Study On Extraction And Residue Utilization Technology Of Bamboo Shoot Shell Brown Pigment

Abstract:Bamboo forest area and demand for bamboo shoot food are increasing day by day in China.A large number of bamboo shoot shells generated during the natural growth process of bamboo and the processing of bamboo shoot food are discarded as waste,which not only causes waste of resources,but also brings environmental pollution problems.In this study,the bamboo shoot shells produced during the processing of bamboo shoots food were used as raw materials.Through the means of step-by-step resource utilization,the extraction process and product stability of brown pigment from bamboo shoot shells,the preparation process and functional properties of dietary fibers from bamboo shoot shells,and the effect of bamboo shoot shell residues on Cr(?)and Ni(?)adsorption performance and adsorption mechanism were studied.The main conclutions were as follows:(1)Optimization of the extraction process of brown pigment from bamboo shoot shells and its stability analysis.The extraction process of brown pigment from bamboo shoot shells by ultrasonic-assisted water extraction was studied.The extraction time,ultrasonic power,ratio of material to liquid,extraction times and particle size were analyzed by taking the absorbance of brown pigment extract as the standard.The effect on the extraction preformance of brown pigment from bamboo shoot shell was optimized,and the stability of brown pigment under different environmental conditions was further analyzed.The research shown that the optimized extraction process conditions of bamboo shoot shell brown pigment:extraction time was 26.5 min,ultrasonic power was 205.5 W,solid-liquid ratio was 1:23.0(g/m L),extraction times was once,particle size was 60 mesh.Under the optimal process condition,the extraction preformance of brown pigment was the best(the absorbance value was 1.302).The results of brown pigment stability studies shown the brown pigment had strong stability to food additives(sucrose and Na Cl)and most of the metal ions(K⁺,Ca²⁺,Mg²⁺and Al³⁺),and also had good resistance to solution p H(acid or alkaline)and high ambient temperature.However,the redox agents(H₂O₂,Na₂SO₃)and light(strong sunlight,ultraviolet light)had certain effects on the stability of the brown pigment.In addition,the bamboo shoot shell brown pigment extracted with water is non-toxic and non-polluting,and can be used in the food field.(2)Preparation process optimization of dietary fiber from bamboo shoot shells and its functional properties analysis.Bamboo shoot shell residue after extraction of brown pigment were used as raw material,the alkaline preparation technology of dietary fiber from bamboo shoot shells was studied.Base on single factor experiment,the influence of Na OH concentration,preparation time,temperature and material-liquid ratio on the yield of dietary fiber was analyzed by taking the yield of dietary fiber as the standard.The process optimization was carried out,and the functional and structural characteristics of dietary fiber were further analyzed.The research shown that the optimized preparation process conditions of bamboo shoot shell dietary fiber by alkaline method:Na OH concentration was1.97%,preparation time was 113 min,preparation temperature was 49?,solid-liquid ratio was 1:40(g/m L).Under the optimal process condition,the yield of dietary fiber was 87.05%.By studying the functional properties of dietary fibers(SDF and IDF),it was shown that the swelling,oil holding,water holding and cation exchange capacity of SDF were better than IDF,and the prepared SDF and IDF have similar surface functional group structures;and the adsorption capacity of sodium cholate on SDF,the scavenging capacity of DPPH free radicals and ABTS⁺free radicals on SDF were stronger than IDF,and the adsorption capacity of IDF to NO₂^-was stronger than SDF,and shows a certain concentration dependence,indicated that the prepared dietary fiber from bamboo shoot shells by alkaline method has good adsorption properties and antioxidant activity,and can be used as a raw material for the production of functional foods.(3)Study on adsorption performance of bamboo shoot shell residue on Cr(?)and Ni(?)Bamboo shoot shell fibers(BFs)were obtained by processing the bamboo shoot shell waste after extraction of brown pigment as raw materials,and their physical and chemical properties such as appearance and surface functional groups were analyzed,and their effects on Cr(?)and Ni(?)were investigated,and the adsorption mechanism of Cr(?)and Ni(?)in water by BFs was further studied.This study had shown that the bamboo shoot shell residues(BFs)produced by the step-by-step extraction of brown pigment and dietary fiber have a pore structure and abundant surface active functional groups(C=O,-SO-,CO,etc.)on the surface,which could effectively remove Cr(?)and Ni(?)from wastwater.In the adsorption process of Cr(?)and Ni(?),the optimal dosage of A-BF and N-BF were 4.0 and 2.0 g/L,respectively,and the adsorption equilibrium time was 180 min;the initial p H of the solution was 2.0?12.0,A-BF shown a good removal effect on Cr(?),while the optimal initial p H of N-BF for Ni(?)adsorption process was 4.0?7.0.Under this condition,the removal rates of Cr(?)and Ni(?)were 98.8%and 96.8%,respectively.The adsorption process of Cr(?)and Ni(?)by BFs was more in line with the Sips isotherm adsorption model and pseudo-second-order kinetic model.The adsorption process was a multi-layer adsorption process dominated by chemical reaction control.The maximum theoretical adsorption capacities of Cr(?)and Ni(?)were 10.58 and 29.70 mg/g,respectively.The adsorption of A-BF on Cr(?)mainly includes electrostatic adsorption and redox process;the adsorption of N-BF on Ni(?)was mainly due to the surface functional groups of N-BF(-SO-,C=O,-OH,CO,etc.)and Ni(?)have electrostatic adsorption,chemical precipitation and complexation,indicating that BFs can be used as a new type of heavy metal adsorption materials in wastwater.This research adopted the step-by-step resource utilization method to systematically study a comprehensive utilization process of bamboo shoot shells,which greatly improved the utilization rate of the added value of bamboo shoot shells and effectively increased the economic benefits of bamboo shoot food processing enterprises.It solved the problems of bamboo shoot shell resource waste and environmental pollution,and had broad prospects for practical application.