed a TPS-based biocarrier system for the orally targeted administration of Mn(II) ions and investigated their antidiabetic effects in C57BL/6 mice with HFD/streptozotocin (STZ)-induced T2DM. Mn(II)-loaded TPS-based nanoparticles (MTNPs) were synthesized, in which negatively charged functional groups in protein and uronic acid in TPS conjugates would act as binding sites for Mn(II) ions, which is responsible for the cross-linking reaction of MTNP. The resulting MTNP had a spherical shape and a mean particle size of around 30 nm with a Mn(II) ion content of 2.24 ± 0.13 mg/g. In T2DM mice, we discovered that MTNP treatment significantly lowered blood glucose levels and improved glucose intolerance. Furthermore, the impact of MTNP on the recovery of FINS, the homeostatic index of insulin resistance (HOMA-IR), and the homeostatic index of ß-cell (HOMA ß-cell) levels was significantly larger (p < 0.05) than TPS alone, demonstrating that Mn(II) ions can enhance TPS's ability to repair HFD/STZ-induced ß-cell damage. Mn(II) ions in MTNP not only acted as cofactors to increase the exocytosis of insulin secretory cells by upregulating the expression of Ca(II)/calmodulin-dependent protein kinase II (CaMK II) but also promoted TPS's lipid-lowering effect in T2DM mice by inhibiting glucogenesis and regulating the lipid metabolism. Our findings suggest that Mn(II) ions can be used not only as cross-linkers in the formation of nanoparticulated TPS but also as cofactors in improving the functional role of TPS in regulating the glucose and lipid metabolism, which will provide insights into the development of TPS-based drug delivery systems for the prevention of type 2 diabetes.

Fabrication of starch/zein-based microcapsules for encapsulation and delivery of fucoxanthin.

As a drug carrier, starch-based microparticle (SMP) has attracted widespread attention. However, because SMP is commonly formed in aqueous media, it is facing the challenge of encapsulation of hydrophobic bioactive. Here, we present an effective method for encapsulating fucoxanthin (Fx), a model hydrophobic bioactive, within SMP formed by self-assembly of short-chain glucans (SCG), using zein nanoparticles as intermediate vectors. SMP exhibited higher encapsulation efficiency to chitosan-coated Fx-zein nanoparticles (∼91%) at a given concentration of 50 µg/mL compared to soybean polysaccharide-coated ones. Fx in SMP was found to be more stable against UV radiation-induced degradation and FeCl3-catalyzed oxidative stresses than free Fx. Furthermore, SMP conferred controlled release of Fx in the duodenum (6%), jejunum (13%), ileum (32%), and colon (42%), implying that this approach could be useful in designing an effective drug carrier for delivering several hydrophobic bioactives to different parts of the intestine.