Studies On The Dissolution And Separation Of Silkworm Pupa Protein Based On Biodegradable Ionic Liquids

The protein from silkworm chrysalis has been widely used in the field of biological medicine,due to its various hydroxyl group and amino active group and hydrolysis products of it with high biological activity.However,the traditional method of preparation of silkworm chrysalis in the industry is alkaline dissolution and acid precipitation,which is long production process,low product yield and heavy environmental pollution.Our group previously reported imidazole ionic liquids as solvents to dissolve and regenerate of silkworm pupa protein from silkworm pupa.However,the used imidazole ionic liquid was high toxic and non-biodegradable,which was unable to meet the requirements of green separation.In this paper,we used renewable biomass resources as the material,hydrogen bond destruction and reconstruction as the science foundation,and biodegradable choline ionic liquid as the medium to extract protein from silkworm pupa.The extraction process,law and mechanism were studied in the paper,which was important to the biomass green separation.The specific content and research conclusions are listed as follows:(1)The study on the separation of protein from silkworm pupa was carried out by the amino acid choline ionic liquids(AAILs).Eight AAILs were synthesized by acid-base neutralization method.The synthesized AAILs were characterized by ~1H NMR and FT-IR spectra to determine their purity.The results showed that the synthesized AAILs were satisfied with the requirements of the dissolution experiments.Under the observation of optical microscope,the AAILs were difficult to completely dissolve the silkworm pupa powder,even if the experiment time was up to 24 h;the dissolution law was studied with[Ch][Gly]as solvent.The results showed that the experiment time and liquid ratio had little influence on the dissolution rate of silkworm pupa,and the higher temperature was good for protein extraction.The results showed that the optimal experiment conditions were 8 h and 80°C,because the longer time could break protein structure and the higher temperature could cause protein denaturation and[Ch][Gly]degradation.(2)The study on the separation of silkworm chrysalis was carried out by fatty acid choline ionic liquids(FCILs).The aicd-alkali neutralization method was finally used to prepare four FCILs by comparing with the ion exchange method.The synthesized FCILs were characterized by ~1H NMR,MS and FT-IR spectra to determine their purity.The performance of the four kinds of FCILs on protein separation were studied.Finally,[Ch][OAc]was chosen as the optimal solvent to explore experiment factors.The effect of experiment time,temperature,ratio of[Ch][OAc]and silkworm pupa on the protein extraction were studied to determine the optimal conditions.Under the optimal conditions,morphology,structure and amino acid composition of the extracted protein was almost same with the raw material.However,the thermal stability and the crystallinity of extracted protein increased and decreased slightly,respectively.