Study On The Binding Characteristics Of Rice Bran Insoluble Dietary Fiber With Cd²⁺

Cd²⁺,which enters the body with diet,accumulates in the body for a long time,which is highly toxic and threatens the health of the body.Many studies have found that insoluble dietary fiber has the ability to bind Cd²⁺in vitro,but at present it is not clear about the binding law of its main fiber components?cellulose,hemicellulose and lignin?with Cd²⁺,in addition,whether insoluble dietary fiber can relieve the toxic damage of the body caused by Cd²⁺needs further study.The current clinical treatment methods?chelating agent method?and nutritional intervention methods used to alleviate the toxicity of Cd²⁺have defects in safety.Therefore,the use of insoluble dietary fiber to alleviate the body Cd²⁺toxicity dietary therapy has research value.Rice bran is rich in resources and low in cost,and is a good source of insoluble dietary fiber.This paper selects rice bran insoluble dietary fiber?Rice bran insoluble dietary fiber,RBIDF?as the experimental raw material,comprehensively evaluated the binding law of its main fiber components with Cd²⁺in vitro,and analyzed the ability of RBIDF to slow down the damage of Cd²⁺to the body.Using RBIDF prepared by enzyme-chemical method as the raw material,and the amount of combined Cd²⁺as a consideration index,the Cd²⁺binding ability of RBIDF prepared by vacuum freeze drying,hot air drying and spray drying was evaluated.The result indicated that vacuum freeze drying was the best drying method to prepare the sample.The Cd²⁺binding capacity of RBIDF,cellulose,hemicellulose and lignin was investigated.Fourier infrared spectroscopy,microscopic morphology and thermal stability results showed that the four samples can be used as potential materials to study the Cd²⁺binding ability.On this basis,the Cd²⁺binding rule of RBIDF and its separated components was analyzed by correlation Cd²⁺binding experiment.The results showed that the optimal Cd²⁺binding pH of the four samples was 6.0,7.0,6.0 and 7.0,and the optimal Cd²⁺binding reaction time was 3,4,3 and 3 h,respectively.The kinetic study found that the four samples had strong affinity for Cd²⁺;the reaction proceeded to 10 minutes and basically reached the binding equilibrium.The equilibrium Cd²⁺binding amount of cellulose was 5.63 mg/g,which was 1.8 and 3.7 times of that of hemicellulose and lignin respectively.The fitting of the kinetic model showed that the Cd²⁺binding behavior of the sample was more consistent with the quasi-first-order kinetic model controlled by the physical diffusion process.Combining with isotherm analysis,the process of Cd²⁺binding of the four samples was endothermic reaction,and heating?40°C?was more favorable for Cd²⁺.At the same time,the initial concentration of Cd²⁺in the solution had an obvious influence on the Cd²⁺binding amount of RBIDF and rice bran cellulose,hemicellulose and lignin.The fitting result of isotherm model illustrated that Langmuir model was more suitable for describing binding Cd²⁺behavior of RBIDF,cellulose and hemicellulose,indicating that homogeneous single molecule chemical binding reaction was dominant.Lignin was more suitable to be described by Freundlich model,indicating that the lignin binding to Cd²⁺was a heterogeneous multi-layer binding process.The inherent law of Cd²⁺binding capacity of RBIDF,rice bran cellulose,hemicellulose and lignin were further explored in this study.The microscopy analysis showed that the microstructures of the four samples changed greatly before and after binding with Cd²⁺.The fourier transform infrared spectroscopy analysis showed that the oxygen-containing groups such as-OH and C=O on the surfaces of the four samples had a strong interaction with Cd²⁺.The X-ray photoelectron spectroscopy results showed that the Cd²⁺binding reaction of binding to with the samples were mainly due to the formation of Cd?OH?₂ precipitates and Cd-O-.At the same time,the effects of minerals or casein hydrolysate on Cd²⁺binding ability of RBIDF and rice bran cellulose,hemicellulose and lignin were investigated.The results suggested that the Cd²⁺binding capacity of RBIDF,cellulose and hemicellulose was higher than mineral ions when the mineral ions coexisted with Cd²⁺at the same concentration?50mg/L?.In the presence of casein hydrolysate,the Cd²⁺binding amount of RBIDF decreased by18.37%.Finally,the ability of RBIDF to slow down the damage of Cd²⁺to the organism was investigated.The results implied that RBIDF preventive treatment can alleviate the decrease of liver organ index and kidney organ index caused by Cd²⁺.RBIDF can reduce the increase of serum ALT and AST and the decrease of CREA and UREA caused by Cd²⁺exposure.At the same time,RBIDF can alleviate the toxic damage and morphological changes of mouse organs exposed by Cd²⁺exposure.At the end of the intragastric cycle,the content of Cd²⁺in feces of mice treated with RBIDF was 4.08 times that of mice treated with Cd²⁺.