| Cellulose nanofibers(CNF)isolated from the cell wall of wood have the advantages of large specific surface area,abundant hydroxyl groups,excellent water holding capacity,etc.,and are an ideal nano-scale polymer carrier material and a novel dietary fiber.Quercetin(QT)is a natural dietary flavonoid with many biological functions such as anti-oxidation,anti-cancer and anti-obesity.However,the instability and low water solubility of quercetin makes its bioavailability low.At present,most of the methods for improving the water solubility of quercetin have the disadvantages of complicated operation,long time consumption,and slight damage to the human body.In this paper,CNF is encapsulated as an effective nanocarrier by a simple,green and non-polluting method to form CNF/QT nanoformulations to alleviate these problems of quercetin application.TEM,SEM,FTIR,XRD and other methods were used to characterize and analyze the composition changes,micromorphology and erystal structure of nanoformuilations during the preparation process.The effects of CNF encapsulation and slow release and various experimental factors were discussed.The functional properties of the nanoformulations were analyzed.At the same time,the nanoformulations were applied to the yoghurt to form functional yoghurt,and the effect of the nanoformulations on the physicochemical properties,rheological properties and antioxidant capacity of the yoghurt was studied.The main research work and results carried out are as follows:(1)Different concentrations of ethanol solution were used as the main solvent,and the CNF/QT suspension was treated with an homogenizer to prepare nanoformulation.It was found by electron microscopy that when the ethanol concentration was 75%,after homogenization treatment,CNF could load well on QT,and QT was optimally encapsulated in CNF matrix to form CNF/QT nanoformulation.The maximum drug loading efficiency was 78.91%,and the maximum encapsulation efficiency was 88.77%.Solid analysis of nano-formulations found that CNF encapsulates QT mainly by hydrogen bonding.This treatment does not change the cellulose I crystal of CNF,but the effect of immobilization and encapsulation inhibits the recrystallization of QT.The nanoformulation is suitable for storage under normal temperature and low temperature conditions,and the heating temperature should not exceed 80℃.(2)The nanoformulations were tested for their functional properties.Compared with pure cellulose,nanoformulations possessed the basic characteristics of CNF and thus had better dietary characteristics.Under the same conditions,CNF/QT nanoformulations were more exposed than pure quercetin.The effective groups have stronger scavenging effects on DPPH free radicals,hydroxyl radicals and superoxide anion radicals,and the antioxidant index value is greater than 2.0,indicating that the antioxidant capacity of the nano-formulation can be maintained in the human physiological environment.(3)The nanoformulation was tested in vitro.The results showed that the release profile of QT accords with the first-order pharmacokinetic equation and can be divided into two stages.The high drug loading efficiency and encapsulation efficiency of nanoformulation made it have a good sustained release characteristics,the cumulative release after 24 hours of detection was less than 50%.(4)The physicochemical properties of the yogurt after adding the nanoformulation showed that the pH,acidity and hardness of the 0.002%and 0.012%nanoformulationyogurt did not change significantly compared with the blank yogurt.As the amount of the nano-formulation increased,the viscosity and the water holding capacityof the yogurt increased.Microscopic observation revealed that the nanoformulation made the protein structure of the yogurt more compact.(5)The results of antioxidant test on yoghurt showed that the DPPH free radical scavenging rate of yogurt with nanoformulation was significantly higher than that of blank yogurt,and yogurt had better antioxidant activities. |
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