Enhance the resistance of probiotics by microencapsulation and biofilm construction based on rhamnogalacturonan I rich pectin.

Microcapsules were always used as functional material carriers for targeted delivery and meanwhile offering protection. However, microcapsule wall materials with specific properties were required, which makes the choice of wall material a key factor. In our previous study, a highly branched rhamnogalacturonan I rich (RG-I-rich) pectin was extracted from citrus canning processing water, which showed good gelling properties and binding ability, indicating it could be a potential microcapsule wall material. In the present study, Lactiplantibacillus plantarum GDMCC 1.140 and Lactobacillus rhamnosus were encapsulated by RG-I-rich pectin with embedding efficiencies of about 65 %. The environmental tolerance effect was evaluated under four different environmental stresses. Positive protection results were obtained under all four conditions, especially under H2O2 stress, the survival rate of probiotics embedded in microcapsules was about double that of free probiotics. The storage test showed that the total plate count of L. rhamnosus encapsulated in RG-I-rich pectin microcapsules could still reach 6.38 Log (CFU/mL) at 25 °C for 45 days. Moreover, probiotics embedded in microcapsules with additional incubation to form a biofilm layer inside could further improve the probiotics' activities significantly in the above experiments. In conclusion, RG-I-rich pectin may be a good microcapsule wall material for probiotics protection.

Regulating the physicochemical, structural characteristics and digestibility of potato starch by complexing with different phenolic acids.

The effects of ferulic acid (FA), protocatechuic acid (PA), and gallic acid (GA) on the physicochemical characteristics, structural properties, and in vitro digestion of gelatinized potato starch (PS) were investigated. Rapid viscosity analysis revealed that the gelatinized viscosity parameters of PS decreased after complexing with different phenolic acids. Dynamic rheology results showed that phenolic acids could reduce the values of G' and G″ of PS-phenolic acid complexes, demonstrating that the addition of phenolic acids weakened the viscoelasticity of starch gel. Fourier-transform infrared spectra and X-ray diffraction results elucidated that phenolic acids primarily reduced the degree of short-range ordered structure of starch through non-covalent interactions. The decrease in thermal stability and the more porous microstructure of the complexes confirmed that phenolic acids could interfere with the gel structure of the starch. The addition of different phenolic acids decreased the rapidly digestible starch (RDS) content and increased the resistant starch (RS) content, with GA exhibiting the best inhibitory capacity on starch in vitro digestibility, which might be associated with the number of hydroxy groups in phenolic acids. These results revealed that phenolic acids could affect the physicochemical characteristics of PS and regulate its digestion and might be a potential choice for producing slow digestibility starch foods.

Preparation and physicochemical properties characterization of hesperetin-grafted pectin conjugate.

Different ratios of hesperetin (HT) were successfully grafted onto pectin from basic water (PB) molecules via free radical-induced reaction. The structure of PB-HT conjugates was characterized by ultraviolet spectroscopy, infrared spectroscopy, X-ray diffraction and scanning electron microscopy. Results indicated that HT was successfully grafted onto pectin molecules, and PB-HT-0.5 showed the highest HT content (103.18 ± 2.76 mg/g). Thermogravimetric analysis indicated that HT crystals showed good thermal resistance and could improve the thermal stability of PB-HT conjugates. Additionally, PB-HT conjugates showed good cytocompatibility and blood compatibility. This study provides a novel and efficient method to synthesize hesperetin-grafted pectin conjugate, which showed potential application in the fields of functional foods in the future.

The role of alkali in sweet potato starch-Mesona chinensis Benth polysaccharide gels: Gelation, rheological and structural properties.

