| Finger citron pomace consisting principally of skins is the processing waste of finger citron pastes or juice.It will cause environmental problems.Finger citron pomace is rich in dietary fiber pectin,and has very important developing Value.In this paper,the extraction and modified technology of pectin from finger citron pomace(FCP)was investigated,and the cadmium adsorption capacity of the modified pecin was explored.The preventive effect of FCP on cadmium induced injury of liver and kidney was also studied.The study can provide application foundation and technical support for comprehensive utilization of finger citron pomace.The main content is as follows:Pectin was extracted by acids-only extraction method and ultrasonic treatment extraction method from finger citron peel.Response surface methodology was used to optimize the extraction process.The extraction yield of FCP was 22.7% under the optimal experimental conditions of 70°C,40 min,1:60(g/m L),1.5 and 350 W for temperature,extraction time,solid-to-solvent ratio,pH and ultrasonic power respectively.Modified finger citron pectin(m FCP)is produced from citrus pectin via pH and temperature modification that breaks it into shorter,non-branched,galactose-rich carbohydrate chains.The esterification degree(DE)of pectin was measured by alkali titration and Fourier transform infrared spectroscopy.The DE of FCP and mFCP were 78.3%-81.5% and 35.4%-45.6%,respectively.The molecular weight(MW)of pectin were determined by high efficiency gel permeation chromatography(HPGPC).The MW of FCP and mFCP were 552.865 kDa-671.713 k Da and 57.015 kDa-63.529 kDa,respectively.These results suggest that the modification process can significantly reduce the DE and MW of the pectin.The cadmium adsorption kinetics and thermodynamic analysis of FCP and m FCP were carried out.The results showed that the adsorption equilibrium concentration of cadmium by the mFCP was significantly higher than that of the FCP under the same concentrations.The cadmium adsorption isotherm curve of the m FCP was best fitted with the LangmuirFreundlich model,which suggested that the process of the adsorption of cadmium by the pectin is mainly involved in the ion exchange process.The cadmium adsorption capacity of FCP was similar to that of commercial citron pectin,which was significantly improved after modification.A 20-day gavage experiment using ICR mice was performed to explore the preventive effect of pectin to cadmium-induced liver and kidney injury.The results showed that both FCP and m FCP significantly alleviated the increased AST,ALT,total bilirubin,?GT,urea nitrogen,creatinine in plasma,and urinary albumin level,which caused by cadmium exposure.In addition,both FCP and mFCP also markedly remitted cadmium induced oxidative stress and increased the activities of SOD,CAT and GPx in the liver and kidney of the mice.The cadmium concentration in the blood liver kidney and urine of the prevention group was significantly lower than that of cadmium exposed mice,while the cadmium content in feces was significantly higher than that of cadmium exposed mice.The intestinal absorption capacity of pectin was analyzed by Ussing-Chamber system.The results suggested that both FCP and mFCP used in this experiment were not able to enter the inner circulation through the intestinal wall.Both FCP and mFCP adsorbe cadmium in the gastrointestinal tract and reduced the cadmium in the intestinal.Cadmium was excrete out of the body through feces,which further prevent the injury of liver and kidney caused by cadmium exposure. |
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