Structure Identification And Preparation Of Peptide From Flaxseed Protein With Hypocholesterolemic

In Inner Mongolia, flaxseed is a kind of advantageous resources. Its annual production is about 31,000 tons. But so far, it is normally used to extract the oil. Flaxseed meals is abandoned or used as feed while it is rich of protein. This action causes a waste of resources. In this paper, flaxseed protein isolate was processed which using flaxseed meal as raw material. Protein hydrolysate of flaxseed was prepared by enzymatic hydrolysis and discussed the hypocholesterolemic activity. Furthermore, the structures which belongs to separation and purification of protein hydrolysate of flaxseed was identified. The results of the research as follows.First of all, the process of the flaxseed isolated protein extraction was researched. By single factor experiments and L9 (34) orthogonal test, the most optimal extraction conditions were as follows. The pH value was 9.5, the temperature was 50℃, the solid-liquid ratio was 1:35, the extraction time was 120min. Under this condition, the flaxseed meal protein extraction rate was 68.14% and the protein purity was 91.22%.Secondly, the flaxseed protein enzymatic hydrolysate with hypocholesterolemic activity were isolated through flaxseed protein. The results shows that the preparation of flaxseed protein enzymatic hydrolysate, the hydrolysate had the highest activity of hypocholesterolemic (52.87%) by protease M under the condition of pH3.0, substrate concentration 1.7%, temperature 50℃, amount of enzyme 61.8AU/g. Compared with flaxseed protein isolates, the hypocholesterolemic activity of flaxseed protein enzymatic hydrolysate increase 32.3% significantly.Finally, flaxseed protein enzymatic hydrolysate with the highest hypocholesterolemic activity of 52.87% was separated and purified. The purpose of this project is to clarify the primary structure and amino acid sequence of hypocholesterolemic activity peptide. Firstly, the ultrafiltration was used to separation of the flaxseed protein enzymatic hydrolysate, the results showed that the relative molecular mass of 10-30 kDa component displayed strongest hypocholesterolemic activity (70.96%). Secondly, the macroporous resin DA201-C was used to separation of the relative molecular mass of 10-30kDa component. The discovery shows that 75% ethanol elution fraction had the highest hypocholesterolemic activity (81.8%). Finally, the 75% ethanol elution fraction was purified into seventeen components of the peak by RP-HPLC. The retention times were the component of 17.053min, 17.722min,18.847min and 22.186min. Utilizing MALDI-TOF-MS/MS identify structural characterization of hypocholesterolemic flaxseed peptides. There are four kinds of hypocholesterolemic flaxseed peptides. The amino sequences were illustrated as follow. RGGPGAPAPPR, QPPAMKNAPR, KGGLIAFAFVR and CLYLDVSATTR.