According to the Chinese traditional black jelly production process, a critical step to ensure the quality of jelly is to add alkali to it. In this study, the effects of sodium carbonate (Na2CO3) and sodium bicarbonate (NaHCO3) on the pasting, rheological, textural, and structural properties of sweet potato starch (SPS)-Mesona chinensis Benth polysaccharide (MCP) gels were evaluated. Adding Na2CO3 at low concentration reduced the final viscosity (FV) of SPS-MCP gels, whereas adding it at a high concentration increased the FV. Adding NaHCO3 can increase the FV of SPS-MCP gels in a concentration-dependent manner. Rheological results indicated that adding NaHCO3 at a low concentration decreased the storage modulus of SPS-MCP gels, whereas adding it at a high concentration increased the storage modulus. The storage modulus of SPS-MCP gels increased with increasing concentration of NaHCO3. The addition of Na2CO3 and NaHCO3 improved the textural properties of SPS-MCP gels and decreased the water mobility. Infrared results indicated that adding alkali can enhance the hydrogen bonding between SPS and MCP. Scanning electron microscopy results suggested that alkali can reduce the size of gels, and make the structure more compact.

Gelling mechanism and interactions of polysaccharides from Mesona blumes: Role of urea and calcium ions.

In this study, the relaxation modulus was used to elucidate the gelling mechanism of polysaccharides from Mesona blumes. The pH of Mesona blumes polysaccharides (MBP) was adjusted could significantly change the relaxation modulus of MBP. The results showed that the hydrogen bonds and electrostatic interaction existed in during the formation of MBP gel. The addition of salt ions (sodium ions and calcium ions), EDTA and urea have different effects on the relaxation modulus of MBP. Result showed that the hydrogen bond was the main force maintaining the MBP gel network structure, followed was calcium ions. And electrostatic interaction was not the decisive role of gel formation. The small molecules with active hydrogen-bond donors and/or acceptors were added into MBP, which proved -COOH was involved in the hydrogen bonds formation of MBP gel. In addition, the entanglement network number (ENN) results quantitatively assessed contribution of interaction: hydrogen bonds interaction > calcium ions (calcium bridge) >electrostatic interaction.

Physicochemical, rheological and thermal properties of Mesona chinensis polysaccharides obtained by sodium carbonate assisted and cellulase assisted extraction.

Mesona chinensis has been used as a Chinese folk medicine and main ingredient used to make "black bean jelly" in Asia for hundreds of years. In this study, two polysaccharides (MCP-C and MCP-S) from Mesona chinensis were extracted by using cellulase assisted extraction (CAE) and sodium carbonate assisted extraction (SAE), separately. Then the different physicochemical characteristics, rheological and thermal properties of two polysaccharides were analyzed by ion chromatography, high-performance gel permeation chromatography (HPGPC), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), rheological and thermogravimetric analysis. Results indicated that the contents of total sugar and uronic acid of MCP-C were higher than MCP-S, while the protein content and molecular weight was lower than that of MCP-S. MCP-S and MCP-C had differences in the surface morphology by SEM, while they all had the typical IR spectra characteristic and amorphous morphology of polysaccharides. The rheological experiments showed that MCP-C and MCP-S exhibited typical pseudoplasticity fluids behavior. The apparent viscosity (η), storage modulus (G') and complex viscosity (η*) of MCP-S were higher than MCP-C. The three-stage decomposition patterns were observed in MCP-C and MCP-S. MCP-S was more stable and had higher initial decomposition temperature (Ti) than MCP-C.

Characterizations and hepatoprotective effect of polysaccharides from Mesona blumes against tetrachloride-induced acute liver injury in mice.

Mesona blumes polysaccharide (MBP), a primary active component extracted from Mesona blumes, has a number of bioactivities. Nevertheless, hepatoprotective activity of MBP has been rarely reported. The purpose of this study is to investigate hepatoprotective effects of MBP on acute liver injury in mice. Results indicated that the MBP could remarkably decrease the increased levels of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) in the serum caused by tetrachloride (CCl4) treatment (P < 0.05). Medium and high dose of MBP treatment (200 mg/kg body weight, 300 mg/kg body weight) not only prominently enhanced the levels of antioxidant enzymes (superoxide dismutase, SOD) and non-enzyme antioxidants (glutathione, GSH) compared with CCl4-induced, but also dramatically decreased lipid peroxidation levels of liver tissues (P < 0.05). In addition, medium and high doses of MBP significantly enhanced the serum levels of IL-1ß and TNF-α (P < 0.05). This study showed that MBP had hepatoprotective activity against acute liver injury caused by CCl4.