Drying Heating Selenium Acidification And Functional Characteristics Of Bovine Serum Albumin

Bovine serum albumin (BSA) was selenized by dry-heating in the presence of selenite, and the functional properties and in vitro antioxidative activity of the selenized BSA were investigated.Firstly, BSA was selenizated by dry-heating in the presence of selenite. The effects of pH, heating temperature and heating time on selenization of BSA were studied. The results showed that the more aggregation and lower solubility were caused at higher temperature, lower pH and longer heating time. Thus the most appropiate condition of selenization was:pH3.0,60℃for1days (d), and the organic selenium content of Se-BSA was0.35%. To increase the content of hydroxyl, BSA was conjugated with maltopentaose through the Mailard reaction and subsequent dry-heated in the presence of selenite. The organic selenium content of Se-MP-BSA was0.79%by dry-heating at pH3.0and60℃for1day.Secondly,the physicochemical properties and functional properties of Se-BSA were investigated.The circular dichroism spectra showed that the change of secondary structure in the BSA molecule by selenization was mild. However, tryptophan fluorescence intensity of BSA decreased by selenization. The differential scanning calorimetry thermograms of BSA showed a disappearing of the1st peak and a lowering of the2nd peak denaturation temperature by selenization. These results indicated molten (partially unfolded) conformations of BSA formed by both selenization methods. The functional properties of BSA such as heat stability and solubilizing ability were improved by selenization alone and further by selenization after glacation,surface hydrophobicity and sulfhydryl content also shows that the tertiary structure of the protein has also changed, MALDI-TOF-MS also shows that selenium after acidification on glycosylated bovine serum protein modification very successful.Thirdly, the antioxidant activities of BSA, including ABTS+free radical scavenging capacity, hydroxyl radical scavenging capacity, reducing power, the hydroxyl radical induced DNA damage and the Fe2+chelating capacity, were remarkably enhanced by selenization.In summary, this finding is the first to describe that BSA can be selenized by dry-heating in the presence of selenite and that the antioxidant activities of BSA are markedly enhanced by selenization. This points to a potentially new method for generating antioxidant food protein and a new method for preparing organic Se.