Investigation And Pilot Processing For Preparating Zinc Chelate With Peptides Of Rice Protein

The researches optimizied the conditions of rice residue enzymolysis and preparating rice peptide-zinc using the enzymolysis chelated with ZnSO₄,and then producing powder of rice peptide-zinc by spray drying.The optimizied conditions of the enzymolysis were confirmed using comb-parenzyme are:enzyme by 1‰(w/v),enzymolysis temperature at 50℃,the ratio of base to water at 1:5(W/V),pH by 8,enzymolysis duration for 4 hour.Protein isoelectric points of residue of rice were determined by zoom determination of acid-base precipitation.Two protein isoelectric points were showed in liquid of residue of rice for two obviously wave of precipitation curve at different pH.It indicated that there are at least two different Isoelectric Point,one of isoelectric points being pH2.8 with highest precipitation rate by 31.95%and extraction degree by 19.02%,another being pH8.6 with highest precipitation rate by 17.79%and extraction degree by 10.67%.The molecular weight of 91.83%peptide had a distrubution lowered than 3000 Da.Optimal conditions for preparating zinc chelator with enzymic hydrolysis peptides from rice protein were investigated by the single factor and orthogonal experiments.The optimal results were showed as followed:quality ratio of hydrolysis peptides and Zn in 4.56:1,pH at 5,chelating temperature at 60℃,duration of chelating reaction for 90 min.The content of zinc in the product is 15.33%.The product was confirmed as zinc chelator with enzymic hydrolysis peptides by chemical characterization and infrared spectrum analysis.For optimal chelating conditions of ZnSO₄ with amino acids,the results showed as following:molar ratio of Met.and ZnSO₄ at 2:1,pH at 4.5,chelating temperature at 90℃for 60 min;The molar ratio of Gly.and ZnSO₄ at 2:1,pH at 5,chelating temperature at 70℃for 90 min;The molar ratio of Lys and ZnSO₄ at 2:1,pH at 8,chelating temperature at 70℃for 90 min.Different kinds of Zn complexs were added to three edible oils for storage experiments.The stabilization of edible oils and cake with rice peptided-zinc was significantly improved compared to the edible oils and cake with ZnSO₄.The rice peptided-zinc showed a significan inhibitory activity against Staphylococcus aureus.Bacillus subtilis and Colibacillary.The MIC of rice peptided-zinc to Staphylococcus aureus,Bacillus subtilis were 3.50g/L,The MIC of rice peptided-zinc to Colibacillary was 3.00 g/L.Spray drying were used to produce rice peptide-zinc.The optimal parameters of spray drying were deterimied at:the inlet and outlet temperatures of spray at 190℃and 95℃,respectively,Feed flow rate at 20 mL·min^-1 and air pressure of feed at 0.12 MPa/cm².Rice peptided-zinc at pilot scale was then produced under the optimal parameters.The powder of rice peptided-zinc made by pilot production had no significant difference compared to the product of lab experiment.There were no abnormal taste and smell,no agglomerate,and no dopant in both powders produced by pilot production and lab experiment.The total numbers of colony and coliform group in the two powders could be fit to national standard.