Extraction And Lipid-lowering Activity Evaluation Of Celery Seeds Protein

In this paper,celery seeds were used as raw material,and celery seeds protein(CSP)was extracted by alkali extraction.The optimum technology parameter was obtained by single factor and orthogonal experiment.The molecular weight of celery seeds protein was determined.Then the protein was divided into different molecular weight fragments to study their difference in bile salts binding capacity.The celery seeds polypeptide(CSPP)was processed from celery seeds by liquid fermentation.The research on the bile salts binding capacity,surface properties and internal structure of CSP and CSPP showed that the molecular weight of CSP was decreased,the apparent morphology and internal structure were changed after fermentation,resulting in the enhancement of lipid-lowering activity and achieved the purpose of this experiment.The process parameters when the extraction rate of CSP reached the maximum were pH 11,the solid-liquid ratio 1:40,the extraction temperature 60? and the extraction time was 60 min.The factors that affect the extraction rate were PH>solid-liquid ratio>extraction temperature>extraction time.The functional properties of CSP were measured and the molecular weight of CSP was analyzed by SDS-PAGE.The CSP was separated into 5 components with different molecular weights by ultrafiltration,that were CSP1(MW>25 kDa),CSP2(20 kDa<MW<25 kDa),CSP3(10 kDa<MW<20 kDa),CSP4(6 kDa<MW<10 kDa)and CSP5(MW<6 kDa).Overall,the potential lipid-lowering capacity increased with the decrease of molecular weights.The lowest molecular weight CSP5 showed the strongest bile salts binding capacity,with an average value of 0.705 ?mol/mg.For more effectively reduce molecular weight of CSP,Bacillus subtilis HYT-151-1 was used to produce CSPP from celery seeds.The best fermentation parameters were determined as follows:fermentation temperature 37?,fermentation time 2 d,inoculation amount 12%.When the concentration was considered as the primary index,three factors including fermentation time,fermentation temperature,inoculation amount had important influence.It was found that the bile salts binding capacity of CSPP were stronger than that of the CSP.At the same time,the molecular weight of CSP was reduced significantly,namely the CSP was converted to smaller molecular polypeptide that was easier to be digested and absorbed by body.This was consistent with previous experiment results that the lower the molecular weight,the better the bile salts binding capacity.This was in agreement with the experimental results of the substance with lower molecular weight showed the better bile salts binding capacity.The microscopic morphology of the CSP and the CSPP were obviously different.The size of CSP particles were not uniform and the surface structure were compact.While the CSPP with the feature of small volume,loose surface and larger specific surface area exposed more active sites.The FTIR was applied to study their secondary structure and the results showed the conformation of the CSPP was changed,and the disorder was enhanced.Meanwhile,the amino acid analysis showed that the amino acids species and quality of the CSPP increased significantly.