Research On Protein Stability In Dry White Wine

Protein is the main substance that determines the stability of dry white wine.It is of great theoretical significance to study the type,quantity and structure of proteins for the stability of proteins in dry white wine.Dry white wine from Helan East Piedmot were used in this experiment.The types of proteins in wine were studied by polyacrylamide gel electrophoresis,and the stability of each protein was studied by heat stability test.The changes of secondary structure of precipitated protein in dry white wine were studied by Raman spectrometry.Plant protease were used to clarify white wine the protein stability were observed.The specific findings are as follows:1.The main proteins in wine are thaumatin-like protein(22k Da),chitinase(33 kDa)and glycoprotein(65 kDa).The quantity of Thaumatin-like proteins were more than chitinases more than glycoprotein.Thaumatin-like protein instabilized glycoprotein has well stability.2.The main secondary structure of proteins in wine is disulfide bond,?-helix and ?-fold.The number of disulfide bonds of precipitated protein decreased,the number of a-helix and ?-folding decreased significantly,and the expansion vibration of phenylalanine ring increased.Protein macromolecules to undergo understanding helices,exposing more peptide chain residues leading structure unstable.3.The plant protease can effectively clarify the dry white wine,reduce the quantity of total protein.Papain clarifies that the optimal condition for wine is to add 100 mg/L at 22? for 48 hours and stir 3 times.Pineapple protease clarifies that the optimal condition for wine is to add 3 mg/L at 18? and stir it 3 times in 24 hours.In summary,the unstable protein in dry white wine is mainly thaumatin-like protein,and the stable secondary structure of dry white wine protein is disulfide bond,?-helix,?-fold.Heat stability tests make the number of disulfide bonds,a-helix,and P-folding reduce,and plant proteases can be applied to the clarification of dry white wine to improve the protein stability of dry white wine.