Preparation Of Orange Peel Modified Adsorbent And Its Application In Purine Removal

In the human body,purine metabolism eventually produces uric acid.Excessive uric acid will cause gout,and large intake of high-purine food is easy to induce gout.With the development of society,gout has become a high incidence of middle-aged and elderly people,and the signs of disease are becoming younger year by year.Therefore,it is of great significance to explore the elimination of purine in food.The commonly used purine removal methods include ultrasonic treatment,changing processing methods,salting out and adsorbent adsorption,etc.Adsorption method is more suitable for liquid samples due to better separation of adsorbent and adsorbent.At present,the research on the adsorption method focuses on purine removal in soybean products and beer,but the research on meat products is less.Citrus peel has the potential to be prepared as adsorbent because of its typical porous structure,abundant substance composition and non-toxic properties.The adsorption material with ideal properties can be obtained by proper modification.It has been modified to prepare adsorbents for the adsorption of bovine serum protein,metal ions in wastewater and free fatty acids in rapeseed oil.Based on this,this topic uses high performance liquid chromatography to determine the content of purine,and uses agricultural and forestry waste citrus peel as raw material chemical modification preparation adsorbent purine adsorption,and then explores its impact on food quality.In order to improve the added value of citrus peel waste to open up a new way and to establish a suitable,reliable,operational purine removal method to provide a theoretical basis.The main research contents and results are as follows:（1）By investigating the column type and the ratio of mobile phases,and the separation effect of p H on the four purines,the chromatographic conditions for purine detection were set as:column Waters T3（4.6×250 mm,5μm）,mobile phase KH₂PO₄-H₃PO₄（0.02 mol/L,p H=4.0）,flow rate 1.0 m L/min,column temperature 30°C,UV detector detection wavelength 254 nm,injection volume 10μL.Under this chromatographic condition,the four purines showed a good linear relationship in the corresponding detection concentration range（R²≥0.9998,detection limit of 0.02～0.04mg/L）,through the precision test and recovery detection,all meet the requirements of the analysis and inspection.（2）The adsorption effect of orange peel adsorption materials prepared by different modified treatment agents on purines is significantly different（P<0.05）,of which MOP1 has the best adsorption performance,that is,orange peel adsorption materials modified by alkali method.On the basis of the preparation of modified adsorbent by alkali method,the best MOP1 modification conditions were determined by using univariate and orthogonal tests,and the adsorption rate and adsorption amount of purine were used as the evaluation index,and the adsorbent treatment process with the best adsorption effect was 43.13%.The adsorption capacity was 49.17 mg/g.The modified adsorbent could be well separated from the purine solution.The resulting MOP1 was used in subsequent tests.By fitting the adsorption kinetic equation and adsorption isotherm,it was found that the correlation coefficient R² of the quasi-secondary kinetics simulation was 0.9927,and the correlation coefficient R² of the Langmuir isothermal adsorption model was greater than 0.99,and the results showed that the adsorption of purine by MOP1 was a chemical adsorption of the single-molecule layer.The results of scanning electron microscopy and infrared spectroscopy showed that chemical modification had an impact on the morphology and microstructure of orange peel.Under scanning electron microscopy,the modified orange peel MOP1 is more loose than the OP surface,some impurities and substances that are not conducive to adsorption are removed,the pores are increased,the pore size is increased,the active site is increased,and the adsorption capacity is enhanced.In the infrared spectral spectrum,the intensity of the MOP1 band changed significantly,indicating that the hydrogen bond stability on the surface of the adsorbent was weakened and the content of free hydroxyl groups increased;-COOCH₃ was saponified into-COO,so that the modified adsorption material MOP1 was modified selective adsorption of purines occurred.（3）Through the univariate and orthogonal tests in the process of MOP1 adsorption purine,the best purine removal conditions were:MOP1 dosing amount of 4000 mg/L,adsorption temperature of 40°C,adsorption time of 100 min,speed of 100 rpm.Under this adsorption condition,the purine adsorption rate was finally measured by the verification test to be 53.06%.（4）MOP1 was used to conduct comparative experiments on purine removal of chicken,chicken soup,beer and soybean milk,and it was found that chicken soup had the best removal effect.After comprehensive consideration,chicken soup was selected as the sample in this chapter to explore its quality changes.When purine was removed from chicken soup with modified adsorbent,the contents of free amino acids except glycine and cysteine were significantly decreased,which had a certain effect on the overall taste of chicken soup,but had no significant effect on the contents of crude fat,nucleotide and water-soluble protein in chicken soup.In terms of color,brightness value of chicken soup decreased,yellowness value increased,polysaccharide content increased.A total of 98 volatile flavor compounds were identified in chicken soup before and after purine removal by MOP1,and the main volatile compounds were aldehydes,hydrocarbons,acids and alcohols.After purine was removed from chicken soup by MOP1,the relative contents of some aroma substances decreased slightly,but the relative contents of flavor substances did not significantly decrease,and the overall flavor was determined by the concentration and sensory threshold of volatile substances in the whole flavor system.Therefore,removing purine from chicken soup with MOP1adsorbent did not have much effect on the physical and chemical quality of samples and their characteristic flavor,and the overall quality was improved to some extent.