Study On Separation And Recovery Of Lycopene From Waste Tomato By Zein Composite Nano-materials

Lycopene(LYC)is one of the beneficial substances contained in tomatoes for human body.LYC cannot exist alone in nature,and human body is impossible to synthesize it.Therefore,separation and extraction of lycopene naturally become the key technology of this paper.Zein is a natural material which can be obtained from corn.Zein has high brittleness and poor mechanical properties in the case of film formation,while the granular materials prepared separately have poor comprehensive performance for adsorption.Under the requirement of green chemistry,zein based adsorption materials are immobilized with green ionic liquid modifiers.Ionic liquids have excellent physical and chemical properties,making them very suitable for experiments in separation and purification.Therefore,extracting lycopene from discarded tomatoes and using green materials as adsorbent can not only protect the environment by recycling the resources,but also contribute to the development of medical treatment in human health.In this paper,a variety of ionic liquids were selected to modify zein,and the modified materials were applied to adsorb and separate lycopene from discarded tomatoes.According to the experimental conditions and the simplicity and accuracy of the operation,the amount of isolated lycopene was detected by HPLC.The main content of this paper includes the following aspects:(1)Zein was used as the main material and modified with several synthesized ionic liquids,which consisted of three alkyl imidazole ionic liquids with different carbon chain lengths.First stage,the preliminary materials were synthesized,and the changes in mechanical properties and hydrophobicity were observed by using different organic acids,salts,and polysaccharides as additives without ionic liquids.A basic material mainly composed of zein is optimized through scanning electron microscopy(SEM).(2)Base on the basic material obtained in the first stage,the materials in the second stage were modified with ionic liquids,resulting in Zein@BIM-IL,Zein@PIM-IL and Zein@HIM-IL.The optimal material was obtained through characterization methods such as Fourier transform infrared spectroscopy(FT-IR),thermogravimetric analysis(TGA),and SEM.And the influence of single factors on adsorption performances of these three materials were investigated.However,two of the materials(PIM-IL and HIM-IL)obtained similar adsorption performance.Hence,further optimization was assisted by response surface method(RSM)and the optimal ratio of these two ILs was 3:7.(3)Based on the previous experimental results,the third stage of the material is further modified using silicone modified ionic liquids to obtain Zein@Si-IL-37,Zein@HIM-Si-IL and Zein@PIM-Si-IL.These three materials were selected through the same characterization methods and the exploration of single factor influencing factors Zein@Si-IL-37.Finally,the content of lycopene in discarded tomatoes was detected by HPLC.Experiments have shown that the hydrophobic and mechanical properties of zein materials modified with silica gel modified imidazole ionic liquids are improved,with larger pores and better adsorption effect,resulting in more stable adsorption.The conclusion of the experiment is Zein@Si-IL-37 as the optimal adsorption material.When the temperature is about 20 ℃,and the solution concentration is between 0.001mg/mL and 0.005mg/mL,after 2h adsorption the material can adsorb the highest amount of lycopene.(4)Base on the adsorption mechanism,a new type of environmentally friendly porous adsorption material,zein and chitosan,was formed and synthesized in this stage.Chitosan can be obtained from natural chitin,which has a high content and is easy to extract.The complex adsorption material was prepared and a small amount of ionic liquid,glutaraldehyde,and surfactants are used to improve the adsorption performance.Through FT-IR,TGA,SEM and other characterization methods were used to obtain the optimized materials,and the performance of lycopene adsorbed was evaluated in combination with HPLC.Finally,solvent elution was used to separate lycopene from the materials,so as to realize the secondary utilization of materials and effectively apply them to actual samples.The experimental conclusion is that the composite material has the best adsorption of lycopene under the conditions of neutral solution environment,adsorption concentration of 0-0.03mg/mL,and adsorption time of 30-40 min.