Study On Extraction Of Protein From Yellow Wine Lees And In Vitro Digestion Of The Protein In The Residue

Yellow wine lees, a residue after yellow wine production, is an abundant and highly nutritiveresource that deserves extensive exploitation. In this paper, based on the high concentration ofprotein of the wine lees, the extraction and functionality properties of the wine lees proteins,and in vitro digestion of the unextractable protein existed in the residues were investigated. Theaim of this paper is to realize the full utilization of proteins of the wine lees.First, the extraction process with NaOH was optimized with responsesurface methodology toobtain a model equation, Y=0.46+0.21x1+0.08x2+0.20x3+ 0.051x4+0.04x1*x1+0.03x2*x1-0.04x2*x2+0.12x3*x1+0.02x3*x2+0.04x4*x1+0.03x4*x3. The maximum yield of extraction was obtainedunder the following conditions, ratio of raw material to water, 1:12, concentration of NaOH, 0.1mol/L, temperature, 60℃, time 4.5 h. Under these conditions, the protein yield was 81.01%with 70.14% purification .In addition, the protein of wine lees was extracted with Viscozymecombined with papain. The model equation, Y= 0.66+0.05 x1+ 0.02x2 +0.03 x3 -0.04 x1*x1-0.07 x2*x2 -0.05 x3*x3 -0.03x5*x5, was obtained. The maximum yield of extraction wasobtained under the following conditions, ratio of enzyme to substrate, 3473U/100g, ratio of rawmaterial to water, 13.9:1, time 4.8 h, temperature, 59.5℃. Under these conditions, the proteinyield was 69.16% with 72.41% purification.Secondly, the properties of the extracted proteins were investigated. The protein extractedwith NaOH was water insoluble, however, the protein extracted with enzyme preparations waswater soluble. The last was further analyzed with SDS-PAGE. There were two clear band near16 and 25 kDa respectively, and the molecular weights of other proteins were below 30 kDa.The result of HPSEC indicated that the proteins extracted by enzyme preparation existedmainly as polypeptides. The proteins were suitable to be additive agents for the protein drink.Finally, In vitro diegestion of the unextractable proteins of the residual lees was estimated bysimulating the digestion condition of broiler with age (21days), including craw,stomach,smallintestine. The results indicated that the deproteined wine lees had similar digestion to the initialwine lees. The deproteined wine lees was still to be utilzed as protein feeds with social andeconomical significances.